Climate change.

Climate change is a long-term shift in global or regional climate patterns. Often climate change refers specifically to the rise in global temperatures from the mid-20th century to present.

Earth Science, Climatology

Fracking tower

Fracking is a controversial form of drilling that uses high-pressure liquid to create cracks in underground shale to extract natural gas and petroleum. Carbon emissions from fossils fuels like these have been linked to global warming and climate change.

Photograph by Mark Thiessen / National Geographic

Fracking is a controversial form of drilling that uses high-pressure liquid to create cracks in underground shale to extract natural gas and petroleum. Carbon emissions from fossils fuels like these have been linked to global warming and climate change.

Climate is sometimes mistaken for weather. But climate is different from weather because it is measured over a long period of time, whereas weather can change from day to day, or from year to year. The climate of an area includes seasonal temperature and rainfall averages, and wind patterns. Different places have different climates. A desert, for example, is referred to as an arid climate because little water falls, as rain or snow, during the year. Other types of climate include tropical climates, which are hot and humid , and temperate climates, which have warm summers and cooler winters.

Climate change is the long-term alteration of temperature and typical weather patterns in a place. Climate change could refer to a particular location or the planet as a whole. Climate change may cause weather patterns to be less predictable. These unexpected weather patterns can make it difficult to maintain and grow crops in regions that rely on farming because expected temperature and rainfall levels can no longer be relied on. Climate change has also been connected with other damaging weather events such as more frequent and more intense hurricanes, floods, downpours, and winter storms.

In polar regions, the warming global temperatures associated with climate change have meant ice sheets and glaciers are melting at an accelerated rate from season to season. This contributes to sea levels rising in different regions of the planet. Together with expanding ocean waters due to rising temperatures, the resulting rise in sea level has begun to damage coastlines as a result of increased flooding and erosion.

The cause of current climate change is largely human activity, like burning fossil fuels , like natural gas, oil, and coal. Burning these materials releases what are called greenhouse gases into Earth’s atmosphere . There, these gases trap heat from the sun’s rays inside the atmosphere causing Earth’s average temperature to rise. This rise in the planet's temperature is called global warming. The warming of the planet impacts local and regional climates. Throughout Earth's history, climate has continually changed. When occuring naturally, this is a slow process that has taken place over hundreds and thousands of years. The human influenced climate change that is happening now is occuring at a much faster rate.

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What Is Climate Change?

Weather vs. climate.

define climate change

Weather describes the conditions outside right now in a specific place. For example, if you see that it’s raining outside right now, that’s a way to describe today’s weather. Rain, snow, wind, hurricanes, tornadoes — these are all weather events.

Climate , on the other hand, is more than just one or two rainy days. Climate describes the weather conditions that are expected in a region at a particular time of year.

Is it usually rainy or usually dry? Is it typically hot or typically cold? A region’s climate is determined by observing its weather over a period of many years—generally 30 years or more.

So, for example, one or two weeks of rainy weather wouldn’t change the fact that Phoenix typically has a dry, desert climate . Even though it’s rainy right now, we still expect Phoenix to be dry because that's what is usually the case.

Want to know more about the difference between weather and climate? Take a look at this video !

define climate change

Alaska's Muir glacier in August 1941 and August 2004. Significant changes occurred in the 63 years between these two photos. Credit: USGS

Climate change describes a change in the average conditions — such as temperature and rainfall — in a region over a long period of time. For example, 20,000 years ago, much of the United States was covered in glaciers. In the United States today, we have a warmer climate and fewer glaciers.

Global climate change refers to the average long-term changes over the entire Earth. These include warming temperatures and changes in precipitation, as well as the effects of Earth’s warming, such as:

  • Rising sea levels
  • Shrinking mountain glaciers
  • Ice melting at a faster rate than usual in Greenland, Antarctica and the Arctic
  • Changes in flower and plant blooming times.

Earth’s climate has constantly been changing — even long before humans came into the picture. However, scientists have observed unusual changes recently. For example, Earth’s average temperature has been increasing much more quickly than they would expect over the past 150 years.

Want to know more about how we know climate change is happening? Check it all out here !

How Much Is Earth’s Climate Changing Right Now?

define climate change

Graph of change in annual global temperatures, compared to the average of global annual temperatures from 1880-1899. Credit: NASA's Goddard Space Flight Center

Some parts of Earth are warming faster than others. But on average, global air temperatures near Earth's surface have gone up about 2 degrees Fahrenheit in the past 100 years. In fact, the past five years have been the warmest five years in centuries.

Many people, including scientists, are concerned about this warming. As Earth’s climate continues to warm, the intensity and amount of rainfall during storms such as hurricanes is expected to increase. Droughts and heat waves are also expected to become more intense as the climate warms.

When the whole Earth’s temperature changes by one or two degrees, that change can have big impacts on the health of Earth's plants and animals, too.

What Causes Climate Change?

A simplified animation of the greenhouse effect. Credit: NASA/JPL-Caltech

There are lots of factors that contribute to Earth’s climate. However, scientists agree that Earth has been getting warmer in the past 50 to 100 years due to human activities.

Certain gases in Earth’s atmosphere block heat from escaping. This is called the greenhouse effect . These gases keep Earth warm like the glass in a greenhouse keeps plants warm.

Human activities — such as burning fuel to power factories, cars and buses — are changing the natural greenhouse. These changes cause the atmosphere to trap more heat than it used to, leading to a warmer Earth.

Does What We Do Matter?

This video shows how Arctic sea ice has been changing since 1984. Credit: NASA

Yes. When human activities create greenhouse gases, Earth warms. This matters because oceans, land, air, plants, animals and energy from the Sun all have an effect on one another. The combined effects of all these things give us our global climate . In other words, Earth’s climate functions like one big, connected system.

Thinking about things as systems means looking for how every part relates to others. NASA’s Earth observing satellites collect information about how our planet’s atmosphere , water and land are changing.

By looking at this information, scientists can observe how Earth’s systems work together. This will help us understand how small changes in one place can contribute to bigger changes in Earth’s global climate.

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climate change

Definition of climate change

Examples of climate change in a sentence.

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'climate change.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

1854, in the meaning defined above

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“Climate change.” Merriam-Webster.com Dictionary , Merriam-Webster, https://www.merriam-webster.com/dictionary/climate%20change. Accessed 19 Nov. 2023.

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What is Climate Change ?

Understanding the big picture.

The Earth’s climate is changing and the global climate is projected to continue to change over this century and beyond. The magnitude of climate change beyond the next few decades will depend primarily on the amount of greenhouse (heat-trapping) gases emitted globally and on the remaining uncertainty in the sensitivity of the Earth’s climate to those emissions. With significant reductions in the emissions of greenhouse gases (GHGs), global annual averaged temperature rise could be limited to 2°C or less. However, without major reductions in these emissions, the increase in annual average global temperatures, relative to preindustrial times, could reach 5°C or more by the end of this century.

The global climate continues to change rapidly compared to the pace of the natural variations in climate that have occurred throughout Earth’s history. Trends in globally averaged temperature, sea level rise, upper-ocean heat content, land-based ice melt, arctic sea ice, depth of seasonal permafrost thaw, and other climate variables provide consistent evidence of a warming planet. These observed trends are robust and confirmed by multiple, independent research groups around the world. Figure 1 shows global average temperature anomalies; since the 1880s global average temperature has warmed approximately 1°C.

Figure 1. Global Average Temperature Anomalies, departure from 1881-1910. 

The plot shows how much global annual average temperatures for the years 1880-2022 have been above or below the 1881-1910 average. Temperatures for years warmer than the early industrial baseline are shown in red; temperatures for years cooler than the baseline are shown in purple. Graphic: Climate Central; Data: NASA GISS and NOAA NCEI. global temperature anomalies averaged and adjusted to early industrial baseline (1881-1910). Data as of 1/12/2023

Observations of the climate system are based on direct physical and biogeochemical measurements, and remote sensing from ground stations and satellites. Information derived from paleoclimate archives provides a long-term context of past climates. Different types of environmental evidence are used to understand what the Earth’s past climate was like and why. Records of historical climate conditions are preserved in tree rings, locked in the skeletons of tropical coral reefs, sealed in glaciers and ice caps, and buried in laminated sediments from lakes and the ocean. Scientists can use those environmental recorders to estimate past conditions, extending our understanding of climate back hundreds to millions of years. Global-scale observations from the instrumental era began in the mid-19th century, and paleoclimate reconstructions extend the record of some quantities back hundreds to millions of years. Together, this provides a comprehensive view of the variability and long-term changes in the atmosphere, the ocean, the cryosphere and at the land surface.


Reconstructions from paleoclimate archives allow current changes in atmospheric composition, sea level and climate systems (including extreme events such as droughts and floods), as well as projections of future climates, to be placed in a broader perspective of past climate variability. Past climate information also documents the behavior of slow components of the climate system including the carbon cycle, ice sheets and the deep ocean for which instrumental records are short compared to their characteristic time scales of responses to perturbations, thus informing on mechanisms of abrupt and irreversible changes. Climate records over past centuries and millennia indicate that average temperatures in recent decades over much of the world have been much higher, and have risen faster during this time period, than at any time for which the historical global distribution of surface temperatures can be reconstructed.

Paleoclimate can help us understand climate change on a geological timescale rather than a few human generations.  Figure 2  presents paleoclimate reconstruction for the Northern Hemisphere(NH), which reveals average annual temperatures, for the period 1983–2012 was very likely the warmest 30-year period of the last 800 years and likely the warmest 30-year period of the last 1400 years.   a) shows the radiative forcing due to volcanic, solar and well-mixed greenhouse gases (WMGHGs). Different colors illustrate the two existing data sets for volcanic forcing and four estimates of solar forcing and the grey line represents WMGHGs for the period 850-2000. b) represents the simulated (red) and reconstructed (shading) Northern Hemisphere temperature anomalies. The thick red line depicts the multi-model mean while the thin red lines show the multi-model 90% range. The overlap of reconstructed temperatures is shown by grey shading.

define climate change

Figure 2. a) Radiative forcing (W/m 2 ) due to volcanic, solar and well-mixed greenhouse gases for the period 850-2000. b)  Reconstructed (grey) and simulated (red) Northern Hemisphere Temperature Anomalies for the period 850-2000.

Model projections ( Figure 3 ) indicate that twenty-first century global average warming will substantially exceed the Last Glacial Maximum period and even the warmest Holocene conditions; producing a climate state not previously experienced .

define climate change

Figure 3.   Model-simulated global temperature anomalies for the Last Glacial Maximum (21,000 years ago), the mid-Holocene (6,000 years ago), and projection for 2071–2095, under RCP8.5

What this means

Earth’s climate is now changing faster than at any point in the known history of the climate, primarily as a result of human activities. There is scientific consensus that unmitigated carbon emissions will lead to global warming of at least several degrees Celsius by 2100, resulting in high-impacts of local, regional and global risks to human society and natural ecosystems. Global climate change has already resulted in a wide range of impacts across every region of the earth as well as many economic sectors.

Impacts related to climate change are evident across regions and in many sectors important to society, such as human health, agriculture and food security, water supply, transportation, energy, and biodiversity and ecosystems; impacts are expected to become increasingly disruptive in the coming decades. There is very high confidence that the frequency and intensity of extreme heat and heavy precipitation events are increasing in most continental regions of the world. These trends are consistent with expected physical responses to a warming climate. The frequency and intensity of extreme high temperature events are virtually certain to increase in the future as global temperature increases. There is high confidence that extreme precipitation events will very likely continue to increase in frequency and intensity throughout most of the world. Observed and projected trends for other types of extreme events, such as floods, droughts, and severe storms, have more variable regional characteristics.

What is Climate Change

Observed changes over the 20th century include increases in global air and ocean temperature, rising global sea levels, long-term sustained widespread reduction of snow and ice cover, and changes in atmospheric and ocean circulation as well as regional weather patterns, which influence seasonal rainfall conditions. These changes are caused by extra heat in the climate system due to the addition of greenhouse gases to the atmosphere. These additional greenhouse gases are primarily input by human activities such as the burning of fossil fuels (coal, oil, and natural gas), deforestation, agriculture, and land-use changes. These activities increase the amount of ‘heat-trapping’ greenhouse gases in the atmosphere. The pattern of observed changes in the climate system is consistent with an increased greenhouse effect. Other climatic influences such as volcanoes, the sun and natural variability cannot alone explain the timing and extent of the observed changes.

Climate , refers to the long-term regional or global average of temperature, humidity and rainfall patterns over seasons, years or decades.

While the weather can change in just a few hours, climate changes over longer timeframes. Climate change is the significant variation of average weather conditions becoming, for example, warmer, wetter, or drier—over several decades or longer. It i s the longer-term trend that differentiates climate change from natural weather variability.

Human activity leads to change in the atmospheric composition either directly (via emissions of gases or particles) or indirectly (via atmospheric chemistry). Anthropogenic emissions have driven the changes in WMGHG concentrations during the Industrial Era. Radiative forcing (RF) is a measure of the net change in the energy balance of the Earth system in response to some external perturbation; positive RF leads to a warming and negative RF to a cooling. The RF concept is valuable for comparing the influence on global mean surface temperature of most individual agents affecting the Earth’s radiation balance. Figure 4  shows the Radiative Forcing and Effective Radiative Forcing (ERF), by concentration change, between 1750 and 2011, with associated uncertainty range.

define climate change

Figure 4. Radiative Forcing (RF) and Effective Radiative Forcing (ERF) of climate change during the Industrial Era, 1750-2011. Solid bars are ERF, hatched bars are RF, green diamonds and associated uncertainties are for RF.

Figure 5.  Total annual anthropogenic greenhouse gas (GHG) emissions (gigatonne of CO 2 -equivalent per year, GtCO 2 -eq/yr) for the period 1970 to 2010, by gases. 

define climate change

Figure 5.  The graph shows human-caused emissions over time for individual greenhouse gases. Carbon dioxide (CO 2 ) from fossil fuel use and industry is the single largest contributor to total emissions at 64%, while CO 2  from land use change and forestry accounts for 11% and methane (CH 4 ) contributes 18%. Source,  IPCC Working Group III, 2022.

The Coupled Model Intercomparison Projects (CMIPs)

Understanding our current and future climate are questions that are too large and too complex to be tackled by a single country, agency or scientific discipline. Through international scientific cooperation and partnerships, the World Climate Research Program  (WCRP) supports the coordination of partners and modeling groups participating in the Coupled Model Inter-comparison Projects, or CMIPs. the CMIPs advance our understanding of the multi-scale dynamic interactions between natural and social systems that affect climate. Over time, as participation in CMIP increased and the number and complexity of climate models expanded, the need for increasingly detailed and organized experiments led to CMIP becoming an integrated framework within which a number of individual Model Intercomparison Projects (MIPs) are organized. MIPs are sets of experiments and simulations designed to test and compare specific aspects of climate models. Each individual MIP lays out an experimental design aimed at improving understanding of:

  • important physical processes in the climate system; or
  • the response of the climate system to external drivers (such as increasing greenhouse gases).

The climate science community relies on models to understand the Earth’s carbon cycle feedbacks in response to anthropogenic emissions, which lead to changes in atmospheric concentrations of greenhouse gases and aerosol, and thus ultimately result in radiative forcings that drive the climate system changes. The CMIPs provide a coordinating framework for these studies by defining a suite of model experiments for coupled atmosphere-ocean general circulation and Earth system models. Next to more process-oriented studies, one suite of experiments under CMIP is always focused on the climate response to different plausible future societal development storylines and associated contrasting emission pathways (scenarios). The goal of these ‘scenarios’ is to outline how future emissions and land use changes could translate into responses in the climate system. While independent of the regularly produced IPCC-UNFCCC Assessment Reports, CMIP results nevertheless are coordinated and directly inform the Assessments. CMIP phase 5 (CMIP5) provided the foundation for the 5 th Assessment Report released in 2013 and 2014, and the 6 th Assessment Report released in 2021 and 2022, is drawing from CMIP6, the latest collection of simulations done by the climate science community around the world.

Coupled Model Intercomparison Project Phase 6 (CMIP6)

The  Sixth Phase of the Coupled Model Intercomparison Project (CMIP6)  comprises 23 individual MIPs. Future climate change simulations are coordinated within ‘ScenarioMIP’ for which approximately 30 climate models contributed results. Additionally, the Diagnostic, Evaluation and Characterization of Klima (DECK) experiments are central to CMIP6 as they involve the historical simulations (1850–near present) that allow evaluation of the model’s simulation of past climate. While MIPs are given priority by CMIP, and organizations can participate in as many or few as they are able, the DECK experiments are mandatory for any model to enter into the CMIP. Figure 6  illustrates the complex and interconnected nature of CMIP6.

define climate change

Figure 6.  CMIP6 experimental organization. The DECK experiments and surrounding inner ring demonstrate the foundational nature of the historical simulations within the CMIP6 framework. Shown in the outer ring are some of the CMIP6 MIPs which attempt to address the topics displayed in the middle ring.

Understanding Future Climate Scenarios

The scenario approach is used to characterize the range of plausible climate futures and to illustrate the consequences of different pathways (policy choices, technological changes, etc). They are chosen to span a wide range without any tie to likelihood; the scenarios serve as ‘what if’ cases. Over the past three decades, the approach to formulating the different ‘scenarios’ has evolved from a climate-centric to an increasingly societal development-centric concept, albeit with the same underlying goal of providing insight into a range of plausible climate outcomes. CMIP5 used Representative Concentration Pathways(RCPs) and CMIP6 introduces the Shared Socio-economic Pathways (SSPs) . To distinguish the magnitude of climate forcing, the numbering reflects a designated amount of radiative forcing (a measure of the extent to which GHGs in the atmosphere warm or cool the climate) measured in watts per square meter (W/m 2 ) reached by 2100 (i.e., 2.6, 4.5, 6.0 and 8.5 W/m 2 of change over pre-industrial, respectively). CMIP6 introduced forcing of 1.9 W/m 2  to offer insight into the climate response that might be reflective of the Paris-Accord target. 

For CMIP6, each SSP drives a corresponding future projection of greenhouse gas emissions and land-use change under the baseline SSP storyline. The SSPs were designed to function in combination with a new and improved version of  RCPs . As such, different climate policy futures can be superimposed on SSPs to represent the influence of different climate policy choices (i.e. switching to renewable energy from fossil fuels) and the ease or difficulty in reaching the end-of-century radiative forcing goal specified by an RCP. The different policy scenarios lead to different levels of radiative forcing, with higher values representing stronger climate warming effects. The particular forcing values were chosen to allow easy comparison of the new scenarios to the RCPs used in the CMIP5 and IPCC AR5. Not all possible combinations of SSPs and forcing scenarios are viable and therefore, some do not have simulations. For example, SSP5 which prioritizes fossil-fuel development, thereby establishing a world with high emissions, is incompatible with a low forcing scenario (i.e. 1.9 W/m 2 ), which would require stricter climate policy and strong mitigation, and therefore low greenhouse gas emissions.

The CMIP model results, as driven by scenarios, have become standard reference inputs for work concerning climate change science, impacts, vulnerability, adaptation, and mitigation. Scenarios should be used as tools to help understand the characteristics and magnitude of emerging climate signals to inform decisions. Focusing solely on end-of-century outcomes is an inadequate way to evaluate the usefulness of a given scenario. For purposes of informing societal decisions, shorter time horizons are highly relevant.

The SSPs represent  possible societal development and policy paths for meeting designated radiative forcing by the end of the century. CMIP6 includes scenarios with high and very high GHG emissions (SSP3-7.0 and SSP5-8.5) and CO 2 emissions that roughly double from current levels by 2100 and 2050, respectively, scenarios with intermediate GHG emissions (SSP2-4.5) and CO 2 emissions remaining around current levels until the middle of the century, and scenarios with very low and low GHG emissions and CO2 emissions declining to net zero around or after 2050, followed by varying levels of net negative CO 2 emissions (SSP1-1.9 and SSP1-2.6). Emissions vary between scenarios depending on socio-economic assumptions, levels of climate change mitigation and, for aerosols and non-methane ozone precursors, air pollution controls. Alternative assumptions may result in similar emissions and climate responses, but the socio-economic assumptions and the feasibility or likelihood of individual scenarios are not part of the assessment. Figure   7  presents projected emissions and additional warming causes for each of the SSPs.  Figure 8  shows global average temperature rise for the primary Scenarios presented in IPCC AR6.

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Figure 7. a) presents the annual anthropogenic (human-caused) emissions over the 2015–2100 period. Shown are emissions trajectories for carbon dioxide (CO 2 ) from all sectors (GtCO 2 /yr) (left graph) and for a subset of three key non-CO 2 drivers considered in the scenarios: methane (CH 4 , MtCH4/yr); nitrous oxide (N 2 O, MtN 2 O/yr); and sulphur dioxide (SO 2 , MtSO 2 /yr), contributing to anthropogenic aerosols in panel (b). b) demonstrates the change in global surface temperature (°C) in 2081–2100 relative to 1850–1900 given the warming contributions by groups of anthropogenic drivers and by scenario, with indication of the observed warming to date. Bars and whiskers represent median values and the very likely range, respectively. Within each scenario bar plot, the bars represent: total global warming (°C); warming contributions from changes in CO 2 ; non-CO 2 greenhouse gases and net cooling from other anthropogenic drivers (‘aerosols and land use’ bar).

define climate change

Figure 8. The amount of climate change by the end of the century depends on decisions we make today. If we reduce CO 2  amounts to stop increasing after 2050, global average temperature will increase from 1-1.5°C, and this is considered a best case scenario (blue line in graph). If we don’t reduce CO 2  and the amounts continue to increase, the worst case scenario warming will be 4.5-5°C (red line in graph). Source,  IPCC Working Group I, 2021.

Narrative descriptions for the Shared Socioeconomic Pathways:

SSP1 “Sustainability”  (Low challenges to mitigation and adaptation) The world shifts gradually, but pervasively, toward a more sustainable path, emphasizing more inclusive development that respects perceived environmental boundaries. Management of the global commons slowly improves, educational and health investments accelerate the demographic transition, and the emphasis on economic growth shifts toward a broader emphasis on human well-being. Driven by an increasing commitment to achieving development goals, inequality is reduced both across and within countries. Consumption is oriented toward low material growth and lower resource and energy intensity. The combination of directed development of environmentally friendly technologies, a favorable outlook for renewable energy, institutions that can facilitate international cooperation, and relatively low energy demand results in relatively low challenges to mitigation. At the same time, the improvements in human well-being, along with strong and flexible global, regional, and national institutions imply low challenges to adaptation.

SSP2 “Middle of the Road”  (Medium challenges to mitigation and adaptation) The world follows a path in which social, economic, and technological trends do not shift markedly from historical patterns. Development and income growth proceeds unevenly, with some countries making relatively good progress while others fall short of expectations. Global and national institutions work toward but make slow progress in achieving sustainable development goals. Environmental systems experience degradation, although there are some improvements and overall the intensity of resource and energy use declines. Global population growth is moderate and levels off in the second half of the century. Income inequality persists or improves only slowly and challenges to reducing vulnerability to societal and environmental changes remain. These moderate development trends leave the world, on average, facing moderate challenges to mitigation and adaptation, but with significant heterogeneities across and within countries

SSP3 “Regional Rivalry”  (High challenges to mitigation and adaptation) A resurgent nationalism, concerns about competitiveness and security, and regional conflicts push countries to increasingly focus on domestic or, at most, regional issues. Policies shift over time to become increasingly oriented toward national and regional security issues. Countries focus on achieving energy and food security goals within their own regions at the expense of broader-based development. Investments in education and technological development decline. Economic development is slow, consumption is material-intensive, and inequalities persist or worsen over time. Population growth is low in industrialized and high in developing countries. A low international priority for addressing environmental concerns leads to strong environmental degradation in some regions. Growing resource intensity and fossil fuel dependency along with difficulty in achieving international cooperation and slow technological change imply high challenges to mitigation. The limited progress on human development, slow income growth, and lack of effective institutions, especially those that can act across regions, implies high challenges to adaptation for many groups in all regions.

SSP5 “Fossil-fueled Development” (High challenges to mitigation, low challenges to adaptation) This world places increasing faith in competitive markets, innovation and participatory societies to produce rapid technological progress and development of human capital as the path to sustainable development. Global markets are increasingly integrated. There are also strong investments in health, education, and institutions to enhance human and social capital. At the same time, the push for economic and social development is coupled with the exploitation of abundant fossil fuel resources and the adoption of resource and energy intensive lifestyles around the world. All these factors lead to rapid growth of the global economy, while global population peaks and declines in the 21st century. Local environmental problems like air pollution are successfully managed. There is faith in the ability to effectively manage social and ecological systems, including by geo-engineering if necessary. While local environmental impacts are addressed effectively by technological solutions, there is relatively little effort to avoid potential global environmental impacts due to a perceived tradeoff with progress on economic development. The strong reliance on fossil fuels and the lack of global environmental concern result in potentially high challenges to mitigation. The attainment of human development goals, robust economic growth, and highly engineered infrastructure results in relatively low challenges to adaptation to any potential climate change for all but a few.

For a complete description of SSP Narratives, see O'Neill et al. 2017

The Representative Concentration Pathways (RCPs), presented in CMIP5, describe four different 21st century pathways. The RCPs include a stringent mitigation scenario (RCP2.6), two intermediate scenarios (RCP4.5 and RCP6.0) and one scenario with high GHG emissions (RCP8.5). Scenarios without additional efforts to constrain emissions (’baseline scenarios’) lead to pathways ranging between RCP6.0 and RCP8.5. Each RCP shows the planet trapping progressively higher amounts of energy from RCP2.6 (the lowest) to RCP8.5 (the highest). Figure 9  shows the GHG emission pathways for each RCP through to the end of the century.

define climate change

Figure 9. GHG Emission Pathways for each RCP from 2000-2100. Source, IPCC Working Group I, 2013

RCP scenarios are described below.

Stringent mitigation scenario (RCP2.6): A "peak-and-decline" scenario; its radiative forcing level first reaches a value of around 3.1 W/m 2 by mid-century and returns to 2.6 W/m 2 by 2100. In order to reach such radiative forcing levels, GHG emissions (and indirectly emissions of air pollutants) are reduced substantially over time. RCP2.6 is representative of a scenario that aims to keep global warming likely below 2°C above pre-industrial temperatures

Medium-low emissions scenario (RCP4.5): A stabilization scenario which assumes action is taken to curb climate change by all countries resulting in a global average temperature rise of no more than 2 ºC and 3 ºC above pre-industrial temperature levels by the year 2100.

Medium-high emission scenario (RCP6.0): A stabilization scenario in which total radiative forcing is stabilized shortly after 2100, without overshoot by the application of a range of technologies and strategies for reducing GHG emissions

High-end emissions scenario (RCP8.5): This scenario represents the extreme end of plausible climate change, delivering an estimated global average temperature increase of approximately 5-6ºC by 2100, relative to pre-industrial temperature levels. RCP8.5 is commonly recognized as ‘business as usual’.

Individual Models vs. Multi-Model Ensembles

Climate models are mathematical representations of processes important in the Earth’s climate system. When a climate model is run it produces a 'simulation' of future climate. Multiple simulations form an ensemble. A multi-model ensemble (MME) therefore is a large number of climate model simulations. CCKP prioritizes use of MMEs for its projections as multi-model ensembles are more robust and proven to be most successful in representing the range of expected changes. Differences between the spatial structure of the data and the structure of the reality it represents must also be understood and considered in order to adequately model the impact of spatial uncertainty on model applications. While, individual models are noisier, on occasion they may better reflect the range of variability compared to the multi-model ensemble that is generally too smooth. Individual models can also have systematic biases that present themselves as strong outliers. A comparison with the multi-model ensemble is helpful to identify these potential biases and outliers.

Variability, Trends, Uncertainty

Decadal, inter-annual, and inter-seasonal variability exists across the climate system. Internal variability can diminish the relevance of trends over periods as short as 10 to 15 years from long-term climate change. A critical effort of projecting climate change is to understand if ‘change’ is part of the natural variability or if projected change reveals trends that are statistically significant from natural variability. Due to this, natural variability trends based on short records are very sensitive to the beginning and end dates and do not, in general, reflect longer-term climate trends.

Uncertainty exists for any future projection. While advances continue to be made in the understanding of climate physics and the response of the climate system to increases in greenhouse gases, many uncertainties are likely to persist. The rate of future global warming depends on future emissions, feedback processes that dampen or reinforce disturbances to the climate system, and unpredictable natural influences on climate, like volcanic eruptions. Uncertain processes that will affect how fast the world warms for a given emissions pathway are dominated by cloud formation, but also include water vapor and ice feedbacks, ocean circulation changes, and natural cycles of greenhouse gases. Although information from past climate changes largely corroborates model calculations, this is also can have a degree of uncertainty due to potentially important factors about which we have incomplete information.

Clark, P., Shakun, J., Marcott, S. et al., 2016: Consequences of twenty-first-century policy for multi-millennial climate and sea-level change. Nature Clim Change 6, 360–369. DOI: https://doi.org/10.1038/nclimate2923

Eyring, V., Bony, S., Meehl, G. A., Senior, C. A., Stevens, B., Stouffer, R. J., & Taylor, K. E. (2016). Overview of the Coupled Model Intercomparison Project Phase 6 (CMIP6) experimental design and organization. Geoscientific Model Development, 9(5), 1937–1958.  https://doi.org/10.5194/gmd-9-1937-2016 .

IPCC, 2013: Climate Change 2013: Technical Summary. The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. URL: https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_TS_FINAL.pdf

IPCC, 2014: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp. URL: https://ar5-syr.ipcc.ch/ipcc/ipcc/resources/pdf/IPCC_SynthesisReport.pdf

IPCC, 2021: Summary for Policymakers. In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. In Press. URL: https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM_final.pdf 

International Institute for Applied Systems Analysis (IIASA), 2014: Representative Concentration Pathways Database. URL: https://iiasa.ac.at/web/home/research/researchPrograms/TransitionstoNewTechnologies/RCP.en.html

Kriegler, E., Edmonds, J., Hallegatte, S., et al., 2014: A new scenario framework for climate change research: the concept of shared climate policy assumptions, Climatic Change 122:401–414. DOI: doi:10.1007/s10584-013-0971-5

O'Neill, B., Tebaldi, C., Van Vuuren, D., et al., 2016: The Scenario Model Intercomparison Project (ScenarioMIP) for CMIP6, Geoscience Model Development 9, 3461–3482. DOI: doi:10.5194/gmd-9-3461-2016

O'Neill, B., Kriegler, E., Ebi, K. et al., 2017: The roads ahead: Narratives for shared socioeconomic pathways describing world futures in the 21st century. Global Environmental Change 42, 169-180. DOI: https://doi.org/10.1016/j.gloenvcha.2015.01.004

O'Neill, B., Carter, T., Ebi, K., et al., 2020: Achievements and needs for the climate change scenario framework. Nature Climate Change 10, 1074-1084. DOI: https://doi.org/10.1038/s41558-020-00952-0

Riahi, K. van Vuuren, D., Kriegler, E.,  et al. 2017: The Shared Socioeconomic Pathways and their energy, land use, and greenhouse gas emissions implications: An overview, Global Environmental Change 42, 153–168. DOI: doi:10.1016/j.gloenvcha.2016.05.009

Van Vuuren, D., Edmonds, J. Kainuma, M., et al., 2011: The representative concentration pathways: an overview, Climatic Change volume 109, Article number: 5. DOI:  doi:10.1007/s10584-011-0148-z

World Climate Research Program (WCRP), 2021: WCRP Coupled Model Intercomparison Project (CMIP). URL: https://www.wcrp-climate.org/wgcm-cmip

World Climate Research Program (WCRP), 2021: PMIP – Paleoclimate Modeling Intercomparison Project. URL: https://www.wcrp-climate.org/modelling-wgcm-mip-catalogue/cmip6-endorsed-mips-article/1064-modelling-cmip6-pmip


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Causes and Effects of Climate Change

Fossil fuels – coal, oil and gas – are by far the largest contributor to global climate change, accounting for over 75 per cent of global greenhouse gas emissions and nearly 90 per cent of all carbon dioxide emissions.

As greenhouse gas emissions blanket the Earth, they trap the sun’s heat. This leads to global warming and climate change. The world is now warming faster than at any point in recorded history. Warmer temperatures over time are changing weather patterns and disrupting the usual balance of nature. This poses many risks to human beings and all other forms of life on Earth.

Industry and Transport

Causes of Climate Change

Generating power

Generating electricity and heat by burning fossil fuels causes a large chunk of global emissions. Most electricity is still generated by burning coal, oil, or gas, which produces carbon dioxide and nitrous oxide – powerful greenhouse gases that blanket the Earth and trap the sun’s heat. Globally, a bit more than a quarter of electricity comes from wind, solar and other renewable sources which, as opposed to fossil fuels, emit little to no greenhouse gases or pollutants into the air.

Manufacturing goods

Manufacturing and industry produce emissions, mostly from burning fossil fuels to produce energy for making things like cement, iron, steel, electronics, plastics, clothes, and other goods. Mining and other industrial processes also release gases, as does the construction industry. Machines used in the manufacturing process often run on coal, oil, or gas; and some materials, like plastics, are made from chemicals sourced from fossil fuels. The manufacturing industry is one of the largest contributors to greenhouse gas emissions worldwide.

Cutting down forests

Cutting down forests to create farms or pastures, or for other reasons, causes emissions, since trees, when they are cut, release the carbon they have been storing. Each year approximately 12 million hectares of forest are destroyed. Since forests absorb carbon dioxide, destroying them also limits nature’s ability to keep emissions out of the atmosphere. Deforestation, together with agriculture and other land use changes, is responsible for roughly a quarter of global greenhouse gas emissions.

Using transportation

Most cars, trucks, ships, and planes run on fossil fuels. That makes transportation a major contributor of greenhouse gases, especially carbon-dioxide emissions. Road vehicles account for the largest part, due to the combustion of petroleum-based products, like gasoline, in internal combustion engines. But emissions from ships and planes continue to grow. Transport accounts for nearly one quarter of global energy-related carbon-dioxide emissions. And trends point to a significant increase in energy use for transport over the coming years.

Producing food

Producing food causes emissions of carbon dioxide, methane, and other greenhouse gases in various ways, including through deforestation and clearing of land for agriculture and grazing, digestion by cows and sheep, the production and use of fertilizers and manure for growing crops, and the use of energy to run farm equipment or fishing boats, usually with fossil fuels. All this makes food production a major contributor to climate change. And greenhouse gas emissions also come from packaging and distributing food.

Powering buildings

Globally, residential and commercial buildings consume over half of all electricity. As they continue to draw on coal, oil, and natural gas for heating and cooling, they emit significant quantities of greenhouse gas emissions. Growing energy demand for heating and cooling, with rising air-conditioner ownership, as well as increased electricity consumption for lighting, appliances, and connected devices, has contributed to a rise in energy-related carbon-dioxide emissions from buildings in recent years.

Consuming too much

Your home and use of power, how you move around, what you eat and how much you throw away all contribute to greenhouse gas emissions. So does the consumption of goods such as clothing, electronics, and plastics. A large chunk of global greenhouse gas emissions are linked to private households. Our lifestyles have a profound impact on our planet. The wealthiest bear the greatest responsibility: the richest 1 per cent of the global population combined account for more greenhouse gas emissions than the poorest 50 per cent.

Based on various UN sources

Industry and Transport

Effects of Climate Change

Hotter temperatures

As greenhouse gas concentrations rise, so does the global surface temperature. The last decade, 2011-2020, is the warmest on record. Since the 1980s, each decade has been warmer than the previous one. Nearly all land areas are seeing more hot days and heat waves. Higher temperatures increase heat-related illnesses and make working outdoors more difficult. Wildfires start more easily and spread more rapidly when conditions are hotter. Temperatures in the Arctic have warmed at least twice as fast as the global average.

More severe storms

Destructive storms have become more intense and more frequent in many regions. As temperatures rise, more moisture evaporates, which exacerbates extreme rainfall and flooding, causing more destructive storms. The frequency and extent of tropical storms is also affected by the warming ocean. Cyclones, hurricanes, and typhoons feed on warm waters at the ocean surface. Such storms often destroy homes and communities, causing deaths and huge economic losses.

Increased drought

Climate change is changing water availability, making it scarcer in more regions. Global warming exacerbates water shortages in already water-stressed regions and is leading to an increased risk of agricultural droughts affecting crops, and ecological droughts increasing the vulnerability of ecosystems. Droughts can also stir destructive sand and dust storms that can move billions of tons of sand across continents. Deserts are expanding, reducing land for growing food. Many people now face the threat of not having enough water on a regular basis.

A warming, rising ocean

The ocean soaks up most of the heat from global warming. The rate at which the ocean is warming strongly increased over the past two decades, across all depths of the ocean. As the ocean warms, its volume increases since water expands as it gets warmer. Melting ice sheets also cause sea levels to rise, threatening coastal and island communities. In addition, the ocean absorbs carbon dioxide, keeping it from the atmosphere. But more carbon dioxide makes the ocean more acidic, which endangers marine life and coral reefs.

Loss of species

Climate change poses risks to the survival of species on land and in the ocean. These risks increase as temperatures climb. Exacerbated by climate change, the world is losing species at a rate 1,000 times greater than at any other time in recorded human history. One million species are at risk of becoming extinct within the next few decades. Forest fires, extreme weather, and invasive pests and diseases are among many threats related to climate change. Some species will be able to relocate and survive, but others will not.

Not enough food

Changes in the climate and increases in extreme weather events are among the reasons behind a global rise in hunger and poor nutrition. Fisheries, crops, and livestock may be destroyed or become less productive. With the ocean becoming more acidic, marine resources that feed billions of people are at risk. Changes in snow and ice cover in many Arctic regions have disrupted food supplies from herding, hunting, and fishing. Heat stress can diminish water and grasslands for grazing, causing declining crop yields and affecting livestock.

More health risks

Climate change is the single biggest health threat facing humanity. Climate impacts are already harming health, through air pollution, disease, extreme weather events, forced displacement, pressures on mental health, and increased hunger and poor nutrition in places where people cannot grow or find sufficient food. Every year, environmental factors take the lives of around 13 million people. Changing weather patterns are expanding diseases, and extreme weather events increase deaths and make it difficult for health care systems to keep up.

Poverty and displacement

Climate change increases the factors that put and keep people in poverty. Floods may sweep away urban slums, destroying homes and livelihoods. Heat can make it difficult to work in outdoor jobs. Water scarcity may affect crops. Over the past decade (2010–2019), weather-related events displaced an estimated 23.1 million people on average each year, leaving many more vulnerable to poverty. Most refugees come from countries that are most vulnerable and least ready to adapt to the impacts of climate change.

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  • agroecology
  • air pollution
  • anti-conservation
  • carbon capture
  • dumping ground
  • eco-footprint
  • environmental justice
  • environmentalism
  • environmentally
  • feed-in tariff
  • reduce, reuse, recycle idiom
  • sequestration
  • skip diving
  • A few scientists say that people are not making climate change happen.  
  • It is true that the temperature of the Earth changed in the past, but most scientists believe that climate change today is happening because of the way people live.  
  • Scott Base is a research center for scientists studying things like Antarctica, wildlife, and climate change.  
  • Surprisingly, climate change can bring a few good things.  

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Climate Change Terms and Definitions

Climate change refers to significant changes in global temperature, precipitation, wind patterns and other measures of climate that occur over several decades or longer.

The seas are rising. The foods we eat and take for granted are threatened.  Ocean acidification  is increasing. Ecosystems are changing, and for some, that could spell the end of certain regions the way we have known them. And while some species are adapting, for others, it’s not that easy.

Evidence suggests many of these extreme  climate changes  are connected to rising levels of carbon dioxide and other greenhouse gases in the Earth’s atmosphere — more often than not, the result of human activities.

Search below for key terms and definitions related to climate change.

Aerosols  are small suspended particles in a gas. Scientists can detect them in the atmosphere. They range in size from one nanometer (one billionth of a meter) to 100 micrometers (one millionth of a meter).

Antarctic sea ice

Antarctic sea ice   is nearly a geographic opposite of its Arctic counterpart because Antarctica is a landmass covered in ice surrounded by an ocean, and the Arctic is an ocean of sea ice surrounded by land.


Anthropogenic  describes a process or result generated by human beings.


Aquaculture  uses a body of water for the cultivation of plants and animals. (Compare to agriculture, which uses land to cultivate plants and animals.) Ponds, lakes, rivers, and the ocean serve as places to breed, rear and harvest aquatic species.

Aquifer  is water-bearing rock from which water can be pumped.

Arctic sea ice

Arctic sea ice  is an integral part of the Arctic Ocean and an important indicator of climate change. During winter’s dark months, sea ice will typically cover the majority of the Arctic Ocean.

Biofuels  are renewable fuels derived from biological materials, such as algae and plants, that can be regenerated. This distinguishes them from fossil fuels, which are considered nonrenewable. Example of biofuels are ethanol, methanol and biodiesel.

Biogenic emissions

Biogenic emissions  are emissions generated by living things.

Biological productivity

Biological productivity  is a measure of the amount of plant and animal growth in a defined region and time.

Carbon  is a configuration of molecules and an elemental building block of all organisms on Earth.

Carbon cycle

Carbon cycle  describes the process by which living things absorb carbon from the atmosphere, sediments and soil, or food. To complete the cycle, carbon returns to the atmosphere in the form of carbon dioxide or methane by respiration, combustion or decay.

Carbon dioxide

Carbon dioxide  is the gas that accounts for about 84 percent of total U.S. greenhouse gas emissions. In the U.S. the largest source of carbon dioxide (98 percent) emissions is combustion of fossil fuels. Combustion can be from mobile (vehicles) or stationary sources (power plants). As energy use increases, so do carbon dioxide emissions.

Carbon sequestration

Carbon sequestration  is the process of removing carbon from the atmosphere and storing it in a fixed molecule in soil, oceans or plants. An organism or landscape that stores carbon is called a  carbon sink . An organism or landscape that emits carbon is called a  carbon source . For example, soils contain inorganic carbon (calcium carbonate) and organic carbon (humus) and can be either a source or a sink for atmospheric carbon dioxide, depending on how landscapes are managed. Because large amounts of carbon are stored in soils, small changes to soil can have major impacts on atmospheric carbon dioxide.

Climate change adaptation

Climate change adaptation  refers to the adjustments societies or ecosystems make to limit the negative effects of climate change or to take advantage of opportunities provided by a changing climate. Adaptation can range from farmers planting more  drought-resistant crops  to coastal communities evaluating how best to protect themselves from sea level.

Climate forcing

Climate forcing  refers to how climate affects the physical, chemical and biological attributes of a region.

Climate science

Climate science  studies how changing climates affect the natural order on a global level. Rising global temperatures bring with them the potential to raise sea levels to raise sea levels, change precipitation and local climate conditions.

Coastal Wetlands

Coastal wetlands include saltwater and freshwater wetlands located within coastal watersheds — specifically USGS 8-digit hydrologic unit watersheds which drain into the Atlantic Ocean, Pacific Ocean, or Gulf of Mexico.


Dimethylsulfide  is the most abundant biological sulfur compound emitted to the atmosphere, mostly from phytoplankton, and encourages cloud formation.

Ecosystem services

Ecosystem services  are the benefits or “services” of an ecosystem to human life, such as clean water and the decomposition of organic matter.


Electrolytes  are chemical substances containing free ions that conduct electricity.

Emissions  are substances released into the air and are measured by their concentrations, or parts per million, in the atmosphere.

Feedstock  is raw material, usually plant or agricultural waste, that can be processed into fuel or energy.

Glaciers  and ice caps form on land . Glaciers accumulate snow, which over time becomes compressed into ice. On average, glaciers worldwide have been losing mass since at least the 1970s.

Global temperature

Global temperature  is an average of air temperature recordings from weather stations on land and sea as well as some satellite measurements. Worldwide, 2006-2015 was the warmest decade on record since thermometer-based observations began nearly 150 years ago.

Global warming

In the early 1960s scientists recognized that carbon dioxide in the atmosphere was increasing. Later they discovered that methane, nitrous oxide and other gases were rising. Because these gases trap heat and warm the Earth, as a greenhouse traps heat from the sun, scientists concluded that increasing levels of “greenhouse gases” would increase  global warming .

Global Warming Potential (GWP)

Global Warming Potential  (GWP) is the ability of a greenhouse gas to absorb heat compared to carbon dioxide over a specified period of time, from 20 to 500 years. The timeframe is important because each gas has a different rate at which it is removed from the atmosphere. For each time period, carbon dioxide is always set at “1”, and other greenhouse gases are compared to carbon dioxide for the same timeframe. For example, the sulfur hexafluoride’s GWP at 20 years is 15,100, meaning it has 15,100 times more warming potential than carbon dioxide in that timeframe.

Greenhouse gases

The main  greenhouse gases  are water vapor (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). Water vapor is the most plentiful at about one percent. The next most plentiful is carbon dioxide at 0.04 percent. The effect of human activity on global water vapor concentrations is too small to be important. The effects of human activity on the other greenhouse gases, however, is large and very important. These gases are increasing faster than they are removed from the atmosphere.

A heat dome is when hot ocean air gets trapped over a large area, resulting in dangerously high temperatures. It occurs when high atmospheric pressure forms over a region, pushing air down, which heats as the air compresses. This forms a “lid” that seals to create a dome of trapped heat, setting the stage for heat waves.

Hydrologic cycle

Hydrologic cycle  is the process by which water moves around the earth. The cycle includes evaporation, precipitation, runoff, condensation, transpiration and infiltration.

Hydrologic model

Hydrologic model  is a computer analysis of large amounts of historical data. It helps predict how variables such as temperature, rain, and carbon dioxide levels might affect the hydrologic cycle.

Ice loss  refers to the retreat of sea ice and land ice mass from its historic extents. This retreat of sea ice and land ice is one of two major causes of the current sea level rise.

An  ice sheet  forms on land and extends over tens of thousands of miles. Greenland and Antarctica have vast ice sheets that together contain more than 99 percent of the freshwater ice on Earth. In Greenland, today’s record summer melts bring rapid and widespread ice sheet loss. In Antarctica, the melt is slower and more localized for now.

An  ice shelf  forms from the outflow of land ice and floats on the sea at the land’s edge. It creates a barrier that slows the flow of land ice into the ocean. In the last thirty years, both rapid disintegration of ice shelves and ice shelf collapses have been observed along Canada and the Antarctic Peninsula.

Methane  is a gas and represents about 8 percent of total U.S. greenhouse gas emissions. The largest sources are wood burning in stoves and fireplaces, livestock digestive systems, and decomposition in landfills.

Mesoscale  is a measure of distance useful for local winds, thunderstorms and tornadoes. It ranges from a few to a few hundred miles.

A  micron , also called a micrometer, is one millionth of a meter, or a thousandth of a millimeter. It is a common measure for particulate matter in the atmosphere. Particles measuring only 2.5 microns (approximately 1/30th the average width of a human hair) lodge deeply into the lungs.

Mitigation potential

Mitigation potential  is a measurement of the amount of carbon that can be stored in order to balance the release of carbon. It is important in discussions about power plants and vehicles.

Nano  refers to nanometer, one billionth of a meter or a hundred-thousandth of a millimeter.

Nitrous oxide

Nitrous oxide  is one of six gases addressed by the Kyoto Protocol international agreement and the main regulator of stratospheric ozone. Animal waste and nitrogen fertilization of soil are the largest contributors. Nitrogen emissions have nearly 300 times the global warming potential of carbon dioxide over 100 years.

Ocean acidification

Ocean acidification  is the change in ocean chemistry due to decreasing pH levels, or increasing acidity, in seawater.

Ground level ozone  is a gas produced through reactions between nitrous oxides (NOX) and volatile organic compounds (VOCs) when burning coal, gasoline and other fuels. VOCs are found in solvents, paints, hairsprays and more common items. Ozone consists of three oxygen atoms and is the main component of smog.

Stratospheric ozone  is a gas found in a layer from six to 25 miles above the Earth’s surface. It acts as a barrier to global warming. Specifically, the ozone layer keeps 95-99% of the sun’s ultraviolet radiation from striking the Earth.

Ozone forming potential

Ozone forming potential  is a measure of the reactivity of an individual chemical compound to the presence of other chemicals that form ozone together.

Particulate matter

Particulate matter  (PM-10) are aerosols including dust, soot and tiny bits of solid materials that are released and move around in the air. Sources are burning of diesel fuels, incineration of garbage, mixing and applying fertilizers and pesticides, road construction, steel making, mining, field burning, forest fires, fireplaces and woodstoves. PM causes eye, nose and throat irritation and respiratory problems.

Polar Vortex

The polar vortex is a large area of low pressure and cold air around Earth’s North Pole.  The phenomenom typically goes unnoticed by those of us living in lower latitudes except for when, every once in a while, the air pressure and winds shift.

Primary production

Primary production  is the production of organic compounds from atmospheric or aquatic carbon dioxide, principally through the process of photosynthesis.

Renewable energy

Renewable energy  is energy from sources that will renew themselves within our lifetime. Renewable energy sources include wind, sun, water, biomass (vegetation) and geothermal heat.

Sea ice , both  Antarctic  and  Arctic  seas, forms from salty ocean water. Overall, the Earth has lost a mass of sea ice the size of Maryland each year since 1979.

Sea level  is the average level between high tide and low tide where the surface of the sea meets a shoreline.

Sea level rise

Sea level rise  describes an increase in the average level between high tide and low tide where the surface of the sea meets a shoreline.

Seed particles

Seed particles  are tiny solid or liquid particles that provide a non-gaseous surface. The surface allows water to make the transition from a vapor to a liquid.

Sediment data

Sediment data  are materials and measurements obtained from taking a vertical core of lake bottom sediment and analyzing the layers.

Sensitivity analysis

Sensitivity analysis  is an interpretation of different sources of variation in the output of a predictive model.

Solar Cycle

The  solar cycle  describes the sun’s activity over its eleven-year period of movement and related variations. The cycle was first determined in 1843 by German astronomer Heinrich Schwabe. Scientists are trying to determine how much solar variations affect the temperature of Earth’s atmosphere.

Solar Power

Solar power   refers to the energy harnessed from the sun, which can then be transformed into different types of energy, including thermal and electric.


Stratosphere  is a layer of the atmosphere nine to 31 miles above the Earth. Ozone in the stratosphere filters out harmful sun rays, including a type of sunlight called ultraviolet B. This type of light causes health and environmental damage.

Synoptic  is used to describe a large-scale weather system more than 200 miles across.

Thermochemical technologies

Thermochemical technologies  are methods of capturing the energy potential of biomass.

Thermodynamic modules

Thermodynamic modules  are the portions of models that predict changes in aerosols due to temperature.

Tillage  refers to cultivation of the soil to improve production of crops.

Trace gases

Trace gases  make up only one percent of the atmosphere. Most of the atmosphere is made up of nitrogen (78 percent by volume) and oxygen (21 percent by volume).


Transpiration  is the evaporation of water into the atmosphere from the leaves and stems of plants. It accounts for approximately 90 percent of all evaporating water.

Transportation Control Measures

Transportation Control Measures  describe travel demand management measures to help reduce air pollutants from transportation sources.

Volatile organic compounds

Volatile organic compounds , or volatile organic carbon, are chemical compounds from solids or liquids that are emitted as gases. VOCs are emitted by thousands of man-made sources including paints, lacquers, cleaning supplies, pesticides, building materials, furnishings, copiers, correction fluids, adhesives, permanent markers, cleaners and disinfectants, fuels, crude oil and cosmetics. Natural sources are trees, termites, cows (ruminants) and agricultural cultivation.

Water column

Water column  is the full depth of a lake from the surface to the bottom.

Wildfires  are unplanned burns in any natural environment, like a forest or a grassland. Wildfire can spread quickly, burning through most anything in their path, causing  injury and death to people and animals .

Experts Answer 8 Important Wildfire Questions

5 Ways to Prevent and Prepare for Wildfires

Wildland-urban interface

The wildland-urban interface is where the wilderness meets a well-populated area. A wildfire that crosses this divide becomes more dangerous because there is a higher chance of burning people’s homes and releasing toxic materials that can cause significant harm to humans and animals. It can also directly lead to more deaths. According to UC Davis researchers, wildfires are crossing the wildland-urban interface more frequently .

define climate change

This plot shows the global temperature change from 1850 to 2022, compared to an estimated 1850-1900 baseline average temperature.

Graph showing the rising level of atmospheric carbon dioxide, showing an increase from roughly 320 parts per million in 1960 to over 400 parts per million in 2021.

This graph shows the rising level of carbon dioxide in our atmosphere since 1960.

Once in the atmosphere, greenhouse gases such as carbon dioxide form a 'blanket' around the planet. This blanket traps the heat from the sun and causes the earth to heat up.

This effect was noticed as far back as the 1980s. In 1988, the Intergovernmental Panel on Climate Change (IPCC) was set up to provide governments with information to tackle climate change.

Evidence has shown that the high levels of greenhouse gases in the atmosphere are the leading cause of increasing global temperatures.

Scientists have been able to rule out natural events as causes of climate change, such as volcanic activity, changes in solar activity, or natural sources of CO2. These may, however, have a very small effect, on top of human contributions.

In their most recent report, the IPCC states that human activity is unequivocally the cause of climate change.

Climate change is not just seen in temperature and carbon dioxide increases. We see it in many other indicators of climate change, which you can explore further on our global climate dashboard .

How fast is the temperature rising?

Since the Industrial Revolution, the average temperature of the planet has risen by around 1°C . This is a rapid change in terms of our global climate system. Previously, natural global changes are understood to have happened over much longer periods of time. It is also important to remember that the world is not warming evenly, so the temperature increase is higher than 1°C in some countries.

Spider graph showing the average global temperature for each month, from 1850 to 2017. On average, most of the warmest years have taken place since 2001.

This image shows that the five warmest years have all occurred since 2006. Cooler years are blue, while warmer years are red.

This graph shows us that global temperatures are increasing. As of 2018, the 20 warmest years on record globally have been in the past 22 years. The Met Office’s State of the UK Climate report for 2021 shows the ten hottest years in the UK since 1884 have all happened since 2002 .

What causes climate change?

What is the greenhouse effect.

When greenhouse gases such as carbon dioxide build in the atmosphere, they act like a blanket around the earth. When sunlight (mostly short-wave radiation) hits this blanket, it passes straight through and continues until it reaches the surface of the planet.

The earth then absorbs this sunlight and emits a different type of light, longer-wave infrared radiation, back out to space. As it leaves the atmosphere, the infrared radiation also hits the greenhouse gas blanket. Most of it goes straight through, but some of it is absorbed and goes back down to earth. This traps the infrared radiation and causes the surface to heat – a process we call the 'greenhouse effect'.

It is crucial to understand that the greenhouse effect is critical to life on earth. Without a blanket of greenhouse gases trapping in heat, the temperature would be bitterly cold, and humans would be unable to survive. However, by adding extra greenhouse gases into the atmosphere, humans have created an enhanced greenhouse effect.

The greenhouse gas blanket is now thicker and is absorbing more infrared radiation than before. In other words, the greenhouse effect is stronger and, instead of keeping the earth at a stable temperature, it is causing the planet to heat up.

What are the sources of greenhouse gases?

One-quarter of human-made greenhouse gas emissions come from burning fossil fuels for electricity and heat production.

Chart showing the human-made greenhouse gas emissions. The biggest emissions come from electricity and heat production (25%), agriculture, forestry and other land use (24%), industry (21%), and transport (14%).

This chart shows the human-made greenhouse gas emissions, taken from the IPCC AR5 report . AFOLU stands for Agriculture, Forestry, and Other Land Use.

Another quarter of human-made greenhouse gas emissions come from Agriculture, Forestry, and Other Land Use (AFOLU).

To feed our livestock and ourselves, people have chopped down large areas of the forest and used the land to grow crops. Forests are very good at removing carbon dioxide from the atmosphere, and so cutting down trees allows carbon dioxide to build up in the atmosphere even more.

Land can also be used to rear livestock, such as cattle for meat and milk. These animals produce additional gases, like methane. They also eat crops that might otherwise have been needed by humans, meaning that even more land is required.

As well as fossil fuels, deforestation and land use, aeroplanes and the production of cement also contribute to emissions of carbon dioxide.

How much warming could we see?

Greenhouse gases can live in our atmosphere for tens or hundreds of years. The gases that are already in our atmosphere are effectively locked in and will contribute to increasing temperatures.

Even if we stop all emissions today, we cannot avoid some level of warming. The amount of warming we will see, beyond what we have already caused, depends on the changes we make. 

How will climate change affect the UK?

Our UK Climate Projections (UKCP) help us see how climate change might affect the UK in the future.

In a high emission scenario (RCP 8.5), we expect that the UK will experience:

  • Warmer and wetter winters
  • Hotter and drier summers
  • More frequent and intense weather extremes

In 50 years’ time, by 2070 we project:

  • Winters will be between 1 and 4.5°C warmer and up to 30% wetter
  • Summers will be between 1 and 6°C warmer and up to 60% drier

These changes could have a big impact on how we live our lives.

  • Read more about climate change in the UK

Explore climate change in your local area

You can find out more about climate change in your local area in this climate change visualisation tool .

This tool is a collaboration with the BBC. It uses our climate projections and records to visualise climate change in the UK.

  • What will climate change look like near me?

The Paris Agreement and global temperature goals

In 2015, almost every country in the world signed a document promising to cut down on greenhouse gas emissions. The aim was to limit the average global temperature to 2°C above pre-industrial temperatures. If possible, countries pledged to aim for a 1.5°C limit.

Since then, the IPCC has published a report explaining the different impacts between a 1.5 or 2°C temperature rise. It showed that there are many benefits for people all over the world in limiting temperatures to 1.5°C. Large and rapid reductions in global greenhouse gas emissions are needed to meet this goal, however.

Chart showing the projected change in average surface temperature, based on the possible emission pathways. The RCP2.6 pathway projects limiting the rise to 2 °C, but the projection is between 3 and 5.5 °C under RCP8.5.

This chart from the IPCC shows two possible futures for our climate. The blue line represents what could happen if we commit to cutting emissions, and the red line represents what could happen if we don't make any changes.

If we want to avoid significant increases in the average surface temperature, we must cut greenhouse gas emissions and switch to renewable energy sources. We must also use land more sustainably and may need to use techniques to remove carbon dioxide from the air.

If we continue to burn fossil fuels and cut down forests at the same rate, the planet could warm by more than 4°C by 2100. This warming could fundamentally change life on earth, with potentially drastic consequences.

What is the difference between 1.5 or 2°C of warming?

Impacts of climate change

Human activity – from releasing greenhouse gases and aerosols into the atmosphere, to changing the use of land – is the main driver of climate change. This has a range of impacts on the climate system, ecosystems, and people.

Changes to the climate system include:

  • Rising ocean levels  – Rising temperatures are causing glaciers and ice sheets to melt, adding more water to the oceans and causing the ocean level to rise. Oceans absorb 90% of the extra heat from global warming: warmer water expands, and so our oceans are taking up more space.
  • Ocean acidification  – Ocean acidification occurs when the ocean absorbs carbon dioxide and becomes more acidic. It is often called the 'evil twin' of climate change.
  • Extreme weather events  – Climate change is causing many extreme weather events to become more intense and frequent, such as heatwaves, droughts, and floods.

Graph showing the rising number of geophysical, meteorological, hydrological and climatological events that cause a loss. The number increases over time, from roughly 250 events in 1980 to over 700 events in 2016.

This graph, from Munich RE's Topics Geo Natural Catastrophes report, shows events causing loss are becoming more frequent.

Climate change can also affect people and ecosystems. For example:

  • Flooding of coastal regions – Coastal cities are at risk from flooding as sea levels continue to rise. 
  • Food insecurity – High temperatures, extreme weather events, flooding, and droughts can damage farmland. This makes it difficult for farmers to grow crops and means that their yield of crops each year is uncertain.
  • Conflict and climate migrants – Climate change is a stress multiplier – it can take existing problems, such as lack of food or shelter, and make them worse. This can cause people to fight over resources (food, water, and shelter), or to migrate.
  • Damage to marine ecosystems – Rising ocean temperatures, ocean acidification, and ocean anoxia (lack of oxygen) are damaging to marine life such as fish and coral reefs.

How can we stop climate change?

Reduce global greenhouse gas emissions.

The most crucial step to limit climate change is to make big and rapid reductions in global greenhouse gas emissions. There are many different ways this can be done and governments, businesses, organisations and individuals around the world can all contribute. In June 2019, the UK became the world’s first major economy to pass a law committing the country to a target of ‘net zero’ emissions by 2050.

You can read more about what they are doing to achieve this, as well as what businesses and individuals can do to help, on the Green GB website .

Stay up to date with the latest climate news

Our climate newsletter shares research and news to give you the latest updates on climate science. We publish the newsletter twice a month and it's easy to sign up.

Find out more and sign up to the climate newsletter .

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What is climate change (grades k-4), nasa stem team, what is climate how is it different from weather, what is climate change, is earth’s climate changing, what is causing earth’s climate to change, what might happen to earth’s climate, how does nasa study climate change, what can you do to help, more about climate change.

This article is for students grades K-4.

A photo of a desert landscape

To learn about climate change, you first must know what climate is.

You might know what weather is. Weather is the changes we see and feel outside from day to day. It might rain one day and be sunny the next. Sometimes it is cold. Sometimes it is hot. Weather also changes from place to p

lace. People in one place might be wearing shorts and playing outside. At the same time, people far away might be shoveling snow.

Climate is the usual weather of a place. Climate can be different for different seasons. A place might be mostly warm and dry in the summer. The same place may be cool and wet in the winter. Different places can have different climates. You might live where it snows all the time. And some people live where it is always warm enough to swim outside!

There’s also Earth’s climate. Earth’s climate is what you get when you combine all the climates around the world together.  

Climate change is a change in the usual weather found in a place. This could be a change in how much rain a place usually gets in a year. Or it could be a change in a place’s usual temperature for a month or season.

Climate change is also a change in Earth’s climate. This could be a change in Earth’s usual temperature. Or it could be a change in where rain and snow usually fall on Earth.

Weather can change in just a few hours. Climate takes hundreds or even millions of years to change.

Earth’s climate is always changing. There have been times when Earth’s climate has been warmer than it is now. There have been times when it has been cooler. These times can last thousands or millions of years.

People who study Earth see that Earth’s climate is getting warmer. Earth’s temperature has gone up about one degree Fahrenheit in the last 100 years. This may not seem like much. But small changes in Earth’s temperature can have big effects.

Some effects are already happening. Warming of Earth’s climate has caused some snow and ice to melt. The warming also has caused oceans to rise. And it has changed the timing of when certain plants grow.

Many things can cause climate to change all on its own. Earth’s distance from the sun can change. The sun can send out more or less energy. Oceans can change. When a volcano erupts, it can change our climate.

Most scientists say that humans can change climate too. People drive cars. People heat and cool their houses. People cook food. All those things take energy. One way we get energy is by burning coal, oil and gas. Burning these things puts gases into the air. The gases cause the air to heat up. This can change the climate of a place. It also can change Earth’s climate.  

A factory emitting pollution into the air

Scientists think that Earth’s temperature will keep going up for the next 100 years. This would cause more snow and ice to melt. Oceans would rise higher. Some places would get hotter. Other places might have colder winters with more snow. Some places might get more rain. Other places might get less rain. Some places might have stronger hurricanes.  

Some NASA satellites look at Earth’s land, air, water and ice. Other tools look at the sun and the energy it sends out. Together, these are important for learning about Earth’s climate. Using all these tools can help scientists learn how climate might change.

Artist's concept of satellites scanning Earth from orbit

Scientists think we can do things to stop the climate from changing as much. You can help by using less energy and water. Turn off lights and TVs when you leave a room. Turn off the water when brushing your teeth. You also can help by planting trees.

Another way to help is by learning about Earth. The more you know about Earth, the more you can help solve climate problems.

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Read What Are Climate and Climate Change? (Grades 5-8)

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What Are the Causes of Climate Change?

We can’t fight climate change without understanding what drives it.

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Low water levels at Shasta Lake, California, following a historic drought in October 2021

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At the root of climate change is the phenomenon known as the greenhouse effect , the term scientists use to describe the way that certain atmospheric gases “trap” heat that would otherwise radiate upward, from the planet’s surface, into outer space. On the one hand, we have the greenhouse effect to thank for the presence of life on earth; without it, our planet would be cold and unlivable.

But beginning in the mid- to late-19th century, human activity began pushing the greenhouse effect to new levels. The result? A planet that’s warmer right now than at any other point in human history, and getting ever warmer. This global warming has, in turn, dramatically altered natural cycles and weather patterns, with impacts that include extreme heat, protracted drought, increased flooding, more intense storms, and rising sea levels. Taken together, these miserable and sometimes deadly effects are what have come to be known as climate change .

Detailing and discussing the human causes of climate change isn’t about shaming people, or trying to make them feel guilty for their choices. It’s about defining the problem so that we can arrive at effective solutions. And we must honestly address its origins—even though it can sometimes be difficult, or even uncomfortable, to do so. Human civilization has made extraordinary productivity leaps, some of which have led to our currently overheated planet. But by harnessing that same ability to innovate and attaching it to a renewed sense of shared responsibility, we can find ways to cool the planet down, fight climate change , and chart a course toward a more just, equitable, and sustainable future.

Here’s a rough breakdown of the factors that are driving climate change.

Natural Causes of Climate Change

Human-driven causes of climate change, transportation, electricity generation, industry & manufacturing, agriculture, oil & gas development, deforestation, our lifestyle choices.

Some amount of climate change can be attributed to natural phenomena. Over the course of Earth’s existence, volcanic eruptions , fluctuations in solar radiation , tectonic shifts , and even small changes in our orbit have all had observable effects on planetary warming and cooling patterns.

But climate records are able to show that today’s global warming—particularly what has occured since the start of the industrial revolution—is happening much, much faster than ever before. According to NASA , “[t]hese natural causes are still in play today, but their influence is too small or they occur too slowly to explain the rapid warming seen in recent decades.” And the records refute the misinformation that natural causes are the main culprits behind climate change, as some in the fossil fuel industry and conservative think tanks would like us to believe.

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Chemical manufacturing plants emit fumes along Onondaga Lake in Solvay, New York, in the late-19th century. Over time, industrial development severely polluted the local area.

Library of Congress, Prints & Photographs Division, Detroit Publishing Company Collection

Scientists agree that human activity is the primary driver of what we’re seeing now worldwide. (This type of climate change is sometimes referred to as anthropogenic , which is just a way of saying “caused by human beings.”) The unchecked burning of fossil fuels over the past 150 years has drastically increased the presence of atmospheric greenhouse gases, most notably carbon dioxide . At the same time, logging and development have led to the widespread destruction of forests, wetlands, and other carbon sinks —natural resources that store carbon dioxide and prevent it from being released into the atmosphere.

Right now, atmospheric concentrations of greenhouse gases like carbon dioxide, methane , and nitrous oxide are the highest they’ve been in the last 800,000 years . Some greenhouse gases, like hydrochlorofluorocarbons (HFCs) , do not even exist in nature. By continuously pumping these gases into the air, we helped raise the earth’s average temperature by about 1.9 degrees Fahrenheit during the 20th century—which has brought us to our current era of deadly, and increasingly routine, weather extremes. And it’s important to note that while climate change affects everyone in some way, it doesn’t do so equally: All over the world, people of color and those living in economically disadvantaged or politically marginalized communities bear a much larger burden , despite the fact that these communities play a much smaller role in warming the planet.

Our ways of generating power for electricity, heat, and transportation, our built environment and industries, our ways of interacting with the land, and our consumption habits together serve as the primary drivers of climate change. While the percentages of greenhouse gases stemming from each source may fluctuate, the sources themselves remain relatively consistent.

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Traffic on Interstate 25 in Denver

David Parsons/iStock

The cars, trucks, ships, and planes that we use to transport ourselves and our goods are a major source of global greenhouse gas emissions. (In the United States, they actually constitute the single-largest source.) Burning petroleum-based fuel in combustion engines releases massive amounts of carbon dioxide into the atmosphere. Passenger cars account for 41 percent of those emissions, with the typical passenger vehicle emitting about 4.6 metric tons of carbon dioxide per year. And trucks are by far the worst polluters on the road. They run almost constantly and largely burn diesel fuel, which is why, despite accounting for just 4 percent of U.S. vehicles, trucks emit 23 percent of all greenhouse gas emissions from transportation.

We can get these numbers down, but we need large-scale investments to get more zero-emission vehicles on the road and increase access to reliable public transit .

As of 2021, nearly 60 percent of the electricity used in the United States comes from the burning of coal, natural gas , and other fossil fuels . Because of the electricity sector’s historical investment in these dirty energy sources, it accounts for roughly a quarter of U.S. greenhouse gas emissions, including carbon dioxide, methane, and nitrous oxide.

That history is undergoing a major change, however: As renewable energy sources like wind and solar become cheaper and easier to develop, utilities are turning to them more frequently. The percentage of clean, renewable energy is growing every year—and with that growth comes a corresponding decrease in pollutants.

But while things are moving in the right direction, they’re not moving fast enough. If we’re to keep the earth’s average temperature from rising more than 1.5 degrees Celsius, which scientists say we must do in order to avoid the very worst impacts of climate change, we have to take every available opportunity to speed up the shift from fossil fuels to renewables in the electricity sector.

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The factories and facilities that produce our goods are significant sources of greenhouse gases; in 2020, they were responsible for fully 24 percent of U.S. emissions. Most industrial emissions come from the production of a small set of carbon-intensive products, including basic chemicals, iron and steel, cement and concrete, aluminum, glass, and paper. To manufacture the building blocks of our infrastructure and the vast array of products demanded by consumers, producers must burn through massive amounts of energy. In addition, older facilities in need of efficiency upgrades frequently leak these gases, along with other harmful forms of air pollution .

One way to reduce the industrial sector’s carbon footprint is to increase efficiency through improved technology and stronger enforcement of pollution regulations. Another way is to rethink our attitudes toward consumption (particularly when it comes to plastics ), recycling , and reuse —so that we don’t need to be producing so many things in the first place. And, since major infrastructure projects rely heavily on industries like cement manufacturing (responsible for 7 percent of annual global greenhouse gas), policy mandates must leverage the government’s purchasing power to grow markets for cleaner alternatives, and ensure that state and federal agencies procure more sustainably produced materials for these projects. Hastening the switch from fossil fuels to renewables will also go a long way toward cleaning up this energy-intensive sector.

The advent of modern, industrialized agriculture has significantly altered the vital but delicate relationship between soil and the climate—so much so that agriculture accounted for 11 percent of U.S. greenhouse gas emissions in 2020. This sector is especially notorious for giving off large amounts of nitrous oxide and methane, powerful gases that are highly effective at trapping heat. The widespread adoption of chemical fertilizers , combined with certain crop-management practices that prioritize high yields over soil health, means that agriculture accounts for nearly three-quarters of the nitrous oxide found in our atmosphere. Meanwhile, large-scale industrialized livestock production continues to be a significant source of atmospheric methane, which is emitted as a function of the digestive processes of cattle and other ruminants.

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Stephen McComber holds a squash harvested from the community garden in Kahnawà:ke Mohawk Territory, a First Nations reserve of the Mohawks of Kahnawà:ke, in Quebec.

Stephanie Foden for NRDC

But farmers and ranchers—especially Indigenous farmers, who have been tending the land according to sustainable principles —are reminding us that there’s more than one way to feed the world. By adopting the philosophies and methods associated with regenerative agriculture , we can slash emissions from this sector while boosting our soil’s capacity for sequestering carbon from the atmosphere, and producing healthier foods.

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A decades-old, plugged and abandoned oil well at a cattle ranch in Crane County, Texas, in June 2021, when it was found to be leaking brine water

Matthew Busch/Bloomberg via Getty Images

Oil and gas lead to emissions at every stage of their production and consumption—not only when they’re burned as fuel, but just as soon as we drill a hole in the ground to begin extracting them. Fossil fuel development is a major source of methane, which invariably leaks from oil and gas operations : drilling, fracking , transporting, and refining. And while methane isn’t as prevalent a greenhouse gas as carbon dioxide, it’s many times more potent at trapping heat during the first 20 years of its release into the atmosphere. Even abandoned and inoperative wells—sometimes known as “orphaned” wells —leak methane. More than 3 million of these old, defunct wells are spread across the country and were responsible for emitting more than 280,000 metric tons of methane in 2018.

Unsurprisingly, given how much time we spend inside of them, our buildings—both residential and commercial—emit a lot of greenhouse gases. Heating, cooling, cooking, running appliances, and maintaining other building-wide systems accounted for 13 percent of U.S. emissions overall in 2020. And even worse, some 30 percent of the energy used in U.S. buildings goes to waste, on average.

Every day, great strides are being made in energy efficiency , allowing us to achieve the same (or even better) results with less energy expended. By requiring all new buildings to employ the highest efficiency standards—and by retrofitting existing buildings with the most up-to-date technologies—we’ll reduce emissions in this sector while simultaneously making it easier and cheaper for people in all communities to heat, cool, and power their homes: a top goal of the environmental justice movement.

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An aerial view of clearcut sections of boreal forest near Dryden in Northwestern Ontario, Canada, in June 2019

River Jordan for NRDC

Another way we’re injecting more greenhouse gas into the atmosphere is through the clearcutting of the world’s forests and the degradation of its wetlands . Vegetation and soil store carbon by keeping it at ground level or underground. Through logging and other forms of development, we’re cutting down or digging up vegetative biomass and releasing all of its stored carbon into the air. In Canada’s boreal forest alone, clearcutting is responsible for releasing more than 25 million metric tons of carbon dioxide into the atmosphere each year—the emissions equivalent of 5.5 million vehicles.

Government policies that emphasize sustainable practices, combined with shifts in consumer behavior , are needed to offset this dynamic and restore the planet’s carbon sinks .

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The Yellow Line Metro train crossing over the Potomac River from Washington, DC, to Virginia on June 24, 2022

Sarah Baker

The decisions we make every day as individuals—which products we purchase, how much electricity we consume, how we get around, what we eat (and what we don’t—food waste makes up 4 percent of total U.S. greenhouse gas emissions)—add up to our single, unique carbon footprints . Put all of them together and you end up with humanity’s collective carbon footprint. The first step in reducing it is for us to acknowledge the uneven distribution of climate change’s causes and effects, and for those who bear the greatest responsibility for global greenhouse gas emissions to slash them without bringing further harm to those who are least responsible .

The big, climate-affecting decisions made by utilities, industries, and governments are shaped, in the end, by us : our needs, our demands, our priorities. Winning the fight against climate change will require us to rethink those needs, ramp up those demands , and reset those priorities. Short-term thinking of the sort that enriches corporations must give way to long-term planning that strengthens communities and secures the health and safety of all people. And our definition of climate advocacy must go beyond slogans and move, swiftly, into the realm of collective action—fueled by righteous anger, perhaps, but guided by faith in science and in our ability to change the world for the better.

If our activity has brought us to this dangerous point in human history, breaking old patterns can help us find a way out.

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Responding to Climate Change

NASA is a world leader in climate studies and Earth science. While its role is not to set climate policy or prescribe particular responses or solutions to climate change, its purview does include providing the robust scientific data needed to understand climate change. NASA then makes this information available to the global community – the public, policy- and decision-makers and scientific and planning agencies around the world.

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Climate change is one of the most complex issues facing us today. It involves many dimensions – science, economics, society, politics, and moral and ethical questions – and is a global problem, felt on local scales, that will be around for thousands of years. Carbon dioxide, the heat-trapping greenhouse gas that is the primary driver of recent global warming, lingers in the atmosphere for many thousands of years, and the planet (especially the ocean) takes a while to respond to warming. So even if we stopped emitting all greenhouse gases today, global warming and climate change will continue to affect future generations. In this way, humanity is “committed” to some level of climate change.

How much climate change? That will be determined by how our emissions continue and exactly how our climate responds to those emissions. Despite increasing awareness of climate change, our emissions of greenhouse gases continue on a relentless rise . In 2013, the daily level of carbon dioxide in the atmosphere surpassed 400 parts per million for the first time in human history . The last time levels were that high was about three to five million years ago, during the Pliocene Epoch.

Because we are already committed to some level of climate change, responding to climate change involves a two-pronged approach:

  • Reducing emissions of and stabilizing the levels of heat-trapping greenhouse gases in the atmosphere (“mitigation”) ;
  • Adapting to the climate change already in the pipeline (“adaptation”) .

Mitigation and Adaptation

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Mitigation – reducing climate change – involves reducing the flow of heat-trapping greenhouse gases into the atmosphere , either by reducing sources of these gases (for example, the burning of fossil fuels for electricity, heat, or transport) or enhancing the “sinks” that accumulate and store these gases (such as the oceans, forests, and soil). The goal of mitigation is to avoid significant human interference with Earth's climate , “stabilize greenhouse gas levels in a timeframe sufficient to allow ecosystems to adapt naturally to climate change, ensure that food production is not threatened, and to enable economic development to proceed in a sustainable manner” (from the 2014 report on Mitigation of Climate Change from the United Nations Intergovernmental Panel on Climate Change, page 4).

Adaptation – adapting to life in a changing climate – involves adjusting to actual or expected future climate. The goal is to reduce our risks from the harmful effects of climate change (like sea-level rise, more intense extreme weather events, or food insecurity). It also includes making the most of any potential beneficial opportunities associated with climate change (for example, longer growing seasons or increased yields in some regions).

Throughout history, people and societies have adjusted to and coped with changes in climate and extremes with varying degrees of success. Climate change (drought in particular) has been at least partly responsible for the rise and fall of civilizations . Earth’s climate has been relatively stable for the past 10,000 years, and this stability has allowed for the development of our modern civilization and agriculture. Our modern life is tailored to that stable climate and not the much warmer climate of the next thousand-plus years. As our climate changes, we will need to adapt. The faster the climate changes, the more difficult it will be.

While climate change is a global issue, it is felt on a local scale. Local governments are therefore at the frontline of adaptation. Cities and local communities around the world have been focusing on solving their own climate problems . They are working to build flood defenses, plan for heat waves and higher temperatures, install better-draining pavements to deal with floods and stormwater, and improve water storage and use.

According to the 2014 report on Climate Change Impacts, Adaptation and Vulnerability (page 8) from the United Nations Intergovernmental Panel on Climate Change, governments at various levels are also getting better at adaptation. Climate change is being included into development plans: how to manage the increasingly extreme disasters we are seeing, how to protect coastlines and deal with sea-level rise, how to best manage land and forests, how to deal with and plan for drought, how to develop new crop varieties, and how to protect energy and public infrastructure.

How NASA Is Involved


NASA, with its Eyes on the Earth and wealth of knowledge on Earth’s climate, is one of the world’s experts in climate science . NASA’s role is to provide the robust scientific data needed to understand climate change. For example, data from the agency’s Gravity Recovery and Climate Experiment (GRACE) , its follow-on mission ( GRACE-FO ), the Ice, Cloud and land Elevation Satellite (ICESat), and the ICESat-2 missions have shown rapid changes in the Earth's great ice sheets. The Sentinel-6 Michael Freilich and the Jason series of missions have documented rising global sea level since 1992.

NASA makes detailed climate data available to the global community – the public, policy-, and decision-makers and scientific and planning agencies around the world. It is not NASA’s role to set climate policy or recommend solutions to climate change. NASA is one of 13 U.S. government agencies that form part of the U.S. Global Change Research Program, which has a legal mandate to help the nation and the world understand, assess, predict, and respond to global change. These U.S. partner agencies include the Department of Agriculture , the Environmental Protection Agency , and the Department of Energy , each of which has a different role depending on their area of expertise.

Although NASA’s main focus is not on energy-technology research and development, work is being done around the agency and by/with various partners and collaborators to find other sources of energy to power our needs.

Related Articles

For further reading on NASA’s work on mitigation and adaptation, take a look at these pages:

  • Earth Science in Action
  • Sustainability and Government Resources
  • NASA's Electric Airplane
  • NASA Aeronautics
  • NASA Spinoff (Technology Transfer Program)

Recent News & Features


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What is climate change adaptation and why is it a priority at COP27?

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Climate change adaptation is increasing the intensity and frequency of extreme weather - something we must adapt to. Image:  Unsplash/Jonathan Ford

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Why adaptation strategies aren't only for governments, trillions are being committed to climate mitigation, but what about climate adaptation, innovative local solutions can create a green future for the sahel.

While investment in climate change adaptation is rising, less than 2% comes from private finance.

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The UN now focuses on climate change as a health issue too. Here's why

Shyam Bishen, Rolf Fricker and Oliver Eitelwein

Medical experts are worried about climate change too. Here's how it can harm your health.

As the world nears the end of what could be the hottest year in recorded history and heads into one predicted to be hotter still, a report underscores the health consequences of the warming climate.

The 8th annual report of the Lancet Countdown on Health and Climate Change, released Tuesday, describes a "grave and mounting threat" if we fail to reduce greenhouse gas emissions, especially given the evidence of worsening world health as the planet warms.

It outlines many ways this warming trend is already impacting the health of Americans. They include heat waves that stress young and old bodies and threaten to overwhelm hospitals; droughts and floods that endanger the food supply; the spread of disease to new areas, the extension and altered timing of allergy seasons; increases in air pollution and the growing scale of lethal fires.

"As we see temperatures continuing to rise and wildfires continuing to get worse, we're just seeing these really stark increases in impacts to health," said Naomi Beyeler, the lead author of the U.S. section of the report.

It's not too late to change the trajectory of global climate change, she and other experts say. But the world is getting close to the precipice .

"We have the tools at hand. We have the money at hand. We can do this," said Dr. Kari Nadeau, chair of the Department of Environmental Health at the T.H. Chan Harvard School of Public Health. Nadeau was not involved in the Lancet report, but praised its analysis and priorities. "It's really a matter of the political will."

Nadeau said she doesn't want to be a purveyor of doom, but climate change and its health impacts are no longer something coming in the future, it's something that is happening now.

"I hope people realize it's going to affect them, their children, their grandchildren and their friends," she said.

There is room for hope, and for improving public health if countries take action, according to Beyeler, of the University of California, San Francisco.

The Lancet report is one of several arriving ahead of COP 28, a meeting of the United Nations Framework Convention on Climate Change that begins Nov. 30 in Dubai.

Countries that committed to the Paris Agreement have pledged to try to keep global temperatures from rising more than 2.7 degrees above pre-industrial times.

That goal is still achievable, but only if governments, companies and banks stop "negligent" investments in oil and gas, according to the Lancet report. "Without profound and swift mitigation to tackle the root causes of climate change, the health of humanity is at grave risk," it says.

Also on Tuesday, the White House released the nation's Fifth National Climate Assessment and the U.N. Framework Convention on Climate Change released an analysis of the climate plans of member nations and found them lacking.

"The climate crisis is not just changing the planet – it is changing children," according to a report from the United Nations Children's Fund, released on Monday.

Who's to blame for climate change? Scientists don't hold back in new federal report.

Human-induced climate change is warming Earth

This year, more than nine in 10 people worldwide encountered high temperatures made much more likely because of human-caused climate change, the Lancet report found. It represents the consensus of more than 100 experts from dozens of research institutions and UN agencies. Topics include 47 indicators of household air pollution, financing of fossil fuels and engagement from international organizations on the health benefits of limiting climate change.

Among its findings:

  • The heat was most extreme in the tropics, concentrating the impact on developing countries.
  • Every country experienced some level of climate-driven heat, including the U.S.
  • Heat-related deaths of people older than 65 years increased by 85% from 1990–2000, above the 38% increase that was expected if temperatures had not changed.

The unprecedented heat this year has sparked widespread alarm among many climate scientists . The global average temperature through October was the highest on record, nearly 2.6 degrees Fahrenheit above the pre-industrial average, the European Union's Climate Change Service said last week.

If the global average temperature rises by 3.6 degrees Fahrenheit above pre-industrial times by mid-century, the world could see a 370% increase in heat-related deaths and increasing food insecurity for more than a half-billion people, the report states.

Health consequences of climate change

Health consequences of climate change come directly from warming temperatures, melting ice that can lead to floods and expose new pathogens and droughts that affect the food supply and the likelihood of forest fires. Contagious diseases are likely to spread more, too, experts said, either through vectors like mosquitoes that can survive in new, warming regions or because people searching for new food sources are coming into closer contact with wild animals, passing on diseases like Ebola.

The increased intensity and frequency of wildfires have undermined air quality improvements since the passage of the Clean Air Act in 1970, Beyeler said, and have even led to reversals in some areas. "There's emerging evidence that smoke may be even more harmful to health than non-smoke particulate pollution," she added.

The scale of the exposures was greater this year than ever before, with tens of millions of Americans breathing in unhealthy air from Canadian wildfires.

This, combined with extreme heat events which especially harm older adults, placed an added burden on the health system, Beyeler noted.

Heat waves occur when temperatures remain elevated for several days in a row, including overnight. They're particularly dangerous because the overnight warmth doesn't give people, animals or crops any chance to recover, Karin Gleason, chief of the monitoring section at the National Centers for Environmental Information, told USA TODAY.

"If you don’t cool down several nights in a row there are higher mortality rates,” Gleason said. “Crops and plants and animals need that recovery overnight so they can deal with the intensity of the daytime highs the next day."

As countries in parts of Europe faced sweltering temperatures this summer, hospitals were "quite stretched," in treating victims of heat-related illness, said Joyce Kumutai, a research associate and climate scientist at the London-based Grantham Institute.

"We saw something close to COVID-era stretching of hospital facilities," Kumutai said.

What individuals can do

Everyone has a role to play in fighting climate change and safeguarding human health, said Titus Schleyer, a research scientist at the Regenstrief Institute, in Indianapolis, who is leading a summit this week focused on using data to fight the medical consequences of climate change.

"It's easy to be hopeless, but that's not going to get us anywhere. That just seals our fate," he said.

He hopes to use medical informatics to reduce the negative effects of climate change, by providing and analyzing large-scale data about the impacts.

"Data is crucial to understanding where is global warming going and what we can do short-term and medium-term," said Schleyer, whose conference this week is part of the American Medical Informatics Association's annual meeting in New Orleans. "We have only one big try and we've got to succeed."

People can consume fewer resources, cut back on airplane travel, recycle, compost and talk to public officials about taking climate action, Schleyer said.

At the community level, switching a single school bus from diesel gasoline to electric power "can improve a child's asthma who rides that busy every day by about 30%," Nadeau said. Within a month after the switch, the child will be 30% less likely to have an asthma attack and also less likely to end up in an emergency room.

Trees combat the "heat island effect" of so much concrete in cities. Investing $1 in planting city trees saves about $5 in emergency room costs, she said. "And you don't have to wait a lifetime to see those economic benefits."

Beyeler added that people can also help reduce pollution from cars by supporting safe walking and biking in their communities.

The Lancet report, Beyeler said, pushes people to see the connections as it tries to "highlight places where we can make progress on both (climate and health) goals at the same time."

Although a lot has gone wrong in the last 18 months, with heat waves and forest fires, Beyeler said, a lot has gone right, too. There has been more investment in renewable energy and away from fossil fuels, she said. At the same time, the federal government has renewed its commitment to COP28's climate goals and to reducing health and climate inequities.

"There is momentum to be built on," Beyeler said. "At the same time, even with that progress, the scale of implementation and action that's needed to get us from where we are now to where we need to be is still tremendous."

C ontact Karen Weintraub at kweint[email protected] and Dinah Voyles Pulver at [email protected]

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input .

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2023 sks weekly climate change & global warming news roundup #46.

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Posted on 18 November 2023 by John Hartz

 story of the week, i’m not screaming into the void anymore..

Two and a half years ago, when I was asked to help write  the most authoritative report on climate change in the United States,  I hesitated. Did we  really  need another warning of the dire consequences of climate change in this country? The answer, legally, was yes: Congress mandates that the National Climate Assessment be updated every four years or so. But after four previous assessments and six United Nations reports since 1990, I was skeptical that what we needed to address climate change was yet another report.

In the end, I said yes, but reluctantly. Frankly, I was sick of admonishing people about how bad things could get. Scientists have raised the alarm over and over again, and still the temperature rises.  Extreme events  like heat waves, floods, and droughts are becoming more severe and frequent, exactly  as we predicted they would . We were proved right. It didn’t seem to matter.

Our report, which was released on Tuesday, contains more dire warnings. There are plenty of new reasons for despair. Thanks to recent scientific advances, we can now  link climate change  to specific extreme weather disasters, and we have a better understanding of how  the feedback loops  in the climate system can make warming even worse. We can also now more confidently forecast catastrophic outcomes if global emissions continue on their current trajectory. But to me, the most surprising new finding in the Fifth National Climate Assessment is this: There has been genuine progress, too. [My bold - JMH]

  Click here to access the entire article as originally posted on the New York Times website.

I’m a Climate Scientist. I’m Not Screaming Into the Void Anymore.  Opinion by Kate Marevel, Climate, New York Times, Nov 18, 2023

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Sunday, Nov 12, 2023

  • Melting African glaciers an early casualty of global warming, say experts  The first global summit devoted to the preservation of glaciers and poles, which took place in Paris this week, has shed light on Africa's little-known glaciers – which the UN warns will be lost to global warming. by Melissa Chemam, Environment, RFI, Nov 11, 2023
  • Peak oil: It never comes, and that’s bad news for the UN climate conferences and global warming , Opinion by Eric Reguly, Business, The Globe & Mail (CA), Nov 10, 2023
  • Fossil fuel interests have large, yet often murky, presence at climate talks, AP analysis finds  by Seth Borenstein & Mary Katherine Wildeman, World, AP/PBS News Hour, Nov 8, 2023
  • COP28 climate dispute: What are "unabated" fossil fuels? by Alister Doyle, Context, Nov 8, 2023
  • The Climate Crisis Is Slipping From The News Right When It Needs Our Attention Most   With front pages dominated by Israel-Palestine, we are losing sight of the worsening catastrophe that needs to remain a top priority. by Nathan J Robinson, Climate Change, Current Affairs, Nov 10, 2023
  • Event information - Upcoming talks in Italy  by Baerbel Winkler, Skeptical Science, Nov 12, 2023
  • The Observer view on COP 28: UK is turning its back on chance to lead climate fight   Once a leader on global heating, Rishi Sunak’s anti-green policies are making Britain look increasingly isolated by The Observer Editorial Board, Comment is Free, The Guardian, Nov 12, 2023
  • After a Last-Minute Challenge to New Loss and Damage Deal, U.S. Joins Global Consensus Ahead of COP28  Latest U.S. actions fit a long pattern of ambivalence, and even disruption, at key moments during 30 years of climate talks. by Bob Berwyn, Justice, Inside Climate News, Nov 10, 2023

Monday, Nov 13, 2023

  • Lightning fires threaten planet-cooling forests  by Matt McGrath & Erwan Rivault, Science, BBC News, Nov 10, 2023
  • Scientists Fear Cataclysmic 'Factor X' Will Emerge From Earth's Permafrost by Pandora Dewan, Health, Newsweek Magazine, Nov 12, 2023
  • November 2023 El Niño update: transport options  by Emily Becker, ENSO Blog, Climate.gov, Nov 9, 2023
  • Thousands of Greenland’s glaciers are rapidly shrinking. Before-and-after photos reveal decades of change by Rachel Ramirez, Climate, CNN, Nov 12, 2023
  • In a U.S. First, a Commercial Plant Starts Pulling Carbon From the Air  The technique is expensive but it could help fight climate change. Backers hope fast growth can bring down costs. by Brad Plumer, Climate, New York Times, Nov 9, 2023
  • The world is planning to blow the fossil fuels production limit that would keep a lid on global heating, report says  by Staff, Reuters/CNN, Nov 8, 2023
  • The continued rise in CO2 is unacceptable. This insanity cannot continue  The cryosphere — Earth’s ice sheets, sea ice, permafrost, polar oceans, glaciers and snow — is ground zero for climate change, and it pays no attention to rhetoric, only to our actions Opinion by Prof Julie Brigham-Grette & Prof Martin Siegert, Euronews, Nov 10, 2023
  • Add another heat record to the pile: Earth is historically and alarmingly hot. Now what?  by Dinah Voyles Pulver, Nation, US TODAY, Nov 13, 2023

Tuesday, Nov 14, 2023

  • An Invisible Killer  Cases of valley fever, fueled by the fungus coccidioides, have quadrupled over 20 years. Climate change, more extreme drought and fires may hasten its spread. by Joshua Partlow, Veronica Penney & Carolyn Van Houten, Climate, Washington Post, Nov 13, 2023
  • Climb aboard four fishing boats with us to see how America's warming waters are changing  by Trevor Hughes, Nation, USA TODAY, Oct 30, 2023
  • What drought in the Amazon means for the planet  by Nicolás Rivero, Climate, Washington Post, Nov 10, 2023
  • Offshore wind is at a crossroads. Here’s what you need to know. by Heather Richards, Energywire, E&E News, Nov 13, 2023
  • How Much Can Trees Fight Climate Change? Massively, but Not Alone, Study Finds .   The research, which comes with important caveats, was partly an effort to address the scientific uproar surrounding an earlier paper. by Catrin Einhorn, Climate, New York Times. Nov 13, 2023
  • The Carbon Brief Quiz 2023  by Joe Goodman, In Focus, Carbon Brief, Nov 14, 2023
  • At a glance - How the IPCC is more likely to underestimate the climate response by John Mason & Baerbel Winkler, Skeptical Science, Nov 14, 2023
  • Report Charts Climate Change’s Growing Impact in the US, While Stressing Benefits of Action   The National Climate Assessment sees sea level rise of 11 inches by 2050 and says the transition to wind and solar energy must go two to 10 times faster to meet U.S. goals for reducing greenhouse gases. by Marianne Lavelle, Katie Surma, Kiley Price  &, Nicholas Kusnetz, Inside Climate News, Nov 14, 2023
  • In a Report Card on Global Warming, Nations Get a Very Poor Grade   Countries are taking “baby steps,” a U.N. official said. In a separate study, Saudi researchers warned of an “existential crisis” for their nation from rising temperatures. by Somini Sengupta, Climate, New York Times, Nov 14, 2023

Wednesday, Nov 15, 2023

  • No place in the US is safe from the climate crisis, but a new report shows where it’s most severe by Ella Nilsen, US, CNN, Nov 1 4, 2023
  • U.S. and China Agree to Displace Fossil Fuels by Ramping Up Renewables  The climate agreement between the two countries is seen as a bright spot as President Biden prepares to meet President Xi Jinping. by Lisa Friedman, Climate, New York Times, Nov 14, 2023
  • 46M Health Professionals Urge Fossil Phaseout as Lancet Countdown Warns of Dire Impacts by Gaye Taylor, The Energy Mix, Nov 14, 2023
  • How soon do yon have to buy heat pumps and EVs to avoid climate catastrophe? by Michael J Coren & Niko Kommenda, Climate, Washington Post, Nov 14, 2023
  • Backed by the EU, Namibia has a $20 billion plan to export green hydrogen.  A secretive tender process raises concerns for nature and citizens. by John Grobler, Joe Lo & Matteo Civillini, News, Climate Home News, Nov 15, 2023
  • Uncounted Emissions: The Hidden Cost of Fossil Fuel Exports   Oil, gas, and coal exports are not counted when countries tally their greenhouse gas emissions under the Paris Agreement. This allows wealthy nations to report progress on emissions reduction goals, while shipping their fossil fuels — and the pollution they produce — overseas. by Bill Mckibben, Yale Environment 360, Nov 14, 2023
  • Cop28 host UAE has world’s biggest climate-busting oil plans, data indicates State oil company’s huge expansion plans make its CEO’s role as president of UN climate summit ‘ridiculous’, say researchers by Damian Carrington, Environment, The Guardian, Nov 15, 2023
  • Greenhouse gases soared to another record and there’s ‘no end in sight ’  by Justine McDaniel. Climate, Washington Post, Nov 15, 2023

Thursday, Nov 16, 2023

  • China’s Wildly Complex Energy Transition, Explained in 8 Charts The world’s biggest polluter is also the world’s top generator of renewable energy. by Emily Pontecorvo, Economy, Heatmap, Nov 15, 2023
  • Last month was by far the world’s hottest October on record The past 12 months (November 2022-October 2023) was the hottest 12-month period for about 125,000 years, 1.3 degrees Celsius above the preindustrial climate. by Jeff Masters, Eye on the Storm, Yale Climate Connections, Nov 15, 2023
  • Beyond climate: Oil, gas and coal are destabilizing all 9 planetary boundaries  by Sean Mowbrey, Mongabay, Nov 14, 2023 ( Note: This story is the first in a three-part miniseries surveying the range of impacts by the fossil fuel industry on the global environment. Part one and part two review harm done to the nine planetary boundaries, while part three looks at circular economy solutions.)
  • More than Half of World’s Largest Companies’ Net Zero Pledges Are False Promises, Study Finds An InfluenceMap analysis finds many corporate climate vows do not match companies’ actual lobbying around climate-related policies. by Dana Durgmand, DeSmog international, Nov 15, 2023

Friday, Nov 17, 2023

  • He won a Nobel Prize. Then he started denying climate change . John Clauser shared the Nobel in physics last year. Now he’s a self-described ‘denier’ of the overwhelming scientific consensus on a warming planet.  by Maxine Joselow, Climte, Washingto Post, Nov 16, 2023
  • Medical experts are worried about climate change too. Here's how it can harm your health.  by Karen Weintraub & Dinah Voyles Pulver, Nation, USA TODAY, Nov 16, 2023
  • Earth is taking a pounding from bigger ocean waves. Why this matters.  by Kasha Patel, Climate, Washington Post, Nov 16, 2023
  • Moving Past Climate Denial  by Amy Westervelt, News, Drilled, Nov 17, 2013

Saturday, Nov 18, 2023

  • Texas approves new textbooks after friction over fossil fuels in the US's biggest oil and gas state &nbsp The Texas education board has approved new textbooks but called on some publishers to change their depictions of fossil fuels in the U.S.'s biggest moil and gas state by Acacia Coronado, AP/ABC News, Nov 17, 2023
  • 025-The Misinformation Machine  by Amber Whittle, The Peel Podcast, Nov 16, 2023
  • Ancient Warming of a Rising Sea by Sarah Kaplan, Bonnie Jo Mount, Simon Ducroquet, Emily Wright & Frank Hulley-Jones, Climate, Washington Post, Nov 17, 2023
  • I ’m a Climate Scientist. I’m Not Screaming Into the Void Anymore. Opinion by Kate Marevel, Climate, New York Times, Nov 18, 2023

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define climate change


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  1. What Is Climate Change?

    Climate change is a long-term change in the average weather patterns that have come to define Earth's local, regional and global climates. These changes have a broad range of observed effects that are synonymous with the term.

  2. Climate Change

    Climate change is the long-term alteration of temperature and typical weather patterns in a place. Climate change could refer to a particular location or the planet as a whole. Climate change may cause weather patterns to be less predictable.

  3. Climate change

    Climate change, the periodic modification of Earth's climate caused by atmospheric changes and the atmosphere's interactions with geologic, chemical, biological, and geographic factors. Loosely defined, climate is the average weather at a distinct place that incorporates temperature, precipitation, and other features.

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    In common usage, climate change describes global warming —the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to Earth's climate.

  6. What Is Climate Change?

    Climate change describes a change in the average conditions — such as temperature and rainfall — in a region over a long period of time. For example, 20,000 years ago, much of the United States was covered in glaciers. In the United States today, we have a warmer climate and fewer glaciers.

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  8. Basics of Climate Change

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    What is Climate Change ? Understanding the Big Picture The Earth's climate is changing and the global climate is projected to continue to change over this century and beyond.

  11. Climate Change

    Climate change is caused by human activities and threatens life on earth as we know it. With rising greenhouse gas emissions, climate change is occurring at rates much faster than anticipated. Its ...

  12. What Is Climate Change?

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  13. Evidence

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    climate change definition: 1. changes in the world's weather, in particular the fact that it is believed to be getting warmer…. Learn more.

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    Climate change. Climate change is impacting human lives and health in a variety of ways. It threatens the essential ingredients of good health - clean air, safe drinking water, nutritious food supply and safe shelter - and has the potential to undermine decades of progress in global health. Between 2030 and 2050, climate change is expected ...

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    Climate change refers to significant changes in global temperature, precipitation, wind patterns and other measures of climate that occur over several decades or longer. The seas are rising. The foods we eat and take for granted are threatened. Ocean acidification is increasing.

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    Climate change is a change in the usual weather found in a place. This could be a change in how much rain a place usually gets in a year. Or it could be a change in a place's usual temperature for a month or season. Climate change is also a change in Earth's climate. This could be a change in Earth's usual temperature.

  21. What Causes Climate Change? Human and Natural Causes

    At the root of climate change is the phenomenon known as the greenhouse effect, the term scientists use to describe the way that certain atmospheric gases "trap" heat that would otherwise...

  22. Climate Change Adaptation and Mitigation

    Responding to climate change involves two possible approaches: reducing and stabilizing the levels of heat-trapping greenhouse gases in the atmosphere ("mitigation") and adapting to the climate change already in the pipeline ("adaptation"). NASA's role is to make climate data available to the global community, including the public ...

  23. What is the Triple Planetary Crisis?

    Climate change is the most pressing issue facing humanity today. Simply put, climate change refers to long-term shifts in temperatures and weather patterns that in the long run will completely alter the ecosystems that support life on the planet. Human activities are the main drivers of climate change.

  24. What is climate change adaptation and why is it vital?

    Climate change adaptation involves adjusting our behaviour and building improved infrastructure to better cope with changing weather patterns. Raising more finance to help developing countries cope with climate impacts, such as more frequent extreme weather events, will be one of the main goals of the upcoming COP27 summit in Egypt.

  25. Climate change and displacement: the myths and the facts

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  26. Climate change effects and your health. Here's what to know.

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  27. 2023 SkS Weekly Climate Change & Global Warming News Roundup #46

    Last month was by far the world's hottest October on record The past 12 months (November 2022-October 2023) was the hottest 12-month period for about 125,000 years, 1.3 degrees Celsius above the preindustrial climate. by Jeff Masters, Eye on the Storm, Yale Climate Connections, Nov 15, 2023.