Portal:Climate change

The Climate Change Portal

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Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. In a broader sense, climate change also includes previous long-term changes to Earth's climate. The modern-day rise in global temperatures is driven by human activities, especially fossil fuel (coal, oil and natural gas) burning since the Industrial Revolution. Fossil fuel use, deforestation, and some agricultural and industrial practices release greenhouse gases. These gases absorb some of the heat that the Earth radiates after it warms from sunlight, warming the lower atmosphere. Earth's atmosphere now has roughly 50% more carbon dioxide, the main gas driving global warming, than it did at the end of the pre-industrial era, reaching levels not seen for millions of years.

Climate change has an increasingly large impact on the environment. Heat waves and wildfires are becoming more common. Amplified warming in the Arctic has contributed to thawing permafrost, retreat of glaciers and sea ice decline. Higher temperatures are also causing more intense storms, droughts, and other weather extremes. Rapid environmental change in mountains, coral reefs, and the Arctic is forcing many species to relocate or become extinct. Even if efforts to minimize future warming are successful, some effects will continue for centuries. These include ocean heating, ocean acidification and sea level rise.

Climate change threatens people with increased flooding, extreme heat, increased food and water scarcity, more disease, and economic loss. Human migration and conflict can also be a result. The World Health Organization calls climate change one of the biggest threats to global health in the 21st century. Societies and ecosystems will experience more severe risks without action to limit warming. Adapting to climate change through efforts like flood control measures or drought-resistant crops partially reduces climate change risks, although some limits to adaptation have already been reached. Poorer communities are responsible for a small share of global emissions, yet have the least ability to adapt and are most vulnerable to climate change.

Many climate change impacts have been observed in the first decades of the 21st century, with 2024 the warmest on record at +1.60 °C (2.88 °F) since regular tracking began in 1850. Additional warming will increase these impacts and can trigger tipping points, such as melting all of the Greenland ice sheet. Under the 2015 Paris Agreement, nations collectively agreed to keep warming "well under 2 °C". However, with pledges made under the Agreement, global warming would still reach about 2.8 °C (5.0 °F) by the end of the century.

There is widespread support for climate action worldwide, and most countries aim to stop emitting carbon dioxide. Fossil fuels can be phased out by ending their subsidies, conserving energy and switching to energy sources that do not produce significant carbon pollution. These energy sources include wind, solar, hydro, and nuclear power. Cleanly generated electricity can replace fossil fuels for powering transportation, heating buildings, and running industrial processes. Carbon can also be removed from the atmosphere, for instance by increasing forest cover and farming with methods that store carbon in soil. (Full article...)

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Throughout Earth's climate history (Paleoclimate) its climate has fluctuated between two primary states: greenhouse and icehouse Earth. Both climate states last for millions of years and should not be confused with the much smaller glacial and interglacial periods, which occur as alternating phases within an icehouse period (known as an ice age) and tend to last less than one million years. There are several icehouse periods in Earth's climate history, namely the Huronian, Cryogenian, Andean-Saharan (also known as Early Paleozoic), Late Paleozoic, Cretaceous, and Late Cenozoic glaciations.

The main factors involved in changes of the paleoclimate are believed to be the concentration of atmospheric greenhouse gases such as carbon dioxide (CO₂) and less importantly methane (CH₄), changes in Earth's orbit, long-term changes in the solar constant, and oceanic and orogenic changes from tectonic plate dynamics. Greenhouse and icehouse periods have played key roles in the evolution of life on Earth by directly and indirectly forcing biotic adaptation and turnover at various spatial scales across time. (Full article...)

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Space sunshade

Credit: User: Mikael_Häggström

The basic function of a space sunshade to mitigate global warming. A 1000 kilometre diameter lens is sufficient, and much smaller than what is shown in this simplified image. As a Fresnel lens it would be only a few millimeters thick.

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WikiProjects


WikiProject Climate change	WikiProject Environment	WikiProject Globalization

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Liu in 2026

Liu Zhenmin (Chinese: 刘振民; born August 1955) is a Chinese diplomat who was named as the country's special envoy for climate change on 12 January 2024. Previously he had served as the Under-Secretary-General for the United Nations Department of Economic and Social Affairs (DESA) from 2017 to 2022. He was appointed to that position effective on 26 July 2017. Prior to that he had served as Vice-Minister for Foreign Affairs of China after a thirty-year career in the Ministry of Foreign Affairs of the People's Republic of China. While at DESA, Liu promoted China's Belt and Road Initiative. (Full article...)

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General images

The following are images from various climate-related articles on Wikipedia.

Image 1Between 1850 and 2019 the Global Carbon Project estimates that about 2/3rds of excess carbon dioxide emissions have been caused by burning fossil fuels, and a little less than half of that has stayed in the atmosphere. (from Carbon dioxide in the atmosphere of Earth)
Image 2CO₂ concentrations over the last 500 million years (from Carbon dioxide in the atmosphere of Earth)
Image 3The Global Carbon Project shows how additions to CO₂ have been caused by different sources ramping up one after another. (from Causes of climate change)
Image 4John Tyndall's ratio spectrophotometer (drawing from 1861) measured how much infrared radiation was absorbed and emitted by various gases filling its central tube. Such measurements furthered understanding of the greenhouse effect that underlies global warming and climate change. (from History of climate change science)
Image 5Concentration of atmospheric CO₂ over the last 40,000 years, from the Last Glacial Maximum to the present day. The current rate of increase is much higher than at any point during the last deglaciation. (from Carbon dioxide in the atmosphere of Earth)
Image 6Sea ice reflects 50% to 70% of incoming sunlight, while the ocean, being darker, reflects only 6%. As an area of sea ice melts and exposes more ocean, more heat is absorbed by the ocean, raising temperatures that melt still more ice. This is a positive feedback process. (from Causes of climate change)
Image 7Mean temperature anomalies during the period 1965 to 1975 with respect to the average temperatures from 1937 to 1946. This dataset was not available at the time. (from History of climate change science)
Image 8The rising accumulation of energy in the oceanic, land, ice, and atmospheric components of Earth's climate system since 1960 (from Earth's energy budget)
Image 9Schematic drawing of Earth's excess heat inventory and energy imbalance for two recent time periods (from Earth's energy budget)
Image 10CO₂ concentrations over the last 800,000 years as measured from ice cores (blue/green) and directly (black) (from Causes of climate change)
Image 11Cumulative land-use change contributions to CO₂ emissions, by region. (from Causes of climate change)
Image 12Atmospheric CO₂ concentration measured at Mauna Loa Observatory in Hawaii from 1958 to 2023 (also called the Keeling Curve). The rise in CO₂ over that time period is clearly visible. The concentration is expressed as μmole per mole, or ppm. (from Carbon dioxide in the atmosphere of Earth)
Image 13Earth heating estimates from a combination of space altimetry and space gravimetry (from Earth's energy budget)
Image 14Air pollution has substantially increased the presence of aerosols in the atmosphere when compared to the preindustrial background levels. Different types of particles have different effects, but overall, cooling from aerosols formed by sulfur dioxide emissions has the overwhelming impact. However, the complexity of aerosol interactions in atmospheric layers makes the exact strength of cooling very difficult to estimate. (from Causes of climate change)
Image 15Terms like "climate emergency" and climate crisis" have often been used by activists, and are increasingly found in academic papers. (from History of climate change science)
Image 16Human fingerprints for global warming (summary of observational evidence that human carbon dioxide emissions are causing the climate to warm). (from Causes of climate change)
Image 17Milutin Milanković (from History of climate change science)
Image 18Correspondence between temperature and atmospheric CO₂ during the last 800,000 years (from Carbon dioxide in the atmosphere of Earth)
Image 19Brown bars indicate drivers that increase global warming, and blue bars indicate those that decrease global warming. Future global warming potential for long lived drivers like carbon dioxide emissions is not represented. (from Causes of climate change)
Image 20Since the 1980s, global average surface temperatures during a given decade have almost always been higher than the average temperature in the preceding decade. (from History of climate change science)
Image 21Annual CO₂ flows from anthropogenic sources (left) into Earth's atmosphere, land, and ocean sinks (right) since year 1960. Units in equivalent gigatonnes carbon per year. (from Carbon dioxide in the atmosphere of Earth)
Image 22Eunice Newton Foote recognized carbon dioxide's heat-capturing effect in 1856, appreciating its implications for the planet. (from History of climate change science)
Image 23Main sources of global methane emissions (2008–2017) according to the Global Carbon Project (from Causes of climate change)
Image 24Warming influence of atmospheric greenhouse gases has nearly doubled since 1979, with carbon dioxide and methane being the dominant drivers. (from Causes of climate change)
Image 25Earth's energy balance and imbalance, showing where the excess energy goes: Outgoing radiation is decreasing owing to increasing greenhouse gases in the atmosphere, leading to Earth's energy imbalance of about 460 TW. The percentage going into each domain of the climate system is also indicated. (from Earth's energy budget)
Image 26The US, China and Russia have cumulatively contributed the greatest amounts of CO₂ since 1850. (from Carbon dioxide in the atmosphere of Earth)
Image 27Increase in the Earth's non-cloud greenhouse effect (2000–2022) based on satellite data (from Earth's energy budget)
Image 28A diagram which shows where the extra heat retained on Earth due to the energy imbalance is going.
Image 29Energy flows between space, the atmosphere, and Earth's surface. Rising greenhouse gas levels are contributing to an energy imbalance. (from Causes of climate change)
Image 30Erratics, boulders deposited by glaciers far from any existing glaciers, led geologists to the conclusion that climate had changed in the past. (from History of climate change science)
Image 31Charles Keeling, receiving the National Medal of Science from George W. Bush, in 2001 (from History of climate change science)
Image 32Longwave-infrared absorption coefficients of water vapor and carbon dioxide. For wavelengths near 15-microns, CO₂ is a much stronger absorber than water vapor. (from Carbon dioxide in the atmosphere of Earth)
Image 33Air-sea exchange of CO₂ (from Carbon dioxide in the atmosphere of Earth)
Image 34James Croll (from History of climate change science)
Image 35Observed temperature vs the 1850–1900 average used by the IPCC as a pre-industrial baseline. The primary driver for increased global temperatures in the industrial era is human activity, with natural forces adding variability. (from Causes of climate change)
Image 36CO₂ sources and sinks since 1880. While there is little debate that excess carbon dioxide in the industrial era has mostly come from burning fossil fuels, the future strength of land and ocean carbon sinks is an area of study. (from Causes of climate change)
Image 37Global average temperatures show that the Medieval Warm Period was not a planet-wide phenomenon, and that the Little Ice Age was not a distinct planet-wide time period but rather the end of a long temperature decline that preceded recent global warming. (from Temperature record of the last 2,000 years)
Image 38The Keeling Curve shows the long-term increase of atmospheric carbon dioxide (CO₂) concentrations since 1958. (from Causes of climate change)
Image 39Top panel: Observed global average temperature change (1870— ).Bottom panel: Data from the Fourth National Climate Assessment is merged for display on the same scale to emphasize relative strengths of forces affecting temperature change. Human-caused forces have increasingly dominated.
(from Causes of climate change)
Image 40Anthropogenic global warming—not global cooling or "imminent ice ages"—dominated peer-reviewed literature in the 1970s, contrary to false claims that climate science subsequently reversed its consensus. (from History of climate change science)
Image 41CO₂ reduces the flux of thermal radiation emitted to space (causing the large dip near 667 cm⁻¹), thereby contributing to the greenhouse effect. (from Carbon dioxide in the atmosphere of Earth)
Image 42Earth's energy imbalance has increased in the 21st century, reaching values twice that of prior estimates from the IPCC. The ability to observe this imbalance is deteriorating because satellites are being decommissioned. (from Earth's energy budget)
Image 43Carbon dioxide observations from 2008 to 2017 showing the seasonal variations and the difference between northern and southern hemispheres (from Carbon dioxide in the atmosphere of Earth)
Image 44Extreme event attribution methods generally involve applying climate change models to scenarios in both the "real" world that is experiencing global warming, and a simulated world that does not suffer the drivers of global warming. Differences between the results of the two processes—especially the frequency, intensity and impacts of extreme weather events—are then analyzed to arrive at the attribution result. (from History of climate change science)
Image 45Meat from cattle and sheep have the highest emissions intensity of any agricultural commodity. (from Causes of climate change)
Image 46The concentration of atmospheric carbon dioxide has been increasing in progressively greater amounts. (from Carbon dioxide in the atmosphere of Earth)
Image 47The growth in Earth's energy imbalance from satellite and in situ measurements (2005–2019). A rate of +1.0 W/m² summed over the planet's surface equates to a continuous heat uptake of about 500 terawatts (~0.3% of the incident solar radiation). (from Earth's energy budget)
Image 48Exterior of a Stevenson screen used for temperature measurements on land stations. (from History of climate change science)
Image 49Modeled simulation of the effect of various factors (including GHGs, Solar irradiance) singly and in combination, showing in particular that solar activity produces a small and nearly uniform warming, unlike what is observed. (from History of climate change science)
Image 50Over 400,000 years of ice core data: Graph of CO₂ (green), reconstructed temperature (blue) and dust (red) from the Vostok ice core (from Carbon dioxide in the atmosphere of Earth)

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... that global warming of the average air temperature rose 0.74 ± 0.18 °C (1.3 ± 0.32 °F) during the past century?

(Pictured left: Animated global map of monthly long term mean surface air temperature (Mollweide projection))

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Climate change in the Arctic

Credit: NASA

the Arctic temperature trend between August 1981 and July 2009. Due to global warming, which is exacerbated at the Arctic, there's a significant warming over this 28 year period.