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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A runaway greenhouse effect occurs when a planet's atmosphere contains greenhouse gas in an amount sufficient to block thermal radiation from leaving the planet, preventing the planet from cooling and from having liquid water on its surface. A runaway version of the greenhouse effect can be defined by a limit on a planet's outgoing longwave radiation, which is asymptotically reached due to higher surface temperatures evaporating water into the atmosphere, increasing its optical depth. This positive feedback loop means the planet cannot cool down through longwave radiation (via the Stefan–Boltzmann law) and continues to heat up until it can radiate outside of the absorption bands of the water vapour.

The runaway greenhouse effect is often formulated with water vapour as the condensable species. The water vapour reaches the stratosphere and escapes into space via hydrodynamic escape, resulting in a desiccated planet. This likely happened in the early history of Venus.

A 2012 study on climate change indicated that "Earth presently absorbs around 240 W m⁻² of solar radiation. Increasing carbon dioxide concentration will make surface warmer with the same outgoing thermal flux. Following this theory, we are not near the threshold of a runaway greenhouse. However, the behaviour of hot, water-vapour-rich atmospheres is poorly understood, and an in-depth study of these is necessary." (Full article...)

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Sea ice

Credit: NASA

This image shows the Arctic as observed by the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) aboard NASA’s Aqua satellite on September 16, 2007. The image denotes a record sea ice minimum in the Arctic.

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WikiProjects


WikiProject Climate change	WikiProject Environment	WikiProject Globalization

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Mafalda Duarte in 2013

Mafalda Duarte is the executive director of the Green Climate Fund, the largest multilateral climate fund in the world. Duarte previously worked at the African Development Bank and World Bank, and has served as CEO of the Climate Investment Funds, managing a portfolio of investments for over 70 countries. She was considered one of the "100 Most Influential Climate Leaders in Business for 2023" by TIME magazine and as the third most powerful woman in business in Portugal in 2023 by Forbes Portugal.

Duarte emphasizes the need for funders to be proactive and work collectively to ensure that poorer countries which have little administrative capacity still get access to aid. She emphasizes the importance of investing in developing nations and including women in decision-making. (Full article...)

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General images

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

Image 1A Sankey diagram illustrating a balanced example of Earth's energy budget. Line thickness is linearly proportional to relative amount of energy. (from Earth's energy budget)
Image 2Increase in the Earth's non-cloud greenhouse effect (2000–2022) based on satellite data (from Earth's energy budget)
Image 3Greenhouse gases allow sunlight to pass through the atmosphere, heating the planet, but then absorb and redirect the infrared radiation (heat) the planet emits. (from Carbon dioxide in the atmosphere of Earth)
Image 4Concentration 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 5Main sources of global methane emissions (2008–2017) according to the Global Carbon Project (from Causes of climate change)
Image 6Meat from cattle and sheep have the highest emissions intensity of any agricultural commodity. (from Causes of climate change)
Image 7Solar irradiance (yellow) plotted with temperature (red) since 1880. (from History of climate change science)
Image 8Erratics, 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 9Scientific consensus on causation: Academic studies of scientific agreement on human-caused global warming among climate experts (2010–2015) reflect that the level of consensus correlates with expertise in climate science.
A 2019 study found scientific consensus to be at 100%, and a 2021 study concluded that consensus exceeded 99%. Another 2021 study found that 98.7% of climate experts indicated that the Earth is getting warmer mostly because of human activity. (from History of climate change science)
Image 10Milutin Milanković (from History of climate change science)
Image 11Between 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 12Since 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 13Schematic drawing of Earth's excess heat inventory and energy imbalance for two recent time periods (from Earth's energy budget)
Image 14Joseph Fourier (from History of climate change science)
Image 15Sea 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 16Air 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 17Earth'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 18The Keeling Curve shows the long-term increase of atmospheric carbon dioxide (CO₂) concentrations since 1958. (from Causes of climate change)
Image 19The concentration of atmospheric carbon dioxide has been increasing in progressively greater amounts. (from Carbon dioxide in the atmosphere of Earth)
Image 20CO₂ 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 21James Croll (from History of climate change science)
Image 22The 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 23Annual 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 24Atmospheric 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 25A diagram which shows where the extra heat retained on Earth due to the energy imbalance is going.
Image 26CO₂ concentrations over the last 800,000 years as measured from ice cores (blue/green) and directly (black) (from Causes of climate change)
Image 27John 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 28James Hansen during his 1988 testimony to Congress, which alerted the public to the dangers of global warming (from History of climate change science)
Image 29Air-sea exchange of CO₂ (from Carbon dioxide in the atmosphere of Earth)
Image 30Warming 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 31Exterior of a Stevenson screen used for temperature measurements on land stations. (from History of climate change science)
Image 32Over 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)
Image 33The rate of global tree cover loss has approximately doubled since 2001, to an annual loss approaching an area the size of Italy. (from Causes of climate change)
Image 34The 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 35Earth heating estimates from a combination of space altimetry and space gravimetry (from Earth's energy budget)
Image 36Extreme 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 37Eunice Newton Foote recognized carbon dioxide's heat-capturing effect in 1856, appreciating its implications for the planet. (from History of climate change science)
Image 38The 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 39Earth'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 40The US, China and Russia have cumulatively contributed the greatest amounts of CO₂ since 1850. (from Carbon dioxide in the atmosphere of Earth)
Image 41CO₂ 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 42Brown 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 43Modeled 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 44Longwave-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 45Top 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 46CO₂ concentrations over the last 500 million years (from Carbon dioxide in the atmosphere of Earth)
Image 47The Fourth National Climate Assessment ("NCA4", USGCRP, 2017) includes charts illustrating that neither solar nor volcanic activity can explain the observed warming. (from Causes of climate change)
Image 48Anthropogenic 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 49Mean 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 50Terms 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)

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... that seagrass meadows hold twice as much carbon dioxide as rain forests per hectare?

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Glacier retreat

Credit: U.S. Geological Survey – Northern Rocky Mountain Science Center (NOROCK) Authors: Myrna H. P. Hall and Daniel B. Fagre, 2003

Animation of Modeled Climate-Induced Glacier Change in Glacier National Park, 1850- 2100. The simulation reflects the predicted exponential rise in atmospheric carbon dioxide (CO₂) concentrations, a 2xCO₂ "global warming" scenario, with a concurrent warming of 2-3 degrees centigrade (4-5 degrees Fahrenheit) by the year 2050. In addition it assumes that precipitation, primarily in the form of rain, will increase over the same time period about 10 percent (based on the research of Dr. Steven Running, University of Montana).