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. Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global temperatures is driven by human activities, especially fossil fuel 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. Carbon dioxide, the primary gas driving global warming, has increased in concentration by about 50% since the pre-industrial era to levels not seen for millions of years.

Climate change has an increasingly large impact on the environment. Deserts are expanding, while 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. Limiting warming to 1.5 °C would require halving emissions by 2030 and achieving net-zero emissions by 2050.

There is widespread support for climate action worldwide. Fossil fuel use can be phased out by 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 capture 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 five known icehouse periods in Earth's climate history, namely the Huronian, Cryogenian, Andean-Saharan (also known as Early Paleozoic), Late Paleozoic 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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Ocean

Credit: User: Splette

The Ocean Circulation Conveyor Belt. The ocean plays a major role in the distribution of the planet's heat through deep sea circulation. This simplified illustration shows this "conveyor belt" circulation.

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WikiProjects


WikiProject Climate change	WikiProject Environment	WikiProject Globalization

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In the news

From the Wikinews Climate change category

Additional News

Monsoons in India become more erratic.^[2]
Climate modellers Syukuro Manabe and Klaus Hasselmann win Nobel Prize.^[3]

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Official portrait, 2010

Carol Martha Browner (born December 16, 1955) is an American lawyer, environmentalist and businesswoman who served as director of the White House Office of Energy and Climate Change Policy in the Obama administration from 2009 to 2011. Browner previously served as Administrator of the Environmental Protection Agency (EPA) during the Clinton administration from 1993 to 2001. She currently works as a Senior Counselor at Albright Stonebridge Group, a global business strategy firm.

Browner grew up in Florida and graduated from the University of Florida and the University of Florida College of Law. After working for the Florida House of Representatives, she was employed by Citizen Action in Washington, D.C. She became a legislative assistant for Senators Lawton Chiles and Al Gore. Browner then headed the Florida Department of Environmental Regulation from 1991 to 1993, where she turned it into one of the most active departments in the state government.

She was the longest-serving administrator in the history of the EPA, staying through both terms of the Clinton presidency. During her tenure, she reorganized the agency's enforcement structure and oversaw two new programs designed to create flexible partnerships with industry as an alternative to traditional regulation. She started a successful program to deal with contaminated lands in urban areas. She took the lead within the administration in defending existing environmental laws and budgets and was the driving force behind a stringent tightening of air quality standards that led to a prolonged political and legal battle. (Full article...)

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General images

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

Image 1Air 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 2The Keeling Curve shows the long-term increase of atmospheric carbon dioxide (CO₂) concentrations since 1958. (from Causes of climate change)
Image 3The 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 4This diagram of the carbon cycle shows the movement of carbon between land, atmosphere, and oceans in billions of metric tons of carbon per year. Yellow numbers are natural fluxes, red are human contributions, white are stored carbon. (from Carbon dioxide in Earth's atmosphere)
Image 5Cumulative land-use change contributions to CO₂ emissions, by region. (from Causes of climate change)
Image 6Over 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 Earth's atmosphere)
Image 7Terms 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 8Modeled 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 9Concentration 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 Earth's atmosphere)
Image 10Exterior of a Stevenson screen used for temperature measurements on land stations. (from History of climate change science)
Image 11Global 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 12Energy 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 13Earth's energy budget (in W/m²) determines the climate. It is the balance of incoming and outgoing radiation and can be measured by satellites. The Earth's energy imbalance is the "net absorbed" energy amount and grew from +0.6 W/m² (2009 est.) to above +1.0 W/m² in 2019. (from Earth's energy budget)
Image 14Longwave-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 Earth's atmosphere)
Image 15The 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 16Mean 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 17CO₂ concentrations over the last 500 Million years (from Carbon dioxide in Earth's atmosphere)
Image 18Meat from cattle and sheep have the highest emissions intensity of any agricultural commodity. (from Causes of climate change)
Image 19Solar irradiance (yellow) plotted with temperature (red) since 1880. (from History of climate change science)
Image 20Annual 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 Earth's atmosphere)
Image 21Correspondence between temperature and atmospheric CO₂ during the last 800,000 years (from Carbon dioxide in Earth's atmosphere)
Image 22Increase in the Earth's non-cloud greenhouse effect (2000–2022) based on satellite data. (from Earth's energy budget)
Image 23Charles Keeling, receiving the National Medal of Science from George W. Bush, in 2001 (from History of climate change science)
Image 24Physical drivers of global warming that has happened so far. Future global warming potential for long lived drivers like carbon dioxide emissions is not represented. Whiskers on each bar show the possible error range. (from Carbon dioxide in Earth's atmosphere)
Image 25Schematic drawing of Earth's excess heat inventory and energy imbalance for two recent time periods. (from Earth's energy budget)
Image 26CO₂ 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 Earth's atmosphere)
Image 27A diagram which shows where the extra heat retained on Earth due to the energy imbalance is going.
Image 28CO₂ concentrations over the last 800,000 years as measured from ice cores (blue/green) and directly (black) (from Causes of climate change)
Image 29The 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 30Milutin Milanković (from History of climate change science)
Image 31Atmospheric 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 Earth's atmosphere)
Image 32Erratics, 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 33Drivers of climate change from 1850–1900 to 2010–2019. Future global warming potential for long lived drivers like carbon dioxide emissions is not represented. (from Causes of climate change)
Image 34Earth'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 35Greenhouse 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 Earth's atmosphere)
Image 36Warming 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 37CO₂ 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 38James Croll (from History of climate change science)
Image 39A 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 40Earth heating estimates from a combination of space altimetry and space gravimetry. (from Earth's energy budget)
Image 41The 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 42John 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 43Air-sea exchange of CO₂ (from Carbon dioxide in Earth's atmosphere)
Image 44James Hansen during his 1988 testimony to Congress, which alerted the public to the dangers of global warming (from History of climate change science)
Image 45The impact of the greenhouse effect on climate was presented to the public early in the 20th century, as succinctly described in this 1912 Popular Mechanics article. (from History of climate change science)
Image 46Main sources of global methane emissions (2008–2017) according to the Global Carbon Project (from Causes of climate change)
Image 47Carbon dioxide observations from 2008 to 2017 showing the seasonal variations and the difference between northern and southern hemispheres (from Carbon dioxide in Earth's atmosphere)
Image 48Sea 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 49Since 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 50Observed temperature from NASA 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 51Joseph Fourier (from History of climate change science)
Image 52Eunice Newton Foote recognized carbon dioxide's heat-capturing effect in 1856, appreciating its implications for the planet. (from History of climate change science)
Image 53The US, China and Russia have cumulatively contributed the greatest amounts of CO₂ since 1850. (from Carbon dioxide in Earth's atmosphere)
Image 54Scientific 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 55The Global Carbon Project shows how additions to CO₂ since 1880 have been caused by different sources ramping up one after another. (from Causes of climate change)
Image 56Between 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 Earth's atmosphere)

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... that global warming millions of years ago put seas in a spin? The circulation of the deep oceans reversed abruptly some 55 million years ago, according to a study of fossilized sea creatures. This rings alarm bells about today's climate change, because the reversal coincided with a period of global warming driven by greenhouse gases." Article on Nature News

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Sea level

Credit: NOAA Laboratory for Satellite Altimetry

Sea level trends between 1993 and 2010. Per the U.S. National Oceanic and Atmospheric Administration (NOAA), "The following maps provide estimates of sea level rise based on measurements from satellite radar altimeters. The local trends were estimated using data from TOPEX/Poseidon (T/P), Jason-1, and Jason-2, which have monitored the same ground track since 1992. An inverted barometer has been applied. The estimates of sea level rise do not include glacial isostatic adjustment effects on the geoid, which are modeled to be +0.2 to +0.5 mm/year when globally averaged."