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The Climate Change Portal

Average surface air temperatures from 2011 to 2020 compared to the 1951-1980 average. Source: NASA.

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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. The current rise in global average temperature is more rapid than previous changes, and is primarily caused by humans burning fossil fuels. Fossil fuel use, deforestation, and some agricultural and industrial practices increase greenhouse gases, notably carbon dioxide and methane. Greenhouse gases absorb some of the heat that the Earth radiates after it warms from sunlight. Larger amounts of these gases trap more heat in Earth's lower atmosphere, causing global warming.

Due to climate change, deserts are expanding, while heat waves and wildfires are becoming more common. Increased warming in the Arctic has contributed to melting permafrost, glacial retreat and sea ice loss. 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 minimise 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 (WHO) calls climate change the greatest threat to global health in the 21st century. Societies and ecosystems will experience more severe risks in the future without action to limit warming. Adapting to climate change through efforts like flood control measures or drought-resistant crops reduces climate change risks, although this may not be possible with increasing warming. Poorer countries are responsible for a small share of global emissions, yet they have the least ability to adapt and are most vulnerable to climate change.

Many climate change impacts are already felt at the current 1.2 °C (2.2 °F) level of warming. Additional warming will increase these impacts and can trigger tipping points, such as the melting 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 2.7 °C (4.9 °F) by the end of the century. Limiting warming to 1.5 °C will require halving emissions by 2030 and achieving net-zero emissions by 2050.

Reducing emissions requires generating electricity from low-carbon sources rather than burning fossil fuels. This change includes phasing out coal and natural gas fired power plants, vastly increasing use of wind, solar, and other types of renewable energy, and reducing energy use. Electricity generated from non-carbon-emitting sources will need to replace fossil fuels for powering transportation, heating buildings, and operating industrial facilities. Carbon can also be removed from the atmosphere, for instance by increasing forest cover and by farming with methods that capture carbon in soil. ( Full article...)

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Trends in atmospheric CO₂ and global temperature change and climate policies

Climate crisis is a term describing global warming and climate change, and their impacts. This term and the term climate emergency have been used to describe the threat of global warming to humanity and the planet, and to urge aggressive climate change mitigation. In the scientific journal BioScience, a January 2020 article, endorsed by over 11,000 scientists worldwide, stated that "the climate crisis has arrived" and that an "immense increase of scale in endeavors to conserve our biosphere is needed to avoid untold suffering due to the climate crisis."

The term is applied by those who "believe it evokes the gravity of the threats the planet faces from continued greenhouse gas emissions and can help spur the kind of political willpower that has long been missing from climate advocacy". They believe that, much as "global warming" drew out more emotional engagement and support for action than "climate change", calling climate change a crisis could have an even stronger impact.

A study has shown that the term invokes a strong emotional response in conveying a sense of urgency; some caution that this response may be counter-productive, and may cause a backlash effect due to perceptions of alarmist exaggeration. ( Full article...)

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Larsen Ice Shelf

Credit: NASA

The collapse of Larsen B Ice Shelf, showing the diminishing extent of the shelf from 1998 to 2002

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WikiProjects


WikiProject Climate change	WikiProject Environment	WikiProject Globalization

In the news

From the Wikinews Climate change category

Additional News

Monsoons in India become more erratic.^[1]
Climate modellers Syukuro Manabe and Klaus Hasselmann win Nobel Prize.^[2]

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Fatih Birol is a Turkish economist and energy expert, who has served as the executive director of the International Energy Agency (IEA) since 1 September 2015. During his time in charge of the IEA, he has taken a series of steps to modernise the Paris-based international organisation, including strengthening ties with emerging economies like India and China and stepping up work on the clean energy transition and international efforts to reach net zero emissions.

Birol was on the Time 100 list of the world's most influential people in 2021, has been named by Forbes magazine among the most influential people on the world's energy scene and recognised by the Financial Times in 2017 as Energy Personality of the Year. Birol is the chairman of the World Economic Forum (Davos) Energy Advisory Board. He is a frequent contributor to print and electronic media and delivers numerous speeches each year at major international summits and conferences. ( Full article...)

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General images

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

Image 1Air-sea exchange of CO₂ (from Carbon dioxide in Earth's atmosphere)
Image 2The US, China and Russia have cumulatively contributed the greatest amounts of CO₂ since 1850. (from Carbon dioxide in Earth's atmosphere)
Image 3Schematic drawing of Earth's excess heat inventory as it relates to the planet's energy imbalance for two recent time periods. (from Earth's energy budget)
Image 4Mean 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 5This diagram of the fast 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 6Scientific 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 7Energy flows between space, the atmosphere, and Earth's surface. Rising greenhouse gas levels are contributing to an energy imbalance of about +0.9 W/m². (from Attribution of recent climate change)
Image 8 Radiative forcing drivers of climate change in year 2011, relative to pre-industrial (1750). (from Carbon dioxide in Earth's atmosphere)
Image 9Frequency of occurrence (vertical axis) of local June–July–August temperature anomalies (relative to 1951–1980 mean) for Northern Hemisphere land in units of local standard deviation (horizontal axis). According to Hansen et al. (2012), the distribution of anomalies has shifted to the right as a consequence of global warming, meaning that unusually hot summers have become more common. This is analogous to the rolling of a dice: cool summers now cover only half of one side of a six-sided die, white covers one side, red covers four sides, and an extremely hot (red-brown) anomaly covers half of one side. (from Attribution of recent climate change)
Image 10Since 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 11Carbon dioxide observations from 2005 to 2014 showing the seasonal variations and the difference between northern and southern hemispheres (from Carbon dioxide in Earth's atmosphere)
Image 12Greenhouse gases allow sunlight to pass through the atmosphere, heating the planet, but then absorb and re-radiate the infrared radiation (heat) the planet emits (from Carbon dioxide in Earth's atmosphere)
Image 13CO₂ concentrations over the last 500 Million years (from Carbon dioxide in Earth's atmosphere)
Image 14Charles Keeling, receiving the National Medal of Science from George W. Bush, in 2001 (from History of climate change science)
Image 15Top 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 Attribution of recent climate change)
Image 16Observed 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 Attribution of recent climate change)
Image 17The 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 18Correspondence between temperature and atmospheric CO₂ during the last 800,000 years (from Carbon dioxide in Earth's atmosphere)
Image 19Solar irradiance (yellow) plotted with temperature (red) since 1880. (from Attribution of recent climate change)
Image 20Concentration 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 21This image shows three examples of internal climate variability measured between 1950 and 2012: the El Niño–Southern oscillation, the Arctic oscillation, and the North Atlantic oscillation. (from Attribution of recent climate change)
Image 22The rate of global tree cover loss has approximately doubled since 2001, to an annual loss approaching an area the size of Italy. (from Attribution of recent climate change)
Image 23Scientific 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 Attribution of recent climate change)
Image 24The 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 25Modeled 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 Attribution of recent climate change)
Image 26A 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 27Contribution to climate change broken down by economic sectors, according to the IPCC AR5 report. (from Attribution of recent climate change)
Image 28James Croll (from History of climate change science)
$Image 29Probability density function (PDF) of fraction of surface temperature trends since 1950 attributable to human activity, based on IPCC AR5 10.5 (from Attribution of recent climate change)$

Image 29 Probability density function (PDF) of fraction of surface temperature trends since 1950 attributable to human activity, based on IPCC AR5 10.5 (from Attribution of recent climate change)
Image 30Graph of CO₂ (green), reconstructed temperature (blue) and dust (red) from the Vostok ice core for the past 420,000 years (from Carbon dioxide in Earth's atmosphere)
Image 31 Erratics, 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 32Atmospheric CO₂ concentrations measured at Mauna Loa Observatory from 1958 to 2022 (also called the Keeling Curve). Carbon dioxide concentrations have varied widely over the Earth's 4.54 billion year history. However, in 2013 the daily mean concentration of CO₂ in the atmosphere surpassed 400 parts per million ( ppmv) - this level has never been reached since the mid-Pliocene, 2 to 4 million years ago. (from Carbon dioxide in Earth's atmosphere)
Image 33The greenhouse effect traps infrared heat, and ultimately raises Earth's surface temperatures. (from Earth's energy budget)
Image 34Annual 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 35Milutin Milanković (from History of climate change science)
Image 36Earth's climate is largely determined by the planet's energy budget, i.e., the balance of incoming and outgoing radiation. It is measured by satellites and shown in W/m². The imbalance (or rate of global heating; shown in figure as the "net absorbed" amount) grew from +0.6 W/m² (2009 est.) to above +1.0 W/m² in 2019. (from Earth's energy budget)
Image 37The Keeling Curve shows the long-term increase of atmospheric carbon dioxide (CO₂) concentrations from 1958–2018. Monthly CO₂ measurements display seasonal oscillations in an upward trend. Each year's maximum occurs during the Northern Hemisphere's late spring. (from Attribution of recent climate change)
Image 38Between 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)
Image 39 James Hansen during his 1988 testimony to Congress, which alerted the public to the dangers of global warming (from History of climate change science)
Image 40In detection and attribution, natural factors include changes in the Sun's output and volcanic eruptions, as well as natural modes of variability such as El Niño and La Niña. Human factors include the emissions of heat-trapping "greenhouse" gases and particulates as well as clearing of forests and other land-use changes. Figure source: NOAA NCDC. (from Attribution of recent climate change)
Image 41Global 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 42Cumulative land-use change contributions to emissions, by region. (from Attribution of recent climate change)
Image 43 John Tyndall's ratio spectrophotometer (drawing from 1861) measured how much infrared radiation was absorbed and emitted by various gases filling its central tube. (from History of climate change science)
Image 44CO₂ 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 Attribution of recent climate change)
Image 45Photosynthesis changes sunlight into chemical energy, splits water to liberate O₂, and fixes CO₂ into sugar. (from Carbon dioxide in Earth's atmosphere)
Image 46Joseph Fourier (from History of climate change science)

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... that global warming is cited as the main reason why southern England is becoming suitable for wine production and that it has similar soils and latitude to the Champagne region of France?

(Pictured left: A vineyard in Wyken, a suburb of Coventry, England)

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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.