The Climate Change Portal

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

Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns. There have been previous periods of climate change, but the current changes are more rapid than any known events in Earth's history. The main cause is the emission of greenhouse gases, mostly carbon dioxide (CO2) and methane. Burning fossil fuels for energy use creates most of these emissions. Agriculture, steelmaking, cement production, and forest loss are additional sources. Temperature rise is also affected by climate feedbacks such as the loss of sunlight-reflecting snow cover, and the release of carbon dioxide from drought-stricken forests. Collectively, these amplify global warming.

On land, temperatures have risen about twice as fast as the global average. 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 and other weather extremes. In places such as coral reefs, mountains, and the Arctic, many species are forced to relocate or become extinct, as their environment changes. Climate change threatens people with food and water scarcity, increased flooding, extreme heat, more disease, and economic loss. It can also drive human migration. The World Health Organization calls climate change the greatest threat to global health in the 21st century. Even if efforts to minimise future warming are successful, some effects will continue for centuries. These include sea level rise, and warmer, more acidic oceans.

Many of these impacts are already felt at the current level of warming, which is about 1.2 °C (2 °F). The Intergovernmental Panel on Climate Change (IPCC) projects even greater impacts as warming continues to 1.5 °C and beyond. Additional warming also increases the risk of triggering tipping points, such as the melting of the Greenland ice sheet. Responding to these changes involves taking actions to limit the amount of warming, and adapting to them. Future warming can be reduced (mitigated) by lowering greenhouse gas emissions and removing them from the atmosphere. This will involve using more wind and solar energy, phasing out coal, and increasing energy efficiency. Switching to electric vehicles, and to heat pumps for homes and commercial buildings, will further limit emissions. Prevention of deforestation and enhancing forests can help absorb CO2. Some communities may adapt to climate change through better coastline protection, disaster management, and development of more resistant crops. By themselves, these efforts to adapt cannot avert the risk of severe, widespread and permanent impacts.

Under the 2015 Paris Agreement, nations collectively agreed to keep warming "well under 2 °C" through mitigation efforts. However, with pledges made under the Agreement, global warming would still reach about 2.7 °C 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. (Full article...)

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Past (prior to 2017) and projected (up to year 2100) Köppen-Geiger climate classification maps.
Past (prior to 2017) and projected (up to year 2100) Köppen-Geiger climate classification maps.

Regional effects of climate change are long-term significant changes in the expected patterns of average weather of a specific region due to climate change. The world average temperature is rising due to the greenhouse effect caused by increasing levels of greenhouse gases, especially carbon dioxide. When the global temperature changes, the changes in climate are not expected to be uniform across the Earth. In particular, land areas change more quickly than oceans, and northern high latitudes change more quickly than the tropics, and the margins of biome regions change faster than do their cores.

Regional effects of climate change vary in nature. Some are the result of a generalised global change, such as rising temperature, resulting in local effects, such as melting ice. In other cases, a change may be related to a change in a particular ocean current or weather system. In such cases, the regional effect may be disproportionate and will not necessarily follow the global trend. The increasing temperatures from greenhouse gases have been causing sea levels to rise for many years.

There are three major ways in which global warming will make changes to regional climate: melting or forming ice, changing the hydrological cycle (of evaporation and precipitation) and changing currents in the oceans and air flows in the atmosphere. The coast can also be considered a region, and will suffer severe impacts from sea level rise. (Full article...)
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Image: Marit Jentoft-Nilsen, NASA
An image of the Earth's cloud cover, which is the amount of sky obscured by clouds, based largely on observations from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Terra satellite. Clouds play multiple critical roles in the climate system. In particular, being bright objects in the visible part of sunlight, they efficiently reflect light to space and thus contribute to the cooling of the planet.


In the news

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Sunita Narain
Sunita Narain

Sunita Narain is an Indian environmentalist and political activist as well as a major proponent of the Green concept of sustainable development. Narain is director general of the India-based research institute for the Centre for Science and Environment, director of the Society for Environmental Communications, and editor of the fortnightly magazine, Down To Earth.

In 2016 Narain was named to Time Magazines list of 100 Most Influential People. ('Full article...)

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

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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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Credit: Mike Scalora
A view of Sand Mountain campground from the side of Sand Mountain at Little Sahara Recreation Area in Utah. The Little Sahara sand dunes are remnants of a large river delta formed by the Sevier River from about 12,500 to 20,000 years ago. The river emptied into ancient Lake Bonneville near the present day mouth of Leamington Canyon. After Lake Bonneville receded, winds transported the sand from the river delta to the current location. The dunes are still moving 5 to 9 feet (1.5 to 3 m) per year. The area is home to typical Great Basin desert wildlife including mule deer, pronghorn antelope, snakes, lizards and birds of prey. Great horned owls make their home among juniper trees in the Rockwell Natural Area.



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  1. ^ Bhargav, Vishal (2021-10-11). "Climate Change Is Making India's Monsoon More Erratic". Retrieved 2021-10-11.
  2. ^ Tiwari, Dr Pushp Raj; Conversation, The. "Nobel prize: Why climate modellers deserved the physics award – they've been proved right again and again". Retrieved 2021-10-11.


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