The cryosphere is an all-encompassing term for the portions of Earth's surface where water is in solid form, including sea ice, lake ice, river ice, snow cover, glaciers, ice caps, ice sheets, and frozen ground. Thus, there is a wide overlap with the hydrosphere. The cryosphere is an integral part of the global climate system. It also has important feedbacks on the climate system. These feedbacks come from the cryosphere's influence on surface energy and moisture fluxes, clouds, the water cycle, atmospheric and oceanic circulation.
In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than 50,000 km2 (19,000 sq mi). The only current ice sheets are the Antarctic ice sheet and the Greenland ice sheet. Ice sheets are bigger than ice shelves or alpine glaciers. Masses of ice covering less than 50,000 km2 are termed an ice cap. An ice cap will typically feed a series of glaciers around its periphery.
The West Antarctic Ice Sheet (WAIS) is the segment of the continental ice sheet that covers West Antarctica, the portion of Antarctica on the side of the Transantarctic Mountains that lies in the Western Hemisphere. It is classified as a marine-based ice sheet, meaning that its bed lies well below sea level and its edges flow into floating ice shelves. The WAIS is bounded by the Ross Ice Shelf, the Ronne Ice Shelf, and outlet glaciers that drain into the Amundsen Sea.
The Antarctic ice sheet is a continental glacier covering 98% of the Antarctic continent, with an area of 14 million square kilometres and an average thickness of over 2 kilometres (1.2 mi). It is the largest of Earth's two current ice sheets, containing 26.5 million cubic kilometres of ice, which is equivalent to 61% of all fresh water on Earth. Its surface is nearly continuous, and the only ice-free areas on the continent are the dry valleys, nunataks of the Antarctic mountain ranges, and sparse coastal bedrock. However, it is often subdivided into East Antarctic ice sheet (EAIS), West Antarctic ice sheet (WAIS), and Antarctic Peninsula (AP), due to the large differences in topography, ice flow, and glacier mass balance between the three regions.
The Cooperative Institute for Research in Environmental Sciences (CIRES) is a research institute that is sponsored jointly by the National Oceanic and Atmospheric Administration (NOAA) Office of Oceanic and Atmospheric Research (OAR) and the University of Colorado Boulder (CU). CIRES scientists study the Earth system, including the atmosphere, hydrosphere, cryosphere, biosphere, and geosphere, and communicate these findings to decision makers, the scientific community, and the public.
Effects of climate change are well documented and growing for Earth's natural environment and human societies. Changes to the climate system include an overall warming trend, changes to precipitation patterns, and more extreme weather. As the climate changes it impacts the natural environment with effects such as more intense forest fires, thawing permafrost, and desertification. These changes impact ecosystems and societies, and can become irreversible once tipping points are crossed. Climate activists are engaged in a range of activities around the world that seek to ameloriate these issues or prevent them from happening.
Economic analysis of climate change is about using economic tools and models to calculate the magnitude and distribution of damages caused by climate change. It can also give guidance for the best policies for mitigation and adaptation to climate change from an economic perspective. There are many economic models and frameworks. For example, in a cost–benefit analysis, the trade offs between climate change impacts, adaptation, and mitigation are made explicit. For this kind of analysis, integrated assessment models (IAMs) are useful. Those models link main features of society and economy with the biosphere and atmosphere into one modelling framework. The total economic impacts from climate change are difficult to estimate. In general, they increase the more the global surface temperature increases.
Due to climate change in the Arctic, this polar region is expected to become "profoundly different" by 2050. The speed of change is "among the highest in the world", with the rate of warming being 3-4 times faster than the global average. This warming has already resulted in the profound Arctic sea ice decline, the accelerating melting of the Greenland ice sheet and the thawing of the permafrost landscape. These ongoing transformations are expected to be irreversible for centuries or even millennia.
In climate science, a tipping point is a critical threshold that, when crossed, leads to large, accelerating and often irreversible changes in the climate system. If tipping points are crossed, they are likely to have severe impacts on human society and may accelerate global warming. Tipping behavior is found across the climate system, for example in ice sheets, mountain glaciers, circulation patterns in the ocean, in ecosystems, and the atmosphere. Examples of tipping points include thawing permafrost, which will release methane, a powerful greenhouse gas, or melting ice sheets and glaciers reducing Earth's albedo, which would warm the planet faster. Thawing permafrost is a threat multiplier because it holds roughly twice as much carbon as the amount currently circulating in the atmosphere.
The Potsdam Institute for Climate Impact Research is a German government-funded research institute addressing crucial scientific questions in the fields of global change, climate impacts, and sustainable development. Ranked among the top environmental think tanks worldwide, it is one of the leading research institutions and part of a global network of scientific and academic institutions working on questions of global environmental change. It is a member of the Leibniz Association, whose institutions perform research on subjects of high relevance to society.
Arctic methane release is the release of methane from Arctic ocean waters as well as from soils in permafrost regions of the Arctic. While it is a long-term natural process, methane release is exacerbated by global warming. This results in a positive climate change feedback, as methane is a powerful greenhouse gas. The Arctic region is one of many natural sources of methane. Climate change could accelerate methane release in the Arctic, due to the release of methane from existing stores, and from methanogenesis in rotting biomass. When permafrost thaws as a consequence of warming, large amounts of organic material can become available for methanogenesis and may ultimately be released as methane.
Between 1901 and 2018, the average sea level rise was 15–25 cm (6–10 in), with an increase of 2.3 mm (0.091 in) per year since the 1970s. This is faster than the sea level had ever risen over at least the past 3,000 years. The rate accelerated to 4.62 mm (0.182 in)/yr for the decade 2013–2022. Climate change due to human activities is the main cause. Between 1993 and 2018, melting ice sheets and glaciers accounted for 44% of sea level rise, with another 42% resulting from thermal expansion of water.
Hans Joachim "John" Schellnhuber is a German atmospheric physicist, climatologist and founding director of the Potsdam Institute for Climate Impact Research (PIK) and former chair of the German Advisory Council on Global Change (WBGU). Since 1 December 2023, Schellnhuber is the Director General of IIASA.
Ottmar Georg Edenhofer is a German economist who is regarded as one of the world's leading experts on climate change policy, environmental and energy policy, and energy economics. His work has been heavily cited. Edenhofer currently holds the professorship of the Economics of Climate Change at Technische Universität Berlin. Together with Earth scientist Johan Rockström, economist Ottmar Edenhofer is scientific director of the Potsdam Institute for Climate Impact Research (PIK), representing the interdisciplinary and solutions-oriented approach of the institute. Furthermore, he is director of the Mercator Research Institute on Global Commons and Climate Change (MCC). From 2008 to 2015 he served as one of the co-chairs of the Intergovernmental Panel on Climate Change (IPCC) Working Group III "Mitigation of Climate Change".
The Wilkes Basin is a large subglacial basin situated generally southward of George V Coast and westward of Prince Albert Mountains in East Antarctica. The feature is approximately 1400 km long and 400 km wide. The Wilkes Basin is considered to be the largest marine-based drainage basin in East Antarctica, and may be in a state of marine ice sheet instability, caused by warm water intrusion into the shelf cavities.
The Dynamic Integrated Climate-Economy model, referred to as the DICE model or Dice model, is a neoclassical integrated assessment model developed by 2018 Nobel Laureate William Nordhaus that integrates in the neoclassical economics, carbon cycle, climate science, and estimated impacts allowing the weighing of subjectively guessed costs and subjectively guessed benefits of taking steps to slow climate change. Nordhaus also developed the RICE model, a variant of the DICE model that was updated and developed alongside the DICE model. Researchers who collaborated with Nordhaus to develop the model include David Popp, Zili Yang, and Joseph Boyer.
The effects of climate change on small island countries are affecting people in coastal areas through sea level rise, increasing heavy rain events, tropical cyclones and storm surges. These effects of climate change threaten the existence of many island countries, their peoples and cultures. They also alter ecosystems and natural environments in those countries. Small island developing states (SIDS) are a heterogenous group of countries but many of them are particularly at risk to climate change. Those countries have been quite vocal in calling attention to the challenges they face from climate change. For example, the Maldives and nations of the Caribbean and Pacific Islands are already experiencing considerable impacts of climate change. It is critical for them to implement climate change adaptation measures fast.
A carbon budget is a concept used in climate policy to help set emissions reduction targets in a fair and effective way. It examines the "maximum amount of cumulative net global anthropogenic carbon dioxide emissions that would result in limiting global warming to a given level". It can be expressed relative to the pre-industrial period. In this case, it is the total carbon budget. Or it can be expressed from a recent specified date onwards. In that case it is the remaining carbon budget.
Ricarda Winkelmann is a German mathematician, physicist, and climatologist. She is a professor of Climate System Analysis at Potsdam University and the Potsdam-Institute for Climate Impact Research. She studies interdependencies between climate, land ice, and the ocean.
