A carbon sink is anything, natural or otherwise, that accumulates and stores some carbon-containing chemical compound for an indefinite period and thereby removes carbon dioxide from the atmosphere. These sinks form an important part of the natural carbon cycle. An overarching term is carbon pool, which is all the places where carbon can be. A carbon sink is a type of carbon pool that has the capability to take up more carbon from the atmosphere than it releases.
In physical geography, tundra is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. The term tundra comes through Russian тундра from the Kildin Sámi word тӯндар meaning "uplands", "treeless mountain tract". There are three regions and associated types of tundra: Arctic tundra, alpine tundra, and Antarctic tundra.
The carbon cycle is that part of the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of Earth. Other major biogeochemical cycles include the nitrogen cycle and the water cycle. Carbon is the main component of biological compounds as well as a major component of many minerals such as limestone. The carbon cycle comprises a sequence of events that are key to making Earth capable of sustaining life. It describes the movement of carbon as it is recycled and reused throughout the biosphere, as well as long-term processes of carbon sequestration (storage) to and release from carbon sinks.
Cloud feedback is a type of climate change feedback that has been difficult to quantify in contemporary climate models. It can affect the magnitude of internally generated climate variability or they can affect the magnitude of climate change resulting from external radiative forcings. Cloud representations vary among global climate models, and small changes in cloud cover have a large impact on the climate.
Peat is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. Sphagnum moss, also called peat moss, is one of the most common components in peat, although many other plants can contribute. The biological features of sphagnum mosses act to create a habitat aiding peat formation, a phenomenon termed 'habitat manipulation'. Soils consisting primarily of peat are known as histosols. Peat forms in wetland conditions, where flooding or stagnant water obstructs the flow of oxygen from the atmosphere, slowing the rate of decomposition. Peat properties such as organic matter content and saturated hydraulic conductivity can exhibit high spatial heterogeneity.
Permafrost is soil or underwater sediment which continuously remains below 0 °C (32 °F) for two years or more: the oldest permafrost had been continuously frozen for around 700,000 years. While the shallowest permafrost has a vertical extent of below a meter, the deepest is greater than 1,500 m (4,900 ft). Similarly, the area of individual permafrost zones may be limited to narrow mountain summits or extend across vast Arctic regions. The ground beneath glaciers and ice sheets is not usually defined as permafrost, so on land, permafrost is generally located beneath a so-called active layer of soil which freezes and thaws depending on the season.
An abrupt climate change occurs when the climate system is forced to transition at a rate that is determined by the climate system energy-balance. The transition rate is more rapid than the rate of change of the external forcing, though it may include sudden forcing events such as meteorite impacts. Abrupt climate change therefore is a variation beyond the variability of a climate. Past events include the end of the Carboniferous Rainforest Collapse, Younger Dryas, Dansgaard–Oeschger events, Heinrich events and possibly also the Paleocene–Eocene Thermal Maximum. The term is also used within the context of climate change to describe sudden climate change that is detectable over the time-scale of a human lifetime, possibly as the result of feedback loops within the climate system or tipping points.
Major environmental issues caused by contemporary climate change in the Arctic region range from the well-known, such as the loss of sea ice or melting of the Greenland ice sheet, to more obscure, but deeply significant issues, such as permafrost thaw, as well as related social consequences for locals and the geopolitical ramifications of these changes. The Arctic is likely to be especially affected by climate change because of the high projected rate of regional warming and associated impacts. Temperature projections for the Arctic region were assessed in 2007: These suggested already averaged warming of about 2 °C to 9 °C by the year 2100. The range reflects different projections made by different climate models, run with different forcing scenarios. Radiative forcing is a measure of the effect of natural and human activities on the climate. Different forcing scenarios reflect things such as different projections of future human greenhouse gas emissions.
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.
Arctic methane release is the release of methane from seas and 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 feedback cycle, as methane is itself a powerful greenhouse gas.
Climate change feedbacks are effects of global warming that amplify or diminish the effect of forces that initially cause the warming. Positive feedbacks enhance global warming while negative feedbacks weaken it. Feedbacks are important in the understanding of climate change because they play an important part in determining the sensitivity of the climate to warming forces. Climate forcings and feedbacks together determine how much and how fast the climate changes. Large positive feedbacks can lead to tipping points—abrupt or irreversible changes in the climate system—depending upon the rate and magnitude of the climate change.
The permafrost carbon cycle or Arctic carbon cycle is a sub-cycle of the larger global carbon cycle. Permafrost is defined as subsurface material that remains below 0o C for at least two consecutive years. Because permafrost soils remain frozen for long periods of time, they store large amounts of carbon and other nutrients within their frozen framework during that time. Permafrost represents a large carbon reservoir, one which was often neglected in the initial research determining global terrestrial carbon reservoirs. Since the start of the 2000s, however, far more attention has been paid to the subject, with an enormous growth both in general attention and in the scientific research output.
Greenhouse gas emissions from wetlands of concern consist primarily of methane and nitrous oxide emissions. Wetlands are the largest natural source of atmospheric methane in the world, and are therefore a major area of concern with respect to climate change. Wetlands account for approximately 20 - 30% of atmospheric methane through emissions from soils and plants, and contribute an approximate average of 161 Tg of methane to the atmosphere per year.
A peatland is a type of wetland whose soils consist of organic matter from decaying plants, forming layers of peat. Peatlands arise because of incomplete decomposition of organic matter, usually litter from vegetation, due to water-logging and subsequent anoxia. Like coral reefs, peatlands are unusual landforms that derive mostly from biological rather than physical processes, and can take on characteristic shapes and surface patterning.
Climate inertia or climate change inertia is the phenomenon by which a planet's climate system shows a resistance or slowness to deviate away from a given dynamic state. It can accompany stability and other effects of feedback within complex systems, and includes the inertia exhibited by physical movements of matter and exchanges of energy. The term is a colloquialism used to encompass and loosely describe a set of interactions that extend the timescales around climate sensitivity. Inertia has been associated with the drivers of, and the responses to, climate change.
Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% of methane released globally was from human activities, while natural sources contributed about 40%. Reducing methane emissions by capturing and utilizing the gas can produce simultaneous environmental and economic benefits.
Terrestrial ecosystems found in the boreal regions of North America and Eurasia cover less than 17% of the earth's land surface, yet contain more than 30% of all carbon present in the terrestrial biome. In terms of carbon storage, the boreal region consists of three ecosystems: boreal forest, peatland, and tundra. Vast areas of the globe and are contributing greatly to atmospheric carbon release due to increased temperature and fire hazard. High northern latitudes will experience the most significant increase in warming on the planet as a result of increased atmospheric greenhouse gases thus placing in jeopardy the carbon sink in these areas. In addition to the release of carbon through the melting of permafrost, high intensity wildfires will become more common and thus contribute to the release of stored carbon. This means that the boreal forest and its fire regime is becoming an increasingly more significant factor in determining the global carbon budget.
Susan M. Natali is an American ecologist. She is the Arctic program director and senior scientist at the Woodwell Climate Research Center, where her research focuses on the impact of climate change on terrestrial ecosystems, primarily on Arctic permafrost. She is also the project lead for Permafrost Pathways, a new initiative launched in 2022 with funding from TED's Audacious Project. On Monday, April 11, 2022, Dr. Natali gave a TED Talk introducing the Permafrost Pathways project at the TED2022 conference in Vancouver, BC.
Jennifer Harden is geologist known for her research on soils, particularly tracking changes in soil profiles over time and the role of soil systems in carbon and nitrogen cycling.
Merritt Turetsky is an American ecosystem ecologist and a professor at the University of Colorado Boulder. She currently serves as the Director of Arctic Security for the University of Colorado. She served as the first woman Director of the Institute for Arctic and Alpine Research (INSTAAR) from 2019-2023. Her research considers fire regimes, climate change and biogeochemical cycling in Arctic wetlands. Turetsky is a member of the Permafrost Action Team (SEARCH), a group of scientists who translate and deliver science to decision-makers.
