Related topics: carbon dioxide · climate change

Plant roots increase carbon emission from permafrost soils

A key uncertainty in climate projections is the amount of carbon emitted by thawing permafrost in the Arctic. Plant roots in soil stimulate microbial decomposition, a mechanism called the priming effect. An international ...

Sea-ice-free Arctic makes permafrost vulnerable to thawing

Permafrost is ground that remains frozen throughout the year; it covers nearly a quarter of Northern Hemisphere land. The frozen state of permafrost enables it to store large amounts of carbon; about twice as much as in the ...

China looks to 'combustible ice' as a fuel source

(PhysOrg.com) -- Buried below the tundra of China’s Qinghai-Tibet Plateau is a type of frozen natural gas containing methane and ice crystals that could supply energy to China for 90 years. China discovered the large reserve ...

Peatland carbon and nitrogen stocks vulnerable to permafrost thaw

Northern peatlands hold large stocks of carbon and nitrogen and thus play a key role in global climate dynamics. However, their vulnerability to climate warming is uncertain, due in part to a lack of spatially explicit, observation-based ...

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Permafrost

In geology, permafrost, cryotic soil or permafrost soil is soil at or below the freezing point of water (0 °C or 32 °F) for two or more years. Ice is not always present, as may be in the case of nonporous bedrock, but it frequently occurs and it may be in amounts exceeding the potential hydraulic saturation of the ground material. Most permafrost is located in high latitudes (i.e. land close to the North and South poles), but alpine permafrost may exist at high altitudes in much lower latitudes. Permafrost accounts for 0.022% of total water and exists in 24% of exposed land in the Northern Hemisphere.

The extent of permafrost can vary as the climate changes. Today, a considerable area of the Arctic is covered by permafrost (including discontinuous permafrost). Overlying permafrost is a thin active layer that seasonally thaws during the summer. Plant life can be supported only within the active layer since growth can occur only in soil that is fully thawed for some part of the year. Thickness of the active layer varies by year and location, but is typically 0.6–4 m (2.0–13 ft) thick. In areas of continuous permafrost and harsh winters the depth of the permafrost can be as much as 1,493 m (4,898 ft) in the northern Lena and Yana River basins in Siberia. Permafrost can also store carbon, both as peat and as methane. The most recent work investigating the permafrost carbon pool size estimates that 1400-1700 Gt of carbon is stored in permafrost soils worldwide. . This large carbon pool represents more carbon than currently exists in all living things and twice as much carbon as exists in the atmosphere.

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