(ORDO NEWS) — Permafrost – frozen rocks that do not thaw for years. It occupies significant territories in North America and especially in Siberia. Global climate change is destroying permafrost more and more rapidly, as described in a new article on the example of the territory of Alaska.
Permafrost – more specifically, permafrost – is an important component of the cryosphere, the sub-zero part of the Earth. Permafrost is located below the surface and is distributed over vast territories in Asia, as well as in North America.
As the name implies, global warming affects the entire globe and its various components: against the background of rising ocean levels, its pH drops, the habitats of living things change, and permafrost, as you might guess, melts.
And it is melting faster and faster – this follows from a new article in the journal Nature Geoscience by geophysicists from the University of Alaska at Fairbanks (USA).
Permafrost scientists argue that an increase in the area of taliks – thawed areas of permafrost – greatly affects the exchange of carbon between such important reservoirs as living organisms, rocks and the atmosphere.
Taliks also determine the transport of various compounds, including nutrients, with water flows. They also lead to the emergence of thermokarst – negative landforms (in other words, rounded pits) associated with the local disappearance of permafrost and subsidence of soil above it.
Geophysicists turned to data on ground temperatures in various parts of Alaska (USA), collected from 1999 to 2020. Among them, 54 sites were selected with a total area of more than 410,000 square kilometers.
It turned out that by the winter of 2017-2018, traces of incomplete freezing and emerging taliks were present in 24 areas. It was in that year that the growth of taliks was maximum – this is due to the high air temperature: little snow fell, and it poorly isolated the permafrost from heat exchange with the surface.
The scientists examined rock sections where the permafrost is thinnest, usually near rivers or lakes. Once upon a time, taliks were confined mainly to the river network and lakes with melt water that arose due to forest fires. Since fire destroys vegetation, in this case it can no longer protect frozen rocks from melting in the warm season.
“We are seeing a kind of transition and are constantly seeing both the formation of new taliks and, in the case of snowy seasons and very frosty winters or cold summers, a reduction in the area of taliks,” said Louise Farquharson, leader of this study.
She emphasizes that the general public should be aware that permafrost is not in a stable, but in a very dynamic state. Farquharson suggests that in the near future the thawing of permafrost will accelerate and vast areas in the north will be covered with talik spots.
What threatens the loss of permafrost – seemingly useless and even interfering with construction and other economic activities? It turns out that its disappearance will lead to the release of material previously “locked” inside the permafrost and to its movement with water flows.
Dissolved organics, nitrogen compounds and various contaminants like mercury will appear on the surface – and they may well get into the river network. Oddly enough, the reduction in permafrost-occupied areas may also hinder construction and threaten some existing buildings and structures.
According to forecasts, if a climate change scenario with high carbon dioxide emissions is realized, then by 2030 the formation of taliks will affect 70% of modern permafrost. The scientists also note that their results apply not only to Alaska and North America, but to the entire Arctic region.
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