{"id":4118,"date":"2022-05-01T22:00:00","date_gmt":"2022-05-01T22:00:00","guid":{"rendered":"https:\/\/modernsciences.org\/staging\/4414\/?p=4118"},"modified":"2022-04-19T04:34:20","modified_gmt":"2022-04-19T04:34:20","slug":"thawing-permafrost-is-roiling-the-arctic-landscape-driven-by-a-hidden-world-of-changes-beneath-the-surface-as-the-climate-warms","status":"publish","type":"post","link":"https:\/\/modernsciences.org\/staging\/4414\/thawing-permafrost-is-roiling-the-arctic-landscape-driven-by-a-hidden-world-of-changes-beneath-the-surface-as-the-climate-warms\/","title":{"rendered":"Thawing permafrost is roiling the Arctic landscape, driven by a hidden world of changes beneath the surface as the climate warms"},"content":{"rendered":"\n
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\n Permafrost and ice wedges have built up over millennia in the Arctic. When they thaw, they destabilize the surrounding landscape.\n Michael Robinson Chavez\/The Washington Post via Getty Images<\/a><\/span>\n <\/figcaption>\n <\/figure>\n\nMark J. Lara<\/a>, University of Illinois at Urbana-Champaign<\/a><\/em><\/span>\n\n

Across the Arctic, strange things are happening to the landscape.<\/p>\n\n

Massive lakes, several square miles in size, have disappeared in the span of a few days. Hillsides slump. Ice-rich ground collapses, leaving the landscape wavy where it once was flat, and in some locations creating vast fields of large, sunken polygons. <\/p>\n\n

It\u2019s evidence that permafrost, the long-frozen soil below the surface, is thawing. That\u2019s bad news for the communities built above it \u2013 and for the global climate.<\/p>\n\n

As an ecologist<\/a>, I study these dynamic landscape interactions and have been documenting the various ways permafrost-driven landscape change has accelerated over time. The hidden changes underway there hold warning for the future.<\/p>\n\n

\n \"Illustration<\/a>\n
\n An illustration shows some of the ways permafrost affects the Arctic landscape.<\/span>\n Victor O. Leshyk, from Schuur et al. 2022. Permafrost and Climate Change: Carbon Cycle Feedbacks from the Warming Arctic. Annual Review of Environment and Resources Volume 47 (in press)<\/a><\/span>\n <\/figcaption>\n <\/figure>\n\n

What is permafrost?<\/h2>\n\n

Permafrost is perennially frozen soil that covers about a quarter of the land<\/a> in the Northern Hemisphere, particularly in Canada, Russia and Alaska. Much of it is rich with the organic matter of long-dead plants and animals frozen in time.<\/p>\n\n

These frozen soils maintain the structural integrity of many northern landscapes, providing stability to vegetated and unvegetated surfaces, similar to load-bearing support beams in buildings.<\/p>\n\n

As temperatures rise and patterns of precipitation change, permafrost and other forms of ground ice become vulnerable to thaw and collapse. As these frozen soils warm, the ground destabilizes, unraveling the interwoven fabric that has delicately shaped these dynamic ecosystems over millennia. Wildfires, which have been increasing across the Arctic, have been increasing the risk<\/a>. <\/p>\n\n

\n \"A\n
\n Thawing permafrost can cause the ground to sink and crack in places, destabilizing roads and buildings.<\/span>\n Orjan F. Ellingvag\/Corbis via Getty Images<\/a><\/span>\n <\/figcaption>\n <\/figure>\n\n

Under the surface, something else is active \u2013 and it is amplifying global warming<\/a>. When the ground thaws, microbes begin feasting on organic matter in soils that have been frozen for millennia. <\/p>\n\n

These microbes<\/a> release carbon dioxide and methane, potent greenhouse gases. As those gases escape into the atmosphere, they further warm the climate, creating a feedback loop<\/a>: Warmer temperatures thaw more soil, releasing more organic material for microbes to feast on and produce more greenhouse gases.<\/p>\n\n

The evidence: disappearing lakes<\/h2>\n\n

Evidence of human-caused climate change is mounting across the permafrost extent.<\/p>\n\n

The disappearance of large lakes<\/a>, multiple square miles in size, is one of the most striking examples of recent patterns of northern landscape transitions.<\/p>\n\n

The lakes are draining laterally as wider and deeper drainage channels develop, or vertically through taliks, where unfrozen soil under the lake gradually deepens until the permafrost is penetrated and the water drains away.<\/p>\n\n

There is now overwhelming evidence indicating that surface water across permafrost regions is declining. Satellite observations and analysis indicate lake drainage may be linked with permafrost degradation<\/a>. Colleagues and I<\/a> have found it increases with warmer and longer summer seasons. <\/p>\n\n

\n \"A<\/a>\n
\n Gullies created by thawing soil drain a lake in the Arctic Coastal Plain of northern Alaska.<\/span>\n Christian Andresen and Mark J. Lara<\/span>, CC BY-ND<\/a><\/span>\n <\/figcaption>\n <\/figure>\n\n

This insight came after some of the highest rates of catastrophic lake drainage<\/a> \u2013 drainage that occurs over a few days due to permafrost degradation \u2013 on record were observed over the past five years in northwestern Alaska.<\/p>\n\n

The disappearance of lakes across the permafrost extent is likely to affect the livelihoods of Indigenous communities as water quality and water availability<\/a> important for waterfowl, fish and other wildlife shift.<\/p>\n\n

Slumping hills and polygon fields<\/h2>\n\n

The thaw and collapse of buried glacial ice is also causing hillsides to slump at increasing rates across the Russian and North American Arctic, sending soil, plants and debris sliding downslope.<\/p>\n\n

One new study in northern Siberia found that the disturbed land surfaces increased over 300%<\/a> over the past two decades. Similar studies in northern<\/a> and northwestern Canada<\/a> found slumping there also accelerated with warmer and wetter summers.<\/p>\n\n

\n \"Several<\/a>\n
\n Slumping hillsides show how easily thermokarst landscape erodes in Canada\u2019s Aulavik National Park.<\/span>\n Sarah Beattie\/Parks Canada<\/a><\/span>\n <\/figcaption>\n <\/figure>\n\n
\n \"A\n
\n An ice wedge dated to the late Pleistocene era in Noatak National Preserve in Alaska.<\/span>\n David Swanson\/National Park Service<\/a><\/span>\n <\/figcaption>\n <\/figure>\n\n

In flat terrain, ice wedges are able to develop, creating unusual geometric patterns and changes across the land. <\/p>\n\n

Over decades to centuries, melting snow seeps into cracks in the soil, building up wedges of ice<\/a>. These wedges cause troughs in the ground above them, creating the edges of polygons<\/a>. Polygonal features naturally form<\/a> as a result of the freezing and thawing process in a way similar to that seen at the bottom of drying mud flats. As ice wedges melt, the ground above collapses.<\/p>\n\n

Even in extremely cold high Arctic environments, the impacts of only a few uncommonly warm summers can dramatically change the surface of the landscape<\/a>, transitioning previously flat terrain into undulating as the surface begins to sink into depressions with the melting of ice in the soil below. Overall rates of ice wedge thawing have increased in response to climate warming<\/a>.<\/p>\n\n

\n \"\"\n
\n Thawing pingo and polygons \u2013 a mound and depressions formed by ice wedges \u2013 in the Northwest Territories, Canada.<\/span>\n Emma Pike \/Wikimedia<\/a><\/span>\n <\/figcaption>\n <\/figure>\n\n
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