Arctic permafrost: The ground is thawing

Prof. Dr Guido Grosse, Head of Permafrost Research Section at the Alfred Wegener Institute.

Permafrost

Greenhouse gases

Climate change

Permafrost is the technical term for permanently frozen soil, which can be found in ca. 23 percent of the land surface in the Northern Hemisphere and has a considerable influence on it. In this regard, important considerations often include how far down the soil is frozen, and how much ice it contains. Many regions are home to large quantities of ground ice, which, when permafrost thaws, leads to melting of the ice and surface sinking. This can dramatically change the landscapes and water cycle in permafrost regions, while also affecting the local vegetation, living conditions for fauna, and infrastructure built atop permafrost, like buildings, pipelines, and roads.

Globally speaking, however, a far more important aspect concerns the tremendous quantities of organic carbon that, in the form of animal and vegetation matter, are stored frozen in permafrost soils and deeper-lying deposits. One could say that, for tens of thousands of years, permafrost has served as the world’s chest freezer, and now the especially intensive warming in the Arctic is causing its contents to thaw and decay. This produces greenhouse gases like carbon dioxide, methane, and nitrous oxide, which are released into the atmosphere and further worsen climate change.

We are exploring the current state of the Arctic permafrost in Siberia, Canada, Alaska, and on Svalbard. We are investigating how susceptible to warming the permafrost is, where it is now thawing and how quickly, and what effects its thawing is having on landscapes, the water cycle and biogeochemical processes like the carbon cycle. We are also working to determine what information on past environmental changes and their effects can be gleaned from permafrost deposits and the climate and environmental indicators from the past (‘proxies’) they contain. To do so, we conduct sample-gathering expeditions to the Arctic; operate long-term permafrost observatories in Siberia, Canada and on Svalbard; analyse satellite- and aerial-survey-based data on landscape and permafrost dynamics; and seek to measure the changes that have already taken place with the aid of numerical models, and to use various climate scenarios to predict future developments.