UCLouvain researchers eye Alaska thaw

32°C. This summer saw the highest temperature ever recorded in southern Alaska. What are the consequences for the environment and ice melt? UCLouvain researchers will go to Alaska (15/08 to 6/09) to analyse soil (permafrost) thawing. The mission’s goal is to understand and clarify thaw impact on the quantities of greenhouse gases emitted in the Arctic.

The historical record of 32° C in southern Alaska in early July 2019 exposed permafrost (permanently frozen ground) to an unprecedented temperature rise. The surface layer of these soils is thawing more and more deeply. It has already been scientifically proven that this induces decomposition of organic matter hitherto protected by freezing, releasing greenhouse gases and amplifying the impact on the global climate.

UCLouvain researchers will go on a mission to collect soils during their maximum thaw period. Why? So far, the frozen ground has been considered ‘inert’. But with this summer’s massive thaw, the soil is releasing mineral elements that can influence soil organic matter and therefore greenhouse gas emissions. The factors controlling the release of these mineral elements are unknown.

UCLouvain scientists will try to predict the impact of such soil changes on the climate over the 21st century. The mission’s purpose: ‘Understanding what minerals permafrost thaw releases into the environment as a result of Alaska’s unprecedented temperature rise’, says UCLouvain researcher and mission coordinator Sophie Opfergelt. ‘The mission is an essential step in clarifying the thaw’s impact on the quantities of greenhouse gases emitted in the Arctic. These clarifications are needed to refine climate predictions for the next 100 years.’

In practice, UCLouvain researchers will carry out soil coring to compare frozen and thawed areas. ‘Our role is to collect soil, vegetation and river water samples in the late summer, the peak thaw season.’ Each researcher is in charge of one aspect: Catherine Hirst will analyse rivers, Elisabeth Mauclet vegetation, and Arthur Monhonval soil. Collected samples will be brought back to Belgium and analysed in UCLouvain laboratories.

The mission is part of the WeThaw research projectfinanced by the European Research Council (ERC). The research is motivated by the fact that permafrost occupies 85 % of Alaska and is particularly sensitive given a soil temperature close to ice's thaw point. On the Arctic scale, predictions indicate that one-third of permafrost will have disappeared by the end of the century.