Palsa Mires: Often Seen, Little Understood, Under Threat

A long term study on multiple Palsa mires in northwest Finland by a team based out of the University of Eastern Finland has resulted in a new publication by Mariana Verdonen with others, supported by the LANDMOD and CHARTER projects. The paper notes that the outlook for Palsa mires is bleak. From their press release,

At the observation sites, palsa area had decreased by more than 75% from 1959 to 2021. However, climate had only a limited impact on the active layer of palsa mounds. Active layer thickness did not significantly increase during the monitoring period, although the lowering and collapse from the edges of palsas indicates that their permafrost core continues to thaw, year after year.

“In one of the observation sites, active layer thickness has in fact been significantly decreasing over the past eight years. This means that permafrost thawing doesn’t necessarily lead to the deepening of the active layer,” says first author, Doctoral Researcher Mariana Verdonen of the University of Eastern Finland, who analysed the data.

Palsa mires found in the northernmost peatlands of Lapland are the main permafrost landforms in Fennoscandia. As the climate warms, palsa mires are expected to disappear and no new palsas have been observed to form.

Palsa mires continue to degrade at a rapid pace

Launch a visual “StoryMap” of summarising this project with images, maps and video here.

You can read and download the article here: Mariana Verdonen, Alexander Störmer, Eliisa Lotsari, Pasi Korpelainen, Benjamin Burkhard, Alfred Colpaert and Timo Kumpula. Permafrost degradation at two monitored palsa mires in north-west Finland. The Cryosphere, 17, 1803–1819, 2023. 

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