 Mean glacial erosion rates modelled beneath the last Eurasian Ice Sheet during the last ice age, with the Trough Mouth Fan (TMF) sediment deposits that were used to constrain these results highlighted. Find out more in Figure 3, Patton et al., 2022 |
During the last ice age, the Eurasian Ice Sheet was immense - the third largest on Earth spanning over 5,500 km from temperate conditions in southern Britain to the frigid polar regions of Svalbard and Siberia. Until now, the influence of this ice on Europe's landscape has not been fully realized, but a new study led by Dr Henry Patton and published in Nature Communications, brings a brand-new perspective on the erosive impact of this great ice sheet that covered Northwest Europe and parts of Asia during the last glacial.
Using multiple strands of geophysical evidence to train a new model of the Eurasian Ice Sheet, Dr Patton and co-authors reveal the extreme and complex nature of glacial erosion over the last 100,000 years, providing an invaluable long-term perspective. The efficiency and interplay of environmental and internal controls governing the patterns of erosion are identified: the key roles of climate, geology and topography, but also the critical importance of the ice sheet's thermal and mechanical regime itself.
The Eurasian Ice Sheet was almost 3,000 m thick in places and thus had a pronounced impact on the landscape through its erosional footprint. Yet, results from this study show that while there has been focused extreme erosion in some areas like the glacial fjords of Western Norway and in the Barents Sea, there were also large swathes of the landscape - like the high elevation plateaus of Sweden and Norway - that the ice hardly affected at all.
Erosion rates impacted by the climate
Much like in Greenland and Antarctica today, the study finds a close link between climate and ice sheet erosion. It shows that a series of rapid ice sheet fluctuations where rates of erosion increased by almost 1 cm per year occurred on incredibly short, decadal, timescales. These brief "bursts of intense erosion" occurred during periods of abrupt warming, such as around 15,000 years ago at the end of the last ice age - when rising temperatures destabilised remaining ice cover over Eurasia.
The rapidly melting ice during these phases vastly increased the meltwater reaching the bed of the ice sheet, forming vast networks of subglacial rivers and promoting faster ice flow that worked to excavate the bedrock and sediments. These meltwater rivers also transported these eroded sediments from beneath the ice sheet and into the adjoining oceans and fjords, creating an ideal environment for algal blooms to flourish and becoming a major marine carbon sink.
But every cloud has a silver-lining. The quantities of sediments and nutrients washed out by Greenland's meltwater in plumes, is also sustaining incredible levels of marine-productivity - a boon for the local fishing industry, who are now experiencing record export levels to international markets.
Areas with increased erosion pose a geohazard problem
The impressive glacial imprint in the landscape, for example along Norwegians coasts, has been sculpted over many ice-age cycles, with deep fjords and submarine troughs carved by repeated ice sheet advances.
However, a legacy of this intense erosion and deep freezing of mountain landscapes are the inherently over steepened and unstable slopes left behind after deglaciation. Failure of these mountain slopes poses a significant geohazard to many communities across formerly glaciated landscapes around the globe, particularly now as temperatures rise and the permafrost and ice binding these cliffs together thaws.
Research Report:The extreme yet transient nature of glacial erosion
Related Links
The Arctic University of Norway
Beyond the Ice Age
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