New evidence pushes the first continental-scale Eurasian Ice Sheet back to 2.4 million years ago
An international team of researchers from Czechia, Denmark and the USA has discovered that the Eurasian Ice Sheet reached continental scale approximately 2.4 million years ago, more than one million years earlier than previously thought.
Timestamping when ice sheets first developed over the northern continents is essential for our understanding of the global climate system and our ability to resolve the drivers of longterm climate change, including the role of atmospheric CO2. An international team of researchers from Czechia, Denmark and the USA has published a paper in the journal Nature Communications that constrains the first expansions of the Eurasian Ice Sheet at ~ 2.4 million years ago (Ma). The paper is led by visiting PhD students Kaleb Wagner and Lotta Ylä-Mella, who visited the Department of Geoscience (AU) from the Institute of Geophysics, Czech Academy of Science, and Charles University in Prague. The method used to date the first expansion of the Eurasian Ice Sheet was developed by researchers at the Department of Geoscience (AU).
The new study resolves a long-standing mismatch between indices of timing of the first Eurasian Ice Sheet expansion in terrestrial and marine records by dating the earliest known glaciogenic sediments in northwest Europe, the Hattem Bed Complex in the Netherlands. Burial dating with cosmogenic 26Al-10Be and detrital zircon fingerprinting indicate that the Fennoscandia-sourced Hattem gravels reached the Netherlands by ~ 2.4 Ma, while ages from the overlying Appelscha Formation record a second ice-sheet advance and glacial destruction of the former Baltic River System at ~ 1.7 Ma.
The new results represent a major departure from the traditional interpretation of the glaciogenic sediment record in northern Europe, because it implies the Eurasian Ice Sheet reached a continental-scale size more than 1 million years earlier than hitherto believed. However, the new ages accord with estimates from North America showing that the Laurentide Ice Sheet reached its maximum extent in northern USA ~2.4 million years ago.