Deep valleys buried beneath the seafloor of the North Sea record how the ancient ice sheets that used to cover Europe expelled water to stop themselves from collapsing.
A new study shows that the valleys took just hundreds of years to form as they transported vast amounts of meltwater away from under the ice and out into the sea. This new realization of when the vast ice sheets melted 20,000 years ago has implications for how glaciers may respond to climate warming today.
Tunnel valleys are massive channels, sometimes up to 150km long, 6km wide and 500m deep, that drain water from beneath melting ice sheets. There are thousands below the seafloor of the North Sea that record the melting of ice sheets that covered the UK and Western Europe over the past two million years.
Lead author James Kirkham said, “This is an exciting discovery. We know that these spectacular valleys are carved out during the death throes of ice sheets. By using a combination of state-of-the-art subsurface imaging techniques and a computer model, we have learnt that tunnel valleys can be eroded rapidly beneath ice sheets experiencing extreme warmth.”
There are no modern analogs for this rapid process, but these ancient valleys, now buried hundreds of meters below the surface of the North Sea seafloor, record a mechanism for how ice sheets respond to extreme warmth that is missing from present-day ice sheet models. Current models do not currently resolve fine-scale water draining processes, despite them appearing to be an important control on future ice loss rates and ultimately sea level rise.
https://phys.org/news/2022-10-ancient-ice-age-valleys-clues.html