Glacial 'footprints' mark climate shifts

 

RESEARCH:SCIENTISTS ARE studying “footprints” on the seabed off the west coast to learn more about climate change. The glaciers that left their mark thousands of years ago come and go in response to climate change and understanding how this works could help predict what might happen in the future.

“We are trying to understand the climate change signals,” Dr Paul Dunlop of the University of Ulster said on the closing day of the Esof meeting. The ridges and drumlins left behind by the glaciers that once blanketed Ireland and much of the rest of Europe 27,000 to 29,000 years ago tells researchers about the retreat of the ice in response to climate change and the final ice collapse at the start of our current warm interglacial period.

At the end of the last big freeze, glaciers weighed down on Ireland and extended well out to sea, to the edge of our continental shelf, he said. The base of the ice marked the seabed and once it started to melt it left behind loose material scraped off the island.

Data for his work comes from comprehensive offshore seabed surveys carried out over several years by the research vessel Celtic Explorer. Once he started to look for signs of a receding glacier, he found them.

Some 50km northwest of Malin Head, for example, the team found ridges 22km long, 1km wide and 12 metres high.

Then, in an ever decreasing arc, there are smaller ridges and debris piles left as the ice shrank back towards the coastline. “You can see the retreat back to Donegal and by 18,000 years ago the coast is free of ice,” Dr Dunlop said.

These deposits are visible along much of the north and western seaboard. “As they grow and decay, ice sheets leave a rich geological record of their behaviour that can help us to unravel the timing and driving mechanisms of major climatic events.”