A newly-discovered set of fossils suggest Greenland's ice sheet was at its smallest within the past 10,000 years between 3,000 and 5,000 years ago.
"What's really interesting about this is that on land, the atmosphere was warmest between 9,000 and 5,000 years ago, maybe as late as 4,000 years ago. The oceans, on the other hand, were warmest between [five and] 3,000 years ago," Jason Briner, PhD, University at Buffalo associate professor of geology, who led the study, said in a University at Buffalo news release.
Researchers believe finding could help them peer into the future of the concern-causing ice sheet. The finding also provides scientists with a tool that will help then pinpoint where and when ice sheets were smaller than they are in modern times.
"Traditional approaches have a difficult time identifying when ice sheets were smaller," Briner said. "The outcome of our work is that we now have a tool that allows us to see how the ice sheet responded to past times that were as warm or warmer than present - times analogous to today and the near future."
In order to determine this information the researchers looked at debris on the sides of the glacier. These ice sheets work as "bulldozers," plowing materials to its edges in heaps called "moraines."
This "bulldozer effect" only takes place when the glacier is growing, so the debris must have been picked up when the ice was "older and smaller."
This particular moraine contained clam fossils between 3,000 and 5,000 years old, suggesting this is when the ice sheet was at its smallest. The fossils were dated through amino acid analysis.
"Because we see the most shells dating to the [five and] 3000-year period, we think that this is when the most land was ice-free, when large layers of mud and fossils were allowed to accumulate before the glacier came and bulldozed them up," Briner said.
