Ancient Moss Reveals Arctic Warming Unprecedented in 44,000 Years

As our climate changes and the Arctic warms, the ice is melting. In fact, temperature rises on Baffin Island in the Canadian high Arctic is causing ice that's been frozen for thousands of years to slowly disappear. Yet this melting ice represents a new opportunity. Scientists have managed to uncover ancient Polytrihcum mosses trapped beneath this ice.

The moss itself has been covered for thousands of years. Yet with recent melting, scientists were able to collect 365 samples from about 110 different locations, cutting a 1,000 kilometer long transect across Baffin Island. The samples represented a range of altitudes and show that current warming trends are unprecedented. Moss samples would have been destroyed by erosion had they been previously exposed.

In the end, the researchers obtained 145 viable measurements through radiocarbon data. This allowed them to determine that most of the samples date from the past 5,000 years when a period of strong cooling overtook the Arctic. They also discovered even older samples which were buried from 24,000 to 44,000 years ago.

What do these samples show exactly? They seem to suggest that the eastern Canadian Arctic is warmer now than in any century in the past 5,000 years. In some places, modern temperatures are unprecedented in at least the past 44,000 years.

"The great time these plants have been entombed in ice, and their current exposure, is the first direct evidence that present summer warmth in the Eastern Canadian Arctic now exceeds the peak warmth there in the Early Holocene era," said Gifford Miller, one of the researchers, in a news release. "Our findings add additional evidence to the growing consensus that anthropogenic emissions of greenhouse gases have now resulted in unprecedented recent summer warmth that is well outside the range of that attributable to natural climate variability."

The findings are published in the journal Geophysical Research Letters.