Arctic warmer than for the past 40,000 years

Now, and for the last 100 years, the Arctic is warmer than any time in the last 44,000 – maybe even 120,000 – years. That means current temperatures have the Arctic warmer than during the early Holocene period, at the end of the last Ice Age, when peak summer sunlight was about 9% greater than today.

The receding ice uncovers ground that hasn’t seen the sun in tens of thousands of years, and with it, dead mosses. Using radiocarbon dating, researchers established that these mosses had been shielded – by ice – for 44,000-51,000 years. Radiocarbon dating only works about 50,000 years back, so these mosses could plausibly have been buried since the last interglacial thaw, 120,000 years ago. Mosses would’ve needed sunlight to take root, and were collected from within a metre of the edge of the ice cap on Baffin Island in the Arctic Circle, so would’ve been exposed this year. This, along with the data on how long the moss has been covered in ice, tells the researchers that the melt we’re seeing now is far outside the bounds of natural variability.

The team coupled this data with ice core samples that provide a record of the area’s climate history – snowfall and melt for each year are recorded in the ice. The Arctic hasn’t been as warm as it is now for about 120,000 years, and the most significant warming has been since 1970. The last 20 years have been the most severe, and the team expect all of Baffin Island’s ice caps to disappear, even if the world gets no warmer than it is today.