We're learning all sorts of things from the disappearing Arctic ice. Scientists have figured out that it's warmer in the Arctic today than it has been for 44-thousand years. How do they know? Easy.
The disappearing ice has revealed ancient mosses that were preserved for millennia by their ice cover. Carbon dating reveals those mosses to be 44-thousand years old. The fact that these mosses are even still around confirms they've been under the ice all that time. Ergo, the last time those mosses were ice free was 44-thousand years ago.