This incredible map shows "Beringa," a region that existed millions of years ago during the Ice Ages. What it reveals is that, oddly, far northern regions like the Yukon and Siberia were hotbeds of ice-free life.
Over at Astrobiology magazine, Aaron Gronstal describes new scientific work that led to the creation of this map. What you see here is the landmass which included a land bridge over the Bering Strait - the same bridge that allowed animals and humans to wander from Northern Europe into North America without being hindered by the Arctic Sea. The timeframe here is the Pleiocene and Pleistocene Eras - between 5.3 million to 12,000 years ago - when ice sheets and glaciers covered most of the northern hemisphere. And yet at the same time, some of the iciest parts of today's warmer world were at that time ice-free and full of life. How did that happen?
Gronstal sums up the research:
Temperatures were still low in Beringia during these epochs, but a lack of moisture due to the rainshadow of the surrounding mountain ranges prevented large-scale formation of ice. As the authors [of the new study] put it, "The interior of Yukon and Alaska was cold enough to support ice sheets but too dry for extensive glaciation." Because of this, Beringia was a key location for life during the Pleistocene, when the Earth's climate fluctuated between ice ages and glaciers often covered large portions of the globe.
As the Earth's climate varied, so did sea levels. This ebb and flow of the sea exposed a land-bridge across the Bering Straight between Alaska and Siberia. Not only was this an important route for the migration of animals between the continents of Asia and North America, it also expanded the ice-free land mass of Beringia. This provided a large area that was relatively rich in food – which was a lifesaver for those struggling to survive in the Earth's frozen North. Beringia was by no means a tropical paradise for life, but the cold, wind-swept desert was an important ecological refuge for plants and animals when glaciation of the Earth was at its peak.
This map is a perfect demonstration of how complicated the results are when we see massive weather shifts on Earth. Some areas that were uninhabitable become habitable in unforeseen ways.