The world as it was, 2.6 million years ago, and will be again!
2.6 million years ago, there was no ice in the Arctic, just as we expect in a few years time (or at least by the end of the century.) Global cooling since that time has left us with Greenlands glaciers and the vast sea ice-fields that we have always associated with the Arctic Ocean. It was the time of the Pliocene (5.3mya to 2.58mya) and we can expect the Anthropocene to have a similar climate and global warming.
This useful analogue with the present situation in Eurasia can be specifically compared to ice-free conditions until the sea-ice expanded from the polar area 4 mya. The Pliocene saw parts of the Arctic region such as Greenland and Svalbard building up ice on land as they rose in height above sea level. With the ocean becoming fresher, both factors created more and more expansion of the sea ice in the Northern Hemisphere until its maximum 2.6mya. Other events were significant too. The opening of the Bering Straits while the closure of the Panama Isthmus took place would stimulate new ocean current formation, which in turn cause atmospheric change
Jochen Kries of the Geological Survey of Norway, Trondheim and his colleagues from the Universities of Tromsø, Plymouth(UK), Stellenbosch (RSA), the Universitat Autònoma de Barcelona and (ICREA (also in Barcelona) write in the journal
Nature Communications today. Their paper is entitled The emergence of modern sea ice cover in the Arctic Ocean.
Diatomaceous fossils from Arctic sediments near Spitzbergen were studied in order to prove the Ocean was ice free until 4 mya. Major world circulations derive from the polar oceans as they both cause heat distribution currents in the atmosphere as well as the oceans. The results from this paper will be useful for climate modelling programs. The fact that the sea ice preceded the land-based ice in the Northern Hemisphere is particularly significant for these computer models. Perhaps we finally have a template for what to expect in our globally-warmed Earths climate.
This data and fuel for computer models was just what we were asking and hoping for in this piece last year, as ice reached its lowest ever and floods and droughts began to be more commonplace.