The Bering Sea which finds its borders between Alaska and Russia was ice free during the last warm period in Earth’s climate history, the Pliocene Warm Period.
Researchers drilled down 700 metres through rock at the bottom of the Bering Sea to acquire cores that contained sediments deposited during the Pliocene Warm Period which occurred between 3.5 and 4.5 million years ago.
Why focus on such a time?
“Evidence from the Pliocene Warm Period is relevant to studies of current climate change because it was the last time in our Earth’s history when global temperatures were higher than today,” said Christina Ravelo, professor of ocean sciences at the University of California, Santa Cruz.
“The information we found tells us quite a bit about what things were like during the last period of global warming. It should benefit the scientists today who are sorting out how ocean circulation and conditions at the poles change as the Earth warms.”
The Pliocene has been the focus of many scientific endeavours over the past several years, all in an effort to shed light on what humanity has set itself on course for.
Currently, observations have shown that the Arctic is warming more rapidly than other locations across the planet and faster than was predicted in global climate models. Ravelo’s team found that a similar phenomenon took place during the Pliocene Warm Period. The sediment samples showed that the average sea surface temperature in the Bering Sea during the period were at least 5 degrees Celsius warmer than they are today, while the global average was only 3 degrees Celsius warmer.
Additionally, the Bering Sea was found to be ice free all year round. Currently, the Bering Sea is only ice free during the summer, but evidence in the sediments deposited found no pebbles or other debris that would have been brought in by encroaching ice flows and left to float to the bottom when they melted at the end of winter.’