Keeping a 53-mile-wide ocean channel open may be the key to preventing abrupt climate change events, scientists say.
The last Ice Age, which lasted from more than 100,000 to 11,000 years ago, was marked by sudden changes in climate. In 2008, scientists discovered that in at least one such event, Greenland warmed by as much as 10 degrees Celsius (20 degrees Fahrenheit) over just a few decades.
Many scientists think the driving force behind these abrupt shifts is changes in the circulation of the Earth's oceans. If a part of this system, known as the Atlantic Meridional Overturning Circulation, becomes destabilized, so the theory goes, that could trigger a sudden climate change.
Researchers think the Bering Strait, the narrow channel between the easternmost point of Russia and the westernmost tip of North America, may have played an important role in regulating AMOC, and thus Earth's climate, for the past 100,000 years.
The strait has been closed off before -- it's thought that humans first migrated to North America from Asia somewhere between 40,000 and 17,000 years ago by walking across a land bridge that joined the two continents. The land bridge is believed to have formed as the glaciers of the last Ice Age rose and caused sea levels to drop, and disappeared beneath the sea once the glaciers melted.
In a paper published Monday in the journal Proceedings of the National Academy of Sciences, National Center for Atmospheric Research scientist Aixue Hu and his colleagues used a computer model to figure out the effect that opening or closing the Bering Strait would have on AMOC.
Extrapolating from current climate conditions, Hu and his team determined that even given the warming effects of greenhouse gases, abrupt climate transitions similar to those in the last glacial time are unlikely to occur as the Bering Strait remains open.
However, if the Bering Strait were closed, that would prevent fresh water from melting glaciers in the Arctic from being carried into the Pacific. This increasing freshening of the Arctic Ocean would form a large rotating ocean current called a cyclonic gyre that would lead to the collapse of the AMOC, according to the paper.
Hu says the results from his model may also help explain why there were no abrupt climate change events between Ice Ages and in the early parts of glacial periods, when the Bering Strait was likely still open.