In a new paper, climate scientists at the University of Massachusetts Amherst and Woods Hole Oceanographic Institution propose that massive amounts of melting sea ice in the Arctic drained into the North Atlantic and disrupted climate-steering currents, thus playing an important role in causing past abrupt climate change after the last Ice Age, from about 8,000 to 13,000 years ago.
In a new paper, climate scientists at the University of Massachusetts Amherst and Woods Hole Oceanographic Institution propose that massive amounts of melting sea ice in the Arctic drained into the North Atlantic and disrupted climate-steering currents, thus playing an important role in causing past abrupt climate change after the last Ice Age, from about 8,000 to 13,000 years ago. Details of how they tested this idea for the first time are online now in Geology.
Raymond Bradley, director of UMass Amherst’s Climate Systems Research Center, and lead author Alan Condron, research scientist at Woods Hole, explain that geologists have considered many theories about abrupt temperature plunges into “glacier-like” conditions since the last glaciers retreated, notably a very cold period about 12,900 years ago, known as the Younger Dryas. Meteorite impact and volcanic eruptions were proposed to explain these episodes, but evidence has been unconvincing, they add.
Now Condron and Bradley, with Ph.D. student Anthony Joyce, say they have new evidence that periodic break-up of thick Arctic sea ice greatly affected climate. Melting of this ice led to freshwater flooding into the seas near Greenland, Norway and Iceland between 13,000 and 8,000 years ago, slowing the strength of the Atlantic Meridional Overturning Circulation (AMOC). They say their experiments show that there was enough cold, fresh water to disrupt ocean salt-temperature circulation patterns and trigger abrupt climate cooling such as the Younger Dryas.
Bradley explains, “Understanding the past helps us understand how the Arctic system works.”
Read more at University of Massachusetts Amherst
Image: One of the last remains of the formerly extensive ice off the coast of Ellesmere Island, Arctic Canada, pictured in July 2002. At the end of the last Ice Age, ice such as this would have covered large parts of the Arctic Ocean and been up to 164 feet (50 meters) thick in places, creating an enormous reservoir of fresh water independent from land-based lakes and ice sheets, say Raymond Bradley of UMass Amherst and Alan Condron of Woods Hole Oceanographic Institute in a new paper on past climate. (Credit: Woods Hole Oceanographic Institution/Alan Condron)
