Onset of Younger Dryas Happened in Matter of Months Not Decades
02.12.2009 - Atmosphere & Space, Water & Oceans, Ice & Snow, Other, Arctic
While investigating a mud core retrieved from ancient Lake Lough Monreach in Ireland, Dr. William Patterson from the University of Saskatchewan in Canada, has succeeded to show that the North Atlantic circulation might have stopped in a matter of months and not decades as was previously thought, triggering rapid climate cooling in Europe. The new data provides the highest resolution record of the Younger Dryas to date.
Some 13,000 years ago, the Northern Hemisphere was hit by a phenomenon which became known to scientists as the Younger Dryas, which saw a sudden drop of temperatures across North America and Europe which resulted in a mini ice age. (The reason for the drop was that the North Atlantic thermohaline circulation, which brings warm waters to Northern Europe via the Gulf Stream, suddenly slowed to a halt as a result of a large amount of freshwater being released into the North Atlantic after a massive glacier lake in North America burst and released volumes of freshwater, slowing the process of deepwater formation in the North Atlantic, which drives the North Atlantic thermohaline circulation and ocean currents, including the Gulf Stream, in the region).
Yet while previous evidence from ice cores retrieved in Greenland suggested the changes might have occurred over the course of a decade. New evidence from the mud cores shows that the changes likely occurred much more rapidly, over a period of a few months. Carbon isotopes in each slice of the mud core provide insight in the lake's productivity, while oxygen isotopes provide information about the temperatures and rainfall during the period. The mud core record essentially shows that both the sudden drop in temperatures and the halt in the lake's productivity happened over the course of a couple of years. It also shows that it took the climate and the lake approximately two centuries to recover.
The possibility of this phenomena repeating itself cannot be excluded as the Greenland Ice Sheet continues to melt and dump freshwater into the North Atlantic, where deepwater formation occurs.