Minor variations in ice sheet size can trigger abrupt climate change

Small fluctuations in the sizes of ice sheets during the last ice age were enough to trigger abrupt climate change, scientists have found.

The team, which included Cardiff University researchers, compared simulated model data with that retrieved from ice cores and marine sediments in a bid to find out why temperature jumps of up to ten degrees took place in far northern latitudes within just a few decades during the ice age.

The analysis, led by Germany's Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI), is published on Thursday (21 August 2014) in the scientific journal Nature.

The research confirms that thicker ice sheets increased ocean circulation and transferred more heat to the north due to a redirection of the prevailing winds. As the north warmed, glaciers retreated, the winds returned to normal conditions, and the north became cooler once again, completing the cycle.

Conor Purcell from Cardiff University's School of Earth and Environmental Sciences, said: "Using the simulations performed with our climate model, we were able to demonstrate that the climate system can respond to small changes with abrupt climate swings. Our study suggests that at medium sea levels, powerful forces, such as the dramatic acceleration of polar ice cap melting, are not necessary to create abrupt climate shifts and temperature changes."

At present, the extent of Arctic sea ice is far less than during the last glacial period. The Laurentide Ice Sheet, the major driving force for ocean circulation during the glacials, has also disappeared. Climate changes following the pattern of the last ice age are therefore not anticipated under today's conditions.