Slight Ice Sheet Fluctuations May Cause Abrupt Climate Change

Typically when we think of climate change, we picture massive glaciers breaking off of Antarctica or tons of ice melting and raising global sea levels. But new research indicates that fluctuations in the sizes of ice sheets, however slight, may cause an abrupt climate change.

At least, that's what researchers from Cardiff University say happened during the last ice age, when temperature jumps of up to 10 degrees took place in far northern latitudes within just a few decades. The study team compared simulated model data with that retrieved from ice cores and marine sediments in order to find out what triggered this climate shift during the last ice age.

Described in the journal Nature, the scientists found 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.

"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," Conor Purcell, from Cardiff University's School of Earth and Ocean Sciences, said in a statement.

Currently, the extent of Arctic sea ice is far less than during the last glacial period. Not to mention that the Laurentide Ice Sheet, which was 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 cannot be predicted given the volatility of today's climate.

"In terms of the Earth's history, we are currently in one of the climate system's more stable phases," explained researcher Gerrit Lohmann. "The preconditions which gave rise to rapid temperature changes during the last ice age do not exist today, but sudden climate changes cannot be excluded in future."