Ice Sheet Fluctuations Can Cause Abrupt Climate Change in a Warming World

It turns out that even small fluctuations can trigger an abrupt climate change. Scientists have discovered that small changes in the sizes of ice sheets during the last ice age were enough to set off a warming event.

Currently, the extent of Arctic sea is far less than during the last glacial period. In addition, the Laurentide Ice Sheet, which was a major driving force for ocean circulation during the glacials, has also disappeared. This means that climate changes following the pattern of the last ice age are not anticipated under today's conditions.

Even so, learning more about the last ice age is crucial when it comes to understanding the warming of today's world. That's why researchers took a closer look with the help of simulated model data and ice cores and marine sediments. By examining this data, they were able to find out why temperature jumps of up to ten degrees occurred in far northern latitudes within just a few decades during the last ice age.

"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," said Conor Purcell, one of the researchers, in a news release. "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."

In the end, the researchers found that thicker ice sheets increase ocean circulation and transferred more heat to the north due to a redirection of the prevailing winds. As the north warmed, the glaciers retreated and the winds returned to normal conditions. The north became cooler once again and completed the cycle.

"In terms of the Earth's history, we are currently in one of the climate system's more stable phases," said Gerrit Lohmann, one of the researchers. "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."

The findings are published in the journal Nature.