Posted for Quirin Schiermeier

A paper this week in Nature (subscription) sheds new light on the causes of pronounced greenhouse-gas and climate fluctuations during glacial times.

The last ice-age, which covered the period from around 110,000 to 10,000 years before now, is famed for a series of climate swings known as Dansgaard-Oeschger events.

Scientists have found evidence in Greenland ice cores for abrupt warming episodes of up to 15 degrees Celsius within few decades, followed by a more gradual cooling. These glacial warm and cold periods swung back and forth between the poles in a kind of thermal seesaw effect, whereby Antarctic temperatures rose when Greenland temperatures dropped, and vice versa.

It has long been assumed that Dansgaard-Oeschger events were triggered by changes in Atlantic ocean-circulation. The new modelling study by Andreas Schmittner and Eric Galbraith now adds new evidence to the idea.

Read the full version of this post on Nature’s Climate Feedback blog…

Image: Eric Galbraith