CO2 emissions 'delaying ice age'

Posted by Emma Woollacott

We have manmade global warming to thank for the fact that we're not all shivering in an ice age, according to research from Cambridge University that's likely to prove highly controversial.

It's long been known that we're due for another one. Interglacials in the past have averaged out at around 11 thousand years, and it’s currently been six hundred years longer than that since the last ice age.

"The mystery of the ice ages, which represent the dominant mode of climate change over the past few million years, is that while we can identify the various ingredients that have contributed to them, it’s the arrangement of these ingredients, and how they march to the beat of subtle changes in seasonality, that we lack an understanding of," says Dr Luke Skinner from the Department of Earth Sciences.

The Cambridge researchers propose that the reason we're not all shivering is the amount of CO2 human beings have been pumping into the atmosphere. If it weren't for that, they say, the next ice age would have been kick-started sometime in the next thousand years.

By looking at the onset of abrupt flip-flops in the temperature contrast between Greenland and Antarctica - extreme climate behaviour that would have only been possible if vast and expanding ice sheets were disrupting ocean circulation - they believe they have been able to identify the fingerprint of the start of an ice age activation, or glacial inception.

They identified an interglacial period some 780 thousand years ago which had nearly identical solar radiation, or insolation to the present day. And, by comparing it to the present, they found thatthat glacial inception would indeed be expected to occur sometime soon.

"From 8,000 years ago, as human civilization flourished, CO2 reversed its initial downward trend and drifted upwards, accelerating sharply with the industrial revolution," says Skinner.

"Although the contribution of human activities to the pre-industrial drift in CO2 remains debated, our work suggests that natural insolation will not be cancelling the impacts of man-made global warming."