Rising levels of carbon dioxide drove much of the global warming that thawed Earth at the end of the last ice age.

That's the conclusion a team of scientists has drawn in a new study examining the factors that closed the door on the last ice age, which ended about 20,000 years ago.

The result stands in contrast to previous studies that showed temperatures rising ahead of increases in atmospheric CO2 levels. This has led some skeptics of human-triggered global warming to argue that if warming temperatures came first, CO2 wasn't an important factor then and so can't be as significant a factor today as most climate scientists calculate it to be.