Ice-Free Arctic May be Nearer Than We Thought: Crater Reveals Warmer World

The Earth may be hurtling toward an ice-free Arctic in the coming years. Researchers have discovered that the icy north experienced an extended period of warm temperatures about 3.6 million years ago, a time when ice was scarce in the Arctic.

Researchers examined a remote meteorite crater in Siberia, where sediments located in Lake El'gygytgyn recorded the unusually balmy climate of the Arctic millions of years ago. At the time, greenhouse gas levels were as high as today, while temperatures were about 14 degrees Fahrenheit higher. The seas levels were also 130 feet higher than they are at present.

In order to understand these warmer conditions a bit better, the scientists took a closer look at sediment cores that were collected from the lake in 2009. They found that not only was the climate warmer, but that the Arctic was likely ice-free at the time.

"There was probably no sea ice, and the whole Arctic was pretty well forested, so it was a very different world," said Julie Brigham-Grette, one of the researchers, in an interview with LiveScience. "So, how did we go from that to the tundra that we have today, and what does this tell us about the future?"

Since the warm Arctic possessed CO2 levels that were at least about 400 parts per million (ppm), the researchers believe that the climate's sensitivity to this gas has been underestimated. In fact, it shows that global warming is actually amplified at the poles; this, in turn, has enormous implications for the future of climate change. It could mean that the rising CO2 levels will eventually create a situation where the Arctic is completely ice ice.

"I think we will feel the effects of climate change quickly--in years or decades--because changes in the Arctic sea ice bring changes in the circulation of the atmosphere and the oceans," said Scott Elias, a professor at Royal Holloway University of London not involved with the study, in an interview with The Guardian. "Arctic sea ice keeps that entire region cool and when it melts, the dark ocean revealed absorbs even more heat."

The extended warm period that researchers witnessed in the Arctic actually raises new questions about the subsequent ice ages. According to the new study, these warm Arctic temperatures persisted past the time when previous studies estimated the start of expanding glaciers in the Northern Hemisphere, according to LiveScience. This, in turn, means that scientists are still unclear when big continental ice sheets began to expand and grow.

That said, the study does reveal a little bit more about the Arctic's climate history, and may show that we may soon be in for some far warmer temperatures in the future.

The findings are published in the journal Science.