West Antarctica Ice Sheet Existed 20 Million Years Earlier than Believed

Antarctica's western ice sheet has existed 20 million years longer than previous believed, according to a new study published in the journal Geophysical Research Letters which indicates that the ice sheet layering West Antarctica came into formation at the start of a global transition from warm greenhouse conditions to a cooler icehouse climate about 34 million years ago.

Today, the West Antarctic Ice Sheet contains about 10 percent of the total ice on Antarctica and is similar in scale to the Greenland Ice Sheet.

Previous studies, which used computer simulations to produce models of the ancient Antarctic, were unable to account for the significant amounts of ice that geological records suggest was present at the time.

But those studies did not take the land elevation of West Antarctica into account. Researchers had always believed that the land elevation of West Antarctica has always been low like it is today. But research published in 2009 and 2012 has indicated that West Antarctica's bedrock was much higher in elevation during the global climate transition than it is today, with a significant amount of its landmass above sea level.

By taking West Antarctica's higher elevation into account, the new computer simulations were able to account for the ice masses the geological record indicated existed at the time.

"Our new model identifies West Antarctica as the site needed for the accumulation of the extra ice on Earth at that time," said lead author Douglas S. Wilson, a research geophysicist at University of California Santa Barbara. "We find that the West Antarctic Ice Sheet first appeared earlier than the previously accepted timing of its initiation sometime in the Miocene, about 14 million years ago. In fact, our model shows it appeared at the same time as the massive East Antarctic Ice Sheet some 20 million years earlier."

In Wilson and his team's model, the nascent Antarctic ice sheet has significant ice on the West Antarctica subcontinent.

"The UCSB researchers computed a range of ice sheets that consider the uncertainty in the topographic reconstructions, all of which show ice growth on East and West Antarctica 34 million years ago," the university wrote in a news release. "A surprising result is that the total volume of ice on East and West Antarctica at that time could be more than 1.4 times greater than previously realized and was likely larger than the ice sheet on Antarctica today."