A new analysis of rocks that have melted out of glaciers in Antarctica provide direct evidence that the icecap is slowly thawing, part of a long-term cycle of natural thawing that has lasted for 10,000 years.
The rocks were found on mountain peaks jutting out of the icecap. These peaks were buried by ice in the past and the rocks were stranded once the ice melted.
Chemical signatures in the rocks allowed a group led by University of Washington geologist John Stone to precisely date when the rocks were freed from the ice. The pattern suggests that the ice has been melting continuously, about 2 inches per year, for the last 10,000 years and shows no sign of slowing.
The melting is not due to human impacts but to long-term climate cycles like those that caused the ice ages, Stone said. He added that human-caused warming of the oceans and the atmosphere in the last 100 years could be speeding the process and that the ice sheet is susceptible to thinning at the edges if the oceans continue to warm.
The ice sheet contains enough water to raise global sea levels by 16 feet, he said, adding that even a foot of sea-level rise could be "disastrous for coastal regions."
Usha Lee McFarling