Antarctic Glacier Will Melt for Decades To Come

The single largest contributor to rising sea levels is the Pine Island Glacier (PIG), located in the West Antarctic Ice Sheet. New research, published in Science, suggests that the glacier may continue thinning for decades to come.

A team of international geologists revealed that 8,000 years ago PIG was thinning as fast as it has been in recent decades, providing them with a useful model for its future behavior. The significant acceleration, thinning and retreat that the glacier is currently experiencing are thought to be caused by "ocean-driven" melting - an increasing amount of warm ocean water is finding its way under the ice shelf, according to a press release announcing the research.

Since PIG started losing ice two decades ago, concerns have risen over the extent to which more ice will melt into the ocean. Current models are unreliable and leave questions regarding the rate and regularity of future sea level rise. Information about past ice sheet change is provided by exposed rocks as the glacier retreats, helping to predict future changes.

Using highly sensitive dating techniques, pioneered by a member of the team, the geologists were able to show that past thinning of PIG lasted for several decades.

"Our geological data show us the history of Pine Island Glacier in greater detail than ever before. The fact that it thinned so rapidly in the past demonstrates how sensitive it is to environmental change; small changes can produce dramatic and long-lasting results. Based on what we know, we can expect the rapid ice loss to continue for a long time yet, especially if ocean-driven melting of the ice shelf in front of Pine Island Glacier continues at current rates," said lead study author Joanne Johnson from the British Antarctic Survey.

"This paper is part of a wide range of international scientific efforts to understand the behavior of this important glacier. The results we're publishing are the product of long days spent sampling rocks from mountains in Antarctica, coupled to some exceptionally precise and time-consuming laboratory analyses. The results are clear in showing a remarkably abrupt thinning of the glacier 8,000 years ago," said Mike Bentley, a professor and co-leader of the project.