Antarctica Pine Island Glacier More Susceptible to Climate Change Than Once Thought

The Antarctic Pine Island Glacier may be more susceptible to climate change than we once thought. Scientists have found that oceanic melting of the ice shelf into which the glacier flows decreased by 50 percent between 2010 and 2012, most likely due to the La Niña weather event. The findings reveal that this glacier is likely to be drastically affected by changing weather conditions.

The Pine Island Glacier has thinned continuously during the past decades, driven by an acceleration in its flow. This acceleration is thought to be caused by thinning of the floating ice shelf created as the glacier slides into the sea. Understanding the processes driving this thinning is crucial to assessing how much it will contribute to rising sea levels.

In order to learn a bit more about this thinning and melting, the researchers took a closer look at the Pine Island Glacier. They found that much of the thinning is due to a deep oceanic inflow of Circumpolar Deep Water (CDW) on the continental shelf neighboring the glacier. The warmer water makes its way into a cavity beneath the ice shelf, melting it from below.

Yet in 2009, researchers found that a higher CDW volume and temperature in Pine Island Bay contributed to an increase in ice shelf melting compared to the last time measurements were taken in 1994. Yet observations in January 2012 showed that ocean melting of the glacier was the lowest ever recorded.

Why was this? The fluctuations in temperature and melting may be explained by particular climatic conditions. In January 2012, there was a dramatic cooling of the ocean around the glacier, possibly due to the La Niña weather event.  These particular observations suggest that there's a complex interplay between geological, oceanographic and climatic processes.

"We found ocean melting of the glacier was the lowest ever recorded, and less than half of that observed in 2010," said Pierre Dutrieux, one of the researchers, in a news release. "This enormous, and unexpected, variability contradicts the widespread view that a simple and steady ocean warming in the region is eroding the West Antarctic Ice Sheet. These results demonstrate that the sea-level contribution of the ice sheet is influenced by climatic variability over a wide range of time scales."

The findings are published in the journal Science.