Over the summer of 2016 in the southern hemisphere, the world’s largest ice shelf, Antarctica’s Ross Ice Shelf, suffered a massive surface melt event that covered an area larger than the state of Texas, with the meltwater pooling in some areas for over two weeks.
The event was triggered by residual heat left over from last year’s El Niño, where warm, wet air from the Southern Pacific flowed over West Antarctica, prompting meltwater to mix with existing snow to form a layer of slush on top of the ice. The meltwater has since re-frozen, but the event is troubling researchers, as West Antarctica is home to the world’s largest ice shelves, ice flows that are already at risk of collapsing due to warm seawater eroding them from underneath. And unfortunately, the National Weather Service’s Climate Prediction Center is forecasting a 50/50 chance for El Niño conditions to form again by the end of 2017.
"The story of melt all over the ice shelf rattled through the science community as it happened," exclaims Robin Bell, a researcher with Columbia University’s Lamont-Doherty Earth Institute. The warm, wet weather also brought rain to the region, an area that typically sees little precipitation. "Who had heard of rain in Antarctica – it is a desert!"
On their own, melting ice shelves don’t contribute a great deal toward sea level rise, as most of the volume of ice is already in the water. However, these ice shelves act as dams that keep the land-based glaciers that feed them stable, and when these shelves collapse the glaciers they were supporting tend to flow rapidly into the ocean, as was the case when the Larsen B ice shelf collapsed in 2002, accelerating sea level rise.