Ragged and remote, Recovery Glacier drains nearly 1 million square kilometers of the East Antarctic Ice Sheet (EAIS), a massive system of glaciers that makes up about two thirds of the Antarctic continent. Past studies have suggested that there are a number of large lakes beneath the glacier, potentially contributing to its unusually fast westward flow along the Shackleton Range. Now, however, a new study suggests that many of these lakes do not exist.
Most previous studies that have suggested that large lakes are present beneath Recovery Glacier were based on altimetry—a satellite-based method that measures a glacier’s volume on the basis of its height. In the new study, however, Humbert et al. used a different technique, called radio echo sounding, to look for the lakes.
In radio echo sounding, an airplane broadcasts radio waves deep into ice and catches the signals as they bounce back, revealing a glacier’s interior structure. Large, flat reflections from the base of the ice sheet typically indicate liquid water. In January 2014, the team carried out an extensive, airborne, radio echo survey of Recovery Glacier and its tributaries, flying a total of 22,700 kilometers along the glacier’s path.
Although the team was able to accurately identify a few lakes beneath Recovery Glacier, they found no evidence of water at most of the sites where past studies have proposed large lakes. Computer models based on the new measurements suggest that the few large lakes that do exist beneath the ice sheet are not likely to be responsible for the glacier’s high velocity, the team reports.
The findings could help scientists more accurately predict how loss of ice from Recovery Glacier will contribute to sea level rise as global temperatures warm. Although the EAIS, which Recovery drains, has traditionally been considered less vulnerable to warming oceans than the Western Antarctic Ice Sheet, recent research suggests that it, too, is losing billions of tons of ice per year. (Journal of Geophysical Research: Earth Surface, https://doi.org/10.1029/2017JF004591, 2018)
—Emily Underwood, Freelance Writer