Wind raising glacier melt rate
STRENGTHENING winds in the Southern Ocean are causing the largest glacier in East Antarctica to melt quicker — a trend contributing to global sea-level rise.
An international team of Australian Antarctic Program scientists have done in-depth research on the Totten Glacier.
The research has shown changing wind speeds over the Southern Ocean are driving an upwelling of warmer water off the Antarctic coast.
Sea floor canyons below the ice then allow warmer water to rise under the floating part of the glacier, causing the underside of the ice to melt quicker.
As the largest glacier in East Antarctica, Totten has the potential to be a significant contributor to sea-level rise. It drains 538,000 square kilometres of East Antarctica and discharges about 70 billion tonnes of ice each year.
Institute for Marine and Antarctic Studies researcher David Gwyther said the study used satellite images of the ice sheet, wind stress data and oceanography observations to determine how the atmosphere and warmer water impacted Totten’s stability.
“Our new research provides strong evidence of the mechanistic links of heat transfer from the atmosphere via the ocean all the way to the ice sheet,” he said.
“This study also suggests that as wind speeds over the Southern Ocean are projected to increase with climate change, the Totten Glacier will melt faster.”
Australian Antarctic Division glaciologist Jason Roberts said periods of stronger wind pushed surface water aside, allowing warmer water to rise and replace it.
“This water can then flow into the shallower and colder seas of the continental shelf around Antarctica,” he said.
“In places such as the Totten Glacier, canyons in the sea floor allow this relatively warm water to penetrate deep under the floating ice and increase melting.”
This summer, Australian Antarctic Division scientists will recover instruments deployed on the Totten Glacier in 2016-17 to measure changes in ice thickness as well as ocean-driven melting to understand ice-shelf thinning.