Can Ice Loss Affect Gravity?
A group of scientists, led by a team from the University of Bristol, has observed a sudden increase of ice loss in a previously stable region of Antarctica. The research is published today in Science.
Using measurements of the elevation of the Antarctic ice sheet made by a suite of satellites, the researchers found that the Southern Antarctic Peninsula showed no signs of change up to 2009. Around 2009, multiple glaciers along a vast coastal expanse, measuring some 750km in length, suddenly started to shed ice into the ocean at a nearly constant rate of 60 cubic km, or about 55 trillion litres of water, each year.
This makes the region the second largest contributor to sea level rise in Antarctica and the ice loss shows no sign of waning.
Dr Bert Wouters, a Marie Curie Fellow at the University of Bristol, who lead the study said: “To date, the glaciers added roughly 300 cubic km of water to the ocean. That's the equivalent of the volume of nearly 350,000 Empire State combined.”
The changes were observed using the CryoSat-2 satellite, a mission of the European Space dedicated to remote-sensing of ice. From an altitude of about 700km, the satellite sends a radar pulse to Earth, which is reflected by the ice and subsequently received back at the satellite. From the time the pulse takes to travel, the elevation of the ice surface can retrieved with incredible accuracy. By analysing roughly 5 years of the data, the researchers found that the ice surface of some of the glaciers is currently going down by as much as 4m each year.
The ice loss in the region is so large that it causes small changes in the gravity field of the Earth, which can be detected by another satellite mission, the Gravity Recovery and Climate Experiment (GRACE).
“The fact that so many glaciers in such a large region suddenly started to lose ice came as a surprise to us,” continued Dr Wouters. “It shows a very fast response of the ice sheet: in just a few years the dynamic regime shifted.”
Data from an Antarctic climate model shows that the sudden change cannot be explained by changes in snowfall or temperature. Instead, the team attributes the rapid ice loss to warming oceans.
Continue reading at the University of Bristol.
Ice image via Shutterstock.
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