Dramatic rise detected in West Antarctic coastal snow

Annual snow accumulation on West Antarctica's coastal ice sheet increased 30 percent during the 20th century, new research has found.

Understanding how the ice sheet grows and shrinks over time enhances scientists' understanding of the processes that impact global sea levels, the authors said.

The study used ice cores to estimate annual snow accumulation from 1712 to 2010 along West Antarctica's coast.

Until 1899, annual snow accumulation remained steady, averaging 33 and 40 centimetres of water, or melted snow, each year at two locations.

Annual snow accumulation increased in the early 20th century, rising 30 percent between 1900 and 2010, according to the new study.

In the past 30 years of the study, the ice sheet gained nearly five metres more water than it did during the first 30 years of the studied time period.

"Since the record is 300 years long, we can see that the amount of snow that has been accumulating in this region since the 1990s is the highest we have seen in the last 300 years. The 20th century increases look unusual," said lead author of the study Elizabeth Thomas, paleoclimatologist with the British Antarctic Survey in Cambridge.

Thomas attributed the higher annual snow accumulation over the last 30 years in part to an intensification of a regional low pressure system and more storms in the region.

These storms could increase with climate change, possibly leading to further increases in snow accumulation, the researchers explained.

Snow accumulation builds up the ice sheet, but the extra flakes have not acted as a life raft for West Antarctica's ice sheet, which previous research has found is rapidly thinning as the climate warms, Thomas said.

The size of the ice sheet depends on how much new snow accumulates and how much of the existing ice melts, she said.

The findings appeared in the journal Geophysical Research Letters.