Scientists have discovered that ocean water warmed by the sun is melting part of the world’s largest ice shelf 10 times faster than the overall average.
The north-west sector of the Ross Ice Shelf in Antarctica, which in total is roughly the size of France, is melting far faster than scientists previously thought, according to a press release from the University of Cambridge.
And scientists have identified an unlikely culprit: inflowing warm water from the ocean’s surface.
“The stability of ice shelves is generally thought to be related to their exposure to warm deep ocean water, but we’ve found that solar heated surface water also plays a crucial role in melting ice shelves,” said lead study author Craig Stewart from New Zealand’s National Institute of Water and Atmospheric Research (NIWA).
Stewart worked on the project while a PhD student at the University of Cambridge. Scientists from the UK university worked with others from the British Antarctic Survey (BAS) and NIWA over four years, collecting data from instruments placed 260-meters deep inside the ice shelf.
The effects of solar heated surface water could have huge consequences for global sea levels, according to the BAS.
Smaller ice shelves floating in warmer ocean water are melting 100-200 times faster than large shelves, said the BAS.
“The difference here is the sheer size of Ross Ice Shelf, which is over 100 times larger than the ice shelves we’ve already seen disappear,” said Poul Christoffersen from Cambridge’s Scott Polar Research Institute.
The collapse of the world’s major ice shelves could lead to a sea level rise of several meters or more, the BAS says.
Researchers’ concerns are intensified due to the shape of the Ross Ice Shelf, which is stabilized because it pushes against Ross Island in the key north-west sector, a phenomenon which is known as a pinning point.
It is close to this area that melt rates are increasing, BAS oceanographer Keith Nicholl said, potentially threatening the stability of the ice shelf if the pressure of the Ross Island pinning point is reduced.
“These ice front pinning points help control the flow of a lot of Antarctic ice shelves, and so the study demonstrates another vulnerability of ice shelves to climate change,” Nicholl said.
The full results were published in the journal Nature Geoscience.