fbpx

More than 40% of Antarctica’s ice shelves have shrunk since 1997, study finds

Warm water on the western side of the continent is melting ice shelves faster than the natural rate, scientists found.

More than 40% of Antarctica’s ice shelves have shrunk, with almost half showing “no sign of recovery”, scientists have said, who believe climate change is probably responsible.

Warm water on the western side of the continent has been melting ice, whereas in the east, ice shelves have either stayed the same or grown as the water is colder there.

Scientists at the University of Leeds have calculated that 67 trillion tonnes of ice was lost in the west while 59 trillion tonnes was added to the east between 1997 and 2021 – resulting in a net loss of 7.5 trillion tonnes.

These ice shelves sit at the end of glaciers and slow their rate of flow into the sea. When they shrink, glaciers release larger amounts of freshwater into the sea which can disrupt the currents of the Southern Ocean.

Dr Benjamin Davison, an expert in Earth observation and the study’s lead, said: “There is a mixed picture of ice-shelf deterioration, and this is to do with the ocean temperature and ocean currents around Antarctica.

Water temperature around the Antarctic
The water temperature on the western side of Antarctica has been warmer than that on the east (Dr Benjamin Davison/University of Leeds/PA)

“The western half is exposed to warm water, which can rapidly erode the ice shelves from below, whereas much of East Antarctica is currently protected from nearby warm water by a band of cold water at the coast.”

Scientists measured year-by-year changes to the ice using satellites that can see through the thick cloud during long polar nights.

They looked at more than 100,000 images taken from space to analyse the health of the ice shelves, which can have knock-on effects for the rest of the globe, and published their findings in the journal Scientific Advances.

The estimated 67 million tonnes of freshwater released into the ocean over the 25-year period affects the ocean currents that transport heat and nutrients around the world.

Salty water sinks to the ocean floor, which helps drive the currents, but more freshwater disrupts this system as it takes longer to reach the bottom.

Scientists believe the ice loss is a result of climate change because there would be more ice regrowing if it was part of a cycle of natural variation.

Dr Davison said: “We expected most ice shelves to go through cycles of rapid, but short-lived shrinking, then to regrow slowly.

“Instead, we see that almost half of them are shrinking with no sign of recovery.”

The Getz ice shelf was seen to lose the most ice – 1.9 trillion over the study period. Only 5% of that was through calving, where large chunks break off and become icebergs. The rest was due to melting.

A further 1.3 trillion tonnes of ice was lost from the Pine Island ice shelf with around a third from calving and the rest from melting.

On the eastern side of the Antarctica, the Amery ice shelf gained 1.2 trillion tonnes of ice because the waters on that side of the continent are much colder.

More from Perspective

Get a free copy of our print edition

News

Leave a Reply

Your email address will not be published. Required fields are marked *

Fill out this field
Fill out this field
Please enter a valid email address.
You need to agree with the terms to proceed

Your email address will not be published. The views expressed in the comments below are not those of Perspective. We encourage healthy debate, but racist, misogynistic, homophobic and other types of hateful comments will not be published.