The Scotsman

Warning over rise in sea level as Antarctic melting increases

- By DANIEL HAMMOND newsdeskts@ scotsman. com

Glaciers i n Antarctica are becoming unstable with a quarter of glaciers now melting in just 25 years, a new study has warned.

Ocean melting has caused ice thinning in west Antarctica by up to 122 metres in places.

This has left affected glaciers unstable as they are losing more mass through melting and iceberg calving than they are gaining through snowfall.

While the majority of the ice sheet has remained stable, a quarter of west Antarctica is “now in a state of dynamical imbalance”.

Ice is being lost five times more than in 1992, with snowf a l l f a i l i ng t o r e s t o r e t he Pine Island Glacier and the Thwaites. Melt water from east and west Antarctica have contribute­d to a 4.6mm rise of the sea level, scientists warn.

Satellite images were anal ysed at t he UK Centre f or Polar Observatio­n and Modelling ( CPOM) based at the University of Leeds. They combined 25 years of European Space Agency satellite altimeter measuremen­ts to track changes in ice and snow.

R e s e a r c h e r s c o mp a r e d images to a model of Antarct i ca’s regional climate and found that melting “triggered imbalances”.

The study used more than 800 million measuremen­ts recorded by the ERS- 1, ERS2, Envisat, and Cryosat- 2 satellites. Together, these measuremen­ts allowed changes in the height of the ice sheet to be separated from those due to weather patterns.

Professor Andy Shepherd, director of CPOM, said: “In parts of Antarctica, the ice sheet has thinned by extraordin­ary amounts.

“We set out to show how much was due to changes in climate and how much was due to weather.”

Researcher­s found that fluctuatio­ns in snowfall tended to drive small changes in height over large areas for years at a time.

The study found the most pronounced changes in thickness were signals of glacier imbalance that have persisted for decades.

Professor Shepherd said: “Knowing how much snow has fallen has really helped us to detect the underlying change in glacier ice within the satellite record.

“We can see clearly now that a wave of thinning has spread rapidly across some of Antarctica’s most vulnerable glaciers, and their losses are driving up sea levels around the planet.”

Co- author Dr Marcus Engdahl, of the European Space Agency, s a i d : “Thi s i s a n important demonstrat­ion of how satellite missions can help us to understand how our planet is changing.

“The polar regions are host i l e environmen­ts and are extremely difficult to access from the ground – because of this, the view from space is an essential tool for tracking the effects of climate change.”

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