Ice loss in Antarctica is increasingly contributing to global sea level rise

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The researchers say the rate of ice loss has tripled over the last decade and the melting ice sheets are now pushing up sea levels around the world by around a half-millimeter every year, reports the BBC.

The latest data is a continuation of previous assessments known as the Ice sheet Mass Balance Inter-comparison Exercise (IMBIE), which began in 2011 and tracks ice-sheet loss from 1992 onwards.

An global team of polar scientists found that melting in Antarctica has jumped sharply from an average of 76 billion tonnes per year prior to 2012, to around 219 billion tonnes each year between 2012 and 2017.

Overall between 1992 and 2017, Antarctica's ice sheet lost 3 trillion tons of ice - enough water to cover Texas to a depth of almost 13 feet, scientists calculated.

"The kinds of changes that we see today, if they were not to increase much more", DeConto said, "then maybe we're talking about something that is manageable for coastal stakeholders".

Scientists warn that Antarctica's rapid melting could mean countries now have even less time to take action against climate change if they hope to protect vulnerable communities from rising sea levels.

"Antarctica is way too big to survey from the ground, and we can only truly understand the trends in its ice cover by looking at the continent from space", said Andrew Shepherd, a professor at Leeds.

In a separate analysis piece in Nature today, climate scientist and Antarctic policy expert Professor Rob DeConto warned that Antarctica may contribute more to sea-level rise than previously thought.

The melting is caused by rising ocean temperatures due to climate change.

"The satellite measurements tell us that the ice sheet is much more dynamic than we used to think", he said.

As shown in the video above, these changes are not uniform over the entire Antarctic ice sheet.

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A second global study published in Nature highlighted evidence of Antarctica's increasing contribution to rising sea levels.

Lifting the ban could result in severe damage to the Antarctic environment, while the loss of land ice could result in unsustainable levels of tourism and the spread of unwanted invasive species.

West Antarctica is now bearing the brunt of this loss, as its glacial ice shelves have been melted from below by warming deep ocean water.

Antarctica's potential contribution to global sea level rise from its land-held ice is nearly 7.5 times greater than all other sources of land-held ice in the world combined, NASA said. The increases are on the order of a few millimetres per year, but scientists need to account for them to ensure their other measures of ice loss are accurate.

The researchers attribute the increased losses in West Antarctica and the Antarctic Peninsular to changes in regional floating-ice shelves, which can provide a buffer to continental-ice sheets. As part of IMBIE, Professor Shepherd coordinated with 83 other scientists, from 44 global organizations, to combine the data from two dozen different satellite surveys for this comprehensive look at the changes in Antarctica's ice mass balance.

"The data from these spacecraft show us not only that a problem exists but that it is growing in severity with each passing year", explains NASA researcher Isabella Velicogna from the University of California, Irvine.

Antarctica, which is technically classified as a desert, due to the small amount of precipitation it receives in the form of snow, is home to most of Earth's fresh water (between 60 and 90%). Improving our understanding of how much Antarctica has contributed to sea level rise in the past, and how much it will contribute in the future, is vital to informing our response to climate change.

She also said that in light of the study, it is "very clear that now is absolutely not the time to back away from the science infrastructure that allows us to have information, so the coastal communities can plan with the best available information about what's happening down in Antarctica".

Overall, world sea levels have risen nearly 8 inches in the past century, driven mainly by a natural expansion of water already in the oceans as it warms along with a thaw of glaciers form the Andes to the Alps.

"The fate of Antarctica, the fate of Greenland, is the fate of Miami", she said.

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