Melting of Antarctica is speeding up, worrying scientists

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The team looked at the mass balance of the Antarctic ice sheet from 1992 to 2017 and found ice losses from Antarctica raised global sea levels by 0.3 inches (7.6 millimeters), with a sharp uptick in ice loss in recent years.

West Antarctica experienced the most acceleration in ice loss among regions studied during the research period, growing from 53 billion tons a year in the 1990s to 159 billion tons annually in the final five years.

This is unedited, unformatted feed from the Press Trust of India wire. It's an untenable situation and one that could lead to runaway melt that would raise sea levels more than 10 feet. Thanks to the satellites that our space agencies have launched, we can now track their ice losses and global sea-level contribution with confidence. "We hadn't seen these kinds of structures near the base of an ice sheet before, and the best explanation is that they formed as this portion of the ice sheet re-grounded".

The only period when the quantity of ice lost dropped was between 1997 and 2002, when Antarctica saw a loss of 38 billion tonnes per year compared to 49 billion per year for the five years prior to that period.

The researchers estimate that ice loss in the period between 1992 and 2017, could be as high as 2,720 billion tonnes (although the number may also be as low as 1,390 billion tonnes, due to uncertainties in the data).

Results from the project - known as the Ice Sheet Mass Balance Inter-Comparison Exercise - were published today in Nature.

The study found more than 10 percent of Antarctica's coastal glacier are now retreating more than 25m per year.

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"A lot of the argument has been made from stakeholders that are not quite as interested in dealing with climate change that the East Antarctic ice sheet is actually gaining mass - therefore we don't need to worry", said Michele Koppes, a glaciologist at the University of British Columbia who was not involved with the study.

This chart show Antarctic ice sheet's contribution to sea level rise over time.

Antarctica is not the only contributor to sea-level rise.

Antarctic ice has retreated and advanced and retreated again many times over the millennia: there has always been argument about how much of the change is because of natural cycles, how much because of human-induced climate change.

"Satellites have given us an awesome, continent-wide picture of how Antarctica is changing", Pippa Whitehouse, of Durham University, said.

This latest IMBIE is the most complete assessment of Antarctic ice mass changes to date, combining 24 satellite surveys of Antarctica and involving 80 scientists from 42 global organizations.

Covering twice the area of the continental United States, Antarctica is blanketed by enough ice pack to lift global oceans by almost 60 metres (210 feet). However, scientists say it's not enough to replace the amount of ice lost.

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Shepherd said the ice on West Antarctica can be melted by very small changes in ocean temperature.

"What we have seen as the climate has warmed is that more warm water is reaching the Antarctic ice sheet and that's what is melting the sea ice", he said.

How has this research contributed to our understanding of climate change?

The biggest losses have come from the Pine Island and Thwaites Glaciers, as well as ice shelf collapse on the Peninsula like that of the much-watched Larsen C break last summer.

The findings not only clarify the past impact of rising temperatures on East Antarctic ice, said Shakun, but confirm the accuracy of models scientists are using to assess past and future consequences of a warming planet.

Duanne White, associate professor at the University of Canberra, commended the paper as "a thorough assessment of the current state of knowledge of Antarctic ice loss".

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