Antarctic ice melting faster than previously thought

Antarctic ice melting faster than previously thought

Loss of ice in Antarctica has caused global sea levels to rise by 7.6 millimeters since 1992, with 40 percent of the increase happening in just the past five years, according to a team of 84 scientists, including discipline-leading experts from the University of California, Irvine.

The report's findings should dispel any lingering doubts that Antarctica's ice mass is shrinking.

By a decade later, between 2002 and 2007, that average annual loss went up to 73 billion metric tons-a 24-billion-metric-ton increase.

Researchers have quantified how much ice the Antarctic has lost in the past 26 years, and it's an ungodly amount: 3,000,000,000,000 tons.

These changes in the rate of ice loss are caused mostly by the melting of ice in West Antarctica, a place where the warm waters of ocean tend to get below the glaciers making them unstable. "This has to be a concern for the governments we trust to protect our coastal cities and communities", said Shephard.

Benjamin Smith, senior principal investigator at the University of Washington Applied Physics Laboratory, said climate scientists are getting a better handle on crucial questions relating to the impact of Antarctic melting, thanks to more advanced satellites.

"Although breakup of the ice shelves does not contribute directly to sea-level rise - since ice shelves, like sea ice, are already floating - we now know that these breakups have implications for the inland ice", said Helen Fricker, a co-author of the review.

Satellites contributing to the project include CryoSat, Sentinel-1 and the U.S.

The East Antarctic Ice Sheet (EAIS) is the largest potential contributor to future sea level rise, but projections are hindered by uncertainty in how the EAIS responded to past warm periods, for example during the Pliocene (5.3-2.6 Myr ago) when atmospheric Carbon dioxide concentrations were last ≥ 400 ppm.

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Shepherd said: "We have long suspected that changes in Earth's climate will affect the polar ice sheets". The latter is increasingly being viewed as posing a potential planetary emergency, because of its enormous size and its role as a gateway that could allow the ocean to someday access the entirety of West Antarctica, turning the marine-based ice sheet into a new sea.

"The detailed record shows an acceleration, starting around 2002, " said Beata Csatho, one of the study authors and a glaciologist at the State University of NY at Buffalo, in an e-mail.

An ice-penetrating radar system, towed behind a snowmobile, turns up odd features beneath the West Antarctic Ice Sheet. This increase has been very small compared to the losses recorded from the rest of the ice sheet, though. The rate of sea-level rise due to Antarctic ice loss has tripled since 2012, he said.

That has made global oceans rise around 7.6 millimetres.

Up to now, scientists have struggled in determining whether Antarctica has accumulated more mass through snowfall than it loses in meltwater run-off and ice flows into the ocean.

In a new study, the most comprehensive to date of the continent's icy status, an worldwide group of 84 researchers analyzed data from multiple satellite surveys, from 1992 to 2017.

The team from northern IL analyzed sediments from the base of the ice sheet in Ross Sea region and found signs of left behind by marine life, which indicated the area was linked to ocean waters sometime in the last 40,000 years, which was more recent than previously thought. However, in the last five years, it too has begun to lose ice, perhaps as much as 28 billion tons per year. The research involved more than 80 scientists from 44 worldwide organizations and used data taken from multiple satellites, as well as air and ground measurements and computer simulations.

The loss was centered on the West Antarctica and the Antarctica Peninsula.

"We're beginning to understand how the retreat of Antarctica's sensitive glaciers probably begins in a warming climate", said Donald D. Blankenship, a UTIG senior research scientist and co-author of the new study. "Things are happening. They are happening faster than we expected".

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