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Antarctica lost an unprecedented amount of ice in the last five years

14 June 2018

According to a new study by the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE), now considered to be the most complete and up-to-date picture of the changes happening to the Antarctic ice sheet, satellites had been recording a fairly steady rate of ice loss from Antarctica, of around 76 billion tonnes per year, between 1992 and 2012.

Antarctica has lost trillion tonnes of ice to global warming over the past quarter of a century, according to a new study, and that loss has been accelerating in recent years, to triple the rate that was seen prior to 2012.

"If you start removing mass from there, you can have a very large scale evacuation of ice into the ocean and significant sea level rise, " she continued.

The high seas are getting even higher, and all that water is largely coming from a colossal Antarctic ice melt that has gotten much worse in recent years.

While West Antarctica is melting away, the East Antarctica ice sheet isn't growing enough to offset ice loss from the rest of the continent.

The new findings are the result of the most complete satellite survey of Antarctic ice sheet change to date, involving 84 scientists from 44 worldwide organizations (including NASA and the European Space Agency). Their mission is to produce the most comprehensive look at what's happening to the world's vulnerable ice sheets in Antarctica and Greenland.

But afterwards, that sped up remarkably, resulting in a three-fold increase from 2012 to 2017, during which the continent lost some 219 billion tonnes of ice every year, pushing the ocean up 0.6 mm annually.

Per the team's calculations, a high emissions scenario - in which carbon emissions rise unabated and environmental protections in Antarctica are not implemented - global air temperature would rise almost 3.5°C above 1850 levels by 2070, with sea level rise averaging somewhere between 10-15 mm every year.

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

The findings, reported in Nature, are part of a special collection of five studies focussed on environmental change in Antarctica and the Southern Ocean.

"We can not count on East Antarctica to be the quiet player, and we start to observe change there in some sectors that have potential and they're vulnerable, " said Velicogna. The Antarctic Peninsula - the portion of the continent that reaches out for the southern tip of South America - has seen an increase from an average of 7 billion tonnes per year, up to 33 billion tonnes per year in that same time period.

"If we aren't already alert to the dangers posed by climate change, this should be an enormous wake-up call", he added.

"These events and the sea-level rise they've triggered are an indicator of climate change and should be of concern for the governments we trust to protect our coastal cities and communities". If sea level continues to change at this rate and acceleration, the researchers estimate that average sea-level rise by 2100 will be closer to 24 inches than 10 inches in 2100. But as the Post notes, "There is no proof the current rate of change in Antarctica will continue".

"I think we should be anxious". "We will not necessarily see exclusively rapid retreat, " said Christianson, noting that as glaciers like Pine Island retreat backwards down a submarine, downhill slope, they will sometimes encounter bumps that slow down their movement.

It's possible, however, that Antarctica alone can add about half a foot to sea level rise by the end of the century, said Andrew Shepherd, the lead author of the study and a professor of earth observation at the University of Leeds in England.

Whether Antarctic mass loss keeps worsening depends on choices made today, argues DeConto, who co-authored a separate paper in this week's Nature outlining two different visions for Antarctica's future in the year 2070. However, he says that now the data is tracking a higher scenario, which could mean almost 6 inches of additional sea level rise in the next century.

Rising sea levels can have a risky impact on coastal habitats and communities as flooding increases along with higher tides and stronger storm surges.

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

Antarctica lost an unprecedented amount of ice in the last five years