Greenland's ice is melting even faster than scientists thought

Tuesday, 22 January 2019

The ice sheets of Antarctica and Greenland may collapse even if we limit global warming.

Ice in Greenland is melting faster than scientists predicted.

Research has revealed the pace of loss has increased four-fold since 2003, the Guardian reported.

Michael Bevis, Ohio State University professor of geodynamics, was the lead author of a new research paper on the topic and said there were two major concerns.

'We knew we had one big problem with increasing rates of ice discharge by some large outlet glaciers.

* Antarctic crack widening quicker than expected, may release giant iceberg**

Melting in Greenland - the world's second largest ice sheet behind Antarctica - was estimated to add more water to global ocean levels each year than any other source - 0.8mm - according to Nasa.

* Atlantic Ocean may spawn four to seven hurricanes in 2018 storm season

'But now we recognise a second serious problem: increasingly, large amounts of ice mass are going to leave as meltwater, as rivers that flow into the sea.'

Glaciers in the country deposit chunks of ice into the Atlantic Ocean, which then melt. But the research shows the largest ice loss has actually taken place in a glacier-free part of Greenland.

Since 2003, the south-west region of the island, which is mostly free of glaciers, has melted faster than the north part of the island.

South-west Greenland is now expected to become 'a major future contributor to sea level rise', the paper said.

The paper also suggested that ice is melting as global temperatures rise, pushing up sea levels as a result. This counters the previously held thought that the biggest contributor to rising sea levels was ice breaking off glaciers.

THE STUDY

The research paper used data from Nasa's gravity recovery and climate experiment (called Grace) and GPS stations to assess changes in ice mass across Greenland.

The study, which was published in Proceedings of the National Academy of Sciences, showed that Greenland lost about 280 billion tons of ice a year between 2002 and 2016. That amount of ice was enough to raise the global sea level by 0.03 inches a year.

If the entire ice sheet on Greenland melted, sea levels would rise by seven metres and drown most coastal areas.

COASTAL AREAS AT RISK

Coastal areas are particularly vulnerable to rising sea levels, so this research amplifies the risk to Pacific island nations and populated areas like Shanghai, Rio de Janeiro and Osaka.

'The only thing we can do is adapt and mitigate further global warming – it's too late for there to be no effect,' Bevis said.

'This is going to cause additional sea level rise. We are watching the ice sheet hit a tipping point.

'We're going to see faster and faster sea level rise for the foreseeable future. Once you hit that tipping point, the only question is: How severe does it get?'

RATE OF LOSS

In 2013, Greenland's ice was melting four times faster than in 2003.

Researchers attributed this both to rising global temperatures from climate change, and the North Atlantic Oscillation - a weather phenomenon that causes fluctuations in atmospheric pressure at sea level.

Recently, scientists have acquired a greater understanding of how Greenland and Antarctica are reacting to a warming ocean and atmosphere, the Guardian reported.

In June 2018, analysis showed that the rate of melting in Antarctica had tripled since 2012.

Associate Professor Rob McKay, from Victoria University of Wellington's Antarctic Research Centre, said after the tipping points were reached at each polar ice sheet, 'retreat potentially becomes unstoppable'.

Professor Christina Hulbe, from the University of Otago School of Surveying, said the work had 'one clear message: we are very close to triggering irreversible change in Earth's polar ice sheets'.

'The threshold for irreversible ice loss in both Greenland and Antarctica is somewhere between 1.5 and 2C global mean warming. We're already at a bit more than 1C warming,' she said.