Melting rate of mile-thick ice sheet ‘at fastest ever’

Christopher Davidson
December 7, 2018

"We are seeing levels of Greenland ice melt and runoff that are already unprecedented over recent centuries (and likely millennia) in direct response to warming global temperatures since the pre-Industrial era", Sarah Das, co-author of the report and scientist at the USA -based Woods Hole Oceanographic Institution said in a statement. "We found a fifty percent increase in total ice sheet meltwater runoff versus the start of the industrial era, and a thirty percent increase since the 20th century alone".

'The melting and sea-level rise we've observed will be dwarfed by what may be expected in the future'. Icebergs breaking off into the ocean from the edge of glaciers are a spectacular example.

From these numbers, the researchers estimated that ice sheet-wide levels of meltwater runoff have jumped 50 per cent in the past 20 years compared with pre-industrial times.

Lead by glaciologist and climate scientist Luke Trusel of Rowan University, a team of US and European researchers analyzed more than three centuries of melt patterns in ice cores from western Greenland. Rather than increasing steadily as the climate warms, Greenland will melt increasingly more for every degree of warming.

The ice cores contain layers that show how ice melted and refroze on contact with the snow-pack underneath each year, revealing the intensity of melting. "We demonstrate that Greenland ice is more sensitive to warming today than in the past - it responds non-linearly due to positive feedbacks inherent to the system".

Rising seas threaten low-lying cities, islands and industries worldwide. Instead, it forms distinct icy bands that stack up in layers of densely packed ice over time.

Runoff from Greenland's ice sheet hit a 350-year high in 2012, when it dumped-according to Nature-240 million Olympic swimming pools worth of water into the ocean.

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Global warming is melting ice in Greenland at "unprecedented rates", experts warned.

Analysis of ice core samples from sites 6,000ft (1,829m) above sea level has enabled the researchers to assess melting dating back 350 years.

"We have had a sense that there's been a great deal of melting in recent decades, but we previously had no basis for comparison with melt rates going further back in time", he said.

"It's not just increasing, it's accelerating", he explained.

Commenting on the report, Gareth Redmond-King, head of climate change at the World Wildlife Fund said: "If governments don't radically up their green ambitions, we're facing a future without coral reefs or Arctic summer ice, where food shortages, floods and fires are part of our everyday reality".

In fact, if the sheet melting continues at "unprecedented rates", which researchers attribute to warmer summers, it could accelerate the already fast pace of sea level rise, a new study has warned.

"Even a very small change in temperature caused an exponential increase in melting in recent years", she said.

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