Originally published on March 19th, 2020 on the Climate News Network
Article by Tim Radford
Greenland’s polar ice is now melting far faster than 30 years ago, Antarctic ice is retreating at an accelerating rate, and sea levels are creeping up.
LONDON, 19 March, 2020 – Greenland and Antarctica, the two greatest stores of frozen water on the planet, are now losing polar ice at a rate at least six times faster than they were at the close of the last century.
The fact that polar ice is melting ever faster has been clear for a decade, but the latest research is authoritative.
To establish the rate of loss, 89 polar scientists from 50 of the world’s great research institutions looked at data from 26 separate surveys between 1992 and 2018, along with information from 11 different satellite missions.
And the finding is in line with the worst-case scenarios considered by the Intergovernmental Panel on Climate Change (IPCC). If this rate of increase continues, sea levels at the close of this century will be at least 17 centimetres higher than the gloomiest official forecasts so far.
Between 1992 and 2017, the global sea level rose by 17.8 millimetres, as 6.4 trillion tonnes of polar ice turned to water and trickled into the oceans – 10.6 mm from Greenland and 7.2 mm from Antarctica.
In the last decade of the last century, the northern and southern icecaps dwindled at the rate of 81 billion tonnes a year. In the last decade, this had risen to 475 billion tonnes a year. This means that a third of all sea level rise is now caused by the loss of polar ice.
The most recent assessment by the IPCC is that, by 2100, sea levels will have risen by 53 cms, putting 360 million people who live at sea level at some risk.
“This would mean 400 million people at risk of annual coastal flooding by 2100”
But the latest finding from the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) scientists is that seas will rise even higher, and even more people will have to move.
“Every centimetre of sea level rise leads to coastal flooding and coastal erosion, disrupting people’s lives around the planet,” said Andrew Shepherd, professor of Earth observation at the University of Leeds, UK, as he and colleagues published their findings of Greenland losses in Nature journal.
“If Antarctica and Greenland continue to track the worst-case climate warning scenario, they will cause an extra 17 cms of sea level rise by the end of the century.
“This would mean 400 million people at risk of annual coastal flooding by 2100. These are not unlikely events with small impacts; they are already under way and will be devastating for coastal communities.”
Professor Shepherd and his IMBIE colleagues established almost two years ago that Antarctica was losing ice at an ever-accelerating rate, but the Greenland survey completes the global picture.
And it remains a picture in which the Arctic seems to be warming at an accelerating rate and sea levels seem to be rising ever faster.
This is not just because the polar ice caps are melting, but also because, almost everywhere, mountain glaciers are in retreat, and the oceans are expanding as sea temperatures rise in response to the steady warming of the planetary atmosphere. – Climate News Network