Planet Earth is losing its frozen mantle faster than ever as the world’s huge ice loss intensifies. Between 1994 and 2017, the polar regions and the mountain glaciers said farewell to a total of 28 million million tonnes of ice. This is a quantity large enough to conceal the entire United Kingdom under an ice sheet 100 metres thick.
More alarmingly, scientists warn, the rate of loss has been accelerating. Over the course of the 23-year survey of the planet’s ice budget, there has been a 65% increase in the flow of meltwater from the glaciers, ice shelves, and ice sheets, Climate News Network reports.
Early in the last decade of the last century, ice loss was counted at 0.8 trillion tonnes a year. By 2017, this had increased to 1.3 trillion tonnes a year, says a new study in the journal The Cryosphere.
The finding should come as no great surprise. Thanks to profligate combustion of fossil fuels and the clearance of forests and grasslands, the planet is warming: 2020 has been awarded the unwelcome title of equal place as warmest year ever recorded, and the last six years have been the six warmest since records began.
Researchers warned last year that the melting rate of Greenland’s ice sheet—the biggest in the northern hemisphere—would soon hit a 12,000 year high. A second group concluded in the same month that ice loss from Antarctica would soon become irreversible.
The latest research, based on satellite data, confirms all fears. “Although every region we studied lost ice, losses from the Antarctic and Greenland ice sheets have accelerated the most,” said Thomas Slater, of the University of Leeds in the UK, who led the research.
“The ice sheets are now following the worst case climate warning scenarios set out by the Intergovernmental Panel on Climate Change,” he told Climate News Net. “Sea level rise on this scale will have very serious impacts on coastal communities this century.”
The scientists measured loss from the land-based ice sheets of Greenland and Antarctica, from the shelf ice around Antarctica and from the drifting sea ice in the Arctic and Southern Oceans, as well as the retreat of 215,000 mountain glaciers worldwide.
During the 23-year-survey, thanks to rising air and ocean temperatures, the Arctic Ocean lost 7.6 trillion tonnes, the Antarctic ice shelves 6.5 trillion tonnes. Melting sea ice will not affect sea levels, but it will expose greater areas of ocean to radiation, which would otherwise be reflected back into space. So the loss of sea ice can only lead to even more warming.
The researchers claim theirs is the first full global survey, but they also concede it can only be incomplete: they did not take the measure of fallen snow on land, nor of the icy soils of the permafrost, and they did not try to measure the loss of winter ice on lakes and rivers. But they note that the duration of ice on lakes has fallen by 12 days in the last two centuries, thanks to atmospheric warming.
However, they could put a measure on ice losses from land—6.1 trillion tonnes from mountain glaciers worldwide, 3.8 trillion tonnes from the Greenland ice sheet, 2.5 trillion tonnes from the Antarctic surface—enough to raise global sea levels by 35 millimetres.
Scientific studies tend to be presented without emotive language. But the researchers call their total of lost ice “staggering”. And they warn: “There can be little doubt that the vast majority of Earth’s ice loss is a direct consequence of climate warming.” − Climate News Network