Climate Change Tracker: Earth has lost 28 trillion tonnes of ice in 23 years
A new report reveals the shocking amount of ice loss and global sea level rise since the 1990s due to man-made global heating
The most emblematic and visible outcome of global heating is the loss of ice at the poles. According to the landmark 2019 UN Intergovernmental Panel on Climate Change (IPCC) report on the ocean and the cryosphere, between 2006-2015, the Greenland ice sheet lost 278 gigatonnes (Gt) of ice per year. In the same time, Antarctica lost ice at 155 Gt/year, while mountain glaciers outside the poles lost ice at the rate of 220 Gt/year. The report put the resulting global sea level rise at .77mm a year.
A new report prepared by scientists from Edinburgh and Leeds universities and University College London, has a scarier story to tell. The study, based on satellite survey data, says that the planet has lost 28 trillion tonnes of ice between 1994-2017. Polar ice sheets, mountain glaciers and sea ice have all seen a dramatic reduction in mass in these 23 years. This has in turn has raised global sea levels by 35mm. The review paper, called Earth’s Ice Imbalance was published in the journal Cryosphere Discussions on 14 August. The report further says that ice loss has increased by 49% over the past 24 years compared to the 1990s and earlier.
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This big melt has a variety of consequences, including the prospect of raising global sea levels by one metre by 2100. One of the writers of the report, Andy Shepherd from Leeds University, told The Guardian, “To put that in context, every centimetre of sea level rise means about a million people will be displaced from their low-lying homelands." This poses a grave threat to coastal communities everywhere, including in India where coastal districts and islands are home to over 177million people. The decline in ice mass in mountain glaciers pose a threat to freshwater resources for mountain communities as well as to people living downstream.
The reduction in ice also prevents the earth from reflecting solar radiation back into space. With exposed seas surfaces and soil as the ice cover disappears, polar regions are now absorbing even more heat, further feeding the loop of even more ice loss.
As other research has pointed out, melting permafrost in the Arctic is also releasing methane—a deadlier greenhouse gas (GHG) than CO2 because it's more efficient in trapping heat—buried deep in the frozen soil. This could result in a global heating spiral.
According to the report 60% of the ice loss has occurred in the northern hemisphere. But this doesn’t mean that Antarctic ice safe. A separate report, published in Nature on 26 August, says that 60% of Antarctica’s ice shelves (these are extensions of the Antarctic ice sheet that floats on the surrounding ocean) are in danger of fracturing. Since these shelves prevent melting inland glaciers from losing their ice to the sea, their collapse would trigger even greater ice loss.
The Earth’s Ice Imbalance report is very clear that the rise in ice loss is a direct result of man-made global heating due to rising greenhouse gas (GHG) emissions. It’s as clear as ever that the only way to stop these catastrophic changes in the Earth’s natural systems is to de-link the world economies from the fatal embrace of carbon-based energy right away.
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FIRST PUBLISHED27.08.2020 | 10:00 AM IST