Between 1994 and 2017, an incredible 28 trillion tonnes (31 trillion tons) of ice was lost from the Earth’s ice sheets, glaciers, and mountains, according to a new report in the journal The Cryosphere. The extent of this worldwide melting has been described as “staggering” by the study authors, who warn that the ongoing loss of ice could lead to catastrophic rises in sea levels.
Researchers from University College London, Leeds University, and Edinburgh University studied satellite data in order to determine global changes in ice coverage over several decades. Speaking to The Guardian, study author Andrew Shepherd explained that “in the past researchers have studied individual areas – such as the Antarctic or Greenland – where ice is melting. But this is the first time anyone has looked at all the ice that is disappearing from the entire planet.”
Yet Shepherd and his colleagues were not prepared for the disaster that their analysis would reveal. "What we have found has stunned us," he said.
Results showed that the rate of ice loss has risen by 57 percent since the 1990s, from 0.8 to 1.2 trillion tonnes per year. Over the 23-year study period, some 7.6 trillion tonnes of Arctic sea ice have disappeared, along with 6.5 trillion tonnes of ice from Antarctic ice shelves, 6.2 trillion tonnes from mountain glaciers, and 3.8 trillion tonnes from the Greenland ice sheet.
The Antarctic ice sheet has also lost 2.5 trillion tonnes, while 0.9 trillion tonnes of Southern Ocean sea ice have vanished as well.
It is thought that the majority of this ice loss has occurred as a direct result of rising air temperatures, with the rest being due to rising ocean temperatures. In light of these findings, the researchers write that “there can be little doubt that the vast majority of Earth’s ice loss is a direct consequence of climate warming.”
As white ice disappears and the dark water and soil beneath are exposed, the Earth loses its ability to reflect solar radiation into space. Instead, this radiation is absorbed and contributes to yet more warming of the planet.
Then, of course, there’s the issue of rising sea levels. According to the study authors, the loss of grounded ice caused a global increase in sea levels of about 35 millimeters (1.4 inches) during the 23-year study period.
"To put that in context, every centimeter of sea-level rise means about a million people will be displaced from their low-lying homelands," explained Shepherd.
While the study only looked at data up to 2017, more recent developments – including the loss of two Canadian ice caps and yet more dramatic losses to the Greenland ice sheet – suggest that the situation is continuing to worsen and that urgent action is now needed.