Ice loss in Greenland is happening at a rate seven times greater than what it was in the ’90s, and this could result in an additional 40 million people being affected by coastal flooding by 2100.
The increase in the scale and speed of losses correlate with the ‘worst-case scenario’ prediction made by the Intergovernmental Panel on Climate Change (IPCC). This means that global sea levels will rise a full 7 cm more than the IPCC’s main prediction of 60 cm.
Rises in sea levels increase the risk of storm surges, which batter coastal towns and cities as defences struggle to hold. The IPCC’s main prediction correlates with around 360 million being affected, but this new evidence may raise that total to 400 million.
The findings are from a paper published in Nature by the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) team. Through this paper, 96 polar scientists from 50 international organizations around the world including Canada have delivered the most thorough picture of Greenland’s ice loss yet.
The IMBIE team processed 26 different surveys to estimate shifts in ice mass between 1992 and 2018. Data from 11 satellite missions from this period were reanalyzed to measure changes in the ice sheet’s volume, flow, and gravity. The team’s observations were then combined with current weather reports and climate models.
The result? Since 1993, 3.8 trillion tonnes of ice have been lost in Greenland and the rates of ice loss have jumped from an average of 33 billion in the ’90s to 254 billion per year in the last decade.
The 3.8 trillion tonnes of ice lost during the study period translates to an approximately 10.6 mm rise in global sea levels, and although this number sounds insignificant, it’s anything but: “The simple formula is that around the planet, six million people are brought into a flooding situation for every centimetre of sea-level rise,” said Shepherd to the BBC. “So, when you hear about a centimetre rise, it does have impacts.”
Around half of the losses were driven by rises in air surface temperatures which have increased much faster in the Arctic than the global average. Another major source of the loss was due to warming oceans which are triggering faster glacial ice flow.
Losses peaked in 2011 with 335 billion tonnes of ice, but the paper did not include 2019 and its intense summer melting. IMBIE team member Ruth Mottram told the BBC ice losses may be in the region of 370 billion tonnes for the year gone by.
The team timed the release of this paper to coincide with major conventions including the annual COP climate convention and the American Geophysical Union Meeting. The IPCC is expected to take the IMBIE team’s findings into account when they publish their sixth assessment report (AR6) in 2022.