Greenland is losing ice seven times faster than in the 1990s, shows a new study by an international research team including Durham University.
The rate of ice loss is in line with the more pessimistic climate warming scenario by the Intergovernmental Panel on Climate Change, which would see 40 million more people exposed to coastal flooding by 2100.
Our researchers are part of an 89-strong team of polar scientists from across the world who have produced the most complete picture of Greenland ice loss to date.
The findings, published in Nature, show that Greenland has lost 3.8 trillion tonnes of ice since 1992 – enough to push global sea levels up by 10.6 millimetres. The rate of ice loss has risen from 33 billion tonnes per year in the 1990s to 254 billion tonnes per year in the last decade – a seven-fold increase within three decades.
The research team combined 26 separate surveys to compute changes in the mass of Greenland’s ice sheet between 1992 and 2018. Altogether, data from 11 different satellite missions were used, including measurements of the ice sheet’s changing volume, flow and gravity.
In 2013, the Intergovernmental Panel on Climate Change (IPCC) predicted that global sea levels will rise by 60 centimetres by 2100, putting 360 million people at risk of annual coastal flooding. But this new study shows that Greenland’s ice losses are rising faster than expected and are instead tracking the IPCC’s high-end climate warming scenario, which predicts seven centimetres more.
The team also used regional climate models to show that half of the ice losses were due to surface melting as air temperatures have risen. The other half has been due to increased glacier flow, triggered by rising ocean temperatures.
Ice losses peaked at 335 billion tonnes per year in 2011 – ten times the rate of the 1990s – during a period of intense surface melting. Although the rate of ice loss dropped to an average 238 billion tonnes per year since then, this remains seven times higher and does not include all of 2019, which could set a new high due to widespread summer melting.
Our scientists in Durham are leading fieldwork campaigns to understand how the Greenland Ice Sheet has changed over the past few thousand years. It is crucial to understand the processes responsible for rapid change if we are to understand how this giant ice sheet will behave in the future.
Photo credit: Ian Joughin, University of Washington