Greenland ice loss rising faster than expected
Edinburgh scientists have contributed to international research showing that Greenland is losing ice seven times faster than it was in the 1990s.
As a result, 40 million more people will be exposed to coastal flooding by 2100.
A team of 89 polar scientists from 50 international organisations have produced the most complete picture of Greenland’s ice loss to date.
The Ice Sheet Mass Balance Inter-comparison Exercise team combined 26 separate surveys to compute changes in the mass of Greenland’s ice sheet between 1992 and 2018.
Data from 11 different satellite missions were used, including measurements of the ice sheet’s changing volume, flow and gravity.
“This research emphasises the importance of international collaboration in assessing a serious global problem. Edinburgh’s role was to provide an independent estimate of Greenland’s ice mass loss from observations collected by the European Space Agency’s satellite, CryroSat. Our aim was to understand the differences between various methods of monitoring Greenland’s Ice Sheet and to produce a robust, reconciled estimate of the mass change and of the contribution of the ice sheet to sea level rise.
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.
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.
However, 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 assessment, led by Professor Andrew Shepherd at the University of Leeds and Dr Erik Ivins at NASA’s Jet Propulsion Laboratory in California, was supported by the European Space Agency (ESA) and the US National Aeronautics and Space Administration (NASA).
As a rule of thumb, for every centimetre rise in global sea level another six million people are exposed to coastal flooding around the planet. On current trends, Greenland ice melting will cause 100 million people to be flooded each year by the end of the century, so 400 million in total due to all sea level rise. These are not unlikely events or small impacts; they are happening and will be devastating for coastal communities.
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.