Increasing melting rates for ice sheets in Antarctica and Greenland match worst-case scenarios for climate warming, potentially exposing 16 million people to annual coastal flooding by the end of the century, warned a new study.
The global sea level rose by 1.8 centimetres because of the rapid melting rates of the ice sheets since the 1990s. Increasing melting rates will raise sea levels by a further 17 cm, according to the study led by Tom Slater from the Centre for Polar Observation and Modelling at the University of Leeds, United Kingdom.
The study — published in journal Nature Climate Change August 31, 2020 — compared the latest results from satellite surveys from the Ice Sheet Mass Balance Intercomparison Exercise (IMBIE), with calculations from climate models.
The IMBIE is a joint collaboration established between scientists supported by the European Space Agency and the United States’ National Aeronautics and Space Administration in 2011. Melting from Antarctica pushed sea levels up by 7.2 millimetres, while Greenland accounted for 10.6 mm, with latest measurements pointing out a rise in the world’s oceans by four mm every year.
One of the primary causes for the rise in global sea levels was thermal expansion, involving the volume of seawater expanding once it gets warmer. Ice melt from ice sheets and mountain glaciers, however, overtook global warming as the main cause of rising sea levels in the past five years. “The melting is overtaking the climate models we use to guide us. We are in danger of being unprepared for the risks posed by sea level rise,” said Slater.
Ice sheets lost ice at rates predicted by the worst-case scenarios put forth in the last report by the Intergovernmental Panel on Climate Change, warned the authors.
The 17 cm-rise in sea levels from ice sheets alone was enough to double the frequency of storm-surge flooding in the largest coastal cities, said Anna Hogg, a co-author and climate researcher in the School of Earth and Environment at Leeds.
Ice sheets from Antarctica and Greenland were not the only ones causing water rise, according to Ruth Mottram, study co-author and climate researcher at the Danish Meteorological Institute.
“In recent years, thousands of smaller glaciers have begun to melt or disappear altogether, as we saw with the glacier Ok in Iceland, which was declared ‘dead’ in 2014,” said Mottram. “This means that melting of ice has now taken over as the main contributor of sea level rise,” she added.