“We risk being unprepared for the risks posed by sea level rise,” says Dr Tom Slater of the University of Leeds.
The global alarm over rising sea levels and the colossal loss of Earth’s ice caps continues with new findings that one scientist calls “breathtaking” in their implications for the future of climate change.
“The melt is outpacing the climate models we use to guide us, and we may be unprepared for the risks posed by rising sea levels,” says Dr Tom Slater of the Polar Observation and Modeling Center at the University of Leeds in the UK.
Slater, his colleague from Leeds, Dr Anna Hogg, and a Danish Meteorological Institute climatologist, Dr Ruth Mottram, have collaborated on research that shows melt rates so far follow the worst-case scenarios predicted by the Intergovernmental Panel on Climate Change (IPCC). Their work was published Monday in the journal Natural climate change, and it’s the latest to warn of sea level projections that could be worse than previously thought.
Since satellite monitoring of the ice caps began in the 1990s, melting Antarctica has caused global sea levels to rise by 7.2mm, with another 10.6mm from Greenland. The latest measurements show that the world’s oceans are now increasing by 4 mm each year; if these rates continue, the ice caps are expected to raise sea levels to a height that threatens an additional 16 million people with annual coastal flooding by 2100.
If the melt continues at the same pace, it will double the frequency of storm surge flooding in many of the world’s largest coastal cities, Hogg says.
The new research is based on a comparison of satellite readings from the Ice Sheet Mass Balance Intercomparison Exercise (IMBIED) with climate model calculations. It comes as global ice melt caused by warming temperatures has outpaced thermal expansion, the process by which the volume of seawater increases as it warms, as the main driver of the sea level rise.
“It’s not just Antarctica and Greenland that are causing the waters to rise,” warns Mottram. “In recent years, thousands of small glaciers have started to melt or disappear completely. … This means that melting ice has now become the main contributor to sea level rise.”
Greenland alone lost a record 532 billion tonnes last year, according to another team of scientists who just published his work 10 days ago. This translates to 3 million additional tons of water every day, or six Olympic swimming pools per second. Even a partial melting of Greenland’s ice would flood islands and low-lying coastal areas, and this latest study suggests it’s not slowing.
“Although we predicted that the ice sheets would lose increasing amounts of ice in response to warming oceans and atmosphere, the rate at which they are melting has accelerated faster than we could have imagined” , Slater said.