New NASA study found that increased melting in Greenland and Antarctica has the potential to double the total sea level rise projected by 2100 when compared to projections that assume a constant rate of sea level rise.
The NASA study reported that if the rate of ocean rise continues to change at this pace, sea level will rise 26 inches (65 centimeters) by 2100 -- enough to cause significant problems for coastal cities, according to the new assessment by Professor Steve Nerem and colleagues from NASA's Goddard Space Flight Center in Greenbelt, Maryland; CU Boulder; the University of South Florida in Tampa; and Old Dominion University in Norfolk, Virginia. The team published their work Februray 12 in the journal Proceedings of the National Academy of Sciences.
"This is almost certainly a conservative estimate," Nerem said.
"Our extrapolation assumes that sea level continues to change in the future as it has over the last 25 years. Given the large changes we are seeing in the ice sheets today, that's not likely."
Nerem and his team used climate models to account for the volcanic effects and other datasets to determine the El Niño/La Niña effects, ultimately uncovering the underlying rate and acceleration of sea level rise over the last quarter century.
Sea level rises in two ways due to rising concentrations of greenhouse gases in Earth's atmosphere increase the temperature of air and water. First, warmer water expands, and this "thermal expansion" of the ocean has contributed about half of the 2.8 inches (7 centimeters) of global mean sea level rise we've seen over the last 25 years, Nerem said.
Second, melting land ice flows into the ocean, also increasing sea level across the globe.