Climate change can lead to rising seas in two ways. – file picMIAMI, Feb 13 – Sea level rise is accelerating and could reach 26 inches (66 centimetres) by century’s end, in line with United Nations estimates and enough to cause significant problems for coastal cities, a study said yesterday.
Nerem said the study is conservative and is based on the constant melting state of the two ice sheets.
“That assumes that there is no rapid, dynamical change in the ice sheet”, he said, referring to his projected rates of rising sea levels. “Given the large changes we are seeing in the ice sheets today, that is not likely”, he added.
Sea level rise, more than temperature, is a better gauge of climate change in action, said Anny Cazenave, director of Earth science at the International Space Science Institute in France, who edited the study.
Of the three inches of sea level rise in the past quarter century, about 55 percent is from warmer water expanding, and the rest is from melting ice.
These increases were measured using satellite altimeter measurements since 1992, including the U.S./European TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 satellite missions. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the USA portion of these missions for NASA’s Science Mission Directorate.
Nerem told InsideClimate News that the study is important because it relies completely on observational data. Authorities from the Tampa Bay Regional Planning Council are constantly observing how sea level rise could impact the region and are planning worst-case scenario projections.
Even with a 25-year data record, detecting acceleration is challenging.
To arrive at their number, Professor Nerem and colleagues adjusted the satellite data for short-term factors such as the El Niño/La Niña climate patterns, as well as the 1991 eruption of Mount Pinatubo, which caused sea levels to drop just before the launch of the TOPEX satellite. It also takes into account the effects of volcanoes and changes in temperature resulting from El Nino and La Nina.
Sea level rise has been considered a definitive indicator of global warming.
The team also used tide gauge data to assess potential errors in the altimeter estimate.
“It’s a big deal”, University of Colorado lead author Steve Nerem said.
By what is presumably a complete coincidence, the funding for the NASA satellites that provide this data is now in danger of being axed as part of the government’s current crack-down on various scientific projects.