Global sea level rise has been accelerating in recent decades, rather than increasing steadily, according to a new study based on 25 years of NASA and European satellite data.
This acceleration, driven mainly by 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, according to lead author Steve Nerem. Nerem is a professor of Aerospace Engineering Sciences at the University of Colorado Boulder, a fellow at Colorado's Cooperative Institute for Research in Environmental Sciences (CIRES), and a member of NASA's Sea Level Change team.
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 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, driven to understand and better predict Earth’s response to a warming world, published their work Feb. 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."
Rising concentrations of greenhouse gases in Earth’s atmosphere increase the temperature of air and water, which causes sea level to rise in two ways. 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.
These increases were measured using satellite altimeter measurements since 1992, including the Topex/Poseidon, Jason-1, Jason-2 and Jason-3 satellite missions, which have been jointly managed by multiple agencies, including NASA, Centre national d’etudes spatiales (CNES), European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and the National Oceanic and Atmospheric Administration (NOAA). NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the U.S. portion of these missions for NASA’s Science Mission Directorate. The rate of sea level rise in the satellite era has risen from about 0.1 inch (2.5 millimeters) per year in the 1990s to about 0.13 inches (3.4 millimeters) per year today.
"The Topex/Poseidon/Jason altimetry missions have been essentially providing the equivalent of a global network of nearly half a million accurate tide gauges, providing sea surface height information every 10 days for over 25 years," said Brian Beckley, of NASA Goddard, second author on the new paper and lead of a team that processes altimetry observations into a global sea level data record. "As this climate data record approaches three decades, the fingerprints of Greenland and Antarctic land-based ice loss are now being revealed in the global and regional mean sea level estimates."
This acceleration, driven mainly by 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, according to lead author Steve Nerem. Nerem is a professor of Aerospace Engineering Sciences at the University of Colorado Boulder, a fellow at Colorado's Cooperative Institute for Research in Environmental Sciences (CIRES), and a member of NASA's Sea Level Change team.
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 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, driven to understand and better predict Earth’s response to a warming world, published their work Feb. 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."
Rising concentrations of greenhouse gases in Earth’s atmosphere increase the temperature of air and water, which causes sea level to rise in two ways. 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.
These increases were measured using satellite altimeter measurements since 1992, including the Topex/Poseidon, Jason-1, Jason-2 and Jason-3 satellite missions, which have been jointly managed by multiple agencies, including NASA, Centre national d’etudes spatiales (CNES), European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and the National Oceanic and Atmospheric Administration (NOAA). NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the U.S. portion of these missions for NASA’s Science Mission Directorate. The rate of sea level rise in the satellite era has risen from about 0.1 inch (2.5 millimeters) per year in the 1990s to about 0.13 inches (3.4 millimeters) per year today.
"The Topex/Poseidon/Jason altimetry missions have been essentially providing the equivalent of a global network of nearly half a million accurate tide gauges, providing sea surface height information every 10 days for over 25 years," said Brian Beckley, of NASA Goddard, second author on the new paper and lead of a team that processes altimetry observations into a global sea level data record. "As this climate data record approaches three decades, the fingerprints of Greenland and Antarctic land-based ice loss are now being revealed in the global and regional mean sea level estimates."
by Katie Weeman and Patrick Lynch, NASA | Read more:
Image: NASA
