NASA researchers have reported the first detection of sea level ‘fingerprints’ that show changes in sea level variability around the world.
They result from changes in water storage on Earth’s continents and in the mass of ice sheets. .
The ocean observations, called sea level ‘fingerprints,’ allow researchers to determine how much the sea level will rise at any point on the global ocean due to glacier melt.
Sea level rise fingerprints (patterns of variation in sea level rise) calculated from observations of mass changes in Greenland, Antarctica, continental glaciers and ice caps, and land water storage made by the GRACE satellites, January 2003 to April 2014
The study, published in the journal Geophysical Research Letters, was conducted by researchers from NASA’s Jet Propulsion Laboratory in Pasadena, California, and the University of California, Irvine (UCI).
As ice sheets and glaciers undergo climate-related melting, they change the Earth’s gravity field, leading to sea level changes that are not uniform around the planet.
For example, when a glacier melts and loses ice mass, its gravitational attraction is reduced.
As such, ocean waters nearby move away, causing sea level to rise faster far away from the glacier.
This resulting pattern in sea level change is known as a sea level fingerprint – and certain areas, particularly in Earth’s middle and low latitudes, are hit even harder, and Greenland and Antarctica contribute differently to the process.
For example, sea level rise in California and Florida caused by the melting of the Antarctic ice sheet is up to 52 per cent greater than its average effect on the rest of the world.
To calculate these sea level fingerprints associated with melting ice sheets, glaciers and changes in land water storage, the team used gravity data data collected by the twin satellites of the US/German Gravity Recovery and Climate Experiment (GRACE) between April 2002 and October 2014.
During that 12-year period, the loss of mass from land ice and from changes in land water storage increased global average sea level by approximately 0.07 inches (1.8 millimeters) per year.
WHAT ARE SEA LEVEL FINGERPRINTS?
Sea level ‘fingerprints,’ are patterns of sea level variability around the world resulting from changes in water storage on Earth’s continents and in the mass of ice sheets.
As ice sheets and glaciers undergo climate-related melting, they change the Earth’s gravity field, leading to sea level changes that are not uniform around the planet.
For example, when a glacier melts and loses ice mass, its gravitational attraction is reduced.
Sea level rise fingerprints calculated from observations of mass changes in Greenland, Antarctica, continental glaciers and ice caps, and land water storage made by the GRACE satellites, between January 2003 to April 2014
As such, ocean waters nearby move away, causing sea level to rise faster far away from the glacier.
This resulting pattern in sea level change is known as a sea level fingerprint – and certain areas, particularly in Earth’s middle and low latitudes, are hit even harder, and Greenland and Antarctica contribute differently to the process.
For example, sea level rise in California and Florida caused by the melting of the Antarctic ice sheet is up to 52 per cent greater than its average effect on the rest of the world.
43 per cent of the increased water mass came from Greenland, 16 per cent from Antarctica and 30 per cent from mountain glaciers.
The researchers verified their calculations using reading of ocean-bottom pressure from stations in the tropics.
‘Scientists have a solid understanding of the physics of sea level fingerprints, but we’ve never had a direct detection of the phenomenon until now,’ said co-author of the study Dr Isabella Velicogna, UCI professor of Earth system science and JPL research scientist.
‘It was very exciting to observe the sea level fingerprints in the tropics, far from the glaciers and ice sheets,’ said lead author Chia-Wei Hsu, a graduate student researcher at UCI.
The findings are published today in the journal Geophysical Research Letters. The research project was supported by UCI and NASA’s Earth Science Division.