Latest satellite measurements from NASA and its partners have revealed the sea levels around the world have risen by nearly 3 inches (8 centimeters) since 1992. Some locations, have even seen an increase by nearly 9 inches (25 centimeters) due to “natural variation.”
The United Nations Intergovernmental Panel on Climate Change in 2013 had previously stated that by the end of the century, global sea levels were expected to rise from 1 to 3 feet. The new findings could make the levels reach the higher end of this spectrum, said University of Colorado geophysicist Steve Nerem in an interview with Reuters.
The latest data is based on records from three consecutive satellite missions, said NASA scientists at a teleconference on Wednesday.
Research also shows that sea level changes are not the same around the world. The west coast of the United States, for instance, has actually seen falling sea levels in recent years. However, this is expected to change.
Satellite data shows that the sea level has been rising at 3.21 mm (0.13 inches) per year. The NASA data shows that sea levels have risen from 58.66 mm (2.31 inches) in August 2014, to 65.53 mm (2.58 inches) in August 2015.
Why do sea levels rise?
The reason behind the rise in sea levels have been attributed to a variety of reasons, scientists said.
- One-third of sea level rise is caused by the expansion of warmer ocean water.
- One-third is due to ice loss from the massive Greenland and Antarctic ice sheets.
- One-third is from melting mountain glaciers.
This ratio could change and produce more rapid increases as a result of the “fate of the polar ice sheets”, NASA scientists said.
How do satellites measure sea levels?
Satellite altimetry provide very accurate data, the U.S. National Oceanographic and Atmospheric Administration (NOAA) said. The ocean is not flat, hence the water is influenced by various forces such as gravity and temperature, NOAA said. Sea levels are measured by radar waves that are bounced off the ocean’d surface using instruments located on orbiting satellites. These instruments record the time it takes for radar waves to bounce back to the satellite, which in turn helps determines the distance and the sea level.
Data from NASA, Reuters and NOAA.
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More details:
- Nearly half of the world’s population lives within 150 kilometers of a coastline.
- NASA scientists say the satellites that helped them track past patterns of sea level change will also help forecast future patterns.
- NASA scientists predict sea levels will rise over the next 10 years on the US west coast even as they fall on China’s east coast.
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