NASA says sea levels have risen 3 inches since 1992

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Photo by Stròlic Furlàn - Davide Gabino via Flickr Photo by Stròlic Furlàn – Davide Gabino via Flickr

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.

Global sea level has risen about 2.85 millimeters (0.1 inch) a year since Topex/Poseidon (on the left) began its precise measurement of sea surface height in 1993 and was followed by Jason-1 in 2001. In this graph, the vertical scale represents globally averaged sea level. Seasonal variations in sea level have been removed to show the underlying trend. Image credit: University of Colorado

Global sea level has risen about 2.85 millimeters (0.1 inch) a year since Topex/Poseidon began its precise measurement of sea surface height in 1993 and was followed by Jason-1 in 2001. In this graph, the vertical scale represents globally averaged sea level. Seasonal variations in sea level have been removed to show the underlying trend. Image credit: University of Colorado

The latest data is based on records from three consecutive satellite missions, said NASA scientists at a teleconference on Wednesday.

A side-by-side comparison of sea surface height in the Pacific Ocean

A side-by-side comparison of sea surface height in the Pacific Ocean

A side-by-side comparison shows sea surface height in the Pacific Ocean during 2015, compared to 1997. Source: NASA

This NASA JPL side-by-side comparison shows sea surface height in the Pacific Ocean during 2015, compared to 1997.

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.

Photo by David Stanley via Flickr

Photo by David Stanley on Flickr

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.


NASA data shows sea levels rising at faster rate

According to NASA scientists and newly released satellite data, global sea levels have risen by eight centimeters (or about three inches) in the past 23 years. But they’re not rising at the same rate everywhere. CCTV America’s Jessica Stone provides insight on why people living along the Pacific coasts of China and the United States should be especially concerned.

NASA data shows sea levels rising at faster rate

NASA data shows sea levels rising at faster rate

According to NASA scientists and newly released satellite data, global sea levels have risen by eight centimeters (or about three inches) in the past 23 years. But they're not rising at the same rate everywhere. CCTV America's Jessica Stone provides insight on why people living along the Pacific coasts of China and the United States should be especially concerned.

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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Josh Willis on the rising sea levels

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