Claim: Global Sea Level Rise is Accelerating

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Claim: Global Sea Level Rise is Accelerating

February 20th, 2018

Awake Goy

Claim: Global Sea Level Rise is Accelerating

By Anthony Watts

There’s been a lot of buzz about this new paper from Nerem et al (see link in references below) where they claim to find global sea level rise acceleration over the past 25 years. I provide this article from NASA Earth Observatory for context for some posts that are coming later. Adjustments to data figure greatly into these new claims. more on that later. For now, have a look at this image below. Notice anything peculiar?

acquired 1992 – 2014 download large image (17 MB, PNG, 5911×2956)

Global sea level rise has been accelerating in recent decades, according to a new study based on 25 years of NASA and European satellite data. This acceleration has been driven mainly by increased ice melting in Greenland and Antarctica, and it has the potential to double the total sea level rise projected by 2100, according to lead author Steve Nerem, a scientist at the Cooperative Institute for Research in Environmental Sciences (CIRES) and the University of Colorado.

If things continue to change at the observed pace, sea level will rise 65 centimeters (26 inches) by 2100, enough to cause significant problems for coastal cities. The team comprised of scientists from NASAs Goddard Space Flight Center, the University of Colorado, the University of South Florida, and Old Dominion University recently published their work in the journalProceedings of the National Academy of Sciences.

This is almost certainly a conservative estimate, said Nerem, who is a member of NASAs Sea Level Change team. 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 is not likely.

Rising concentrations of greenhouse gases in Earths 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 7 centimeters (2.8 inches) of global mean sea level rise that has been observed over the past 25 years, Nerem said. Second, the water from melting land ice flows into the ocean, which also increases sea level around the world.

The rate of sea level rise has risen from about 2.5 millimeters (0.1 inch) per year in the 1990s to about 3.4 millimeters (0.13 inches) per year today. These increases have been measured by satellite altimeters since 1992, including the TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 missions, which have been jointly managed by NASA, Frances Centre national’d’etudes spatiales (CNES), the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and the U.S. National Oceanic and Atmospheric Administration (NOAA). The maps on this page depict the changes in sea level observed by those satellites between 1992 and 2014.