Twenty-five years of satellite data confirm rising sea levels


Credit: NOAA

Tampa, Fla. (February 12, 2018) -Twenty-five years of satellite data prove climate models are correct in predicting that sea levels will rise at an increasing rate.

In a study published in the journal Proceedings of the National Academy of Sciences, researchers found that since 1993, ocean waters have moved up the shore by almost 1 millimeter per decade. That's on top of the 3 millimeter steady annual increase. This acceleration means we'll gain an additional millimeter per year for each of the coming decades, potentially doubling what would happen to the sea level by 2100 if the rate of increase was constant.

"The acceleration predicted by the models has now been detected directly from the observations. I think this is a game-changer as far as the climate change discussion goes," said co-author Gary Mitchum, PhD, associate dean and professor at the University of South Florida College of Marine Science. "For example, the Tampa Bay area has been identified as one of 10 most vulnerable areas in the world to sea level rise and the increasing rate of rise is of great concern."

Dr. Mitchum is part of a team led by University of Colorado Boulder Professor Steve Nerem, PhD, that used statistical analysis to enhance previous studies based on tide gauge data, which have also suggested acceleration over the last century. However, satellites give a better view of sea level rise, because samples are collected over the open ocean, rather than just along the coastline.

Experts have long said warming temperatures are heating ocean waters and melting ice sheets in Greenland and Antarctica. As it continues, the next generation will experience a far different landscape than it does today.

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1 Comment
  1. Dave Burton says

    This article is about attempts to measure mid-ocean sea-level by satellite altimetry, a process which is fraught with problems. (Note: satellites cannot measure coastal sea-level.)

    We have much better quality (longer & more accurate) measurements of sea-level from tide gauges at the coasts, than of mid-ocean sea-level via satellite altimetry. Yet this article unfortunately ignores the better quality coastal data, in favor of the lower quality satellite data.

    For reasons that nobody completely understands, sea-level measurements by satellite altimetry vary considerably from one satellite to another. Satellite altimetry is notoriously distorted by numerous error sources, including the fact that there are no stable geological benchmarks in space. That’s one of the reasons satellite altimetry measurements are so notorious for being subject to substantial and often mysterious corrections/revisions, and it is one of the reasons that NASA and the Europeans both keep proposing Geodetic Reference Antenna in SPace (GRASP & E-GRASP) missions. Unfortunately, none of those missions have flown.

    The longest single-satellite measurement record of sea-level is only about a decade. Fortunately, the data is much better from coastal sea-level measurements, with tide gauges. At many locations we have accurate coastal sea-level measurements going back more than a century; at some locations the measurement data goes back about two centuries!

    What those long measurement records show is that there’s been no significant acceleration in the rate of sea-level rise in at least ninety years. Over that time period, average atmospheric CO2 level has increased by about 100 ppmv, but that increase, and the associated global warming, have not detectably affected the rate of coastal sea-level rise.

    Here are graphs of two long, high-quality, sea-level measurement records from tectonically stable locations with very typical sea-level trends, on opposite sides of the Earth:

    If you know what “acceleration” looks like in a graph, it should be obvious that rising CO2 levels aren’t causing significant sea-level rise acceleration. If you don’t grok that, then this primer might help:

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