Sea level rises are slowing: new paper

Just three weeks ago, Ross Garnaut - the economist who advises the Gillard Government on global warming - claimed the seas were rising faster than ever:

    SEA-LEVEL rises caused by global warming may be worse than predicted…

    Ross Garnaut, Julia Gillard’s climate change adviser, yesterday issued a gloomy review of the latest science on global warming, finding the “awful reality” is that previous research may have underestimated the impact of increasing levels of carbon dioxide in the atmosphere…

    While temperatures continue to rise around the midpoints of the UN Intergovernmental Panel on Climate Change range of projections, he says ”the rate of sea-level rise has accelerated and is tracking above the range suggested by the IPCC”.

A new paper in the Journal of Coastal Research disagrees with Garnaut. Sea level rises are actually decelarating:

    Without sea-level acceleration, the 20th-century sea-level trend of 1.7 mm/y would produce a rise of only approximately 0.15 m from 2010 to 2100; therefore, sea-level acceleration is a critical component of projected sea-level rise. To determine this acceleration, we analyze monthly-averaged records for 57 U.S. tide gauges in the Permanent Service for Mean Sea Level (PSMSL) data base that have lengths of 60–156 years. Least-squares quadratic analysis of each of the 57 records are performed to quantify accelerations, and 25 gauge records having data spanning from 1930 to 2010 are analyzed. In both cases we obtain small average sea-level decelerations. To compare these results with worldwide data, we extend the analysis of Douglas (1992) by an additional 25 years and analyze revised data of Church and White (2006) from 1930 to 2007 and also obtain small sea-level decelerations similar to those we obtain from U.S. gauge records....

    Our analyses do not indicate acceleration in sea level in U.S. tide gauge records during the 20th century. Instead, for each time period we consider, the records show small decelerations that are consistent with a number of earlier studies of worldwide-gauge records. ...

    It is essential that investigations continue to address why this worldwide-temperature increase has not produced acceleration of global sea level over the past 100 years, and indeed why global sea level has possibly decelerated for at least the last 80 years.
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