22 April, 2011

No Acceleration of Global Sea-Level, I

The renowned, crazed NASA employee, Dr James Hansen, a notorious, irrationally misanthracist fruitcake, has predicted that sea-levels may rise five metres a century or (on days when his navel lint sends messages by way of his breakfast cereal, perchance) over twenty-five metres.*  The famed, award-winning profiteer of doom, Al. Gore, a serial liar, has predicted that sea-levels will rise by more than seven metres by the end of this century.  The late Robyn Williams predicted a rise of one hundred metres.  In the Fourth Assessment Report (4AR) of the Intergovernmental Panel on Climate Change (IPCC), however, Bindoff et al. (2007) project a global sea-level rise relative to 1990 of up to 79 cm by 2100.  The data suggest that even the less outrageous predictions of Prof. Bindoff et alii are unlikely to occur.
From J.R. Houston and R.G. Dean, “Sea-Level Acceleration Based on U.S. Tide Gauges and Extensions of Previous Global-Gauge Analyses” in the Journal of Coastal Research:
The current sea-level trend of about 1.7 mm/y will produce a rise of about 19 mm [sic] over 110 years from 1990 to 2100, but a rise to 79 cm will require an acceleration of about 0.10 mm/y2 [...].
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.  The decelerations that we obtain are opposite in sign and one to two orders of magnitude less than the +0.07 to +0.28 mm/y2 accelerations that are required to reach sea levels predicted for 2100 by Vermeer and Rahmsdorf (2009), Jevrejeva, Moore, and Grinsted (2010), and Grinsted, Moore, and Jevrejeva (2010).  Bindoff et al. (2007) note an increase in worldwide temperature from 1906 to 2005 of 0.74ºC.  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.§
UPDATE:  see “A Fairy Tale:  Jimmy and the Lump of Coal”.

*  Hansen, in “Climate Change:  On the Edge”, writes, “How far can it go?  The last time the world was three degrees warmer than today—which is what we expect later this century—sea levels were 25m higher.  So that is what we can look forward to if we don’t act soon.”
†  see, for example, earlier posts here and here.
‡  110 years of 1.7 mm a year would equal 187 mm or about 19 cm, not 19 mm.
UPDATE II:  James R. Houston kindly responded to an enquiring e-mail, writing that the “mm” is indeed an error for “cm”.
§  of course, one simple explanation could be that temperatures did not rise by 0.74ºC.

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