Tuesday, June 21, 2011

Sea level hockey stick

Michael Mann and 5 other, less infamous would-be "scientists" have just published a paper about the hockey stick "scientific" method applied to the sea level:
Climate related sea-level variations
over the past two millennia
They used salt-marsh sedimental sequences on the U.S. East Coast (which is a very limited region of the world ocean, of course) as their proxies. The identity of the proxies doesn't matter because they were processed through the crackpot known as Michael Mann so you may guess in advance what the resulting graph of the sea level is.

Picture taken from a Real Climate article about the paper.

Yes, it is a slightly warped hockey stick! ;-)

It's remarkable that in this case, there doesn't even exist a plausible model that would agree with the statement that the sea level rise has accelerated. Note that the red curve above, coming from the models, has the same slope around the year 1000 AD as it had recently.

The flat shaft of the blue hockey stick is created by an interplay of several methods. They include both the MBH hockey stick fallacy that creates hockey sticks even out of red noise; as well as the dropping resolution of (or "diffusion in") similar reconstructions as you try to go further into the past.

Note that the sea level hockey stick graph claims that the sea level has never deviated by more than 5 centimeters throughout the whole first millennium! Well, that's very unlikely. The graph above shows that in the last 7,000 years, the sea level was nearly constant but you may still see that the slope is of order 50 cm, and not 5 cm, per millennium.

Ten thousand years ago, the rate was maximized at around 10 meters per millenium - which continued for 10,000 years or so. Of course, the continental ice sheets ultimately melted and there was almost nothing left which is why the sea level was so constant recently. But it's very unlikely that the precision of this constancy could have been so high.

Much like in the temperature hockey stick, the article doesn't really bring any valid evidence that the sea level was this constant. What they actually claim is if one averages and smoothes the sea level and combines the noise in various proxies so that all the wiggles disappear, then all the wiggles disappear. That's nice but it's a tautology and it doesn't say anything about the actual variations of the sea level in the last 2,000 years.

Check The Global Warming Policy Foundation for some climatologists' reactions to the paper and Pop Science for an uncritical presentation of the claims.

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