Tuesday, January 15, 2008 ... Deutsch/Español/Related posts from blogosphere

Ice caps in the crocodile empire

This weekly dose of peer-reviewed skeptical literature about the climate looks into Science magazine:

Isotopic Evidence for Glaciation During the Cretaceous Supergreenhouse
André Bornemann and eight co-authors investigate whether there were ice caps in the Turonian, a warm period roughly 90 million years ago that lasted for 4 million years.



The tropical sea surface temperature constantly exceeded 35 °C, more than by 10 °C warmer than the current temperatures, and crocodiles used to live in the Arctic region.

However, new data involving the Oxygen 18 isotope indicate that during this era, there was a roughly 200,000-year-long period when the Antarctic ice cap did exist and it was about 50% of its current size. In contradiction with the common assumptions, 10 °C of global warming is apparently not enough to prevent ice sheets from growing. See also
CCNews
Daiji World
The Telegraph
Needless to say, such a finding implies that the estimates of possible sea level rise - even in the case of hypothetical insane alarmist warming - would have to be scaled back a lot.




Greenland melt: natural rates

Let me add one more new article. In Journal of Geophysical Research, Petr Chýlek and three co-authors argue, among other things, that the Greenland melt is now actually slower than it was in the 1900s, 1930s, 1940s, 1950s, and 1960s. The available data see no signal - a man-made deviation from the normal natural rates.

Rain in Israel

You may also want to know that a study showed that the Israeli precipitation rates remain essentially unchanged in the last 60 years, despite occassional vague fears that global warming might be changing precipitation patterns.

Water cycle driven by plants

One more comment. Paul Ferguson and Ján Veizer argue in Journal of Geophysical Research that the water vapor fluxes are largely controlled by plant breathing (60% in average), especially in regions with limited vegetation (70%) which might be surprising. Abiotic evaporation is a small portion of the cycle. Forget about CO2 or temperature as the primary direct driver of water feedbacks. If you were ever computing the evaporation in the water vapor feedback that may amplify the greenhouse effect and you thought that the evaporation of H2O was controlled directly by temperature, you probably overestimated this positive feedback amplifying the warming effect of CO2 by a factor of three.

Thanks to Benny Peiser.

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