Tuesday, January 15, 2008

Study challenges glacial melt-global warming theory!

Here we are. A roller-coaster ride that climate scientists subject us to.
The Inter-governmental Panel on Climate Change has injected fears of a doomsday approaching us.
No sooner has the Nobel gone to the protagonists of such a theory, a study at the University of California San Diego's Scripps Institution of Oceanography have come out with a shocker.
But that shocker may well pave the way for climate scientists to employ newer study strategies and approach the topic in a different way.
The researchers (Richard Norris, professor of paleobiology at Scripps Oceanography, and Andre Bornemann, a postdoctoral researcher at Scripps Oceanography and who continues the research at Universitat Leipzig in Germany) have found that though temperatures were much higher during the Cretaceous period (about 90 million years ago in the time of the dinosaurus) glaciers continued to be formed.
The temperatures then were found to be 35-37°C (95-98.6°F), about 10°C (18°F) warmer than today, thus creating a supergreenhouse climate.
Now this goes against the conventional thinking so far put forth and held by protagonists of the doomsday climatic changes.
What supports this research is that at least two other studies, one in Russia and other in New Jersey, found that sea level during that age actually fell by as much as about 25-40 m (82-131 feet).
The IPCC, in fact, has put out alerts saying that sea-levels would actually rise in the present age due to global warming. How then did sea levels 90 million years back fall despite the world simmering at 10°C more than present temperatures?
The new study, "Isotopic Evidence for Glaciation During the Cretaceous Supergreenhouse" is published in the January 11th issue of the journal Science.
It examined geochemical and sea level data retrieved from marine microfossils deposited on the ocean floor 91 million years ago during the Cretaceous Thermal Maximum.
They used two independent isotopic techniques and studied microfossils to gather geochemical data on the growth and eventual melting of large Cretaceous ice sheets. The researchers compared stable isotopes of oxygen molecules (d18O) in bottom-dwelling and near-surface marine microfossils, known as foraminifera, to show that changes in ocean chemistry were consistent with the growth of an ice sheet. The second method in which an ocean surface temperature record was subtracted from the stable isotope record of surface ocean microfossils yielded the same conclusion.
These independent methods provided them evidence to conclude that an ice sheet about 50-60 percent the size of the modern Antarctic ice cap existed for about 200,000 years.
Norris wonders how even the super-warm climates of the Cretaceous Thermal Maximum were not warm enough to prevent ice growth.
Then what about now?
The researchers suspect that past greenhouse climates may have aided ice growth by increasing the amount of moisture in the atmosphere and creating more winter snowfall at high elevations.
As humans continue to add large amounts of carbon dioxide and other greenhouse gases that accelerate the heating of the atmosphere and oceans, research on Earth's past climate conditions is critical to predict what will happen as Earth's climate continues to warm.
Will this new study warrant a change in an approach of scientists in taking what happened during the Cretaceous period as an input to current studies?
Maybe, we have missed something crucial!

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