From: farrar@datasync.com (Paul D. Farrar)
Newsgroups: sci.geo.meteorology,sci.environment
Subject: Re: Global warming/climate change: a new approach
Date: Wed, 05 Feb 1997 06:42:07 GMT

On 4 Feb 1997 01:05:47 GMT, fkrogstad@aol.com (FKrogstad) wrote:

>>C. Arnold is carrying on that fine tradition. His claim that solar output
>
>>rather than CO2 level is the major factor determining global temperature
>>does not stand up to even the most superficial examination. During the
>>Cretaceous era, (the "age of the dinosaurs"), the solar heat output was
>>less than it is now, and the CO2 level was higher. If C. Arnold is
>correct,
>>then the Cretaceous Earth should have been a very cold place, whereas in
>>fact it was much warmer than it is today. There were no polar icecaps,
>and
>>almost the entire planet enjoyed a tropical climate.
>
>Solar output lower? - CO2 level was lower? - The earth was warmer?
>I'm intrigued!  How did you measure these things?
>
>Finn

It is an intriguing subject. You need to take a look at Crowley &
North, 1991, _Paleoclimatology_, which has a chapter on the
Cretaceous, plus several other relevant chapters. I don't know your
level of expertise, but this book does assume the reader is fairly
advanced in paleoclimatology, and has access to a good library.
Unfortunately, I do not know of a book aimed at a more general
audience.

For the short answer, the lower solar output is mainly an assumption
based on the what is known about the lives of solar-type stars. The
proxies we have for solar variation at later times, such as 14C and
10Be are not available for that time. There are several lines of
evidence which point to higher (not lower) CO2, such as sediment
ratios of calcite/aragonite indicating a higher partial pressure of
CO2.

--
Paul D. Farrar
http://www.datasync.com/~farrar