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Re: Late Cretaceous Arctic Climates

Nor is ice alone the determinant for raising and lowering global sea level
(although it is the primary one in operation on scales of 400 kyr or
less). Swelling and unswelling of mid-ocean ridges (related to the
geodynamo) is known to produce fairly substantial sea level changes. Also,
changes in ocean temperature (governed by, among other things, the
presence of circum-equatorial, circum-polar, or thermohaline circulation)
can cause thermal contraction or expansion of the seas.

Dora Smith wrote:
> I don't think that ice alone accounts for changes in climate.   What is
> more, the mechanims that govern changes in ice and in climate are
> dynamically complex, and unstable.
> Yours,
> Dora Smith
> Austin, TX
> tiggernut24@yahoo.com
> ----- Original Message -----
> From: "David Marjanovic" <david.marjanovic@gmx.at>
> To: "DML" <dinosaur@usc.edu>
> Sent: Tuesday, July 28, 2009 3:45 AM
> Subject: Re: Late Cretaceous Arctic Climates
>>>  Collin... exactly what I'm talkin' about.  Eventually, the myth that
>>>  "it was too warm in the Mesozoic for ice" will melt away.
>>>  Interestingly enough, there's been quite a stir lately in the
>>>  climatology world about how climate models are really, really
>>>  terrible at handling CO2. If we can't get it right for today's and
>>>  "recent" ice-age climates......
>> Hang on a second. How much ice is necessary to account for the sea-level
>> changes? Does that amount really necessitate inland ice, or are mountain
>> glaciers (like those in southern Alaska which reach the sea through a
>> temperate rainforest) enough to explain the sea-level changes and the
>> Australian glacier sediments?
>> The sea level is supposed to have changed by 25 m, right? 22 m is the
>> difference between today and 400,000 years ago when Greenland and West
>> Antarctica were ice-free. Is there a way to distribute that much ice
>> over
>> the high-altitude and high-latitude mountains of the Early Cretaceous
>> world?
>> Finally, how much CO2 was there really in the air in the EK? Some
>> proxies
>> consistently give way too high numbers (for the Cenozoic at least), and
>> the best one -- counts of stomata in *Ginkgo* and *Metasequoia* --
>> doesn't
>> go that far back.

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
Fax: 301-314-9661

Faculty Director, Earth, Life & Time Program, College Park Scholars
Faculty Director, Science & Global Change Program, College Park Scholars
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA