FW: Climate Changes Mid-late Dinosaur era.

["Edels" <edels@email.msn.com>]

I meant to send this to the Dino Mailing List, but I just hit reply, instead
of reply all.   -       A. Edels

-----Original Message-----
From: Edels [mailto:edels@email.msn.com]
Sent: Wednesday, July 04, 2001 3:45 AM
To: gautam@majumdar.demon.co.uk
Subject: RE: Climate Changes Mid-late Dinosaur era.


I suppose that I should elaborate a bit more:

If the CO2 level increases along with temperature and humidity, then the
plant productivity will increase accordingly.  In the evening some of the
EXCESS CO2 will be absorbed by the plants, and this will then increase the
overnight output of O2.  Increased O2 levels could lead to increased risk of
fires, which in turn would lead to increased CO2 (due to the large amounts
of plant material as fuel for the fires).


Selected quote from the paper: "Plate Techtonics and the
Radiations/Extinctions of Dinosaurs, the Pele Hypothesis" by Robert E. Sloan
(Dept. of Geology and Geophysics, University of Minnesota, Minneapolis, MN
55455),  from "DinoFest International: Proceeding of a Symposium sponsored
by Arizona State University"
pp.533-539.  -

    "1.  A high carbon dioxide generated extinction at the end of the
Jurassic and beginning of the Cretaceous with the introduction of large
amounts of carbon dioxide released from the mantle which triggered the onset
of the Cretaceous greenhouse and, 2. Falling oxygen levels, in the presence
of elevated carbon dioxide, cause respiratory stress in the exact time
interval when metabolic needs were increasing because of falling global
temperatures.  The second type may have been the ultimate cause for most of
the terminal Cretaceous extinction."

The levels of O2 at the end of the Cretaceous MAY HAVE BEEN as high as 35%
(as opposed to our current levels of 21%).

I hope this makes sense.

Allan Edels

-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
Gautam Majumdar
Sent: Wednesday, July 04, 2001 2:32 AM
To: Dinosaur@usc.edu
Subject: Re: Climate Changes Mid-late Dinosaur era.


Edels <edels@email.msn.com> wrote
>My understanding is that several things were occurring:
>
>6)     Due to the increased humidity and temperature, plant life was very
>abundant.  This also led to increased CO2 and this helped keep the
>temperature high (and the herbivores well fed!).

Should it not be the other way round ? Increased CO2, temperature and
humidity will increase bioproductivity and plant mass but that in turn
will actually lower the atmospheric CO2 level.

This has been suggested for the rapid drop of CO2 level in Devonian.

Elick J M, Driese S G, Mora C I, Very large plant and root traces from
the Early to Middle Devonian: Implications for early terrestrial
ecosystems and atmospheric p(CO2), Geology 1997; 26: 143

Also, rising temperature does not always increase CO2 production from
the forests.

Grace J, Rayment M, Respiration in the balance, Nature 2000; 404: 819-20

Gautam Majumdar                 gautam@majumdar.demon.co.uk