Re: [asa] CO2 content

The argument my friend makes on the basis of the Azolla pitch is this:

"It isn't the fact that the world isn't getting warmer, it is that the
fact that the world is getting warmer is a big ho hum--... The world
used to have 3500 ppm of CO2. Today we have 380 ppm and are horrified
at the prospect of going to 600 ppm."

The presentation data does indicate that the planet survived a 3500
ppm level. I don't know of any claims that it can't, but perhaps there
are some. What such a world looks like is another story, of course.

Burgy

On 8/27/08, j burg <hossradbourne@gmail.com> wrote:
> A better link appears to be
>
> http://www.hgs.org/en/cev/838
>
> This page is the cover for an Houston Geological Society meeting
> earlier this year.
>
> Speaker: Dr. Jonathan Bujak
> Senior Partner Bujak Research Limited
>
> The abstract reads:
>
> From Greenhouse to Icehouse – The Azolla Trigger
> Implications for Climate Change and
> Arctic Petroleum Source Rocks
>
> Dr. Jonathan Bujak(1)
> Bujak Research Limited
>
> The modern icehouse world is characterised by bipolar glaciation,
> resulting from relatively low levels of atmospheric CO2 and thermal
> isolation of the poles from lower latitude warm oceanic currents. In
> contrast, the Mesozoic greenhouse world had no permanent glaciation at
> either pole, with the greenhouse state continuing through the
> Cretaceous / Tertiary boundary into the Paleocene. At the end of the
> Paleocene, the Paleocene Eocene Thermal Maximum (PETM) was triggered
> by extreme levels of greenhouse gases due to extensive volcanism and
> the expulsion of submarine methane hydrates. This resulted in the
> highest temperatures known for the Cenozoic, characterising a
> supergreenhouse state that persisted through the Early Eocene. It is
> therefore surprising that various independent parameters indicate that
> the supergreenhouse was truncated in the earliest Middle Eocene by an
> initial shift towards modern icehouse conditions.
>
> Estimates of atmospheric CO2 values show a major decrease at this
> time, but this cannot be explained by normal sequestration processes.
> Instead, a unique geological event is proposed to explain this fall,
> centered on processes within the Arctic Ocean Basin. "The Azolla
> Model" is based on Arctic Coring Expedition (ACEX) cores from
> Lomonosov Ridge, plus unpublished data from 65 Arctic petroleum
> exploration wells(2). The model combines oceanographic reconstructions
> for the basin with a major decrease in greenhouse gases during the
> Middle Eocene.
>
> The Early Eocene Arctic Ocean Basin was largely enclosed following
> uplift of the Greenland Mantle Plume, with elevated temperatures,
> evaporation and precipitation leading to increased runoff and the
> development of extensive surface freshwater layers. These were
> colonised in the earliest Middle Eocene by floating mats of the
> opportunistic freshwater fern Azolla, which persisted for up to
> 800,000 years as a series of repeated cyclical events. Modern Azolla
> is one of the fastest growing plants on the planet and draws down
> large quantities of carbon and nitrogen. Calculations of carbon
> drawdown combined with the large potential areas of Azolla development
> in the Arctic, plus the 800,000 year time frame indicate levels of CO2
> sequestration that are easily sufficient to shift the world from
> Mesozoic-to-Early Eocene greenhouse towards the modern icehouse world.
>
> The model also indicates the deposition of potentially widespread
> petroleum source rocks across the Arctic due to the massive carbon
> drawdown. The model is currently being tested by multidiscipilinary
> teams at ACEX and various universities worldwide. It has already
> attracted considerable popular attention, including articles in
> National Geographic (May 2005), Nature (June 1, 2006), and the New
> York Times (November 20, 2004).
>
> The earlier link I sent appears as a link at the bottom of the page
> and is the text of the speech given.
>
> JB
>

-- 
Burgy
www.burgy.50megs.com
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