Re: [asa] CO2 content

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Lomonosov Ridge, plus unpublished data from 65 Arctic petroleum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

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Received on Wed, 27 Aug 2008 08:19:11 -0600