Re: [asa] CO2 content

Burgy:

> Attached is a chart showing CO2 content over time.
>
> The claim is that this shows rising CO2 is not a problem.
>
> What is the rebuttal to this claim?

I addressed the geologic context of global climate change in my talk
at the ASA meeting this year. An audio of my presentation and the PP
slides can be obtained at the ASA website.

We are currently in an "ice house" global climate, the other major
"Ice house" was during the late Carboniferous and early Permian
Periods. These were both times of historically low CO2 levels and
continental glaciation ("ice ages"). There have been times in
geologic history in which the CO2 levels have been much higher than
at present. In early Earth history, very high levels of methane and
CO2 were compensated by lower solar irradiance. During the
Phanerozoic, greenhouse climates have existed during which the poles
were ice free with forests above the arctic and antarctic circles.
Significantly, times of very rapid warming associated with elevated
CO2 levels have been associated with times of mass extinction. The
greatest extinction in Earth history at the end of the Permian (when
over 90% of species are estimated to have gone extinct) was likely
the result of a runaway greenhouse.

The current release of greenhouse gases by the burning of fossil
fuels is without question a major contributor to the current
increases in global average temperatures. What is unique about the
climate change now occurring is not the magnitude of change (from a
long-term geologic perspective) but that it is being significantly
caused by us. Furthermore, such increases in global temperature have
not occurred since modern humans have been on Earth. The current CO2
levels and global temperature rise has not occurred for over 400,000
years. Human populations, particularly the poor and those already
living at the margins economically or environmentally, will be
significantly affected.

Feedback mechanisms and rapid carbon storage and release have the
potential to generate very rapid changes in global climate that would
outstrip the ability of species and ecosystems to adapt, and pose
serious challenges to human populations. These feedback mechanisms
pose a real danger if our release of greenhouse gases continues
unabated. Should we pass a tipping point for these feedbacks, we
could lose the ability to change course. We must take immediate
action to reduce our production of greenhouse gases to avoid such an
outcome. The most practical and immediately effective thing we can
do is energy conservation. Unfortunately there is great resistance
to the lifestyle changes that this will require. We also must make a
focused and deliberate effort to move away from use of fossil fuels
(we are already at or near peak oil production anyway). The
technology largely exists for making a significant change in our
energy use -- the political and social will does not.

The scientific consensus on the issue of human-caused global climate
change is extremely strong and broad. The reports of the
International Panel on Climate Change are to my knowledge the most
extensively reviewed and supported scientific documents ever
written. They are freely available on the web. Far from being
extremist, they are very conservative documents and their predictions
have consistently underestimated observed changes.

Keith

Keith B. Miller
Research Assistant Professor
Dept of Geology, Kansas State University
Manhattan, KS 66506-3201
785-532-2250
http://www-personal.ksu.edu/~kbmill/

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Received on Sun Aug 24 17:02:30 2008