[asa] Re: more CO2

From: Joel Moore <redsoxfan1977@gmail.com>
Date: Sat Feb 03 2007 - 14:24:04 EST


I didn't see any responses to your question about the effects of
deforestation on CO2. Deforestation was responsible for about 20% of
the rise on CO2 during the 1990s according to the current best
estimate in the most recent IPCC summary for policymakers. Here are
the relevant sentences from that summary:

"The primary source of the increased atmospheric concentration of
carbon dioxide since the pre-industrial
period results from fossil fuel use, with land use change providing
another significant but smaller
contribution. Annual fossil carbon dioxide emissions4 increased from
an average of 6.4 [6.0 to 6.8] * GtC (23.5 [22.0 to 25.0] GtCO2) per
year in the 1990s, to 7.2 [6.9 to 7.5] GtC (26.4 [25.3 to 27.5]
GtCO2) per
year in 20002005 (2004 and 2005 data are interim estimates). Carbon
dioxide emissions associated with
land-use change are estimated to be 1.6 [0.5 to 2.7] GtC (5.9 [1.8 to
9.9] GtCO2) per year over the 1990s,
although these estimates have a large uncertainty. {2.3, 7.3} "

*"In general, uncertainty ranges for results given in this Summary
for Policymakers are 90% uncertainty intervals unless stated
otherwise, i.e., there is an
estimated 5% likelihood that the value could be above the range given
in square brackets and 5% likelihood that the value could be below
that range. Best
estimates are given where available. Assessed uncertainty intervals
are not always symmetric about the corresponding best estimate. Note
that a number of
uncertainty ranges in the Working Group I TAR corresponded to 2-sigma
(95%), often using expert judgement. "

You can download the summary at

Sorry about the late response. I'm not on the list-serv but read the
archives once or twice a week.


> From: George Murphy <gmurphy@raex.com>
> Date: Sun Jan 28 2007 - 17:32:02 EST
> I appreciate many of the recent posts on global warming. I write a
> column for Lutheran Partners, a journal for ELCA clergy, on issues
> of science and technology in ministry, & will probably do my next
> one on global warming. I've saved some of the recent posts & expect
> that they'll be helpful for that.
> One question. 15-20 years ago there was a lot of discussion about
> loss of rainforests, especially in the Amazon, & the contribution
> of this to shifting O2 - CO2 proportions in the atmosphere. How
> significant a contribution is this in comparison with use of fossil
> fuels & other contributions to greenhouse gases?
> Shalom
> George
> http://web.raex.com/~gmurphy/

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Received on Sat Feb 3 14:14:39 2007

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