On Mar 1, 2006, at 10:43 AM, Steven Krivit wrote:
Does anybody wish to comment on this sentence?
"The primary greenhouse gas is water vapor, not carbon dioxide.7 "
Quote Source: http://www.nationalcenter.org/TSR020905.html
Quote Reference: "The Greenhouse Effect and Greenhouse Gases: An
Overview," Energy Information Administration, U.S. Department of
Energy (available at http://www.eia.doe.gov/cneaf/pubs_html/
attf94_v2/chap2.html) for a good summary of this issue
understandable to the layman.
The above link appears to be no longer current.
The author of the above referenced line appears to have no
appreciation for the effect high altitude water vapor, or of global
warming on high altitude water vapor, and thus for the powerful
feedback effect that is present.
There is a notable lack of H2O in the DOE Global Warming Potentials
link:
http://www.eia.doe.gov/oiaf/1605/gg02rpt/pdf/appendixg.pdf
In fact, it states: "Short-lived gases such as water vapor, carbon
monoxide, tropospheric ozone, and other ambient air pollutants (e.g.,
nitrogen oxide, and non methane volatile organic compounds), and
tropospheric aerosols (e.g., sulfur dioxide products and black
carbon), however, are present in very different quantities spatially
around the world, and consequently it is difficult to quantify their
global radiative forcing impacts. GWP values are generally not
attributed to these gases that are short-lived and spatially
heterogeneous in the atmosphere.11 "
However, it is high altitude water vapor that is the ultimate
concern. Low altitude water vapor increases the Earth's albedo, but
high altitude water vapor acts as a greenhouse gas, both here and on
Venus. There is a good discussion of the Earth greenhouse effect at:
http://en.wikipedia.org/wiki/Greenhouse_effect
however, this discussion is centered on things as they are now, not
as they will be as runaway global warming occurs. For that Venus
serves as a better model. The non-linear response of high altitude
water vapor to sea warming is astounding. See:
http://www.nasa.gov/centers/ames/news/releases/2002/02_60AR.html
which states: "Rabbette analyzed clear-sky data above the tropical
Pacific from March 2000 to July 2001. She determined that water vapor
above 5 kilometers (3 miles) altitude in the atmosphere contributes
significantly to the runaway greenhouse signature. She found that at
9 kilometers (5.6 miles) above the Pacific warm pool, the relative
humidity in the atmosphere can be greater than 70 percent - more than
three times the normal range. In nearby regions of the Pacific where
the sea surface temperature is just a few degrees cooler, the
atmospheric relative humidity is only 20 percent. These drier regions
of the neighboring atmosphere may contribute to stabilizing the local
runaway greenhouse effect, Rabbette said."
Additionally, methane is lighter than air. As far as I know, little
has been made of this fact. In the atmosphere, methane ultimately
oxidizes to form CO2 and water vapor. Methane released directly into
the air can thus be assumed to oxidize mostly at a high altitude.
The coming arctic methane release will have a significant effect in
the upper atmosphere due to methane's atmospheric life of 12 years.
(For methane life see Table G1 in
http://www.eia.doe.gov/oiaf/1605/gg02rpt/pdf/appendixg.pdf).
I earlier made a number of relevant comments on vortex, summarized
with references at
http://mtaonline.net/~hheffner/LastResort.pdf
and in 1998 debates on s.p.f, summarized with a few more current
related references at
http://www.mtaonline.net/~hheffner/MJonesSPF.pdf
Horace Heffner
