Re: Global warming deniers

On Fri, 21 Apr 2006 12:01:20 -0000, Robert Grumbine <bobg@xxxxxxxxx> wrote:
In article <4rfg42h1b306ecfp9014r6q0pholavj433@xxxxxxx>,
catshark <catshark@xxxxxxxxx> wrote:
On Thu, 20 Apr 2006 16:49:19 -0000, bobg@xxxxxxxxx (Robert Grumbine) wrote:

In article <e247ba$27c$4@xxxxxxxxxxxxxxxxx>,
Paul J Gans <gans@xxxxxxxxx> wrote:
Robert Grumbine <bobg@xxxxxxxxx> wrote:
In article <1145393941.108159.218350@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Kermit <unrestrained_hand@xxxxxxxxxxx> wrote:

[large snip of water vapor stuff]

Carbon dioxide, once in the atmosphere, is up there for
decades to centuries to millennia (it's not very meaningful
to put a single number down for time scale, due to the multiple
source/sink interactions) -- up for a long time. As such,
it is a driver of climate. Also means that if we decide that
380 ppm is a bad concentration to have, and it should be 280
instead, it will be a long time (millennia in this case) before
the system can pull that much carbon out of the atmosphere on
its own, even if we immediately stopped emitting more.

I haven't been following this thread, so sorry if this has already been
mentioned: PBS' Nova just had a show on "global dimming" tonight
<http://www.pbs.org/wgbh/nova/sun/>

It seems that particulate pollution has been significantly reducing the
sunlight hitting the Earth's surface and, therefor, retarding the effect of
global warming. But as we reduce particulate pollution for health reasons,
global warming will increase at a faster rate than the models are presently
predicting, meaning we may have much less time than we think to rein in
greenhouse gasses.

The aerosols come from either more or less direct result of
combustion, or by gas to particle reactions of, for instance,
sulphates. This was probably part of the cooling observed
in the 50's through 70's. It was part of the reason that scientists
in the 60's were considering cooling (aerosols production) as well as
warming (greenhouse gas emissions) -- at the time it wasn't obvious
which would be the dominant effect in the short term.

The aerosols, however, are short-lived in the atmosphere. They
fall out or rain out over a few years. This is why Pinatubo, for
instance, only had notable effect on temperatures for about 1 year,
observable for 2-3. The carbon dioxide emitted in combustion
stays up for decades to millennia, so it's a very poor Red Queen's
race to try to control the warming by aerosol emission. (I've
had people seriously suggest this to me. Very, very bad idea.)

The NOVA program, I've heard, was fairly good. Haven't
seen it myself.


I Saw it, I highly recommend perusing the transcript when
it becomes available. A noteworthy point I thought that
in the days immediately after 9/11 when US air traffic was
grounded, the difference between daytime highs and nighttime
lows increased by two degrees. There was a long term
study (by Russian scientists, I think) referenced that
showed how pan evaporation rates have decreased over a
thirty year period.

There was a suggestion that particulate emissions from
the US and Europe contributed to the extended drought
that plagued Ethiopia in the 70s and 80s, less evaporation
to fuel the seasonal monsoons. Water drops in clouds
form around the particulates, but smaller and greater
in number giving more reflective area. The return of the
monsoons (though not in full force) coincides with a reduction
of particulate and aerosol emissions in the US and Europe.

Thats a few choppy highlights from the episode.


In any case, major aerosol production only hides, say, 3-5 years
of the attendant greenhouse gas warming. The really nasty surprises
which may be in store come from the lags in the climate system
itself -- what we see now is the response to greenhouse gas
levels of the mid 1970s. About a 30 year lag.


Extended forecast: Hot and Dry.

So, can we expect more excitement if melting ice from the polar
regions cool ocean currents and melting permafrost releases
methane?


--
Robert Grumbine http://www.radix.net/~bobg/ Science faqs and amateur activities notes and links.
Sagredo (Galileo Galilei) "You present these recondite matters with too much
evidence and ease; this great facility makes them less appreciated than they
would be had they been presented in a more abstruse manner." Two New Sciences

.

Relevant Pages

  • Re: Global warming deniers
    ... it will be a long time (millennia in this case) before ... global warming will increase at a faster rate than the models are presently ... in the 60's were considering cooling (aerosols production) as well as ... warming (greenhouse gas emissions) -- at the time it wasn't obvious ...
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    ... CLEARING SOME AIR OVER WARMING IN EUROPE ... But aerosols also scatter incoming radiation from the sun back into space, thereby cooling the atmosphere just above the ground level, says Pascal Yiou, an atmospheric scientist at the Laboratory of Climate Sciences and the Environment in Gif-sur-Yvette, France. ... Yiou and his colleagues recently studied the link between aerosols and cooling by analyzing temperature and daytime visibility data gathered at 342 weather stations throughout Europe from the late 1970s through 2006. ...
    (sci.physics)
  • Re: Cycling not related to global warming
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    (uk.rec.cycling)
  • Re: AGW IS STILL A SCAM
    ... to cause all the warming that occurred during the 1990s. ... have been caused by the the reduction in aerosols. ... CO2 is not a greenhouse gas? ...
    (sci.geo.meteorology)