On 9/16/2012 12:43 PM, John Clark wrote:
On Sun, Sep 16, 2012 at 1:44 AM, meekerdb <[email protected]
<mailto:[email protected]>> wrote:
> In fact it [CO2] has been less than half the current level
during the last 600 thousand years
There have been at least 4 times in the last 600 thousand years when
the CO2 levels were nearly as high as they are now. And the link
between CO2 and temperature is far from clear. During the late
Ordovician period 450 million years ago there was a huge amount of CO2
in the atmosphere, about 4400 ppm verses 380 today, and yet the world
was in the grip of a severe ice age. During the last 600 million years
the atmosphere has almost always had far more CO2 than now, abut 3000
ppm on average. The only exception was a period that lasted from 315
million years ago to 270 where there was about the same amount of CO2
as we have now. The temperature was about the same then as it is now
too, and during the late Ordovician that I mentioned before it was
much colder, but other than a few very brief ice ages during the last
few million years the temperature has always been warmer than now.
> But it is not just the level that is worrisome, it is the
rapidity of increase, which would appear as instantaneous on the
paleoclimate studies.
If you adjust the scale of a graph you can always make a gentle rise
look like a near vertical wall.
>> And I think people sometimes forget that CO2 is not the
most important greenhouse gas, water vapor is
> But water vapor equilibrates with ocean temperature very
quickly, whereas CO2 takes hundreds of years to come into
equilibrium. Water vapor is the most important green house gas,
but it acts as a positive feedback, amplifying other warming (or
cooling) effects.
If water always produced positive feedback then with all the water on
this planet life would never have existed in the first place, but
things are more complicated than that. Let me ask you something, if
the world's temperature increases will that create more clouds or
fewer clouds? It's a very simple question with profound consequences
because clouds regulate the amount of solar energy that runs the
entire climate show. Increased temperature means more water evaporates
from the sea, but it also means the atmosphere can hold more water
before it is forced to form clouds. So who wins this tug of war?
Nobody knows, its too complicated. Water vapor is a far more powerful
greenhouse gas than CO2 and unlike CO2 it undergoes phase changes at
earthly temperatures, it can be a solid a liquid or a gas which makes
it much more complicated than CO2 which is always just a gas, at least
on this planet.
And then there is the important issue of global dimming, the world may
be getting warmer but it is also getting dimmer. For reasons that are
not clearly understood but may be related to clouds, at any given
temperature it takes longer now for water to evaporate than it did 50
years ago.
John K Clark
John,
Did you see the study of the connection between cloud formation and
cosmic rays?
--
Onward!
Stephen
http://webpages.charter.net/stephenk1/Outlaw/Outlaw.html
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