Re: [asa] CO2 content

On Thu, Aug 28, 2008 at 8:59 AM, j burg <hossradbourne@gmail.com> wrote:

> The argument my friend makes on the basis of the Azolla pitch is this:
>
> "It isn't the fact that the world isn't getting warmer, it is that the
> fact that the world is getting warmer is a big ho hum--... The world
> used to have 3500 ppm of CO2. Today we have 380 ppm and are horrified
> at the prospect of going to 600 ppm."
>
> The presentation data does indicate that the planet survived a 3500
> ppm level. I don't know of any claims that it can't, but perhaps there
> are some. What such a world looks like is another story, of course.
>
> Burgy
>

As Keith has already said the planet will reach equilibrium eventually. The
problem is the rate of change. Even the so-called Azolla event took 800,000
years to drop 4 degrees C. We will do that difference in temperature in
around a century with the BAU scenario. When your rate of change differs by
three orders of magnitude it *will* have a profoundly negative effect.

One of the things that is still confuses scientists is that temperature and
CO2 change is not tightly coupled. With greater CO2 we may even be in a
period of greater instability which means our ability to predict is
degraded. We are now outside the bounds of CO2 Pearson which was used for
this talk put it this way:

Overall, the *p*CO2 values for the early Cenozoic show considerably more
> variability than do the values for the late Cenozoic. This may be partly due
> to the magnification of errors that occurs at low pH values, but it may also
> reflect *greater instability of the global carbon system during warm
> periods*. The relative constancy of *p*CO2*p* CO2 is stabilized by a
> homeostatic feedback mechanism involving the greenhouse effect45<http://www.nature.com/nature/journal/v406/n6797/full/406695a0.html#B45>.
> This is because radiative forcing is amplified at low *p*CO2, hence small
> variations would be damped more efficiently by homeostasis.

It's the difference in CO2 levels and not the absolute numbers that are an
issue since the CO2 temperature relationship is logarithmic. Give our lower
starting point means smaller changes in CO2 have a larger effect than during
the early Cenozoic. It's not the temperature it's the RATE OF CHANGE which
is important. As Jim Hansen put it we can easily be put into a "different
planet". What that planet looks like is anyone's guess (although a big ho
hum is a guess that is less likely than all the others). Our real choices
are between bad, real bad, and apocalyptic. I tend to be more optimistic
than Jim Hansen so I don't go as far as he does but I simply don't have any
hard evidence that says he is wrong. Even if I am right and he is wrong, the
merely bad scenario will affect the poor and the oppressed much more than
the rich and the free. As Christians that should concern us.

Rich Blinne
Member ASA

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Received on Thu Aug 28 13:08:22 2008