Re: [asa] Limted role for CO2

On 2/5/07, Janice Matchett <janmatch@earthlink.net> wrote:
>
>
> Even research from the Intergovernmental Panel on Climate Change-- the
> United Nations agency that heads the worldwide effort to combat global
> warming -- is bereft of anything here inspiring confidence. In fact, *according
> to the IPCC's own findings, man's role is so uncertain that there is a
> strong possibility that we have been cooling, not warming, the Earth.*Unfortunately, our tools are too crude to reveal what man's effect has been
> in the past, let alone predict how much warming or cooling we might cause in
> the future.
>

Note no quote. I'll give one for you.

 *The understanding of anthropogenic warming and cooling influences on
climate has improved since **the Third Assessment Report (TAR), leading to *
*very high confidence7** **that the globally averaged net **effect of human
activities since 1750 has been one of warming, with a radiative forcing of
+1.6 [+0.6 **to +2.4] W m**-2**.** (see Figure SPM-2). {2.3. 6.5, 2.9}

7 In this Summary for Policymakers the following levels of confidence have
been used to express expert judgments on the correctness of the underlying
science:
very high confidence at least a 9 out of 10 chance of being correct; high
confidence about an 8 out of 10 chance of being correct.

*
 So uncertain that we have a greater than 90% confidence otherwise.

 *
> "Solar activity can explain a large part of the 20th-century global
> warming," he states, particularly because of the evidence that has been
> accumulating over the past decade of the strong relationship that cosmic-
> ray flux has on our atmosphere. So much evidence has by now been amassed, in
> fact, that "it is unlikely that [the solar climate link] does not exist."*
>

 *• Changes in solar irradiance since 1750 are estimated to cause a
radiative forcing of +0.12 [+0.06 to +0.30]*
*W m**-2**, which is less than half the estimate given in the TAR. {2.7}*
**
Compare the size of the forcing with the anthropogenic component. Note is
not said that the link doesn't exist but rather that it is 5X smaller than
the anthropogenic component.

 The sun's strong role indicates that greenhouse gases can't have much of an
> influence on the climate -- that C02 et al. don't dominate through some kind
> of leveraging effect that makes them especially potent drivers of climate
> change. *The upshot of the Earth not being unduly sensitive to greenhouse
> gases is that neither increases nor cutbacks in future C02 emissions will
> matter much in terms of the climate.*
>
>
 Even doubling the amount of CO2 by 2100, for example, "will not
> dramatically increase the global temperature," Dr. Shaviv states. Put
> another way: "Even if we halved the CO2 output, and the CO2 increase by 2100
> would be, say, a 50% increase relative to today instead of a doubled amount,
> * the expected reduction in the rise of global temperature would be less
> than 0.5C. This is not significant."*
>

Note the bait and switch. He went from doubling to halving. Doubling amount
of CO2 will increase temperature by most likely 3 degrees C and no less than
1.5 degrees C. Again from AR4:

 The equilibrium climate sensitivity is a measure of the climate system
response to sustained radiative
forcing. It is not a projection but is defined as the global average surface
warming following a doubling of
carbon dioxide concentrations. It is *likely *to be in the range 2 to
4.5°Cwith a best estimate of about 3°C,
and is *very unlikely *to be less than 1.5°C.

In IPCC-speak, likely means 66% confidence or greater (all ranges are going
to be likely by definition because they are one sigma ranges), very unlikely
is 90% confidence.

>
>

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Received on Mon Feb 5 13:17:14 2007