<[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
>
>> http://msnbc.msn.com/id/14834318/
>
> Hansen may be a climate science expert, but this particular argument
> hasn't much to do with climate science as such and is awfully weak. If
> we start ten years later, we'll just have to reduce emissions more
> steeply to get to the same end result. It won't be too late, rather
> it'll require a greater effort to get to the same end goal.
Unless you are considering the development of technology that actually
removes CO2 from the air, this is incorrect because of how long CO2
concentrations will remain elevated. Reducing emissions (unless you mean by
over two thirds almost instantly, to levels below that being sequestered
now) does not lower concentrations immediately. Even lowering them to below
the 2Gt/yr naturally sequestered now is no guarantee, will the natural sinks
still take up the same annual amount? Will those sinks fill?
I think Hansen is likely considering the possible natural carbon feedbacks
too. We may find the net response from the natural carbon cycle becomes
positive very soon. I also agree with Michael's response concerning ice
sheets and the general point about the response of a complex system.
It is not simply a question of reaching a given point of time with the same
total carbon emissions, the path not mattering.
As for the general question of whether or not this is out of Hansen's area
of expertise, I still disagree. I personally think he is using more gut
than computational model to arrive at such a conclusion, but it is still a
question of climatology.
Coby
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