[asa] Re: Costs of CO2 Mitigation

From: John Burgeson (ASA member) <hossradbourne@gmail.com>
Date: Wed Dec 31 2008 - 12:44:19 EST

Fascinating stuff.

BTW, I just had an exchange of emails on this subject with a friend of
many years (12) who happens to be a Republican Rep from Colorado. I
was pleased to find out that we share similar views of the issues. In
the exchange I sent a copy of my article written for the Rico Bugle
this month.

I'd appreciate any comments on the article from the ASA list --
particularly Rich and Randy. It may be accessed at

www.burgy.50megs.com/gw.htm

I tried very hard to present the issues fairly, Ias I saw them.

On 12/30/08, Rich Blinne <rich.blinne@gmail.com> wrote:
> One of the things that get in the way of effective CO2 mitigation is
> the past cost models of environmental cleanup. That is to remove ever
> increasing amounts of whatever "toxin" it takes exponentially more
> resources to remove it. This paradigm has been used by the denialists
> to insure there is inaction. For example, Roger Pielke, Jr. oscillates
> between the "models are wrong" and "it's just too expensive". In both
> cases, we do nothing. What undergirds this approach is there is a real
> risk with an exponentially increasing cost model that you could end up
> spending too much. A new approach to the economics can be found in
> today's PNAS.
>
> http://www.pnas.org/content/105/52/20621.abstract
>
>> One approach in climate-change policy is to set normative long-term
>> targets first and then infer the implied emissions pathways. An
>> important example of a normative target is to limit the global-mean
>> temperature change to a certain maximum. In general, reported cost
>> estimates for limiting global warming often rise rapidly, even
>> exponentially, as the scale of emission reductions from a reference
>> level increases. This rapid rise may suggest that more ambitious
>> policies may be prohibitively expensive. Here, we propose a
>> probabilistic perspective, focused on the relationship between
>> mitigation costs and the likelihood of achieving a climate target.
>> We investigate the qualitative, functional relationship between the
>> likelihood of achieving a normative target and the costs of climate-
>> change mitigation. In contrast to the example of exponentially
>> rising costs for lowering concentration levels, we show that the
>> mitigation costs rise proportionally to the likelihood of meeting a
>> temperature target, across a range of concentration levels. In
>> economic terms investing in climate mitigation to increase the
>> probability of achieving climate targets yields "constant returns to
>> scale," because of a counterbalancing rapid rise in the
>> probabilities of meeting a temperature target as concentration is
>> lowered.
>
>
> The constant returns to scale is key. This means that by linearly
> increasing the percentage of GDP we get a linearly increased
> probability of achieving our temperature goals, e.g. less than three
> degrees C rise because that would create a "different planet". The
> methodology that is used by Schaeffer et al is to focus on the error
> bars of the climate sensitivity. They create a concept known as the
> "allowed climate sensitivity". This is reverse-engineered from the
> desired temperature target and the consequent forcing. Since the
> climate sensitivity is not known precisely there is a probability that
> the CO2 targets actually achieve the temperature targets. As was
> presented by Jim Hansen at the 2008 AGU most of this uncertainty is
> due to the uncertainty of the aerosol climate sensitivity and not the
> CO2 sensitivity proper which is well-understood and well-bounded.
> (This is the reason why there is a >95% consensus on the existence of
> AGW.) After all the number crunching is done what is found out is that
> a linear increase in spending produces a linear increase in the
> probability that we will hit our temperature targets. You can see the
> linearity from Figure 5 of the paper. I put a copy up here:
>
> http://docs.google.com/Presentation?docid=dgzxjjjz_51fsrwcvf8
>
> Since the 3 degrees C target is the "different planet" line and we
> want near certainty that this isn't crossed the minimum spending needs
> to be 1% of GDP. (This is also quite a bit less than the 3% GDP target
> proposed by IPCC 2007.) If we spend this amount we may get "lucky"
> and have a much better result. The is eminently doable and does not
> warrant the Pielke throw up the hands in despair approach.
>
> Rich Blinne
> Member ASA
>
>
>
>

-- 
Burgy
www.burgy.50megs.com
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Received on Wed Dec 31 12:45:06 2008

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