Re: Constraints on Climate Sensitivity Tightened

I want to point out that atmospheric CO2 and its effect on
temperature is only half the story. High atmsopheric CO2
also reduces ocean pH, and this has become a real and
measureable effect. It is this data that convinces me,
that we have a real problem with artificial CO2
production:

http://www.research.noaa.gov/spotlite/archive/spot_gcc.html

On Thu, 27 Apr 2006 06:20:34 -0600
  "Rich Blinne" <rich.blinne@gmail.com> wrote:
> There is some really good news in last week's Nature
>concerning climate
> sensitivity. Climate sensitivity is how much the average
>temperature goes up
> when CO2 doubles. If there is high climate sensitivity
>we might hit a
> "tipping point" popularized by Time Magazine giving
>breathless headlines
> about being very worried. One reason for the worry was
>high climate
> sensitivity could produce such an effect because we (the
>whole world) are
> doing such a poor job of controlling CO2. But, now we
>have this:
>
> Climate sensitivity constrained by temperature
>reconstructions over the past
> seven centuries
>
> Gabriele C.
>Hegerl1<http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#a1>,
> Thomas J. Crowley
> 1<http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#a1>,
> William T.
>Hyde1<http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#a1>and
> David J. Frame
> 2
><http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#a2>
> Top of
>page<http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#top>
> Abstract
>
> The magnitude and impact of future global warming
>depends on the sensitivity
> of the climate system to changes in greenhouse gas
>concentrations. The
> commonly accepted range for the equilibrium global mean
>temperature change
> in response to a doubling of the atmospheric carbon
>dioxide
> concentration1<http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#B1>,
> termed climate sensitivity, is 1.5–4.5 K (ref.
> 2<http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#B2>).
> A number of observational studies3,
> <http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#B3>4,
> <http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#B4>5,
> <http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#B5>6,
> <http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#B6>7,
> <http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#B7>8,
> <http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#B8>9,
> <http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#B9>10<http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#B10>,
> however, find a substantial probability of significantly
>higher
> sensitivities, yielding upper limits on climate
>sensitivity of 7.7 K to
> above 9 K (refs
> 3–8<http://www.nature.com/nature/journal/v440/n7087/full/nature04679.html#B3>).
> Here we demonstrate that such observational estimates of
>climate sensitivity
> can be tightened if reconstructions of Northern
>Hemisphere temperature over
> the past several centuries are considered. We use
>large-ensemble energy
> balance modelling and simulate the temperature response
>to past solar,
> volcanic and greenhouse gas forcing to determine which
>climate sensitivities
> yield simulations that are in agreement with proxy
>reconstructions. After
> accounting for the uncertainty in reconstructions and
>estimates of past
> external forcing, we find an independent estimate of
>climate sensitivity
> that is very similar to those from instrumental data. If
>the latter are
> combined with the result from all proxy reconstructions,
>then the 5–95 per
> cent range shrinks to 1.5–6.2 K, thus substantially
>reducing the probability
> of very high climate sensitivity.
>
> The last sentence is critical as it looks like the
>doomsday scenario is
> excluded. Richard Kerr for the journal Science put it
>this way:
>
> While newly climate-conscious news reporters seek signs
>of apocalyptic
>> change in hungry polar bears and pumped-up hurricanes,
>>evidence-oriented
>> researchers are working to nail down some numbers. They
>>are concerned with
>> climate sensitivity: how much a given increase in
>>atmospheric carbon dioxide
>> will warm the world. If it's extremely high, continued
>>emissions of
>> greenhouse gases could ignite a climatic firestorm. If
>>it's very low, they
>> might merely raise the global thermostat a notch or two.
>>
>> Now two new studies that combine independent lines of
>>evidence agree that
>> climate sensitivity is at least moderately
>>strong--moderate enough so that a
>> really scorching warming appears unlikely. Even with the
>>most conservative
>> assumptions, says climate researcher Chris E. Forest of
>>the Massachusetts
>> Institute of Technology in Cambridge, the studies cool
>>the maximum warming.
>> And the reinforced low end of the range, he says, means
>>continued emissions
>> will fuel a substantial warming in this century.
>>
> ...
>
>> "Combining multiple lines of evidence is certainly the
>>way to go," says
>> Forest. An extremely high climate sensitivity "is
>>probably less likely than
>> we thought a year ago," agrees climate researcher Reto
>>Knutti of the
>> National Center for Atmospheric Research in Boulder,
>>Colorado. More
>> importantly, "we start to see a much better agreement on
>>the lower bound,"
>> says Knutti. "We can be pretty sure the changes will be
>>substantial" by the
>> end of the century, he says.
>>
>
> Maybe now we can get past the "destroying the planet"
>red herring. Can we
> just be good stewards trying to solve a significant but
>not impossible
> problem? One positive thing that came from the NAE
>debate on the enivornment
> was the "what about the poor?" question coming from both
>sides of the
> debate. Any "solution" needs to take that into
>consideration. By not needing
> to adopt draconian solutions we can make sure the poor
>are not unduly
> burdened. The goals expressed by the President last
>Saturday of being good
> stewards AND preserving jobs is a worthy one for this
>organization.
Received on Thu Apr 27 09:45:27 2006