RealClimate – Climate Scientists Use The Blog
:: RealClimate is new blog, launched in December 2004 by a group of concerned climate scientists, which describes it as a commentary site:RealClimate is a commentary site on climate science by working climate scientists for the interested public and jo…
it would be constructive if younbwereto present a 1000 word precis of this to the editor of TCS . I for one would endorse threir running it, but then , I would endorse a full fledged public debate between the warring parties in this matter at AEI.
What is your position on the Bristlecone Pines?
(I’m referring to MM’s suggestion that they are in some way anomalous)
[Response: Thanks for the question. Much has been written on the potential influence of non-climatic factors in recent centuries (potentially associated with co2 effects) on the growth pattern of certain high elevation drought stressed trees such as the Bristlecone Pines you refer to. In Mann et al (1999) [Mann, M.E., Bradley, R.S. and Hughes, M.K., Northern Hemisphere Temperatures During the Past Millennium: Inferences, Uncertainties, and Limitations, Geophysical Research Letters, 26, 759-762, 1999], an attempt was made to remove these potential non-climatic influences. This was done by subtracting the anomalous pattern of growth that emerges over the past couple centuries in these chronologies relative to other tree-ring chronologies that otherwise exhibit very similar patterns of growth back in time, but which are unlikely to be influenced by the same non-climatic factors. More discussion of these issues (and references to relevant past work) can be found in the paper. -Mike]
Isn’t it a bit wrong to use the the word ‘independent’ [above]?
-If the various reconstructions use a common core of proxies, they wouldnt seem to be statistically independent to me -not that I am a statistician.
[Response: No, its an appropriate description. Several of the reconstructions that have been performed are based on entirely independent proxy data and entirely independent methodologies. Other reconstructions use a small number of common series but an independent methodology. None of the reconstructions use largely the same dataset, or precisely the same methodology. -Mike]
The Hockeystick theory & indeed part 4 of your defined consensus, that things are so bad that serious action is required, requires that there was not a period (the medieval warming) when average temperatures were several degrees warmer than now.
On the other hand many students of history have said that there was & pointed out that there were extensive Norse settlements in Greenland which died out apparently because of worsening climate. What convinces you that this period was illusory?
[Response: Sigh…. Try here for what the hockey stick implies (and doesn’t), here and here for more about the medieval warm period, and Jared Diamond for information about the Norse settlements. – gavin]