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April 02, 2008
Letter to Nature Geoscience
Posted to Author: Pielke Jr., R. | Climate Change | Prediction and Forecasting
Nature's Climate Feedback blog provides a nice summary of a correspondence that I authored published today in Nature Geoscience:
Today in a letter to Nature Geoscience (subscription required), Roger Pielke, Jr, questions whether models from that 2001 generation improve on the predictive power of their forbears.Posted on April 2, 2008 08:16 AMPielke checks predictions from all four IPCC reports, dating back to 1990, against reality. Each report made a series of 'if-then' statements about the likely results of various emissions scenarios; in hindsight, Pielke can pick out which of these possible greenhouse experiments has actually been running on Earth since 1990 and compare the results to the IPCC's shifting hypotheses.
Whereas the 2001 projections undershot the observed temperatures and sea levels, the 1990 projections overshot them, he concludes. Projections of temperature and sea level fell substantially between the 1990 and 1995 IPCC reports, when aerosols were added to models and carbon-cycle simulations were tweaked. But because they dropped too far, the adjusted post-1995 projections "are not obviously superior in capturing climate evolution", says Pielke.
Comments
Hi Roger,
Well, I'm shocked. I don't know how you could manage to get something that actually has science in it published in a major publication on the subject of climate change projections. Congratulations!
If you want to (and are allowed to) follow up your terrific achievement with another paper that has actual science, I have a good topic.
You could write a paper that recommends that the IPCC should drop its "scenario" analysis completely, and switch to probabilistic predictions of *all* climate forcing variables, with resulting probabilistic predictions for temperature rise.
For example, Figure 10.26 of AR4 has approximately the following methane concentrations (in ppb) in the year 2020 for various scenarios:
B1 = 1920
B2 = 1980
A1F1 = 2000
A2 = 2010
A1T = 2010
A1B = 2020
Those (ridiculous) projections could be replaced by realistic probabilistic predictions, e.g.
5% probability methane concentration will be less than 1700 ppb,
50% probability methane concentration will be less than 1800 ppb, and
95% probability methane concentration will be less than 1900 ppb.
The same thing could be done for each climate forcing (warming and cooling) agent, e.g., CO2, black carbon, sulfur dioxide, organic carbon, etc.
I think this would probably be too much real science for Nature. But you the man! Maybe you can get it published. :-)
Mark
Posted by: Mark Bahner ![[TypeKey Profile Page]](http://sciencepolicy.colorado.edu/prometheus/nav-commenters.gif)
at April 2, 2008 07:11 PM
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