On today’s weblog, several examples of quotes are reproduced below that demonstrate the limitations of our current understanding of human- and natural- climate variability and change. The quotes are from individuals (Mike MacCracken, Joel Smith and Anthony Janetos, and Jim Hansen, each of whom is a well respected scholar) and from a CCSP Committee.
1. From page 145 of the 2006 Response to the Public Comment of the CCSP Report “Synthesis and Assessment Product 1.1 Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences?”
“Owing to natural internal variability, models cannot be expected to reproduce regional patterns of trend over a period as short as 20 years from changes of radiative forcings alone.”
2. From MacCracken, Michael, Joel Smith and Anthony C. Janetos, 2004. Reliable regional climate model not yet on horizon. Nature Vol. 429, No 6993, p. 699,
June 17, 2004.
“The US National Assessment of the Potential Consequences of Climate Variability and Change (USNA) – in which we were involved-did not attempt to provide regional or even national predictions of climate change……”
Later in the letter in Nature, they conclude with,
” We strongly agree that much more reliable regional climate simulations and analyses are needed. However, at present,…….such simulations are more aspiration than reality.”
3. From the February 2004 issue of Scientific American Magazine
Jim Hansen has an interesting quote on page 24 in “Defusing the Global Warming Time Bomb”
“It will not be possible to optimize strategies for dealing with global
warming until all important climate forcings, including carbonaceous
aerosols, have been well quantified.”
Clearly, if we accept that
“The needed focus for the study of climate change and variability is on the regional and local scales. ”
the conclusion on the Climate Science weblog that
“In terms of climate change and variability on the regional and local scale, the IPCC Reports, the CCSP Report on surface and tropospheric temperature trends, and the U.S. National Assessment have overstated the role of the radiative effect of the anthropogenic increase of CO2 relative to the role of the diversity of other human climate climate forcing on global warming, and more generally, on climate variability and change”;
“Global and regional climate models have not demonstrated skill at predicting climate change and variability on multi-decadal time scales “;
“Attempts to significantly influence regional and local-scale climate based on controlling CO2 emissions alone is an inadequate policy for this purpose. ”
have published supportive quotes from what might be expected to be unlikely individuals. The quotes that are reproduced above should be discussed widely by the climate science community, including the individuals who are quoted to determine if they continue to agree with what they published.