date: Sat, 31 May 2008 11:42:14 -0400 from: Mike MacCracken subject: New Nature paper to: Phil Jones Hi Phil--According to news accounts, very interesting result in your new Nature paper. Being retired, I don't have direct access and wonder if you could send a copy along. I just finished a review paper on climate change science, etc.--basically a summary across the IPCC WG I and II assessments, and in it, as it allowed some personal reflections, I took issue with whether the obs during the years of WW II had had all the biases removed yet--not thinking there might be a problem just after the war years. What has struck me is how different an impression one gets of the 20th century change if one puts one's finger over the war year results--just seems very suspicious, and my recollection is that you are already making some pretty large adjustments over that period to things like nighttime marine air temperature (due to more measurements being near the wheelhouse instead of at the bow of the ship, etc.). I think it is also interesting that in the regional results on attribution in the new IPCC report (so figure SPM.4, for example), the only region and time that the observations are outside the model band is apparently during the war years for the global ocean (North America and South America during that period are also a bit problematic). Your new result will help a bit, but not seem to resolve that problem, so I guess I am wondering if there is work continuing on looking at the observations for that period? What it seems to me really needs to be done (though hard with limited data) is to extend the reanalyses back to before WW II--and then figuring out if the patterns look consistent, etc. with later patterns. On this issue of the sulfates, only the very newest inventories are trying to differentiate between surface and elevated SO2 emissions--even though this makes a very large difference in atmospheric lifetimes. I have done a bit of looking at the net forcing for GHGs and aerosols over time and it is interesting how the sulfates offset (considering both direct and indirect influences) the GHGs until the early 1970s or so--then the GHG effect takes off. All the movement to elevated SO2 emissions was done to reduce pollution, and it makes me wonder if the Chinese and Indians might soon go to the solutions the US and Europe used in the 1930s-60s---namely, filter out the particles and loft the SO2 (leading to a lot of sulfate). This would seem to mean that for a few decades we may get a growing sulfate offset to the forcing (so little temperature rise--and perhaps a lessening of political pressure to do something), and then as GHGs climb, wow, what a lot of warming potential. What is troubling is that I have not found any group looking at SO2 emission inventories for China and India and differentiating surface and lofted emissions--our EPA is going to work with them on CO2 emissions, but not SO2, and these really need to be compiled. Best regards, Mike MacCracken