date: Mon Jun 2 15:50:26 2008
from: Phil Jones
subject: Re: New Nature paper
to: Mike MacCracken
Mike,
I mentioned over the weekend the several thousand British logbooks
that are being digitized. Most are done, but the data now need to be QC'd
before adding. These will certainly help with the 1940s. As I hope I said,
I only think this is going to affect the period from 1940-1955.
Digitization costs, so we're only doing about half of the British logbooks
that haven't been already done.
Once all done, this will likely move the sulphates drop later - more
to where it probably occured in the 1950s through the late 1970s.
The trouble with using tropospheric sulphate to help slow warming is
that at some point the Indians and the Chinese are going to come under
increasing pressure on local air pollution. As you say, they were stopped
in Europe and North America for this issue and the slightly further afield acid rain.
Cheers
Phil
At 16:42 31/05/2008, you wrote:
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
Prof. Phil Jones
Climatic Research Unit Telephone +44 (0) 1603 592090
School of Environmental Sciences Fax +44 (0) 1603 507784
University of East Anglia
Norwich Email p.jones@uea.ac.uk
NR4 7TJ
UK
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