date: Fri Sep 18 16:02:25 2009
from: Phil Jones
subject: Re: comments on Thompson et al. Nature paper
to: Thomas C Peterson
Tom,
I recall talking about this paper to Mike at the last CCPP meeting in DC.
It should be easier to explain the revised record, but it may mean that sulphate aerosols
become less important. Skeptics will use anything to undermine things. The change when
corrections are applied (which should be submitted soon) will make the 1940s warmer
overall, so will affect the key AR4 diagram from D&A - well the specific ocean one.
This paper has just been accepted - attached.
You can also get another at
Congratulations! Your recently accepted article, "Low-frequency
variations in surface atmospheric humidity, temperature and
precipitation: Inferences from reanalyses and monthly gridded
observational datasets", is now available on the AGU Papers in Press site:
[1]http://www.agu.org/journals/jd/papersinpress.shtml#id2009JD012442
Another one with Dave Thompson is on the J. Climate accepted page as well.
I wish I could find some time to write papers as first author!!!
Cheers
Phil
At 14:01 18/09/2009, you wrote:
Hi, Phil,
Dick Reynolds and I passed on a copy of the Thompson, Kennedy, Wallace and Jones paper
on the large discontinuity...to Mike MacCracken. I thought you might enjoy his
comments, the key one being:
The only disappointment about the article from my view are its limited comment on the
implicationsI think they will be huge.
Regards,
Tom
*************************
Hi Tom and DickThank you very much for sending along the paper, I had not yet seen it
though understood the UK efforts were looking at this period.
I was interested in how the US contribution to the measurements grew starting in
something like 1939 (when Lend-Lease started) and grew more gradually than when it shut
downso it is indeed the whole period that will be affected.
The only disappointment about the article from my view are its limited comment on the
implicationsI think they will be huge. It is this (uncorrected) warmth that has been the
basis for so much of the interest in solar contributions to climate change, so that will
be seriously impacted, getting us back to where many of us think we should be, with
solar changes in heating being weighted about equally with GHG changes in heating and
not having to search out all sorts of exotic feedbacks to show how a small solar change
could have a disproportionately large effect. So, I think it will mean the
detection-attribution studies weigh solar less and find the human influence going back
further in time.
Many of the Skeptics have also using that early 1940s level to be the end of natural
warming post the Little Ice Age, saying human influences played little early role
(though methane concentration was up a lot, and CO2 some, so there was actually a
significant forcing prior to the early 1940s, but its influence was misestimated as
there was this focus on the Sun (how it can be so constant is truly amazing, but that is
what it appears).
I think there was also an important and unfortunate psychological result of the 1940s
high pointnamely it hid the early human influences and so let the argument be made that
natural variability (internal and external) was larger than it has been, so the problem
was not as bad as it really is. I have for quite a number of years asked people to put
their finger over the WWII period and then look at the global record, and one gets a
quite different impression of hat has been happening and its relation to human
activities, etc. Basically, now, it will seem much more evident that human activities
started earlier.
I think the new result will also affect the estimate of the aerosol offsetthe only way
to be explaining the mid-20th century was with a pretty large sulfate cooling. Now, that
wont be nearly so necessary, likely making that aerosol effect smaller, which will be
interesting. It will therefore also affect the ideas about geoengineering with sulfate
aerosols.
And finally, the result may help in figuring out why estimates of sea level rise during
the 20th century have been so far below observationsIPCCdrawing from the model
results--could only explain a small share of 20th century rise. Less sulfate and solar
influence and more even warming over time might well help in this regard.
So, again, fascinatingit will be nice now to have a citation for a situation that I have
been pointing out in talks and my 2008 review paper.
Best, Mike
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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