Friday, June 1, 2012

4774.txt

cc: mann@multiproxy.evsc.virginia.edu,tom@ocean.tamu.edu,k.briffa@uea.ac.uk, t.osbornatXYZxyz.ac.uk
date: Fri, 03 Mar 2000 13:04:24 +0000
from: Phil Jones <p.jonesatXYZxyz.ac.uk>
subject: Nature paper and beyond
to: Shaopeng Huang <shaopeng@geo.lsa.umich.edu>,hpollack@geo.lsa.umich.edu


Dear Shaopeng and Henry,
First, congratulations on the Nature paper. Can you send me some
reprints when you get them ?

I was at a meeting this week with Tom Crowley and we were discussing
ways to reconcile the high-freq proxies with your borehole data. Here
are a couple of our thoughts. Involving Mike Mann and others here in CRU, as
they all have an input.

1. I've shown that the borehole data in Europe agree well with the long
instrumental data in both the UK and Europe. The biggest differences/problems
seem to come with the North American borehole data, which show the 16/17/18th
data much cooler than the European/Asian/African data in the 16/17th century.
I'm still reminded by the potential effects of land-use changes, principally
in the eastern US, which could be making your North American series too
cool. I realise you've taken great care with the selection, but this is
a nagging doubt and will be picked up by the few skeptics trying to divide
us all about the course of change over the last millennium. Is it possible
to subdivide the North American borehole data into regions where we can
be confident of no land-use changes (possibly and thinking aloud say Canada
and the western US and Alaska) ? The aim of this (possibly joint work) is
to try and reconcile the low- and high-freq proxies. Tom Crowley has a
series for the NH where he's combined about 20 series (a few of which are
in Mike's and the series we've produced here but he has over half the series
from less-well resolved proxies - shallow marine and lake sediments) and
he gets something very similar to Mike and CRU.

2. As all our (Mike, Tom and CRU) all show that the first few centuries of
the millennium were cooler than the 20th century, we will come in for some
flak from the skeptics saying we're wrong because everyone knows it was
warmer in the Medieval period. We can show why we believe we are correct
with independent data from glacial advances and even slower responding
proxies, however, what are the chances of putting together a group of
a very few borhole series that are deep enough to get the last 1000 years.
Basically trying to head off criticisms of the IPCC chapter, but good
science in that we will be rewriting people's perceived wisdom about
the course of temperature change over the past millennium. It is important
as studies of the millennium will help to show that the levels of natural
variability from models are reasonable. Tom has run his EBM with current
best estimates of past forcing (Be-10 as a proxy for solar output and Alan
Robock's ice core volcanic index) and this produces a series similar
to all series of the last 1000 years.

The above is just ideas of how we, as a group, could/should try and reduce
criticisms etc over the next year or so. Nothing is sacred. Your North
American borehole series could be correct as it is annual and most of the
high-freq proxy series respond mainly to summer variations. Is yours really
annual when there is a marked seasonal snow cover season ?

Cheers
Phil



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.jonesatXYZxyz.ac.uk
NR4 7TJ
UK

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