Wednesday, January 18, 2012


date: Sun, 18 Dec 2005 13:53:03 -0700
from: Jonathan Overpeck <>
subject: [Wg1-ar4-ch06] Follow-up from Christchurch

Hi Chapter 6 Friends - Just wanted to thank you all for a great IPCC
meeting and solid progress toward the SOD of Chapter 6, as well as
give you a report on the TS meeting that took place on Friday. I'm in
transit, so haven't been able to see any emails, but I suspect
Eystein is also sending some updates on what we need to be doing.
We'll have to work fast and hard to make all the deadlines, but I
think its safe to say that our chapter will have real impact. I want
to personally thank you for your dedication to our team effort!


The TS/SPM meeting on Friday was exhausting, as appears to be
traditional for all things IPCC. But, it was quite impressive in
terms of how paleo was viewed by the broader WG1 team of authors.
This is reflected in the decision to consider (without any pushing
from me, believe it or not) several new figures from our chapter.
Below I list these along with the others that will need refinement
for use by the TS. Please note where I insert "ACTION ITEM" - these
are very time sensitive assignments that should be carried out ASAP
(i.e., before the new year where possible). Note that everything
(i.e., figures) in the TS will also have to be in our chapter.

1) the orbital box. Eystein and I have the draft completed by Valerie
et al in New Zealand. We will read/edit (ACTION ITEM) and send around
to the group for further editing. The TS version might have to be
altered to reflect the broader audience, and I'm not yet sure what
figure would best go with the TS version. I believe Valerie (ACTION
ITEM) is exploring (with Stefan?) a nice figure that illustrates the
mechanisms of orbital forcing.

2) there will also be an model evaluation box in the TS that will
have paleo. Once I get more feedback on this (Chap 8 is leading on
this box), I'll connect the rest of our team with this effort, with
Bette in the role of lead chap 6 person.

3) there will a sea level box led by Chap 5. I'm not sure what the
fig will look like in this box, but if Dick (ACTION ITEM) can produce
his new Chap 6 sea level figure FAST, we can float it as a possible
contributor to the TS Box figure. It would be great to get paleo sea
level perspectives in this box!

4) there will be expanded discussion of abrupt change with focus on
paleo - Richard Alley is leading this, and I think that will be a
real plus in making sure the discussion isn't just model based

4) Keith's sites through time figure is also still a TS item. There
will hopefully also be a fig showing the distribution of instrumental
sites. Keith has the ACTION ITEM on his figure. Peck and Eystein can
help get the data released to Keith and Tim if needed - just let us

5) Keith's 6.8 figure will have to be worked on to find the best mode
of presentation, and I have a separate email on this one for him and
Tim. The TS team would like to see inserted on the fig (e.g., along
the lower edge of the figure, perhaps) some depiction of how the site
number used changes back in time, and some color coding to denote how
our expert judgement suggests the implied confidence in the recons
change back in time. I'm guessing this will require some phone
conversations to think through with Keith (ACTION ITEM for Eystein,
Peck and Keith).

6) A NEW FIGURE - depicting inferred solar forcing over the last X
centuries. The request is that we show Judith Lean et al's latest for
1600 to present. This could include the volcanic forcing too, but it
seems more appropriate that we stick with our plan to add this to the
expanded 6.8. We'll have to try both figs (this new one, and the
expanded 6.8) figure w/ and w/o the volcanic series (i.e., detrended
multi-core average excess sulfate from each of two polar regions) on
each fig. I think Keith/Tim gets the ACTION ITEM on all this figure
stuff - Perhaps David (ACTION ITEM) can send Judith's latest solar
recon to Keith?

7) Expanded/modified recent forcing figureS by Fortunat (ACTION
ITEM). One will be for Chap 6, the other will combine Chap 2 and 6
perspectives into a single figure for the TS. I'll send a separate
fig to Fortunat with the details, but everyone likes his new rate of
change depiction, and the TS team also wants a ice core tropospheric
aerosol record too (e.g., for the last couple centuries - Jean Jouzel
thought we could do this using Greenland ice core data, and we'd add
this to the TS fig (and either a chap 2 or 6 figure, since everyting
in the TS has to also be in a chapter.

8) A NEW FIGURE for the TS (and maybe not chapt 6, since we already
have 6.8 and 6.10 with most of the info) should be the one of Keith's
that we showed in our plenary talk on Thursday - the multi-model
range of simulated change over the last 1000 (red shading)
superimposed on our chap 6 observed record (represented by grey
shading as in the fig we showed). Requested modifications for
Keith/Tim (ACTION ITEM) include: a) using a 20th century ref period
as in the current Fig 6.8, b) adding (where possible) simulations
that include natural forcing only (and thus not enough warming in
20th century) and c) adding one or more EMIC simulations using the
new Lean solar recon (at least over the last 400 years, with all the
other forcing). This last one is tricky, since no one at the TS mtg
thought such a simulation exists, BUT it seems it is ok for us to
get/use a new long simulation by one of the EMIC models used in Chap
10. Peck (ACTION ITEM) needs to figure out how to get this, but
Thomas Stocker indicated he'd help. Stafan - what about you guys
doing this? Who else could we ask for fast turnaround?

9) Another NEW FIGURE (that I actually fought including since we
don't want to be seen showing off our own stuff) of Last Interglacial
(LIG) Change. The TS team (and Susan) really liked this paleo
message, so we came up with a proposed scheme (which I already
discussed with Bette - who has the ACTION ITEM) that will involve the
inclusion of more than one LIG climate simulation, plotted with
observations superimposed, and perhaps more than one LIG ice sheet
reconstruction as well. Should Tarasov and Peltier be considered for
this fig (forced by ice-core inferred LIG climate)? Are there others?
For this figure to work, it has to be a synthesis of multiple
studies, not just the recent Otto-Bleisner et al effort.

So, that is the news - all good from the view point of chap 6
exposure/impact, but of course, not so good in terms of the
additional fast-turn-around work that is needed. The other tough
issue is that - after several negotiating sessions with Susan (the
last one with Jean Jouzel helping) - the best we could do is get our
page limit increased from 30 to 35 pages. That doesn't sound too bad,
except that we have to a) get all our existing material into less
space than now (we're currently at an estimated 36 pages) AND b) get
the new figures mentioned above in (two I think - solar, plus the LIG
fig). We can do it, but everyone has to be thinking NOW about how to
reduce our text.

Again, many thanks for all the travel and hard work over the last two
weeks. Also (in advance) for all the hard work coming up this month
and the next two.

Best, Peck
Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences

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