Tuesday, April 10, 2012

3273.txt

cc: Keith Briffa <k.briffaatXYZxyz.ac.uk>, Eystein Jansen <eystein.jansenatXYZxyz.uib.no>
date: Mon, 18 Jul 2005 11:50:46 -0600
from: Jonathan Overpeck <jtoatXYZxyzrizona.edu>
subject: Re: thoughts and Figure for MWP box
to: Tom Crowley <tcrowleyatXYZxyze.edu>

<x-flowed>
Tom - thanks. Let's see what Keith says too. My comments below (BOLD)

>a few comments -
>
>1) are you trying to choose between my way of
>presenting things and your way - ie, w w/out
>composite?

IF YOU USE A COMPOSITE IN THE BOX FIGURE, THEN IT
SHOULD MATCH ONE OF THE COMPOSITE SERIES IN THE
TEXT FIGS. THAT WOULD BE OK?

2) with your data, do they all go through from beginning to end?

KEITH HAS TO ANSWER

3) why include chesapeake, which is likely a salinity record?

KEITH HAS TO ANSWER, BUT DON'T NEED A SALINITY RECORD.

4) some of your data are from virtually the same
site - Mangazeja and yamal are both w. siberia -
I composited data available from multiple sites
to produce one time series, which is equally
counted against the other regions, which might
(greenland, w.U.S., e. Asia) or might not have
multiple records in them

KEITH HAS TO ANSWER

>5) I am not sure whether it is wise to add me to
>the CA list, just because the reviewer is
>supposed to be impartial and a CA loses that
>appearance of impartiality if he has now been
>included as a CA - may want to check with Susan
>S. on this one to be sure - still happy to
>provide advice

WE CAN CHECK W/ SUSAN (WE HAVE A FEW THINGS TO
DISCUSS W/ HER). LETS SEE WHAT THE FIG DISCUSSION
LEADS TO FIRST. FRANKLY, I'D RATHER HAVE YOUR
COMMENTS ON OUR NEW DRAFT BEFORE WE COMPLETE THE
FOD, BUT I SEE YOUR POINT. IT HAS BEEN NICE
HAVING YOUR INDEPENDENT COMMENTS.

>6) I am happy to go in either direction -
>include or not include my figure - all I need
>are specific directions as to what to do, as
>CLAs you people need to decide, and then just
>tell me what or what not to do

THANKS - LETS SEE WHAT KEITH SAYS ABOUT ALL THIS.

>7) I am a little unhappy with the emphasis on
>hemispheric warmth - lets face it, almost all of
>the long records are from 30-90N - the question
>is: how representative is 30-90N to the rest of
>the world? for the 20th c. one can do
>correlations with the instrumental record, but
>co2 has almost certainly increased the
>correlation scale beyond what it was
>preanthropogenic. you could correlate with
>quelcaya - not sure how many other records
>there are that are annual resolution - in the
>tropics I have produced a tropical composite
>(corals + Quelc.) but it only goes back to ~1780
>- corals just don't live v long - in that
>interval at least the agreement is satisfactory
>with the mid latitude reconstruction but there
>is only 100 years extra of independent
>information beyond the instrumental
>record...THIS MAY NEED TO BE ADDRESSEDAS A
>GENERAL ISSUE SOMEWHERE (SHORTLY) IN YOUR DOC

I AGREE THAT WE NEED TO BE CLEAR ON THIS. KEITH?

>
>tom
>THANKS AGAIN, PECK
>
>
>Jonathan Overpeck wrote:
>
>>Hi Keith, Eystein and Tom: See below (BOLD) for
>>my comments. Thanks for moving this forward and
>>making sure we do it right (i.e., without any
>>bias, or perception of bias).
>>
>>>Dear Peck, Eystein and Tom
>>>At this point we thought it was important to
>>>review where we think we are with the MWP
>>>Figure.
>>>
>>>First, we have no objection to a Figure . Our
>>>only concerns have been that we should
>>>1/... be clear what we wish this Figure to
>>>illustrate (in the specific context of the MWP
>>>box) - note that this is very different from
>>>trying to produce a Figure in such a way as to
>>>bias what it says (I am not suggesting that we
>>>are, but we have to guard against any later
>>>charge that we did this). We say this because
>>>there are intonations in some of Peck's
>>>previous messages that he wishes to "nail"
>>>the MWP - i.e. this could be interpreted as
>>>trying to say there was no such thing, and
>>
>>
>>SORRY TO SCARE YOU. I **ABSOLUTELY** AGREE THAT
>>WE MUST AVOID ANY BIAS OR PERCEPTION OF BIAS.
>>MY COMMENT ON "NAILING" WAS MADE TO MEAN THAT
>>ININFORMED PEOPLE KEEPING COMING BACK TO THE
>>MWP, AND DESCRIBING IT FOR WHAT I BELIEVE IT
>>WASN'T. OUR JOB IS TO MAKE IT CLEAR WHAT IT WAS
>>WITHIN THE LIMITS OF THE DATA. IF THE DATA ARE
>>NOT CLEAR, THEN WE HAVE TO BE NOT CLEAR. THAT
>>SAID, I THINK TOM'S FIGURE CAPTURED WHAT I HAVE
>>SENSED IS THE MWP FOR A LONG TIME, AND BASED ON
>>OTHER SOURCES OF INFO - INCLUDING KEITH'S
>>PROSE. THE IDEA OF A FIGURE, IS THAT FIGURES
>>CAN BE MORE COMPELLING AND CONNECT BETTER THAN
>>TEXT. ALSO, THERE ARE MANY WAYS TO LOOK AT THE
>>MWP, AND AS LONG AS WE DON'T INTRODUCE BIAS OR
>>ANYTHING ELSE THAT WILL DILUTE THE MESSAGE IN
>>THE END, THE IDEA IS TO SHOW THE MWP IN MORE
>>WAYS THAN TWO (THAT IS, THE EXISTING FIGS IN
>>THE TEXT THAT KEITH AND TIM MADE).
>>
>>> 2/ ...agree that we have done this in the best way.
>>>The truth is that there IS a period of
>>>relative warmth around the end of the 1st and
>>>start of the 2nd millennium C.E. , but that
>>>there are much fewer data to base this
>>>conclusion on (and hence the uncertainty
>>>around even our multiple calibrated
>>>multi-proxy reconstructions are wide). The
>>>geographical spread of data also impart a
>>>northern (and land) bias in our early proxy
>>>data.
>>
>>
>>NEED TO BE CLEAR ABOUT THIS BIAS IN THE CAPTION AND BOX TEXT
>>
>>>My understanding of Tom's rationale with the
>>>Figure is that we should show how, because the
>>>timing of maximum pre-20th century warmth is
>>>different in different records, the magnitude
>>>of the warmest period (for the Hemisphere , or
>>>globe, as a whole) is less than the recently
>>>observed warmth.
>>
>>
>>YES, BUT IN A WAY THAT SAYS "LOOK, HERE ARE THE
>>ACTUAL REGIONAL CURVES - CHECK IT OUT FOR
>>YOURSELF" INSTEAD OF JUST SAYING (IN A
>>SCIENTIFICALLY MORE STANDARD MANNER - HERE ARE
>>THE VARIOUS, MOST ROBUST, LARGE AREA
>>RECONSTRUCTIONS. IN MY MIND, THE LATTER
>>(KEITH/TIM FIGS IN THE MAIN TEXT) WILL BE THE
>>MOST APPEALING/CONVINCING TO PALEOCLIMATE
>>SCIENTISTS, BUT TOM'S MIGHT HELP THERE, AND
>>CERTAINLY WITH NON-PALEO SCIENTISTS AND POLICY
>>FOLKS. MIGHT HELP... IF IT DOESN'T NOTHING
>>LOST, BUT IF IT COULD HURT CONVEYING
>>UNDERSTANDING, THEN ITS BAD TO USE THE NEW
>>FIGURE.
>>
>>>The reconstructions we plot in Chapter 6
>>>already express the mean Hemispheric warmth
>>>(after various selection and scaling of data),
>>>and so the additional information that the MWP
>>>box figure should show must relate to the
>>>scatter of the proxy data. There seems to be a
>>>consensus that this is best done by showing
>>>individual records , and we are happy to agree.
>>>What we worry very much about, however, is
>>>that we should not produce a Figure that then
>>>conflicts with the picture of proxy evidence
>>>for Hemispheric mean warmth as a whole,shown
>>>in the main Chapter Figure. By showing a
>>>composite (as Tom has done) and scaling
>>>against another (30-90degrees N) temperature
>>>record - this is just what is done.
>>
>>
>>ABSOLUTELY RIGHT - CAN'T HAVE CONFLICT.
>>
>>>As we promised, Tim has produced a similar
>>>Figure, using the same series plus a few
>>>extras, but omitting the composite mean and
>>>the scaling against instrumental temperatures.
>>>The idea was to include as many of the
>>>original input series (to the various
>>>reconstructions) as we could - though
>>>avoiding conflicting use of different versions
>>>of the same data. The precise selection of
>>>records will have to be agreed and,
>>>presumably, based on some clear, objective
>>>criteria that we would need to justify (this
>>>will not be straight forward). This, along
>>>with Tom's plot (forwarded by Peck) is in the
>>>attachment.
>>>
>>>We would like to get your opinion now, and
>>>especially Tom's, on the points regarding the
>>>composite and scaling. We would be in favour
>>>of just showing the series - but do they make
>>>the point (and emphasise the message of the
>>>text in the box)? Or does the scatter of the
>>>various series as plotted, dilute the message
>>>about the strength of 20th century mean
>>>warming (note the apparently greater scatter
>>>in the 20th century in our figure than in
>>>Tom's)? Can you all chip in here please.
>>>best wishes
>>
>>
>>WHAT ABOUT THE IDEA THAT WE ONLY SHOW THE
>>SERIES FOR THE MWP, SINCE THE COMPARISON TO THE
>>20TH CENTURY IS DONE WELL (AND BEST?) IN THE
>>TEXT FIGS (WHICH I'M ATTACHING JUST IN CASE TOM
>>DOESN'T HAVE, ALONG WITH THE TEXT - IF YOU HAVE
>>TIME, TOM, PLEASE READ COMMENT ON ANYTHING YOU
>>WISH, BUT CERTAINLY THE LAST 2000 YEARS BIT -
>>ASSUME YOU'LL BE DOING THIS AT THE REVIEW STAGE
>>ANYHOW...)
>>
>>ANOTHER THING THAT IS A REAL ISSUE IS SHOWING
>>SOME OF THE TREE-RING DATA FOR THE PERIOD AFTER
>>1950. BASED ON THE LITERATURE, WE KNOW THESE
>>ARE BIASED - RIGHT? SO SHOULD WE SAY THAT'S THE
>>REASON THEY ARE NOT SHOWN? OF COURSE, IF WE
>>ONLY PLOT THE FIG FROM CA 800 TO 1400 AD, IT
>>WOULD DO WHAT WE WANT, FOCUS ON THE MWP ONLY -
>>THE TOPIC OF THE BOX - AND SHOW THAT THERE WERE
>>NOT ANY PERIODS WHEN ALL THE RECORDS ALL SHOWED
>>WARMTH - I.E., OF THE KIND WE'RE EXPERIENCING
>>NOW.
>>
>>TWO CENTS WORTH
>>
>>
>>>Keith and Tim
>>>P.S. We agreed in Beijing that we should definitely ask Tom to be a CA .
>>
>>
>>TRUE - BUT HAS ANYONE CONFIRMED W/ TOM. TOM, YOU OK W/ THIS?
>>
>>THANKS - A GREAT DISCUSSION, AND LETS SAY THE
>>JURY IS STILL OUT ON THIS FIGURE UNTIL WE ALL
>>ARE COMFORTABLE WITH WHAT IT LOOKS LIKE IN THE
>>END.
>>
>>BEST, PECK
>>
>>>
>>>--
>>>Professor Keith Briffa,
>>>Climatic Research Unit
>>>University of East Anglia
>>>Norwich, NR4 7TJ, U.K.
>>>
>>>Phone: +44-1603-593909
>>>Fax: +44-1603-507784
>>>
>>>
>>>Attachment converted: Macintosh HD:mwpbox_figures.pdf (PDF /�IC�) (0008A8AE)


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

Mail and Fedex Address:

Institute for the Study of Planet Earth
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
direct tel: +1 520 622-9065
fax: +1 520 792-8795
http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/
</x-flowed>

No comments:

Post a Comment