**USGS/CCSP SAP 3.4 "Abrupt Climate Change" Teleconference**

**Friday, December 21, 2007 12:00PM-2:30PM**

> U.S. Geological Survey
>
> 12201 Sunrise Valley Dr.
>
> Reston, VA 20192

**[Goal of the Meeting:]{.underline}**

To summarize the major peer review comments and the proposed responses
on a chapter-by-chapter basis for SAP 3.4.

**[Attendance:]{.underline}**

*Federal organizing committee:*

Jack McGeehin, USGS, Designated Federal Officer (DFO)

Dave Anderson, NOAA

Dave Verardo, NSF

Pat Jellison, USGS

*FACA members:*

Carrie Morrill, NCDC, NOAA

Richard Seager, LDEO, Columbia University

Ed Cook, LDEO, Columbia University

Pat Bartlein, University of Oregon

Andrew Weaver, University of Victoria, Canada

Peter Clark, Oregon State University

Ed Brook, Oregon State University

Tom Delworth, GFDL, NOAA

Robin Webb, NOAA

Shawn Marshall, University of Calgary, Canada

Konrad Steffen, CIRES, University of Colorado

**[At 12:00PM the teleconference begins:]{.underline}**

Jack McGeehin, opening comments:

No members of the public have registered for the teleconference.
Proceedings will be recorded digitally. Transcripts of the meeting
minutes and the peer review comment tables will be supplied to two
members of the public who have requested to see written contents of
meeting.

Proposal that the next FACA workshop take place on April 16-17 or the
next week in April 2008. Several committee members have conflicts.
Details to be confirmed later.

Recent guidance from CCSP suggests that SAP authors should not reference
"submitted" papers in a SAP, as they have not been widely circulated or
peer-reviewed. At a minimum, referenced literature should be "in press."

January 29 is the due date (back at USGS) for the next draft as well as
the deadline for submitting completed peer review tables.

From January 30 to February 12 the document will go through a copy edit
like before (looking for typos, formatting consistency, etc....).
Concurrently, a formal USGS policy review is scheduled to take place.

Then from February 13^th^ to 20^th^ the authors will have the draft back
to incorporate copy edit and policy review changes.

Public comment period is estimated to start on February 25^th^. Slips
from that starting date, will affect the committee's ability to meet in
April.

Cross-cutting of SAPs, to coordinate information shared between the SAPs
is encouraged by CCSP. Referenced SAPs should be at the peer review
stage of the process or farther along. Authors should stay away from
policy sensitive statements in other SAPs, such as the statements in the
recommendations sections.

**[Ed Cook leads discussion of Chapter 3: Hydrological Variability and
Change]{.underline}**

Common complaint by peer reviewers was that the chapter is too North
American or U.S.-centric. Ed Cook states that this is a misapprehension
by the reviewers due to the fact that they were not told the chapter's
focus was on the United States and North America, not the planet. There
are no plans to extend analysis or review to much more of the world than
what has been done already. The approach is to touch on significant
droughts elsewhere in the world and cross-reference other SAPs that
include more information on the global examples.

Some peer reviewers thought the chapter was missing some relevant
references. This will be addressed and corrected in the next revision.

Largest omission pointed out by peer reviewers is a discussion about
floods. Floods are mentioned in key findings and recommendations
sections, but there is little discussion of floods in the body of the
chapter. The authors will try and address that in the "other impacts"
section toward the end of the chapter. Also they will mention it more at
the beginning of the chapter and explain why they are focusing more on
drought than floods.

Pat Bartlein notes that SAP 3.3 talks about floods and gives the example
of the 1993 Mississippi Valley floods as a significant case study. Might
be able cross-reference that SAP. Place to put that discussion is at the
end of the chapter in the other impacts section.

Robin Webb says that the authors need to address the peer review comment
on water quality as an abrupt climate change issue. Question is whether
or not there are good examples to draw upon.

Ed Cook agrees and confirms that water quality show be included to a
degree, although not extensively.

Robin Webb mentions that he has spoken with the reviewer who made the
water quality comment. Robin suggested to the reviewer that he could
help the authors address this section of the report.

Robin Webb suggested that the chapter could address salinity changes in
the past as one possible component.

Ed Cook agrees with Robin.

Pat Bartlein agrees and suggests that he and Robin could write a summary
using this example and other paleoenvironmental data, pointing out that
if these conditions were met again it could cause problems in the
present day.

Richard Seager wonders if water quality implies interactions between
either flooding and/or declines in water supply to people.

Robin Webb points out an example from SAP 5.3 with New York City's
concern of whether prolonged dryness followed by flooding ends up
washing "nasty stuff" into the city's water affecting the quality.
Unaware of examples from the paleo record. Suggests a cross-reference to
SAP 5.3 on this matter, but finds it difficult to relate it to abrupt
change.

Richard Seager suggests a connection between abrupt increases in
precipitation intensity that began in the 1990s and how increasing
amounts of sediment began flocking into reservoirs. Richard suggests
that he could write something about this.

Robin Webb offers to send him what he has compiled from SAP 5.3.

Ed Cook asks for Pat Bartlein to comment on the mid-Holocene drying part
of the report and a few sections questioned by reviewers about the
relevance of examples such as Africa in the report.

Pat Bartlein explains that the main role of the Africa example is to
illustrate the onset of aridity in response to progressive changes in
boundary conditions or controls. Also illustrates how climate extremes
reinforce drought conditions and have implications for North America in
the future. He also mentions this example bridges to the global monsoon
story. Another issue that came up in review was the relevance of
focusing on the Holocene. Pat Bartlein points out that the instrumental
record and the proxy record for the last millennium is subject to
boundary conditions and controls that are similar to today. Suggests
that authors need to do a better job of explaining what boundary
conditions and controls are and relating them to the present day.

Ed Cook mentions that the authors need to tighten up the use of terms of
uncertainty (e.g. "unlikely"; "highly unlikely") and use them more
consistently throughout the chapter. Should be tied in to the IPCC
approach.

Ed Cook says that there is some disagreement with reviewers
interpretations of the scientific literature, and the authors will
defend their opinions in responding to these reviewers. Often these are
questions of interpreting model results.

Richard Seager says that he will look more closely at the model results
so they can be described more accurately.

Dave Verardo suggests that what has been discussed is on the right
track. You must seriously consider a reviewer's comments, but you don't
have to necessarily agree with them. The comments are being handling in
a positive fashion.

Jack McGeehin asks if the committee feels comfortable that the authors
are on the right track and are effectively addressing the peer review
comments for this chapter? Also, does the committee feel that a follow
up meeting is warranted to deal with anything unresolved in your minds
related to the peer review comments in this chapter?

There are no objections raised relative to the approach taken by the
chapter authors in addressing the peer review questions, nor is there
any indication that the committee would need a follow-up meeting to
further address peer review matters.

Ed Cook asks how much public comments must be considered for future
revisions.

Jack McGeehin explains that the public comments must be addressed just
as they have been in this peer review process. He notes that the
"public" may include scientists making important criticisms. Every
public comment must be addressed.

**[Tom Delworth leads discussion of Chapter 4: The Potential for Abrupt
Change in the Atlantic Meridional Overturning
Circulation:]{.underline}**

Tom Delworth says that comments received were from nine reviewers with
174 comments total. All very useful.

Tom Delworth explains that uncertainty terms were questioned by several
reviewers, especially the use of "very unlikely" for the collapse of the
AMOC in the 21^st^ century. Reasonable question to ask. However, to use
the term "likely" implies a 1 in 3 chance of a collapse of the MOC in
the 21^st^ century and the authors disagree with this high percentage
likelihood. Although some changes will indeed be made regarding some of
the uncertainty issues raised by reviewers, such as observational and
modeling uncertainties that are important and do frame the question.
Some reviewers point out that if a collapse of the AMOC is "very
unlikely" why is further research on this topic even relevant? And how
can we even continue to make research recommendations? Tom Delworth
defends the need for more work to better understand and delineate
instrumental and paleo uncertainties, which could then be used to frame
a new research agenda.

Robin Webb says that there is more to abrupt climate change than
collapse of the MOC and asks if the chapter addresses questions like
potential impacts on droughts or tropical cyclone activity?

Tom Delworth explains that section six of the chapter deals with impacts
of the AMOC. Links between AMOC and droughts and tropical storms are
discussed but based on models alone, not observations.

Dave Verardo asks if the expression "models don't predict a change" (as
recommended by a reviewer) was considered.

Tom Delworth thinks this is a useful distinction, but to the exclusion
of the term "very unlikely," which is a more meaningful term.

Robin Webb asks how the AMOC community over the past decade or so
transitioned from terms like "as likely as not" to "very unlikely." Is
this discussed in the chapter?

Tom Delworth explains that these reasons are not fully explained in the
report. However, there is some discussion of how the older models were
either low resolution, flux adjusted or idealized models. More recent
models of greater complexity and resolution don't show that higher
likelihood of collapse.

Robin Webb states that the concept of abrupt climate change has been
linked with "Day After Tomorrow" scenarios of sudden collapse of the
MOC. We need to show why we are not as concerned or alarmed by this
possibility as the popular press.

Tom Delworth says that by making the "very unlikely" prediction for the
collapse of the AMOC, we are stating that there is a 1 in 10 chance, or
up to 10%, of it happening, and such a collapse would have significant
climatic impacts. He doesn't think that is being dismissive.

Peter Clark comments that Andrew Weaver has addressed this concept in
the published literature.

Richard Seager asks about Greenland mass balance and if it was factored
into the "very unlikely" determination.

Tom says that it is not addressed extensively.

Richard Seager thinks that in any discussion of the AMOC for the 21^st^
century it is important to consider what might happen in Greenland.

Tom Delworth does not think that the melting fluxes from Greenland would
be enough to collapse the MOC, but recognizes that this is a good point.

Tom Delworth says that one of the recommendations made in the chapter
points out that ice sheet models are not integrated into these
projections.

Andrew Weaver says that even taking GRACE numbers and multiplying them
by 10 doesn't come close to providing enough water to collapse the MOC
in models.

Richard Seager says that it may not cause a collapse but what about an
abrupt transitioning to a weaker MOC? That might be enough to cause a
sudden and measurable climate change.

Andrew Weaver says that collapses are abrupt, but weakenings are gradual
transitions (on the time table of the forcings).

Robin Webb asks Richard Seager if he envisions any abrupt impacts
related to a weakening MOC (e.g. droughts, floods, tropical cyclones
etc.). You can go along gradually, but there may be thresholds.

Richard Seager answers no, he is not thinking there will be any
non-linear response to the climate system. He reiterated, however, the
uncertainty related to lack of ice sheet data in MOC models. Could this
be significant?

Andrew Weaver thinks no. Paleo evidence shows only a few instances
(Heinrich events) where there may have been enough melting to collapse
the MOC. Conditions in the North Atlantic are not like that today.
Collapse of the MOC is not impossible, though. That's why the authors
leave the likelihood at up to 10%. Turning the discussion around, how
could we justify a 1 in 3 chance of MOC collapse by calling it
"unlikely"? Very difficult to justify a 1 in 3 change of MOC collapse in
the next 90 years.

Koni Steffen does not see how you can collapse the Greenland ice sheet
in 90 years. Steffen confirms that the chance of collapse due to mass
balance is very low from Greenland specifically.

Shawn Marshall says that it would be useful for the cryo chapter to
provide uncertainty statements to the probability of different levels of
Greenland collapse and subsequent sea level rise, something the authors
have not done yet for their chapter. This would help the discussion in
the MOC chapter.

Tom Delworth summarizes this point: there is no way to support a 1 in 3
chance of collapse, but the uncertainties involved here (e.g. ice melt,
modeling capabilites, etc.) should be outlined and explained more
clearly in the next revision.

Tom Delworth says that reviewers requested more specific recommendations
in section about recommended activities. Some changes have been made,
but thinks it would not be wise to go overboard in specificity of
recommendations.

Jack McGeehin reiterates about the dangers of being too specific with
policy recommendations and to use general terms instead of directly
pointing to specific technologies, observing platforms, etc.

Tom Delworth says that the third overarching topic from peer review
comments relates to the paleo section organization. Asks Peter Clark to
comment.

Peter Clark agrees and states that he and Jean (Lynch-Stieglitz) will
work on it together.

Tom Delworth states that the fourth overarching reviewer theme has to do
with wanting more discussion about the role of sea ice affecting the
AMOC. Will consider these suggestions as appropriate in various sections
of the chapter.

Peter Clark pointed out a peer review comment that appeared in the
executive summary and asked if it also appeared in the AMOC chapter.
Specifically, the comment was: "Thus it is much more appropriate to say
that \'In a 1% increasing to 2xCO2 scenario, the models show X\'.
However, in this section, it is necessary to add in a caveat about the
quality of the models. The AR4 models have not in general been evaluated
for their sensitivity to \'known\' forcings relevant to past episodes of
rapid MOC change (the 8.2 kyr event for instance). Thus the sensitivity
of these models is relatively unconstrained. It may well be that all are
deficient due to a misrepresentation of the effects of sub-grid scale
eddies or overflow processes. Thus, in this of all model projections,
the consensus of the models cannot be taken as a pdf."

Tom Delworth states that this comment does not appear in the report;
however it did appear in related ways through the discussion of the
models in other parts of the chapter.

Dave Verardo asks if the group is comfortable with the future research
directions discussion of the chapter when weighed against the
conclusions reached? Is the front end of the chapter balanced with the
back end?

Tom Delworth once again points to the importance of noting more
prominently uncertainties that are the mark of our understanding at the
present point. It's those uncertainties that are the rational of our
research agenda in Section 8 of the chapter. Decision to use IPCC
uncertainty scale, means that "very unlikely" is the only term he would
be comfortable with.

Andrew Weaver asks if question refers to a reviewer's comment that there
is a "very unlikely" probability of collapse, yet there is a plan in
place to reduce uncertainty, which sounds like a "money grab" or "self
serving."

Dave Verardo clarifies that the "very unlikely" probability makes it
more difficult to promote a research agenda vision.

Andrew Weaver and Tom Delworth point out that they have discussed an
increased focus on the Labrador and Norwegian Seas to broaden the
examples and scenarios used in the chapter.

Dave Verardo says that he broached this topic because this is the kind
of question that will come up. It is important to identify a strategy
for a problem that better informs about that problem.

Tom Delworth asks Dave Verardo if he is suggesting that because of the
"very unlikely" term, the proposed research agenda has very little
relevance.

Dave Verardo is concerned that it might come across that way in the
final draft. He just wants the authors to be conscious of the language
they use in tying their research recommendations to their conclusions.

Tom Delworth thinks that it is important to clearly articulate that the
very unlikely determination is based on our present understanding, but
that understanding includes quite a few uncertainties.

Dave Verardo concurs.

Robin Webb, getting back to his earlier point, thinks that even small
changes to the MOC could result in abrupt impacts. Could this be
articulated better?

Tom Delworth points out that they do articulate this in the chapter.

Robin Webb says that his point is that this is why the research is
important, whether or not you shut down the MOC completely.

Shawn Marshall wonders whether there shouldn't be two statements of
uncertainty, one related to the shifts of deepwater formations that
could have regional impacts.

Andrew Weaver has difficulty thinking of a mechanism in which it could
happen. How do you have an abrupt 30% weakening?

Robin Webb, points out Richard Seager's earlier discussion in which you
get enough melt water from Greenland, that you don't shut down the MOC
but you dump enough fresh water that you would maybe shut down Labrador
as an example.

Robin Webb says that he doesn't want the group to convey a message that
they walk away from discussions of possible changes in MOC because of a
very low likelihood of complete shut down.

Andrew Weaver says that there is a whole community out there that
believes in the "Day After Tomorrow" scenario. It's being taught in
schools. We walk a very fine line between cautioning the public with
something that has a small likelihood and people blowing this
information out of proportion. Andrew thinks the discussion was handled
appropriately.

Robin Webb discusses challenges in seasonal forecasting and what we
expected from ENSO forcings being modulated by changes in the Atlantic
SSTs. Changes in the Atlantic can be small but impacts on precipitation
patterns in the US can be dramatic/abrupt. Committee should convey that
we need to understand this. Role of Atlantic is relatively unknown as to
how it affects our droughts.

Richard Seager says the thing that needs to be recognized is that the
variability we have seen in the circulation has impacts including over
Africa and the SW US. Some people have said that these occurrences were
abrupt in the 60s and 90s. Presumably, they will be occurring in the
future as well. They will have climate impact. Potentially some
predictability there. That type of Atlantic variability still needs to
be addressed.

Robin Webb says that if natural variability is impacting circulation
then we don't need a collapse in the AMOC to see similar potential
changes.

Andrew Weaver asks where is the abrupt coming in here as it has been
defined in our report? We're talking about natural variability here.

Robin Webb refers to earlier reference to a gradual transition of
changes, but those changes might cross thresholds of SST gradients in
the North Atlantic that would then cause abrupt impacts.

Richard Seager says that one of the most abrupt changes that occurred in
the 20^th^ century was the drying of the Sahel which seems to have had
something to do with the Atlantic ocean. That was abrupt.

Tom Delworth says that is speculation that it had anything to do with
the AMOC.

Richard Seager says that we can't prove that it was the overturning
circulation, that's why he says it's related to the North Atlantic
Ocean. These things will be happening in the future and we better
predict them.

Peter Clark suggests a simple statement in the text along the lines of
the very unlikely occurrence of an abrupt collapse of the MOC, but that
subtle transitions in the MOC may lead to significant impacts.

Andrew Weaver says that they could add a statement that says that it is
likely that the overturning will weaken.

Peter Clark says that that could be an additional justification for why
this is an important question.

Andrew Weaver suggests that rather than assigning an uncertainty value
to the impacts, which are tenuous at best, we could make a statement
that a likely slowing of the MOC could cause impacts that are abrupt.

Committee agrees that this is a good way of phrasing it.

Jack McGeehin asks if the committee feels comfortable that the authors
are on the right track and are effectively addressing the peer review
comments for this chapter? Also, does the committee feel that a follow
up meeting is warranted to deal with anything unresolved in your minds
related to the peer review comments in this chapter?

There are no objections raised relative to the approach taken by the
chapter authors in addressing the peer review questions, nor is there
any indication that the committee would need a follow-up meeting to
further address peer review matters.

**Koni Steffen leads discussion of Chapter 2: Rapid Changes in Glaciers
and Ice Sheets and their Impacts on Sea Level**

Koni Steffen is pleased with peer review comments. He begins with the
peer review comments stating that the chapter needs more of a focus on
the paleo record of the ice sheets -- what it shows and why it is
important. This will be addressed in the next draft. Peter Clark will
handle some of this.

Second key point: reviewers ask for more information on ice sheet
hydrology. This is emerging as a field and reviewers ask the authors to
address this at least in some part as a paragraph or a page. Koni
Steffen agrees. This will be addressed in next draft.

Another reviewer thinks there needs to be more discussion on glaciers
and ice caps, the reviewer believe glaciers were not discussed in
detail. Koni Steffen emphasizes that glaciers are not really an issue
for abrupt climate change, like they are sea level rise. This is an
abrupt climate change report. Also, some of the reviewers remarks are
obsolete, as there is only 20-40 cm of sea level rise in glaciers and
small ice caps.

Koni Steffen has made first pass on peer review comments and has
responded to about half the reviewer comments already. Needs to get in
contact with his other co-authors.

Koni Steffen points out that his co-authors all agree that there is not
an issue for abrupt climate change from large ice sheets at present. We
do not even have the tools needed to make a prediction. The dynamic
response cannot be sufficiently described with interaction of ocean.
There is consensus that at least in the northern hemisphere, we cannot
throw out enough ice at once within a hundred years to make a dramatic
change of the ice sheet. It is dramatic enough to give a review of the
accuracy itself at this time.

Koni Steffen says that some reviewers think that there should be some
more balance in the chapter. He says that he can easily strike a balance
in the next draft and bring more literature into the discussion. Bring
in more GRACE data to show the range of estimates and uncertainties of
ice volume loss from Greenland.

Koni Steffen asks if Shawn Marshall or Peter Clark have anything to add.

Shawn Marshall confirms that most of the reviewer comments will be dealt
with relatively easily. Shawn Marshall reiterates an earlier comment
that this chapter should adopt uncertainty terms used in the other
chapters and make sure they are used in the executive summary.

Koni Steffen agrees. Says that this was raised by one or two reviewers.
Koni has started to tackle this, but points out that there needs to be
consensus with the co-authors. Koni asks Peter Clark where he stands
with the paleo addition to the chapter.

Peter Clark explains that the paleo section is fairly brief. Looks at
what we know about sea level change over the last couple glacial cycles
and a little bit on longer time scales, but not specific ice sheet
history, just global sea level history. Some good points are made in the
section. New paleo information on the ice sheet history could be brought
in without too much work.

Peter Clark points out that the comment on better use of uncertainty
statements did come up in the executive summary as well.

Koni Steffen asks about dealing with the discussion of topics like small
glaciers in a report focused on abrupt climate change. Surely, small
glaciers are important but are not likely to be a factor in an abrupt
climate change, like sea level.

Peter Clark says that sea level is the major discussion for this
chapter, as well as how the rate of ice discharge might influence
climate -- but it's abrupt sea level and abrupt climate.

Koni Steffen says that abrupt refers to how quickly.

Peter Clark agrees. Thinks that the reviewer is stating that these small
glaciers are changing abruptly now relatively to what they have done
before, but in terms of sea level, their influence is not abrupt.

Koni Steffen points out that ¼ of the whole chapter is about small
glaciers. He does not feel like the authors have neglected this topic.

Peter Clark says that there was a comment in the executive summary about
the changes being seen in the ice sheets. How confident are we that it
is a start of a trend versus variability?

Koni Steffen says the authors can address that. New data of frontal
positions of ice fronts over past two hundred years. Lots of variability
over that time. Periods of warmth similar to present (e.g. 1930s) have
been documented where the ice edge didn't move.

Peter Clark says it's not so much that we are looking at this as the
start of a trend, but the lessons we are learning about ice sheet
behavior.

Koni Steffen agrees. We don't even know how long a trend lasts because
we are just at the upslope. That's why we have to be careful about
taking apart a trend versus what is variability. We should concentrate
on our inability to explain some of the processes.

Shawn Marshall asks about the paleo section. Much of the detail already
provided or suggested by reviewers is outside the realm of abrupt. SAP
1.2 gives a very detailed discussion of the paleo in the arctic. Is it
appropriate to refer to that document for further detail?

Jack reiterates the benefit of cross-cutting references between other
SAPs.

Koni Steffen states that he is a reviewer for SAP 1.2. Already knows
that there is a well-written section on the paleo of Greenland. Koni
expresses concern about the sequence of both SAPs. They are both at
about the same place, but SAP 1.2 is a bit behind 3.4 He wonders if it
is possible to refer to another SAP that is forthcoming.

Jack McGeehin says we can extract material from SAPs if they have been
through their peer review process, as long as we stay in contact with
the authors. Not sure about 1.2, but thinks it is okay. We will need to
stay in very close contact.

Koni Steffen thinks it's a good idea to repeat some of the same
material, not just reference another report. It's important that our
report stand alone and be well-rounded.

Pat Jellison states that it is probably safe to refer to other SAPs,
stating that they are addressing a topic in detail. CCSP's advice for
dealing with SAPs that have not yet been through their expert review is
to site the references that the other report has sited.

Jack McGeehin suggests that there may be time to mesh the two reports
closer in the spring after SAP 1.2 has been through its peer review.

Koni Steffen points out that our authors can help to shape SAP 1.2 as
well through expert review.

Pat Bartlein says that the hydro chapter should say something about the
melting of small glaciers on water supply. Asks if there is anything in
this chapter on the topic?

Koni Steffen says not on water supply. Predictions are of ice loss.
Impacts not discussed. Large body of literature. He says that his
authors could try and help out to make it more visible in the hydro
chapter.

Jack McGeehin asks if the committee feels comfortable that the authors
are on the right track and are effectively addressing the peer review
comments for this chapter? Also, does the committee feel that a follow
up meeting is warranted to deal with anything unresolved in your minds
related to the peer review comments in this chapter?

There are no objections raised relative to the approach taken by the
chapter authors in addressing the peer review questions, nor is there
any indication that the committee would need a follow-up meeting to
further address peer review matters.

**Ed Brook begins discussion on Chapter 5: Potential for Abrupt Changes
in Atmospheric Methane.**

Ed Brook explains that most reviewer comments are minor and can be fixed
by tweaks and clarification.

Long discussion in chapter of Paleocene-Eocene thermal maximum and its
relevance to abrupt release of methane to the atmosphere today. Needs
some tightening up in response to some reviewer comments.

Two reviewers suggested that more specific recommendations for research
in the area of methane hydrates and the ice core record. Ed Brook says
that the authors strayed away from this because of the potential
conflict of interest issues. He thinks that the authors can add some
research recommendations without appearing to be too self-serving.

Biggest issue raised by a reviewer is that the chapter does not deal
with the "clathrate gun" hypothesis. The reviewer felt that the authors
were dismissive of the idea of late Quaternary changes in methane and
that climate might be driven by methane hydrates. Reviewer raised
several criticisms of the arguments that the authors used without
explaining the criticisms, so they are hard to respond to. Response will
be to better articulate what the clathrate hypothesis is and elaborate
more on the authors' arguments against it while incorporating the
appropriate level of uncertainty.

Ed Brook asks about the issue of including recommendations by reviewers
for research in an area that might be perceived as a conflict of
interest. Ed points to the recommendation by one reviewer of
recommending more research on the ice core methane record, which is
something that Ed Brook does. He points out that the such work would be
appropriate.

Jack McGeehin points out that we have called on this group to advise us
as experts on this matter. All scientifically warranted research
recommendations should be considered.

Dave Verardo thinks this is fine as long as the authors can tie a
research recommendation with a need to answer substantive scientific
questions -- and not advocate for their own research.

Jack McGeehin asks how many such reviewer comments were there?

Ed Brook says that there were two reviewers who made similar comments.
He could see adding a bullet or two in the recommendations.

Pat Jellison states that the earlier comment about not advocating a
particular platform or program applies here. As long as you proposing a
research direction that advocates a particular data need or activity,
she thinks the authors are clear. It would be an omission to leave it
out if there is a definite need and if the reviewers have called for it.

Jack McGeehin asks if the committee feels comfortable that the authors
are on the right track and are effectively addressing the peer review
comments for this chapter? Also, does the committee feel that a follow
up meeting is warranted to deal with anything unresolved in your minds
related to the peer review comments in this chapter?

There are no objections raised relative to the approach taken by the
chapter authors in addressing the peer review questions, nor is there
any indication that the committee would need a follow-up meeting to
further address peer review matters.

Jack McGeehin suggests combining the intro chapter with executive
summary for this last part of teleconference.

**Peter Clark leads discussion about the intro chapter and the executive
summary.**

Intro chapter has three reviews and the executive summary has four
reviews. Many issues are raised by overlapping reviewers from the other
chapters so many points are reiterated from earlier. Not much that is
substantive. Will work with the chapter lead authors to address these
comments.

Executive summary:

There is a question of uncertainty in the Ice chapter and how it is
stated. The same reviewer brings up the same comment for the hydro
chapter. Peter doesn't remember much discussion of uncertainty terms in
that chapter.

Richard Seager acknowledges this and suggests that the authors will be
revisiting this issue for the next draft. There are several comments on
this point in their chapter as well.

MOC and methane chapter use the appropriate terminology throughout and
it's noticeably absent in the other chapters and their contributions to
the executive summary.

Intro chapter:

Again, overlapping comments with chapters. Peter will work with chapter
lead authors. Nothing fatal. All pretty straightforward.

Andrew Weaver agrees with this assessment: very straightforward.

Jack McGeehin asks if the committee feels comfortable that the authors
are on the right track and are effectively addressing the peer review
comments for this chapter? Also, does the committee feel that a follow
up meeting is warranted to deal with anything unresolved in your minds
related to the peer review comments in this chapter?

There are no objections raised relative to the approach taken by the
chapter authors in addressing the peer review questions, nor is there
any indication that the committee would need a follow-up meeting to
further address peer review matters.

Jack McGeehin tries to establish more details for next meeting of the
committee in the spring. Logistics difficult. Suggests April 23-24. Koni
Steffen has offered to host, even in his absence. Peter Clark offers to
host it, as well, in Corvallis, Oregon.

Koni Steffen asks about deadlines.

Jack McGeehin reiterates schedule from the beginning of the meeting.

Pat Jellison and Jack McGeehin thank everyone for their participation
before the meeting concludes.