Several news stories have come out flowing Chris Landsea’s "http://sciencepolicy.colorado.edu/prometheus/archives/science_policy_general/000318chris_landsea_leaves.html">resignation
from the IPCC last week. These news stories provide some additional
information that allows for some insight into the scientific dispute
between Landsea and NCAR’s Kevin Trenberth, as well as into the broader
political context of the IPCC.

The Scientific Dispute

Landsea wrote in his letter that he resigned from the IPCC, in part,
because “It is beyond me why my colleagues would utilize the media to push
an unsupported agenda that recent hurricane activity has been due to
global warming,” and one of those colleagues, Trenberth, was the Lead
Author for the IPCC responsible for writing the chapter on hurricanes to
which Landsea was to contribute. In an "http://www.washingtonpost.com/wp-dyn/articles/A29397-2005Jan22.html">article
in yesterday’s Washington Post Trenberth again asserted that the very
active 2004 hurricane season was influenced by global warming:

“Trenberth, who in an interview Friday called Landsea’s charges
“ridiculous,” said he participated last fall in a media conference call
organized by Harvard University professors “to correct misleading
impressions that global warming had played no role at all in last year’s
hurricane season.” He added he would have welcomed opposing views in the
assessment, even though he believes “if global warming is happening, how
can hurricanes not be affected? It’s part of the overall system.”"

And Sunday’s Boulder Daily Camera contained a similar "http://www.dailycamera.com/bdc/science/article/0,1713,BDC_2432_3491666,00.html">report:
“In a telephone interview with the Camera, Trenberth said the [Harvard]
press conference had been called to rebut statements by Landsea and others
who have said “global warming had nothing to do with hurricanes.”"

The scientific dispute between Landsea and Trenberth over whether or not
global warming played a role in the 2004 hurricane season is easily
addressed. Landsea writes that the assertion that the 2004 hurricane
season was linked to global warming was not supported by peer-reviewed
science, “All previous and current research in the area of hurricane
variability has shown no reliable, long-term trend up in the frequency or
intensity of tropical cyclones, either in the Atlantic or any other basin.
The IPCC assessments in 1995 and 2001 also concluded that there was no
global warming signal found in the hurricane record.” Yesterday’s Boulder
Daily Camera contains a similar perspective from MIT’s Kerry Emanuel,
another expert on hurricanes, “I think it’s extremely difficult to pin the
last season on global warming. That does not preclude that there may be a
global warming signal buried in there somewhere, but nobody in my field
thinks that we’ve seen it.”

It seems that Trenberth could easily respond to Landsea by producing a
single peer-reviewed study supporting his claims. While one such study
would not automatically overturn the many studies on hurricanes and
climate change (see RealClimate on this "http://www.realclimate.org/index.php?p=109#more-109"> general point),
it would provide a scientific basis for Trenberth’s statements, which
Landsea characterized as “far outside of current scientific
understanding.” For his part, Trenberth had earlier acknowledged that his
views on this subject are "http://www.ucar.edu/communications/staffnotes/0410/hurricane.html">controversial.
Absent at least one peer reviewed study to support Trenberth’s claims, it
would seem that he is, at best, a bit forward on his skis.

Why does peer review matter? As the folks at RealClimate have recently href = "http://www.realclimate.org/index.php?p=109#more-109">written
peer review is a “necessary but not sufficient condition” for the
production of good science. Consequently, “observers would thus be well
advised to be extremely skeptical of any claims in the media or elsewhere
of some new “bombshell” or “revolution” that has not yet been fully vetted
by the scientific community.” Presumably a good example of where such
skepticism would have been appropriate was in response to the "http://www.med.harvard.edu/chge/hurricanespress.html">news conference
held by Harvard Unveristy in October, 2004 – it was titled, “Experts to
warn global warming likely to continue spurring more outbreaks of intense
hurricane activity: Problem Tied to Rising Sea Temperatures From Trapped
Greenhouse Gases; Trend Portends More Storm Damage Costs for FL, AL, LA,
TX, NC and SC.” It was this news conference in which Trenberth and
colleagues asserted a link between global warming and the 2004 hurricane
season, but provided no peer-reviewed science to back up these claims.

So even if Trenberth’s claims about a linkage between global warming and
the hurricanes of 2004 are proven correct through future research, public
pronouncements on science, particularly in highly politicized contexts,
will always be much stronger if they are backed by peer-reviewed
scientific knowledge. And right now there does not appear to be a
peer-reviewed basis for Trenberth’s claims. If the climate science
community wants to assert the importance of "http://www.realclimate.org/">peer review when evaluating the claims
of those scientists opposed to action on climate change (and quite
rightfully so in my opinion) then it seems appropriate that scientists who
advocate action on climate change should be held to the same standard.

Political Context

A second reason Landsea gave for resigning from the IPCC was the response
of IPCC officials to his concerns, “The IPCC leadership saw nothing to be
concerned with in Dr. Trenberth’s unfounded pronouncements to the media,
despite his supposedly impartial important role that he must undertake as
a Lead Author on the upcoming AR4.” In particular, it seems odd that the
head of the IPCC would assert that Trenberth’s statements accurately
reflected the work of the third IPCC assessment (in 2001), since they
clearly do not (and also by Trenberth’s admission as well). Landsea wrote
much of the IPCC conclusions on hurricanes for the 2001 report, so he
ought to know.

But more troubling than a lack of knowledge of the substance of the
science of the IPCC reports is the political stance on climate taken by
the head of the IPCC. The Independent "http://news.independent.co.uk/world/environment/story.jsp?story=603752">reported
yesterday that the head of the IPCC recently called for deep and
dramatic emissions reductions to save humanity.

“Dr Rajendra Pachauri, the chairman of the official Intergovernmental
Panel on Climate Change (IPCC), told an international conference attended
by 114 governments in Mauritius this month that he personally believes
that the world has “already reached the level of dangerous concentrations
of carbon dioxide in the atmosphere” and called for immediate and “very
deep” cuts in the pollution if humanity is to “survive”.”

In taking such a political position in the highly charged context of
climate change, Dr. Pachauri has placed himself in a highly conflicted
position. If he were to have accepted Landsea’s complaint as valid, it
could be seen as admitting that an IPCC scientist is “overselling” the
science in support of a political agenda. This could harm the prospects
for advancing the political agenda that Dr. Pachauri advocates, so there
is a strong incentive for Pachauri to dismiss Landsea’s concerns. (We
have discussed politics and the IPCC on many occasions, "http://sciencepolicy.colorado.edu/prometheus/archives/climate_change/000246politics_and_the_ipc.html">here
and "http://sciencepolicy.colorado.edu/prometheus/archives/author_pielke_jr_r/index.html#000234">here.)
These dynamics seem consistent with the "http://sciencepolicy.colorado.edu/prometheus/archives/climate_change/000323a_third_way_on_clima.html">argument
made recently by Von Storch et al., “Judgments of solid scientific
findings are often not made with respect to their immanent quality but on
the basis of their alleged or real potential as a weapon by “skeptics” in
a struggle for dominance in public and policy discourse.”

So long as people within the IPCC leadership sees its role as political
advocate rather than honest broker, and acts accordingly, we should not be
surprised to see future controversies erupt in the IPCC. The solution is
not to retreat into the illusion that it can deal only with science, but
to openly confront the reality that its very existence is based on the
need to connect science with policy.

[Some disclosures: I know both Landsea and Trenberth quite well. I have
"http://sciencepolicy.colorado.edu/publications/index.html?newSearch=true&doSearch=Submit&selectedLists[]=1″>collaborated
with Landsea on a number of occasions, e.g., "http://sciencepolicy.colorado.edu/admin/publication_files/resource-76-1999.10.pdf">here.
I also have co-authored a "http://sciencepolicy.colorado.edu/homepages/roger_pielke//hp_roger/abstracts/hurricanes.html">book
on hurricanes (with my father, published by John Wiley, 1997), and on
pp. 186-188 you can see our views on hurricanes and climate change. And
you can find various other articles on hurricanes, climate change, etc.
that I have authored or co-authored "http://sciencepolicy.colorado.edu/publications/index.html?newSearch=true&doSearch=Submit&selectedLists[]=1">here.]