29 June 2010

Divining the Climate.

Figure 1. Dr. Kirsten Zickfeld, lead author of "Divinations."
PNAS is at it again. Fresh from its publication of a truly despicable article on the credentials of consensus climatologists vis-à-vis those of their skeptical colleagues, the official organ of The National Academy of Sciences is now offering up Expert judgments about transient climate response to alternative future trajectories of radiative forcing (June 28, 2010. doi: 10.1073/pnas.0908906107) — a production to which we will here refer as "Divinations" — short for "Divining the Climate: A Survey of Oracular Opinion."

The lead author, Kirsten Zickfeld (Figure 1), works for Environment Canada. Don't be fooled by the blond hair and the baby blues. Zickfeld's got smarts. Among other things, she studies mathematical models of "thermohaline circulation" (THC), which is the scientific name (because both temperature and salinity are involved) for currents such as the Gulf Stream that deliver tropical warmth to higher latitudes — see , for example, the The Two Mile Time Machine by Richard Alley for an accessible introduction and here for an update.

Cursory review of Zickfeld's publications yields the following conclusions:
  1. She's a serious scientist with considerable expertise in computers and modeling.

  2. In contrast to "all-but-the-kitchen-sink" simulations, Zickfeld's models are phenomenological — she calls them "reduced form models." They consist of a relatively small number (< 10), of differential equations, something this site views as a plus.

  3. Zickfeld's views her models as subroutines that can be plugged into larger schemes , so-called "integrated assessment models" (IAMs), that estimate the combined consequences of climatological processes and social policies .

  4. She's a true believer. Early on in her doctoral dissertation, we read the following:
    "Consequences of this [increased] rate of warming [since 1860], which is unprecedented at the human time-scale, are being observed in natural systems worldwide: glaciers shrink, sea-ice extent and thickness decrease, plants flower and birds breed earlier, and a number of plant and animal species extend their ranges northwards or upwards (for a review cf. Walther et al. 2003). ... [A]s long as anthropogenic emissions of greenhouse gases are not effectively reduced, climate will continue to change. The most recent IPCC report projects a global mean temperature increase by 1.4–5.8 ±C relative to 1990 at the end of this century (Houghton et al. 2001). ... . [T]hese changes will mainly be felt through local modifications in other climate variables including precipitation, soil moisture, storminess and annual or diurnal temperature ranges. Extreme occurrences in most of these variables, i.e., droughts, floods and storms are likely to increase in magnitude and frequency in a warmer world (Houghton et al. 2001)." [References in the original]
That was in 2003. Since then, Zickfeld has continued to beat the drum. Interestingly, but not surprising given her research interests, her truth criterion is the output of more complicated simulations — general circulation models (GCMs) and the like. To this end, she parameterizes her models (adjusts the constants) to maximize concordance with the more detailed schemes. There is nothing wrong with this, of course. But it is important to note that what she is doing in no way makes independent contact with the real world.

Divinations. As summarized by The Independent,
"The 14 scientists, all experts in ... climate research, were asked about the probability of a tipping point [irreversible change] being reached some time before 2200 if global warming continued on the course of the worst-case scenarios predicted by the Intergovernmental Panel on Climate Change (IPCC).

Nine ... said that the chances of a tipping point ... were greater than 90 per cent, with only one saying that the chances were less than 50:50. "
Figure 2. Searching on "recovery act" at nsf.gov yields 6350 hits.
And the Joke's On Whom? Climate Depot is having fun with this, characterizing it as a "laugh riot" — the joke being that the due dates of tipping points past have come and gone absent catastrophe. But really, the joke's on us. These days, scientific research costs big bucks. You think it's coincidental, that
  1. A good chunk of stimulus change (Figure 2) went to research projects, and

  2. Scientists overwhelmingly favor the growth of government?
If you do, I've got a deal for you on a bridge.

A Non-representative Sample. The authors of "Divinations" went to considerable lengths (here) to achieve a common focus among interviewees. This is commendable. But like Zickfeld's truth criterion (above), their definition of "experts" is arguably myopic. All fourteen are associated with the IPCC (Table I). Nine were "Lead Authors" of one or more chapters of AR3 or AR4 (Third and Fourth Assessment Reports); the remainder, "authors," save for one, who was a "Reviewer." Additionally, six of the interviewees (Allen, Collins, Flato, Forest, Knutti and Weaver) are slated to participate in AR5 as Coordinating Lead or Lead Authors, and a seventh (Karl), as a Review Editor.

With rare exceptions, IPCC authors subscribe to the Panel's contention that anthropogenic increases (that's us) in atmospheric carbon is the principal driver of climate warming. To suggest that the experts polled by Zickfeld et al. represent anything more than the views of the converted is therefore equivalent to suggesting that the views of Roman Catholics, for example, represent those of all monotheists, or for that matter, of all Christians. Or, as Tom Lehrer put it in his inimitable characterization of existence, "Life is like a sewer. What you get out of it depends on what you put into it!"

Table I. Experts Interviewed by Zickfeld et al.
NameInstitutionIPCC Role1
Allen, M.University of Oxford, Oxford, UKL2
Collins, M.Hadley Centre for Climate Prediction and Research, Exeter, UKL
Flato, G.Canadian Centre for Climate Modelling and Analysis, Victoria, BC, CanadaL
Forest, C.Massachusetts Institute of Technology, Cambridge, MA, USAA3
Karl, T.National Climatic Data Center, Asheville, NC, USAL
Knutti, R.National Center for Atmospheric Research, Boulder,CO, USAL
Rahmstorf, S.Potsdam Institute for Climate Impact Research,Potsdam, GermanyL
Schlesinger, M.University of Illinois, Urbana-Champaign, IL, USAL
Schneider, S.H.Stanford University, Palo Alto, CA, USAL
Senior, C.Hadley Centre for Climate Prediction and Research, Exeter, UKA
Stainforth, D.University of Oxford, Oxford, UKA
Stone, P.Massachusetts Institute of Technology, Cambridge, MA, USAR4
Weaver, A.J.University of Victoria, Victoria, BC, CanadaL
Wigley, T. National Center for Atmospheric Research, Boulder, CO, USAA

1. Contributions to Third and Fourth Assessment Reports - Working Group I (The Physical Science Basis). AR3 authors taken from http://www.ipcc.ch/ipccreports/tar/wg1/pdf/TAR-APPENDICES.PDF; AR 4 authors, from List of authors from Climate Change 2007: The Physical Science Basis and http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-annexes.pdf.
2. Lead author of one or more chapters. May also have been a co-author of additional chapters.
3. Co-author of one or more chapters.
4. Reviewer.

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