24 May 2010

And if the Climate Cools?

Skeptic Conference. The Heartland Institute is a conservative think tank, often portrayed as being in the pocket of big oil and tobacco. Last week, Heartland put on its "4th International Conference on Climate Change" in Chicago. Leading skeptic climatologists participated, along with like-minded members of the political class.

Superficially, the conference resembled a meeting of one of the smaller scientific societies. But, for those readers who have never attended one, it's important to point out that this was not a scientific meeting in the usual sense. To be sure, there were plenary sessions with keynote speakers, concurrent sessions, sessions on science, economics and public policy and so forth. And many of the participants were Ph. D.s with expertise in relevant disciplines. But there were no contributed sessions at which the general membership of scientific societies get their 15 minutes in the spotlight. So far as I can tell, you didn't get to speak at the Heartland conference unless invited, and you didn't get invited unless you stood in opposition to conventional wisdom. "Luke warmists," such as the Pielkes (father and son), were not in attendance, though, for all I know, they may well have simply declined invitations. In short, the conference was more like a workshop at which invited participants linked by commonalities of interest, methodology, etc., exchange findings and ideas. Nothing wrong with that — workshops can be extraordinarily useful — often far more so than the sprawling affairs put on by outfits such as the American Association for the Advancement of Science. But workshops, unless specifically conceived to address controversy, do not as a rule represent wide ranges of opinion. Nor did the conference in Chicago.

Figure 1. Alternating periods of warm and cool temperatures during the past 5000 years. From Easterbrook (2010).

Figure 2. Projected global cooling during the next 20-30 years. Note, in addition to the three scenarios (blue), IPCC predictions (red) that forecast continued warming. From Easterbrook (2010).
The Looming Threat of Global Cooling. One presentation, the subject of today's post, has attracted considerable attention. It was delivered by Don Easterbrook, Emeritus Professor of Geology at the University of Washington, who offered the following three-fold take:
  1. Global temperatures are always in flux, with alternating periods of warmer and cooler temperatures coming every 20-30 years (Figure 1).

  2. The alternations correlate with the Pacific Decadal Oscillation (PDO) and with solar activity (sunspot cycle) — see Livingston and Penn (2009) for discussion of recent changes in solar activity, including the possibility that sunspots may disappear by 2015, and here for review of renewed interest in the sun as the ultimate driver of terrestrial climate.

  3. The next thirty years is likely to witness significant cooling. Just how much cooling, Easterbrook didn't predict, but instead gave three possible scenarios (Figure 2). Not shown is really severe cooling comparable to what the world experienced during the so-called "Maunder Minimum" (1600-1650), at which time sunspots virtually disappeared. The Maunder corresponds to one of several colder episodes within the Little Ice Age (LIA), itself a period of reduced temperatures that may have begun as early as 1300 and is generally agreed to concluded by the end of the 19th century.
Predictions of temporary cooling are not new. Two years ago, Keenlyside et al. (2008) forecast several decades of regional cooling in the North Atlantic due to reductions in meridional overturning circulation (MOC). (The term MOC refers to ocean currents, such as the Gulf Stream, that deliver the warmth of tropical waters to higher latitudes.) What makes Easterbrook's presentation noteworthy is the assertion that the coming chill is part and parcel of the repetitive ups and downs of a climate system that is never at equilibrium. His views are thus of a piece with those of Syun-Ichi Akasofu, founding director of the International Arctic Research Center of the University of Alaska Fairbanks, who has long championed the idea that contemporary climate change is best viewed as the superposition of multi-decadal oscillations ("natural" variability) on long-term warming, the latter being reflective of the earth's recent emergence from the LIA.

A Relevant Anecdote. I am reminded of a story related to me by an acquaintance who works at a university that is up to its eyeballs in environmental nonsense generally, Anthropogenic Global Warming (AGW) in particular:
"We were interviewing prospective graduate students. So in walks this girl who, after the usual pleasantries, announced that she wanted to study the consequences of global warming to, I think it was tree physiology. 'And what will you do,' I asked, 'if the climate cools?' She looked at me disbelieving. So I pulled a copy of Richard Alley's book (Allee, 2001) off the shelf and showed her a couple of figures indicating enormous fluctuations (Figure 3) in temperatures past that, whatever their cause, had nothing to do with human activity. She looked at them, muttered something about not knowing much about paleoclimatology and terminated the interview. That was back around 2000, and before the recent stabilization of global temperatures. I sometimes wonder what she thinks of it."
Figure 3. Snowfall accumulation and temperature estimated from analysis of Greenland ice cores over the past 17,000 years. Note the extent to which temperature variations associated with the LIA and MWP (left) are dwarfed by earlier fluctuations. From Alley, R. (2001).

Figure 4. Carbon isotope ratios in the bones of Greenland Vikings and estimated fractions of their diets obtained from the sea. As the climate cooled, the Vikings became increasingly dependent on marine sources of sustenance. From Arneborg et al. (1999).
What-Iffers. The prospective graduate student aspired to join the ranks of those I have elsewhere called "what-iffers," scientists who have built their careers by piggy-backing on the global warming hysteria. These people do "what if" studies: what are the consequences to X if the climate warms, where X is a species, a renewable resource, an ecological process, etc.

Like the dinosaurs in Jurassic Park, scientists move in herds: Jump on the bandwagon; don't make waves; follow the gold. Of course, there are risks. Hitching your wagon to a star doesn't work if the star turns out to be a meteor. That's a risk to yourself. The risk to science is that the more folks on the wagon, the less ithe likelihood of someone's noticing that the wheels are coming off. There's also a risk to society. With both the scientists and the funding agencies riding the AGW wagon, the social and economic costs of carbon abatement tend to be neglected. Flogging the horses — this is a Green wagon — racing full tilt to the precipice just round the bend are the ideologues, the politicians and the NGO apparatchiks.

Intriguingly, Michael Mann, he of the hockey stick (Mann et al., 1998) is now a "what-iffer," having recently been awarded (along with four others) $1.8 million to study the effects of global warming on malaria (search on "vector-borne diseases). Of the total, his employer, Penn State University, will skim roughly $600K off the top in overhead — not chump change in an age of decreased funding for public universities. And one wonders why Penn States's investigation of Mann's role in Climategate amounted to a white wash.

What Vikings Ate. Paleoclimatologists study ice cores, tree-rings and other proxy variables believed to correlate with temperatures past. In Greenland, there ids additional evidence (Arneborg, J., et al., 1999) for cooling as the Medieval Warm Period (MWP) transitioned to the LIA. This evidence comes from changing carbon isotope ratios in Viking bones exhumed from a graveyard (Figure 4). From these data one concludes that, with the passage of time, the Greenland Norse obtained more and more of their food from the sea and less and less from terrestrial sources, i.e., milk and meat from their livestock. This, of course, is what one would expect if the climate cooled.1

When asked about the Greenland Vikings, AGW proponents will tell you that the LIA was confined to the North Atlantic basin, possibly caused by a shut down of the Gulf Stream, i.e., reduced MOC. Likewise, they will tell you that the MWP, if it existed at all, was also a local phenomenon. For a good review of evidence to the contrary, that the MWP was a global phenomenon, albeit with regional variations, go here.

"Natural" climatic variability, by which I mean variation independent of human activity, doesn't invalidate the anthropogenic hypothesis. Depending on one's view, it could either have exacerbated or partially masked late twentieth century warming. At the same time, evidence for past climates as warm those we are presently experiencing undercuts the claim that human activity is responsible for unprecedented warmth. This explains the Climategate correspondents' furious reaction to publication of the paper by Soon and Baliunas (2003) and their characterization of the MWP as "putative."

If the Climate Cools. Easterbook maintains that the socio-economic consequences of global cooling are likely to be far worse than the those of the warming imagined by AGW activists. He gives four reasons:
  1. Extreme cold kills more efficiently than extreme heat.

  2. Colder temperatures will reduce food production.

  3. Colder temperatures will increase per capita demand for energy.

  4. The effects of reduced food production and increased energy demand will be exacerbated by the world's burgeoning population.
To this it should be added that warmist policy prescriptions for reducing atmospheric carbon, reduced energy production overall and increased dependence on biofuels especially, will limit mankind's ability to respond to problems consequent to global cooling. Nor will the resulting disasters occur at some distant time in the future. If Easterbrook is correct, the cooling is already on us, and this past year's winter, but a foretaste of what is to come.


1. Readers more interested in the Greenland Norse than in the climate may enjoy John Harris' The Lost Viking. Harris' believes that the Greenland settlers, having effectively been enslaved by the Church, decamped for the New World seeking freedom eventually wound up in British Columbia. This is unconventional. Nor is the present author competent to evaluate its plausibility.


Allee, R. 2001. The Two Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future . Princeton Univ. Press. Princeton, N.J.

Arneborg, J., et al. 1999. Change of diet of the Greenland Vikings determined from stable carbon isotope analysis and 14C dating of their bones. Radiocarbon. 41: 157-168.

Keenlyside, N. S., Latif, M., J. Jungclaus, J., Kornblueh, L. and E. Roeckner. 2008. Advancing decadal-scale climate prediction in the North Atlantic sector. Nature. 453: 84-88.

Mann, M.E., Bradley, R.S. and M. K. Hughes. 1998. Global-Scale Temperature Patterns and Climate Forcing Over the Past Six Centuries. Nature. 392: 779-787.

Penn, M. and W. Livingston. 2009. Are sunspots different during this solar minimum? Eos. 90: 257-264. See also here.

Soon, W. and and S. Baliunas. 2003. Proxy climatic and environmental changes of the past 1000 years. Clim. Res. 23: 89–110.

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