|THE POLITICALLY INCORRECT GUIDE TO GLOBAL WARMING
Washington, DC: Regnery, 2007
The result most frequently cited as a flaw in the theory that humankind contributes significantly to the current warming of Earth is the plot of reconstructed temperatures known as the "Hockey Stick Graph." Jerry Mahlman of NOAA so nicknamed this graph of global mean temperatures since the year 1000 CE because its relative flatness across most of that period, followed by a sharp upturn after 1900, to him resembled an actual hockey stick with its shaft laid horizontal and the blade sticking up.
It is probably the objection at the top of Deniers' lists. (See the sidebar at right for my comments on their other common claims.)
Horner devotes considerable space to attacking this graph, so it seems logical to examine his attack in greater detail.
When trying to raise scientific objections, global-warming deniers rely on a set of stock arguments. I'll list them here in condensed form:
Some of these are true. Some could be true. Some contradict each other. Most are false. I'll deal with them as briefly as I can.
Number 1 could be true. Some recent data suggest that both prehistorical and recent temperature swings correlate well with changes in solar output. But scientists monitoring the Sun say its output has not changed significantly for the past 30 years; if anything, it has declined slightly.
Numbers 2 and 3 are plausible; but if mainstream scientists do not correct for them, they deserve every slam the Deniers want to lay on them. (They do make those corrections.)
Number 4 is false. The jury is still out on number 5. Antarctica may be gaining ice in the center, but the West Antarctic Ice Sheet is shrinking. Greenland's icecap appears to be melting at increasing speed, but again the jury is still out on the net change in volume. And there is plenty of evidence for warming in the Arctic: shorter winters and disappearing ice at Eskimo villages, melting permafrost in Siberia, increasing runoff from glaciers in Greenland.
Numbers 6 and 9 are true. But 6 is irrelevant, and 9 does not preclude the spikes being started by a CO2 uptick too small to see in the proxy data. Also, as Horner admits on page 217, the time resolution is too poor for certainty.
Number 7 is true but irrelevant. Unless another factor forces a temperature change, the total amount of H2O in the atmosphere stays constant over time. Today, that other factor is CO2 concentration, which has risen by 40% from its preindustrial value. As for number 8, the fact that CO2 concentration was greater at times in the distant past than it is today works against the deniers; those were times of higher global temperatures.
Number 10 is false. Volcanoes do produce large quantities of CO2, but mankind produces 100 times as much in any given year. And volcanoes have been erupting throughout Earth's existence, at a decreasing rate; they cannot explain recent warming. They also produce massive quantities of dust, which cool the planet. This is the reason mean temperature dropped after Mt. Pinatubo exploded in 1991.
Methane is a potent greenhouse gas, 20 times as potent as CO2 in fact. However, CO2 lasts 20 times longer in the atmosphere. Cows are good methane producers. But cows and other ruminants have increased in proportion to the human population. So have rice paddies — which also emit copious quantities of methane. So number 11 is partly true, but that works against the Deniers.
Computer models are targets of opportunity for the Deniers. They are always being refined, so the Deniers can point to the discrepancy between last year's and this year's results to claim that the models are unreliable. While they are useful, and becoming more so as they account for more physical phenomena, they will never give the precise predictions the Deniers demand. So number 12 is true, but the Deniers' condemnation merely shows they do not understand how climate modelling works. (And, oddly, this distrust of climate models doesn't prevent them from publishing the modelling results that seem to disprove warming.)
Number 13 is a false conclusion. Weather is not climate, and the inability to consistently predict weather conditions for all points on Earth has nothing to do with the ability to predict large-scale, long-term climate changes. The Deniers' claim is exactly analogous to saying that because one cannot predict the size and timing of a specific wave hitting the beach at Makaha, it's impossible to predict good surfing conditions. Number 14 is false for the same reason. As mentioned, number 15 is wrong because the cooling of the 1980s and 1990s was due to dust produced by volcanic eruptions. And number 16 is just ludicrous. Taken together, they are merely misdirection.
Informally known as MBH98, the graph is the work of Mann, Bradley and Hughes, with climatologist Michael Mann being the principal author and as such bearing the brunt of criticism. That criticism began with former mining executive Stephen McIntyre and economist Ross McKitrick. They contended in a 2003 paper that the 20th-century upward spike in temperature was due to flawed methodology, and further that this methodology would produce a similar plot if operated on sets of random data. Mann, Bradley and Hughes published a followup paper in 2004, acknowledging and correcting a number of mistakes but saying their initial reconstruction was not substantially changed.
As a result of the controversy, the U.S. Congress tasked the National Research Council (NRC) of the United States National Academy of Sciences (NAS) with investigating the MBH98 reconstruction. The NRC convened a panel of twelve scientists from various disciplines. Their report, published in 2006, states that "global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries." It also observes that a number of independent analyses have confirmed the 20th-century portion of the MBH98 plot.
A second investigation was undertaken at the behest of Congressman Joe Barton (R-TX), then chairman of the House Science and Commerce Subcommittee, and an ardent skeptic of global warming — second only to Sen. James Inhofe in the Congress in his denunciation of the idea that human activities affect the climate. This investigation was conducted by a team of statisticians led by Edward Wegman, chair of the NAS Committee on Applied and Theoretical Statistics. This team analyzed the statistical methods used in MBH98. It also considered the funding sources Mann, Bradley and Hughes used for their work, the agreements governing that funding, their curricula vitae, and their professional relationships with other scientists. This is not your typical review of a scientific paper; indeed, in my opinion it's arguable that it more closely resembles a criminal investigation.1
It's also noteworthy that, while the Wegman Report does an in-depth analysis of the methods used in MBH98 and even provides an appendix on "The Mathematical Underpinnings of PCA" (Principal Component Analysis), its conclusions and recommendations do not address any mistakes made by Mann et. al. Rather, its conclusions and recommendations flow from the social-networking section of the report. Briefly stated, those conclusions are that Mann and his co-authors were too insular in their collaborations, too secretive about their data and source code, and that they should not have participated in writing the third IPCC assessment.
Horner is correct in saying that the NRC panel did not confirm the MBH98 conclusions that 1998 was the hottest year of the last millennium and that the decade of the 1990s was hotter than any other decade in the last 1,000 years. It merely found these conclusions "plausible." Now, "plausible" is an interesting word. In a political context ("plausible deniability"), it connotes a subterfuge: someone who actually knows about an event can probably get away with saying he doesn't know about it. However, it has a different connotation in science.2 It means that there is no scientific evidence against the conclusion.
In addition to misunderstanding this meaning of "plausible", Horner ignores the other conclusion of the NRC panel: namely that they agreed the last few decades of the 20th century are the warmest in the past 400 years. So on this point I have to give Horner a "close, but no cigar" — and we're not playing horseshoes here.
The truth is that the National Academy of Sciences report, Surface Temperature Reconstructions for the Last 2,000 Years, did not invalidate Mann's work. A pre-publication version, released on 22 June 2006, supports Mann's general assertion that the last decades of the Twentieth Century were warmer than any time since 1600.3
But you'd never learn this from reading the 13 pages Horner devotes to demolishing the Hockey Stick. He quotes selectively from the several followup studies, ending by saying that the National Academy of Sciences panel "inescapably indicted the Hockey Stick, the UN IPCC, and the Mann team itself." In addition, he laces his treatment with sarcastic comments like "This dodginess was sufficient that a full-blown controversy ensued, thanks only to M&M's persistence and willingness to subject themselves to the Kyoto establishment's nastiness." (page 126)
(Inasmuch as this took place within the U.S., which is not a signatory to Kyoto, and under the aegis of the Bush administration, it is hard to understand how the so-called "Kyoto establishment" got away with it. But, according to GW skeptics, they have a mysteriously potent ability to silence opposition.)
In short, Horner vastly overplays his hand. He quotes selectively from the several followup studies of the Hockey Stick, most of which were generally supportive. The bottom line is that these followups did find errors in MBH98, but concluded that they had only a small effect on the shape of the 20th-century temperature spike.
In addition to using most of the standard Denier arguments I list in the sidebar, Horner comes up with a few of his own. One is to conflate indoor and outdoor pollution:
Consider asthma cases, which are going up despite air pollutants going way, way down. One could draw many inferences from this set of data, but certainly not that air pollution is the culprit; indeed it is more reasonable (though certainly unscientific) to conclude even that declining pollution causes asthma. The regulator's instinctive response, however, is the one we now see occurring, which is to twist the data and squander billions more to expand regulatory fiefdoms.
– Page 44
Horner's problem here is the implicit assumption that air pollution is one single thing. I don't know what's causing the number of asthma cases to rise. I can, however, see that it might be due to indoor air pollution. Other known causes include pets, pollen, dust mites, bananas, and anything with latex: balls, rubber bands, pencil erasers, even rugs.4 This has nothing to do with the kind of air pollution he's referring to. That's outdoor pollution, and — unlike indoor pollution — is subject to federal regulation. It's the regulation he's fighting, as in this next ploy:
As luck or design has it, many environmental regimes, including Kyoto and its progeny, set technically impossible standards and goals, which protects against the risk that industry might actually meet the standards and free themselves from the regulatory reach of the bureaucrats.
– Page 45
Kyoto merely sets percentage reductions in overall CO2 emissions. If these reductions are technically impossible to achieve, what reason does Horner have to hope that industry might meet them on its own? None, of course. But he's on message, hewing to the party line: regulation bad, voluntary compliance good. Too bad the big emitters of CO2 — electric-power utilities — never do much in the way of voluntary compliance.5
Of course, Horner also brings up the matter of how costly prevention measures will be, claiming as usual that they will inevitably bankrupt the world.6 Finally, he trots out the old, tired argument that, while "alarmists" won't shut up about the way the government is preventing them from speaking out, it is actually the skeptics who are being suppressed. Here's what he says about James Hansen, his third whipping boy.
Hansen's shrill cries conjure a picture of Climate Cassandras having mouths stuffed with socks and wrapped with duct tape, crammed into the trunk of an old Buick en route to the Jersey Meadowlands. This is mostly incorrect. In truth, those whose voices have been run out of the debate through one form or another hail from the more sober, "look before you leap" school, and it is the cuddly environmentalists' global warming goons who lord over [sic] an unwritten speech code, which must be enforced in order to maintain the consensus.
– Page 95
The bottom line is that this is all time-tested political tactics. It's high time we thrust it aside and got on with doing something about the real problem of global climate change.