Sunday, September 23, 2007

The emperor's skimpy new bikini thong

Truth does less good in the world than the appearance of it does harm.

- La Rochefoucauld

While scientific criticism of the "global warming" craze has slowed down the bandwagon only with great difficulty, the reports of the Intergovernmental Panel on Climate Change (IPCC) have superficially responded to at least some of the theoretical and empirical failures of the earlier stages of the hysteria. But in the end, there's less to their response than meets the eye.

The first decade of "global warming" from the late 80s to the mid-90s and covering the first two IPCC reports, was dominated by theoretical dogmatism: carbon dioxide (CO2) and other infrared (IR)-active gases increase IR opacity in the lower atmosphere and therefore must lead to higher surface temperatures - as if the lower atmosphere were purely radiative and didn't also have convection, turbulence, and water phase transformations. From the late 90s until recently, the third IPCC report was dominated by another form of dogmatism, attempts to "prove" that in fact the Earth is experiencing warming from increases in IR-active gases, the most famous such attempt being the "hockey stick." Over all of its history, the craze has been about dogmatic preconceptions: that opacity-driven global warming will happen or must be happening or must have already happened. Bullying, arm-twisting, and media demonization of critics then follow.

Silently abandoning the "hockey stick." The fourth and most recent IPCC report (2007) is interesting insofar as it exhibits for the first time a limited but noticeable acceptance of criticisms that have "leaked" from the larger scientific report (which has always had a reasonable level of skepticism) into the "executive summary" for policymakers (which is all anyone outside of science ever looks at).

The most important is the partial retraction of the "hockey stick" as a basis for understanding the recent history of Earth's climate. The "hockey stick" was an egregious scientific blunder that the IPCC had to at least partially acknowledge. Failure to do so was fatal to the credibility of the previous report.

The "hockey stick" was a collection of scientific papers that attempted to reconstruct the Earth's climate history over the last 1000 years. It remains one of the most striking cases of "junk" or "pathological" science ever perpetrated. The resulting temperature history purported to show that Earth's temperature was roughly steady from 1000 to 1980 CE, at which point it supposedly suddenly started to increase at a dramatic rate. This "junk" result was the centerpiece of the third IPCC report and their claims that "global warming" wasn't just a conceptual possibility, but already happening in a big way.

Bludgeoned by the "hockey stick." Nothing about this result is consistent with what is known about the Earth's recent climate history. Like much else in the "global warming" craze, the "hockey stick" required a suspension of disbelief, a setting aside of normal scientific methods and everything that is well-established about the Earth's climate history. Usual scientific skepticism and standards were replaced by panic-driven authoritarianism. In a reasonable atmosphere, the "hockey stick" would have been taken apart and dismissed by normal scientific criticism as laughable. But not under the spell of a generation-long hysteria and backed by the apparent authority of the IPCC. The "hockey stick" contradicts the well-established fact that the Earth experienced a long period of exceptional warmth from about 800 to about 1300 CE, the Medieval Warm Period, followed by the Little Ice Age from about 1300 to about 1650 CE.* The Earth has been warming, in fits and starts, since then and probably experienced its most recent period of peak warmth in the 1920s and 1930s.

The "hockey stick" created massive confusion inside and outside the scientific world. It made everyone think they were living inside of those (very inadequate) climate computer models. That, I suppose, was the point: an apparent, if ultimately illusory, empirical validation of these models.

Taking apart the "hockey stick." To follow the full sordid tale, take a look at ClimateAudit. A detailed technical examination of what's wrong with the "hockey stick" can be found here (PDF).

1. The "hockey stick" is physically wrong: Temperature is not enough to characterize static climate. You need humidity and the water phase state to independently account for the role of water. At least two local variables are needed and really more.

Plus there's the mistake of a "global average temperature" standing in for the Earth's temperature distribution (a field in space).

2. The "hockey stick" was methodologically wrong. Using biological and geological proxies - such as coral reefs, tree rings, and relic seed - to infer past temperature trends is fine in and of itself. But these proxies were then combined in a thoroughly botched way that led one proxy (California pine cones) to far outweigh the rest, producing bizarre results.

The pine cones themselves are far more sensitive to water than to temperature in any case.

3. The "hockey stick" was ethically wrong: The groups responsible for it refused for considerable time to release their data sets and methodology. When others attempted to reproduce it by "reverse engineering," they got wrong answers, but quickly uncovered the methodological and conceptual errors, which the "hockey stick" people refused to acknowledge.

4. The "hockey stick" is empirically wrong. The final result doesn't match what is otherwise known about climate history. It doesn't jibe with actual surface thermometer or satellite radiative temperatures. It implies no Medieval Warm Period or Little Ice Age following, although these are well-established.

I'm left with the same question I had nearly a decade ago: how did anyone with scientific training get taken in by this?

The final blow. Recently, NASA, one of the main American contributors to the junk science of "global warming," released a revision to their 20th century temperature reconstructions that silently retracted the "hockey stick" for the whole of the 20th century and the first years of the 21st, implicitly acknowledging that the warming period from roughly 1910 to 1940 was very probably the hottest period of the last 150 years. Certainly anyone alive then will remember the Dust Bowl and those exceptionally warm years of the two World Wars - followed by the harsh winters and surge of hurricanes of the 1940s, 1950s, and 1960s. Mark Steyn wittily summed up the "1998 - The Non-Warmest Year of the 20th Century" situation here (this is a cached version, since the original has apparently been taken down).

But that's not the end of the story. Built into the post-1980 part of the "hockey stick" was the bizarre habit of using extrapolated temperatures for the last 25 years, instead of the actual annual temperatures. That's how the "hockey stick" managed to miss one of the most important developments of the last decade.

Real century-and-a-half climate trends. ClimateAudit and other sites discuss sounder and more honest reconstructions of recent climate history. By their nature, such reconstructions are necessarily fragmentary and approximate. But clear trends emerge from many spots on the globe and from diverse proxies. Modern surface temperature trends from the 1850s on exhibit five distinct periods.

I. 1860-1910: No strong trend.

II. 1910-1940: Strong warming. Probably the warmest and driest period in the last 150 years. Familiar to students of military history (the World Wars) and the Dust Bowl. Fewer hurricanes.

III. 1940-1976: Strong cooling. Period of more blizzards and ice storms. Historically familiar: post-World War II cold winters; more hurricanes.

IV. 1977-1994: Moderate warming. Fewer blizzards, hotter and drier summers. Fewer hurricanes.

V. 1995-present: Apparent neutral-to-moderate cooling trend. Colder and snowier winters, wetter years over all. More hurricanes. See here.

Of course, the measured surface temperature records are biased, with northern hemisphere land observations overrepresented, and include a significant and difficult-to-isolate "urban heat island" effect. But interestingly, the satellite measurements (inferring temperatures from measured radiative fluxes) show no strong trend in the last 30 years.

Still wrong on the post-1980 climate. The good word from NASA apparently didn't get out in time: the IPCC still accepts the "hockey stick" results for the post-1980 climate, claiming an accelerating warming trend, based on temperature and sea level trends that are actually centuries-old and have little or nothing to do with human activity.

This impression was reinforced by the misuse of time-series extrapolation techniques that continue to pollute people's notions of recent Earth temperatures. Instead of using actual measured, year-to-year surface and satellite temperatures, extrapolations from the most recent warming period (late 70s to mid 90s) to subsequent years are trumpeted as "evidence" that the Earth is dramatically warming. Contraindicating surface and satellite temperatures have now been "officially corrected" in the 2007 IPCC report using the same misguided methods.

All of this underscores how bad theory continues to trump fact in the "global warming" craze. They constitute striking cases of what statisticians call "confirmation bias" - believing what you want to believe, accepting only confirming evidence and ignoring or twisting counterevidence - instead of cross-checking to see if you're wrong. Much of climate and geoscience is now polluted with circular reasoning of this type when it comes to recent climate history.

As with any craze, fact and preconception continue to be confused in striking ways, abetted by thermodynamic claptrap. The most striking example is the attempt to enlist the recent upsurge in north Atlantic hurricane activity as another support for "global warming." The computer climate models cannot resolve structures smaller than a few 100 km in size - not even something as big as a hurricane. We'll learn why in a short while.
* Centennial-to-millennial climate "waves" of this type are driven, in part or wholly, by variations in the solar magnetic cycle, a topic we'll learn about later.

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