November 15, 2004

Predictable Distortion

Filed under: Arctic, Climate History

The Arctic Climate Impact Assessment group releases a hyperbolic report predicting dire consequences for the Great White North. But when it comes to accuracy, they’re skating on thin ice.

Fast on the heels of our last World Climate Report on the omission of key facts in a story on the decline of Antarctic Krill comes another high-latitude horror. It’s called “Impacts of a Warming Arctic,” a report from the Arctic Climate Impact Assessment (ACIA) group. And it is a quintessential example of what World Climate Report Editor Patrick Michaels writes about in his new book, Meltdown: The Predictable Distortion of Global Warming by Scientists, Politicians, and the Media.

Indeed, the ACIA report is a predictable document, with the slick format of the infamous U.S. National Assessment of global warming—a report that had to be pulled from public distribution as a federal document because it failed to meet legal standards for scientific accuracy.

ACIA resembles the National Assessment in other ways, too. It selectively presents data and projects a future change that in aggregate is much larger than what is likely. Further, it neglects the fact that we already know, to a surprisingly small range of error, what that warming will be, at least in coming decades.

Start off with ACIA’s climate history, reproduced as our Figure 1. We’ve never seen it before. There’s no scientific citation for it. It appears warmer than any other published record.

ACIA Temperatures

Figure 1. ACIA temperature history of the Arctic (60ºN to 90ºN), taken directly from the ACIA report.

Accurately assessing regional temperatures is a complicated process, especially in the Arctic. So you’d think the producers of a tome on Arctic climate would naturally review the refereed scientific literature, see who had published the primary papers on Arctic climate history, and feature their work prominently.

But none of these big shots were included. Here’s who and what got missed.

Igor Polyakov. Might not his 2002 paper titled, “Trends and Variations in Arctic Climate Systems” merit inclusion? He studied land and a small amount of ocean data from 62.5° northward, all the way back to 1870 (ACIA starts in 1900, and uses land-only data from 60°North). His temperature history is reproduced as our Figure 2.

Polyakov Temperatures

Figure 2. Polyakov temperature history of the Arctic (62.5ºN to 90ºN) (Source: Polyakov et al., 2003).

It’s obvious that, over the region as a whole, current temperatures are similar to those measured 70 years ago. And during some of the years back in the 1930s, things were really hot. “…Northward of 62°5 North, the 1938 maximum of annual arctic surface air temperature anomaly reached 1.69°C, compared with the 2000 maximum of 1.49°C”, Polyakov writes.

Further:

“Two distinct warming periods from 1920 to 1945, and from 1975 to the present, are clearly evident…compared with the global and hemispheric temperature rise, the high-latitude temperature increase was stronger in the late 1930s to the early 1940s than in recent decades.”

No mention of this in ACIA. That’s what we mean by “predictable distortion.”

Jonathan Kahl. In 1993, University of Wisconsin climatologist Jonathan Kahl examined (then) recently declassified records over the Arctic Ocean, taken by drops from Fail-Safing B-52s and poor sorry Soviets down on the ice. In his Nature paper, “Absence of evidence for greenhouse warming over the Arctic Ocean in the past 40 years,” he found a net decline in Arctic temperature. His history only runs from 1958 through 1986.

Unlike Polyakov’s record, Kahl’s is only over the Arctic Ocean. But there’s none of this in the ACIA record. It’s obvious that inclusion of more ocean data would have resulted in much less warming.

Roman Pryzbylak. Here’s another expert who actually published in the scientific literature on Arctic Temperatures, yet was ignored by ACIA. He has several histories from different latitude bands. One, from the far North (poleward of 70°N), shows a substantial cooling from 1940 through 1970. This period also cools in ACIA, but the rate is 30 percent less.

Aside from the lack of inclusion of the Arctic Ocean data from sources such as Kahl, what accounts for ACIA’s warm bias? Well, it depends upon what the word “Arctic” means when monitoring temperature. For ACIA, it’s land-only stations north of 60°N. For Polyakov, the Arctic begins at 62.5°N. It turns out that the band between those two latitudes has some of the most pronounced warming on the planet. (The Arctic Circle is 66.5°).

We’ve probably flogged this dead equine enough. Let’s go from the past to the future.

ACIA runs two different scenarios for atmospheric carbon dioxide through five different climate models. They correctly concentrate on the one with lower emissions—which is a good idea, given that observed emissions in recent decades are much more on that track than they are on their outlandishly high alternative scenario.

Guess what? As all readers of these pages know, the five models give five different warming trends. (This allows the press to conclude that “Even with the modest emissions scenario, scientists say temperatures could rise as much as 5.5°C in the next 100 years!”).

No one has a clue what will happen to our technology in 100 years. The past 60 years saw the development of the atomic bomb, nuclear power for energy, the computer, the hybrid automobile, and Viagra. Obviously the next 100 are going to produce a lot of technological surprises, too! But the only prediction we can make with confidence is that market forces (not greenie scaremongers) are going to increase energy efficiency in a way that may indeed displace the use of some fossil fuels. As an example, there’s a point where petroleum can become so expensive—due to decreasing supply—that there is tremendous pressure to find an alternative fuel for personal transportation.

Back to the models, though. Figure 3 is taken from the ACIA report and shows projected trends in Arctic and global temperatures from these computer models. Note that they are all straight lines! They just differ in their amount of warming.

Projected Temperatures

Figure 3. Projected future temperatures for the Arctic, according to the ACIA report. The colored lines represent the projections made from five climate models, while the black arrows depict an extension of the temperature trend observed for the past several decades.

Now, you don’t have to be a genius to figure out which of these models is likely to be right. Note to the future forecasters at ACIA: Look out the window!

Because, indeed, if, as everyone (including us) believes, that the preferential warming in high-latitude winter is a “greenhouse” signal, then dreaded greenhouse warming is indeed upon us. And, in the Arctic, as it is for the Earth in general, the warming trend since the mid-1970s has indeed taken the functional form of a straight line. So we can adjudicate between the models and reality–which we did by dressing up Figure 3 (black arrows).

Now, the only way this is wrong is for the functional form of all of these models (straight-line warming) to be wrong. If that’s the case, we scientists have returned precious little of your global warming research budget of about $20 billion over the years. Thanks for the $$$!

Indeed, the answer to the question, “How much will the Arctic warm in the next 100 years?” is already pretty well known, and it works out to 3.2°C, which is approximately the warming produced by the coolest climate model. (the same analysis using global temperatures works out to a similarly cool result—a rise of only1.6°C by the year 2100).

But that would have spoiled the fun, wouldn’t it? Because that low Arctic figure is about what the average Arctic temperature was for the three-millennia period from about 4,000 to 7,000 years ago. And the Inuit thrived on polar bears and seals, no doubt in a Rousseauian paradise of long life, health, and beautiful people, before the terrible disturbance by the rest of us.

Note to our readers: This is just the first diatribe on ACIA. There are so many fish crammed into this tiny barrel that it seems unsportsmanlike to use live rounds.

References:

Arctic Climate Assessment (ACIA), 2004. Impacts of a warming Arctic. Cambridge University Press, Cambridge, UK, pp139.

Kahl, J.D., et al., 1993. Absence of evidence for greenhouse warming over the Arctic Ocean in the past 40 years. Nature, 361, 335-337.

Polyakov, I.V., et al., 2003. Variability and Trends of Air Temperature and Pressure in the Maritime Arctic, 1875-2000. Journal of Climate, 16, 2067-2077.

Pryzbylak, R., 2000. Temporal and spatial variation of surface air temperature over the period of instrumental observations in the Arctic. International Journal of Climatology, 20, 587-614.




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