Leonardo DiCaprio — a newly designated U.N. Messenger of Peace — is hot. Former Vice President Al Gore is hot. President Obama is hot, as is his entire administration. The World Meteorological Organization is hot. The climate industry is hot. The believers in the eternal free lunch are hot, in amusing juxtaposition with the recent Australian, German and British shock at the discovery that climate policies are hugely expensive after all. The international bureaucrats are hot. Paul Krugman is hot. The consultants are hot.
But back to the hotties: They will congregate at Turtle Bay on Sept. 23 for the United Nations Climate Summit 2014, freshly manicured as they emerge from their private jets and limousines spouting the usual propaganda about "carbon pollution." (Carbon dioxide is not "carbon," and to call it "pollution" answers the central question before it is asked.) And the grills already are glowing bright red at the tailgating parties, because they have been informed by the U.N. in a "Catalyzing Action" discussion that:
Climate change is not a far-off problem. It is happening now and is having very real consequences on people's lives. Climate change is disrupting national economies, costing us dearly today and even more tomorrow.
As discussed below, any ongoing economic "disruptions" are not being caused by the weather; governments are a far more likely culprit. In any event: The summit begins with the assertion (or assumption) that warming is happening now and over time will get worse in terms of its costs. (Note that the latter assertion is ambiguous in that it does not distinguish between climate phenomena and any attendant effects that might be magnified by, say, an increase in coastal construction, to the extent that we accept the casual assertions made by some about global warming and flooding.)
And so the scientific basis for the assertion that "climate change. ... [i]s happening now" is entirely obscure. Of equal interest is the recent trend in the IPCC predictions of temperature increases per decade relative to the 1980-1999 and 1986-2005 periods, respectively. In the fourth assessment report (The Physical Science Basis, 2007, Table SPM.3), the range of predicted temperature increases is 0.11 to 0.64 degrees Celsius per decade; in the fifth assessment report (2013, p. 11-52), the range is 0.10 to 0.23 degrees C per decade.
Accordingly, the recent IPCC projections are falling, an observation that when combined with the global temperature pause may explain why there seems to be a trend in recent news reports emphasizing increases in atmospheric greenhouse gas concentrations (summarized above) rather than the purported effects in terms of extreme weather events. It is the effects that are not known; the increases in greenhouse gas concentrations are not disputed by anyone.
With respect to the effects of greenhouse gas concentrations, the evidence suggests that increases in extreme weather events have not happened despite the predictions of many. The past two years have set a record for the fewest tornadoes ever in a similar period, and there has been no trend in the frequency of strong (F3 to F5) tornadoes in the United States since 1950. The number of wildfires is in a long-term decline. It has been eight years since a Category 3 or higher hurricane landed on a U.S. coast; that long a period devoid of an intense hurricane landfall has not been observed since 1900. The 2013 Atlantic hurricane season was the least active in 40 years, with zero major hurricanes. There has been no trend in the frequency or intensity of tropical cyclones, and global cyclone activity and energy are near their lowest levels since reliable measurements began by satellite in the 1970s.
There is no long-term trend in sea-level increases correlated with atmospheric greenhouse gas concentrations. The record of changes in the size of the Arctic ice cover is far more ambiguous than often asserted, because the satellite measurements began at the outset of the warming period from roughly the late 1970s through the mid- to late 1990s; and the Arctic sea ice extent now does not differ from the 1981-2010 average as a matter of statistical significance. The Antarctic sea ice appears to be at a record. The Palmer Drought Severity Index shows no trend since 1895. Flooding in the United States over the last century has not been correlated with increases in GHG concentrations.
Moreover, the fifth assessment report (2013, p. 12-78, Table 12.4) discusses a different set of potential adverse effects that really are "extreme": a collapse of the Atlantic Meridional Overturning Circulation ("very unlikely" with "high confidence"); ice sheet collapse ("exceptionally unlikely" with "high confidence"); permafrost carbon release ("possible" with "low confidence"); clathrate methane release ("very unlikely" with "high confidence"); tropical forests dieback ("low confidence" in such projections); boreal forests dieback ("low confidence" in such projections); disappearance of summer Arctic sea ice ("likely" with "medium confidence"); long-term droughts ("low confidence" in such projections); and a collapse in monsoonal circulations ("low confidence" in such projections).
So: The worst of these potential extreme events is the possible disappearance of the summer Arctic ice, an outcome that IPCC now views only as "likely" with "medium confidence," only under an extreme scenario called "RCP8.5," and one inconsistent with the recent satellite evidence. "Extreme" may be in the eye of the beholder; but IPCC displays little confidence in the inevitability of such events.
It would be interesting and fun — but somewhat in the realm of metaphysics — to ask why the U.N. Climate Summit 2014 is denying the science as reported by IPCC. The more straightforward question is: What would the effect of an enforced global emissions agreement be, using an IPCC climate model? One such model is the MAGICC/SCENGEN climate simulator developed at the National Center for Atmospheric Research. An obvious scenario, however unlikely, is adoption of policies similar to those of the Obama administration by the rest of the world, including China and India.
Let us adopt the IPCC temperature sensitivity assumption: a 3.0 degree warming by 2100 attendant upon a doubling of greenhouse gas concentrations from pre-industrial levels. If the entire world were to reduce greenhouse gas emissions by 17 percent below 2005 levels by 2020 — the Obama policy — the predicted temperature reduction would be about 0.04 degrees C by 2050, and 0.15 degrees C by 2100. (Note that the standard deviation of the surface temperature record is about 0.11 degrees C.) What costs would be justified in pursuit of such outcomes?
Accordingly, the U.N. is denying the prediction trends of the IPCC climate models, denying the IPCC discussions of the evidence, and denying the IPCC modeling evaluation of the Obama policies if adopted by the entire world. Why?
Zycher is the John G. Searle scholar at the American Enterprise Institute.