The U.S. Supreme Court is currently addressing a question of crucial importance to the U.S. economy: Is carbon dioxide, from fossil-fuel burning for energy production a “pollutant” that requires regulation? The petitioners, led by the Commonwealth of Massachusetts, demand regulation—interpreting the Clean Air Act differently than the respondent, the U.S. Environmental Protection Agency.

CO₂ is non-toxic and naturally present in the atmosphere—but also a greenhouse (GH) gas and therefore a potential cause of anthropogenic global warming (AGW).

The oral arguments and scientific amicus curiae briefs, pro and con, never addressed the basic issue: Is CO₂ the principal cause of current warming? The plaintiff’s amici included two Nobelists in chemistry—although this tactic may backfire when law clerks discover that the two have little demonstrated competence in disciplines relevant to the issue.

Absence of good science is evident in the arcane legal dispute about “standing.” To buttress his claim that anthropogenic global warming would injure Massachusetts, its assistant attorney general, James Milkey, invoked sea-level rise and loss of coastal lands, relying on a previous affidavit but suggesting the court not inquire into its merits. Indeed, his opponent, Deputy Solicitor General Gregory Garre, did not challenge him. Yet Mr. Milkey’s argument is seriously flawed.

All available data show that global sea levels have risen 400 feet since the peak of the most recent ice age 18,000 years ago. In recent millennia, the rate has been 18 cm (7 inches) per century—and there is good argument for this rate to continue until the next ice age. Tidal gauges around the world show no acceleration during the 20th century but only a steady rise—in spite of strong global warming before 1940.

How can this be? Evidently, the rise expected from melting glaciers and a warmer, expanding ocean is largely offset by loss of water from increased ocean evaporation and consequently more ice accumulation on the Antarctic continent. Hence, a short-lived warm period (lasting decades or even centuries) would not accelerate the ongoing sea-level rise of 18 cm per century. In other words, no harm to Massachusetts from anthropogenic global warming.

This idea, discussed in my book “Hot Talk, Cold Science,” seems to be penetrating to more climate scientists. For example, in 1990, the U.N.-Intergovernmental Panel on Climate Change (IPCC) estimated a “best-value” rise of 66 cm by the year 2100; in 1996, the U.N. panel reported 49 cm (with a range of 13-94 cm); in 2001, the U.N. panel gave 9-88 cm, while the 2007 report estimates a more reasonable range of 14-43 cm. By contrast, the affidavit Mr. Milkey relies on gives 58—and as much as 130 cm. Incidentally, James Hansen, an amicus for the petitioners, claims up to 600 cm by 2100. Evidently, Mr. Hansen—and Al Gore, who listens to him—are climate contrarians.

It is strange that both briefs ignore the only relevant evidence, published in May 2006 by the federal Climate Change Science Program (CCSP). Instead, the petitioners give undue weight to a hurriedly assembled National Academy report of June 2001. They are 90 percent sure that current warming is anthropogenic but don’t explain why. By contrast, the federal climate-change program report shows quite clearly that greenhouse models cannot explain the observed patterns of warming. (See esp. Fig. 5.4G at Temperature Trends in the Lower Atmosphere Steps for Understanding and Reconciling Differences.) This disparity leads to the inescapable conclusion that most of the warming is of non-greenhouse origin and therefore part of a natural climate cycle. In other words, models exaggerate the effects of CO₂, and even drastic efforts to control emissions are unlikely to affect global climate.

In fact, there is good reason to consider rising CO₂ levels a blessing—a thesis supported by published economic studies. Agronomists agree that, as the essential plant food, more CO₂ would enhance growth of crops and forests. Longer growing seasons and fewer frosts would benefit agriculture. Further, ocean warming inevitably increases evaporation and therefore precipitation, raising global supplies of fresh water. In addition, most warming would occur mainly at night in winter at high latitudes. Such warming may delay or even cancel the next ice age, expected to follow the present warm interglacial period.

Thus, the drive to regulate CO₂—and effectively control energy—appears to be based on ideology rather than science or any real concern about climate. Quoting Lenin: “The establishment of socialism in capitalist nations requires only targeting their supply of energy.”