Let us put aside initially any dispute about the science and evidence underlying the Paris COP-21 agreement to limit global greenhouse gas (GHG) emissions. Let us ask instead what the agreement ostensibly would achieve and what it would cost. If we apply the EPA climate model under a set of assumptions that strongly exaggerate the effectiveness of international emissions reductions, the Paris emissions cuts, if achieved by 2030 and maintained fully on an international basis through 2100, would reduce temperatures by that year by 0.17 of a degree.

The US contribution to that dubious achievement—the Obama climate action plan—would be 0.015 of a degree. Add another 0.01 of a degree if you believe that the Obama pseudo-agreement with China is meaningful. (It is not.)

Activists gather in Seattle, Washington for a climate science march | @RLTheis via Twenty20

This effort to reduce GHG emissions would impose costs of at least 1 percent of global GDP, or roughly $600 billion to $750 billion or more per year, inflicted disproportionately upon the world’s poor. Would those arguing that the US should preserve the Paris status quo please explain how it can be justified simply as a straightforward exercise in benefit-cost analysis?

And about those emissions promises: They are incorporated in “Intended Nationally Determined Contributions” (INDCs), which few supporters of the agreement seem actually to have examined. If, again, the goal is some unspecified reduction in global GHG emissions intended to moderate future temperature increases, then the Paris “strategy” is preposterous because the agreement does not and even in principle could not contain a mechanism to enforce the INDCs.

More important: Most of the INDCs promise GHG emissions cuts relative to a “business as usual” baseline, that is, relative to a future emissions path unconstrained by any policies at all. Since emissions are closely correlated with economic growth, a nation can “achieve” its promise by overestimating future economic growth slightly; when future growth proves lower than projected, the same will be true for GHG emissions. Thus will the “commitments” be met without any actual change in underlying emissions behavior at all. INDC fulfilled!

The Chinese commitment is particularly amusing. They promise that their GHG emissions will peak “around 2030.” How high will that peak be? No one knows. What will their emissions be after the peak? No one knows.

But, you say: Is there not a looming crisis? Well, no. It certainly is true that anthropogenic climate change is “real” in the sense that increasing atmospheric concentrations of GHG are having a detectable effect, important evidence of which is declining temperatures in the lower stratosphere.

But the surface and lower-atmosphere temperature records are not consistent with a looming crisis view: Surface temperatures have been roughly flat since 1998 (or perhaps since the early 2000s, as 1998 was a strong El Niño year). The satellite record is very similar. More generally, the record of temperature anomalies since the late 19th century does not correlate well with increasing GHG concentrations; how, for example, do the proponents of GHG reductions propose to explain the warming from 1910 through roughly 1940?

Almost all of the climate models have overestimated the recent temperature record. Global temperatures appear to be on a long-term upward trajectory, but the degree to which that trend is anthropogenic is far from clear, as the earth since roughly 1850 has continued to emerge from the Little Ice Age. The degree to which warming over, say, 1977–98 was anthropogenic is unsettled in the scientific literature, and the Intergovernmental Panel on Climate Change (IPCC) in its fifth assessment report (AR5) has reduced its estimated range of the effect in 2100 of a doubling of GHG concentrations from 2.0–4.5 to 1.5–4.5 degrees C.

Related reading: ExxonMobil Endorses the Paris Climate Agreement

More to the point, there is little evidence of severe or even “strong” climate effects attendant upon increasing GHG concentrations. Increases in sea levels have been roughly constant at about 3.3 mm per year since the early 1990s, despite increasing GHG concentrations. There appears to be a close correlation between sea levels and the El Niño/Southern Oscillation. The data presented in the IPCC AR5 for the 20th century are not consistent with the crisis view, and increases in sea levels appear to have been more or less constant for the past 8,000 years. For the more recent decades: As we do not know the extent to which rising temperatures are anthropogenic, the same follows for temperature effects on sea levels, as the latter can be due to ice melt and thermal expansion not anthropogenic in origin.

The data on the Arctic and Antarctic sea ice extents are mixed. Relative to the 1981–2010 average, the Arctic sea ice in recent years crudely is below or at the bottom of the 95 percent confidence interval surrounding that mean, although the newest data show that the 2017 Arctic sea ice is at the same level as in 2006. For the Antarctic, recent years are above or at the top of the confidence interval. There is some evidence that the eastern Antarctic ice sheet (about two-thirds of the continent) is gaining mass, while the western ice sheet and the peninsula are losing mass, with a net gain for the continent as a whole. There does not appear to be an accepted explanation for this phenomenon in the peer-reviewed literature.

There has been no trend in total US tornado activity since 1954, and a declining trend in strong-to-violent tornadoes. There has been no trend in the frequency of tropical cyclones since the early 1970s, no trend in the frequency of global hurricanes, and no trend in tropical accumulated cyclone energy (crudely, the destructiveness of cyclones and the cyclone season), but an increase in accumulated cyclone energy in 2016 to the level observed in 2006. The annual number of US wildfires shows no trend since 1985. The Palmer Drought Severity Index shows no trend since 1895. There is no correlation between US flooding and increasing GHG concentrations. IPCC in the AR5 is deeply dubious (Table 12.4) about the various severe effects often hypothesized (or asserted) as future impacts of increasing GHG concentrations.

Back to the agreement: Apart from the absence of an enforcement mechanism, notice as well that the agreement contains no actual target for global reductions in GHG emissions. Instead, the agreement simply lumps together the dubious INDCs submitted by the individual governments, which again may or may not represent actual future emissions reductions.

Related reading: An Agreement to Prop up the Climate Industry

Not to worry, say the proponents: The agreement puts in place a review process and recalibration of targets every five years. That means, obviously, that the initial promises might not be met; precisely how is it that the revisions five years from now, and five years after that, ad infinitum, will prove any more meaningful than the “landmark” promises just made?

What is blatantly obvious is that this “review” process has nothing to do with emissions reductions; it is instead a mechanism guaranteeing endless meetings and Conferences of the Parties and permanent employment for the climate industry into the indefinite future. As an aside, the monitoring is to be done in part with satellite surveillance; am I alone in noticing the Big Brother flavor of this exercise?

Is there a plausible reason that the US should remain a party to this charade? No, obviously, and President Trump has three central paths to an exit. The best would be submission of the agreement to the Senate for ratification and a certain defeat; this course would preserve the Senate in its role of treaty ratification, thus strengthening our constitutional institutions.

The second would be a withdrawal from the United Nations Framework Convention on Climate Change, of which the Paris agreement is a part, an action that would fulfill Mr. Trump’s commitment to “stop all payments of United States tax dollars to UN global warming programs,” including the green climate fund, the purpose of which is to put the less-developed world on welfare rather than the road toward free markets.

The least preferable course—but still vastly better than the Obama policy—would be a withdrawal from the Paris agreement itself in accordance with the four-year schedule specified in the treaty. This option is the least preferable because it would ratify the Obama claim that the Paris agreement is a mere executive action not requiring Senate ratification.

Related reading: Marching in Step on Climate Change?

Because the central ideological goal of the climate industry is an elimination of fossil fuels, the planet will never be saved and the goalposts will be moved continually. Accordingly, the Paris agreement is silly and destructive as a strategy to engender environmental improvement, but it works beautifully as a mechanism to transform the climate industry into a perpetual motion machine. Mr. Trump would be wise to reject it.