Theodore Kupfer’s attack on my remarks last week in these pages about President Trump’s withdrawal from the Paris climate accord cannot be allowed to pass without comment.

Mr. Kupfer cites Svante Arrhenius as the originator of the theory of the greenhouse-gas generation of global warming in the 1890s. Arrhenius predicted in an 1896 paper that doubling carbon-dioxide emissions would increase temperatures by six centigrade degrees but ten years later reduced that estimate by two-thirds, and even that has proved to be unfounded.

Arrhenius’s perspective was of someone trying to promote milder temperatures in Sweden, by increasing greenhouse gases, and concluded that it would take at least 3,000 years for any such hoped-for warming to come to pass. It is doubly bizarre for Mr. Kupfer to cite him as a source in that Arrhenius, one of the founders of the Nobel Prize, which he quickly received for chemistry, is chiefly known as a leader of the Swedish Society for Racial Hygiene.

Arrhenius lobbied the government of Sweden successfully to create the Swedish Institute for Racial Biology in 1922, which trained and inspired a number of the leading champions of Nazi racial ideas in the Thirties. He said and did nothing that contradicts anything I wrote here last week about climate and carbon dioxide.

Mr. Kupfer accuses me of over-frequent recourse to the adjective “unestablished,” but that is an unexceptionable word in challenging what is claimed to be, in Al Gore’s infamously inaccurate phrase, “settled science.” Mr. Kupfer advocates moderation in these matters, calls for caution, and assimilates me to the extreme advocates of climate disaster, such as Naomi Klein (a Marxist who knows nothing about science but is rubbing her hands in contemplation of the collapse of capitalism).

Yet Mr. Kupfer effectively follows in the footsteps of the leaders of the climate-alarm movement who claim everything is proved and beyond debate and that we have either to dismantle our economies, live under thatch, bicycle between points, abolish carbon use and carbon dioxide itself other than in photosynthesis (to ensure we have oxygen to breathe), or await the consummation of the suicide of earthly life.

Mr. Kupfer’s only substantive complaint about what I wrote is that I understated the rise in global temperature in the past two years. I thought it sufficient to acknowledge that they were “relatively warm years.” They were El Niño years of an artificial spike in warming, as he must know, the first such years since 1998. I accept that they seem to have been the warmest years ever, but these statistics are subject to subsequent adjustment and are, in any case, aberrant.

My basic point of the gradual and inconclusive nature of the data to date — my debunking of the hysterical claims of the climate alarmists — stands. The world temperature declined by a fifth of a centigrade degree between 1880 and 1910, and by a tenth of a degree between 1940 and 1970. There was minimal human emission of carbon dioxide in the earlier period and a 40% increase in the second, and yet the results are similar.

There has been no significant recorded global warming at the mid-troposphere, by satellites, balloons, or ocean registers, in this century. The graph that Mr. Kupfer used in his rebuttal of me is the NASA-GISS version, which differs sharply from the same tendentious organizations’ graph of eight years ago.

None of their climate models explain the hiatus of the past 20 years, if the recent El Niño is omitted. There are also wide variances of figures in surface temperatures recorded by various independent government agencies. If the major El Niño years of 1998 and 2016–2017 are factored in, the relationship of the figures Mr. Kupfer cites to carbon use is, I regret to confirm to him, unestablished.

Since electricity can’t be stored and has to be used immediately, the whole idea of covering the landscape with windmills and solar panels (almost all manufactured in and imported from China despite candidate Obama’s promise of green American jobs in huge numbers) was nonsense. Traditional energy sources have to be maintained for when the sun isn’t out and the air is still.

That is to say that the entire Obama policy of the Paris pledge to reduce carbon use by 28% by 2030, which would be pursued by the Obama administration’s Clean Power Plan, was impossible and, in normal policy parlance, insane.

Theodore Kupfer has done enough research to see how parlous the claims of the climate alarmists are, both in their recitation of alleged warming and in their rickety efforts to connect global temperature changes to human behavior and economic practices. His essay was billed as “A Sensible Approach to Climate Change.”

I can vigorously embrace that concept, and it was in support of it that I wrote what I did. The Paris climate accord was nonsense — the chief behavioral offenders promised nothing. The most environmentally prudent countries smiled benignly like purring tabbies, and the great American sucker promised to disembowel its economy to counter what was promised to be the hell-for-leather pollution and increased carbon emissions of the chief offenders.

The Obama administration was relying on the easily revocable Clean Power Plan with the moral weight of the unratified Paris accord to keep the United States under future administrations on the straight and narrow path of self-impoverishment for the benefit of a more selfish world. That President Trump has seen it differently should be a matter of uproarious national thanksgiving, in this week of all weeks, and of some international relief.

The Obama environmental policy was of a piece with the Obama green light to Iran to become a nuclear military power while deluging it with unfrozen scores of billions of dollars. It was a wrong-headed assault upon the national interest as almost any informed person would define it.

Since Mr. Kupfer and I agree on the environmental objective and the need to move cautiously, and because he did not demur in the slightest from my disparagement of the renewable-energy chimera, I am at a loss to identify our cavil.

CBLetters@gmail.com. From the National Review.