Then as now, a buoyant market throve on fear. The Roman Catholic Church was a bank whose capital was secured by the infinite mercy of Christ, Mary, and the Saints, and so the Pope could sell indulgences, like checks. The sinners established a line of credit against bad behavior and could go on sinning. Today a world market in “carbon credits” is in formation. Those whose “carbon footprint” is small can sell their surplus carbon credits to others, less virtuous than themselves.

The modern trade is as fantastical as the medieval one. There is still zero empirical evidence that anthropogenic production of CO2 is making any measurable contribution to the world’s present warming trend. The greenhouse fearmongers rely entirely on unverified, crudely oversimplified computer models to finger mankind’s sinful contribution. Devoid of any sustaining scientific basis, carbon trafficking is powered by guilt, credulity, cynicism, and greed, just like the old indulgences, though at least the latter produced beautiful monuments. By the 16th century, long after the world had sailed safely through the end of the first millennium, Pope Leo X financed the reconstruction of St. Peter’s Basilica by offering a “plenary” indulgence, guaranteed to release a soul from purgatory.

Now imagine two lines on a piece of graph paper. The first rises to a crest, then slopes sharply down, then levels off and rises slowly once more. The other has no undulations. It rises in a smooth, slowly increasing arc. The first, wavy line is the worldwide CO2 tonnage produced by humans burning coal, oil, and natural gas. On this graph it starts in 1928, at 1.1 gigatons (i.e., 1.1 billion metric tons). It peaks in 1929 at 1.17 gigatons. The world, led by its mightiest power, the U.S.A., plummets into the Great Depression, and by 1932 human CO2 production has fallen to 0.88 gigatons a year, a 30 percent drop. Hard times drove a tougher bargain than all the counsels of Al Gore or the jeremiads of the I.P.C.C. (Inter-Governmental Panel on Climate Change). Then, in 1933 it began to climb slowly again, up to 0.9 gigatons.

And the other line, the one ascending so evenly? That’s the concentration of CO2 in the atmosphere, parts per million (ppm) by volume, moving in 1928 from just under 306, hitting 306 in 1929, to 307 in 1932 and on up. These days it’s at 380. Boom and bust, the line heads up steadily. Even though such transitory influences as day and night or seasonal variations in photosynthesis cause clearly visible swings in the curve, the 30 percent drop between 1929 and 1932 caused not a ripple. One could not even see a 1 ppm bump in the smoothly rising curve. Thus it is impossible to assert that the increase in atmospheric CO2 stems from human burning of fossil fuels.

I met Dr. Martin Hertzberg, the man who drew that graph and those conclusions, on a Nation cruise back in 2001. He remarked that while he shared many of the Nation’s editorial positions, he approved of my reservations on the issue of supposed human contributions to global warming, as outlined in columns I wrote at that time. Hertzberg was a meteorologist for three years in the U.S. Navy, an occupation which gave him a lifelong mistrust of climate modeling. Trained in chemistry and physics, a combustion research scientist for most of his career, he’s retired now in Copper Mountain, Colorado, still consulting from time to time.

Not so long ago, Hertzberg sent me some of his recent papers on the global warming hypothesis, a construct now accepted by many progressives to be as infallible as Papal dogma on matters of faith or doctrine. Among them was the graph described above so devastating to the hypothesis.

As Hertzberg readily acknowledges, the CO2 content of the atmosphere has increased by about 21 percent in the past century. The world has also been getting a little bit warmer. The not very reliable data on the world’s average temperature (which omit most of the world’s remote regions, while over-representing urban areas) shows about a 0.5°C increase in average temperature between 1880 and 1980, and it’s still rising, more sharply in the polar regions than elsewhere. But is CO2, at 380 ppm in the atmosphere, playing a significant role in retaining the 94 percent of solar radiation that’s absorbed in the atmosphere, as against water vapor, also a powerful heat absorber, whose content in the tropical atmosphere can be as high as 2 percent, the equivalent of 20,000 ppm? As Hertzberg says, water “is overwhelming in the radiative and energy balance between the earth and the sun. Carbon dioxide and the greenhouse gases are, by comparison, the equivalent of a few farts in a hurricane.” And water is exactly that component of the earth’s heat balance that global warming computer models fail to account for.

It’s a notorious inconvenience for the Greenhousers that data also show CO2 concentrations from the Eocene period, 20 million years before Henry Ford trundled his first Model T out of the shop, to be 300 to 400 percent higher than current concentrations. The Greenhousers deal with other difficulties like the medieval warming period’s higher-than-today’s temperatures by straightforward chicanery, misrepresenting tree-ring data (themselves an unreliable guide) and claiming the warming was a local, insignificant European affair.

We’re warmer now, because today’s world is in the thaw following the last Ice Age. Ice ages correlate with changes in the solar heat we receive, all due to predictable changes in the earth’s elliptic orbit round the sun, and in the earth’s tilt. As Hertzberg explains, the cyclical heat effect of all of these variables was worked out in great detail between 1915 and 1940 by the Serbian physicist, Milutin Milankovitch, one of the giants of 20th-century astrophysics. In past postglacial cycles, as now, the earth’s orbit and tilt gives us more summer days between the equinoxes.

Water covers 71 percent of the surface of the planet. As compared to the atmosphere, there’s at least a hundred times more CO2 in the oceans, dissolved as carbonate. As the postglacial thaw progresses the oceans warm up, and some of the dissolved carbon emits into the atmosphere, just like fizz in soda water taken out of the fridge. “So the greenhouse global warming theory has it ass-backwards,” Hertzberg concludes. “It is the warming of the earth that is causing the increase of carbon dioxide and not the reverse.” He has recently had vivid confirmation of that conclusion. Several new papers show that for the last three-quarter million years, CO2 changes always lag global temperatures by 800 to 2,600 years.

It looks like Poseidon should go hunting for carbon credits. Trouble is, the human carbon footprint is of zero consequence amid these huge forces and volumes, and that’s not even to mention the role of the giant reactor beneath our feet: the earth’s core.

Alexander Cockburn is the co-editor of CounterPunch and a regular columnist for The Nation.