I began this series of critiques of the greenhouse fearmongers with an evocation of the papal indulgences of the Middle Ages as precursors of the “carbon credits”–ready relief for carbon sinners burdened, because all humans exhale carbon, with original sin. In the Middle Ages they burned heretics, and after reading through the hefty pile of abusive comments and supposed refutations of my initial article on global warming I’m fairly sure that the critics would be only too happy to cash in whatever carbon credits they have and torch me without further ado.

The greenhouse fearmongers explode at the first critical word, and have contrived a series of primitive rhetorical pandybats, which they flourish in retaliation. Those who disagree with their claim that anthropogenic CO2 is the cause of the small, measured increase in the average earth’s surface temperature are stigmatized as “denialists,” a charge that scurrilously combines an acoustic intimation of nihilism with a suggested affinity to those who insist the Holocaust never took place.

The greenhousers endlessly propose that the consensus of “scientists” on anthropogenic climate change is overwhelming. By “scientists” they actually mean computer modelers. The Intergovernmental Panel on Climate Change (IPCC) and their computer-modeling coterie include very few real climatologists or atmospheric physicists. Among qualified climatologists, meteorologists and atmospheric physicists, there are plenty who do not accept the greenhousers’ propositions. Many others have been intimidated into silence by the pressures of grants, tenure and kindred academic garrotes.

Peer review, heavily overworked in the rebuttals I have been reading, is actually a topic on which the greenhousers would do well to keep their mouths shut, since, as the University of Virginia’s Pat Michaels has shown, the most notorious sentence in the IPCC’s 1996 report (“The balance of evidence suggests a discernible human influence on global climate”) was inserted at the last minute by a small faction on the IPCC panel after the scientific peer-review process was complete. The former head of the US National Academy of Sciences (and president of the American Physical Society), Frederick Seitz, wrote in the Wall Street Journal, “I have never witnessed a more disturbing corruption of the peer-review process than the events that led to this IPCC report.”

I should acknowledge one imprecision in my description of Dr. Martin Hertzberg’s graph in my first column–“the smoothly rising curve of CO2″–which prompted several intemperate responses, charging that I couldn’t possibly expect CO2 or carbon levels to drop just because of a one-third cut in manmade CO2. Indeed, I should have written, “One could not even see a 1 part per million bump in the smoothly rising curve.” 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: empirical scientific evidence that the human contribution is in fact less than a fart in a hurricane, as Dr. Hertzberg says.

As for the alleged irrefutable evidence that people caused the last century’s CO2 increase, the “smoking gun” invoked by one of my critics, Dr. Michael Mann, and his fellow fearmongers at realclimate.com, the claim is based on the idea that the normal ratio of heavy to light carbon–that is, the carbon-13 isotope to the lighter carbon-12 isotope, is roughly 1 to 90 in the atmosphere, but in plants there’s a 2 percent lower C13/C12 ratio. So, observing that C13 in the atmosphere has been declining steadily though very slightly since 1850, they claim that this is due to man’s burning of fossil fuels, which are generally believed to be derived from fossilized plant matter. On the naïve and scientifically silly assumption that the only way that plant-based carbon can get into the atmosphere is by people burning fuels, they exult that here indeed is the smoking gun: Decreases of C13 in the atmosphere mean that our sinful combustions are clearly identifiable as major contributors to the 100 ppm increase in CO2 since 1850.

This is misguided, simply because less than a thousandth of the plant-based carbon on earth is bound up in fossil fuel. The rest of the huge remaining tonnages of plant-based carbon are diffused through the oceans, the forests, the grasslands and the soil. In other words, everywhere. Obviously, lots of this C13-deficient carbon has the chance to oxidize into CO2 by paths other than people burning fuel, i.e., the huge amount of plant material that’s naturally eaten or decayed by the biosphere.

Perhaps even more significant, cold ocean waters absorb lightweight C12 preferentially, resulting in lots of C13-deficient carbon in the oceans. This low-C13 carbon most certainly would have been released massively into the atmosphere over the course of the world’s warming trend since 1850, when the Little Ice Age ended. All of these larger natural pathways for emitting low-C13 carbon into the atmosphere have been considerably accelerated by this same warming trend. So once again, the greenhousers have got it ass-backward. The 100 ppm increase in CO2 can’t be uniquely attributed to humans because at least as plausibly it could be the effect, not the cause, of the warming that started after the Little Ice Age denied by Dr. Michael “Hockey Stick” Mann.

I had promised that this third column would pose the question “Are things really so bad?” a theme I will take up in this series, along with a continuation of these rebuttals. I had hoped to deal with criticisms at the end of the series. I have changed my plans, since committed greenhousers like George Monbiot charge that I have ignored their rebukes. In actual fact I was offline, in Russia, flying thither over the Arctic and thus able to make a direct review of the ice cap. So wait a couple of weeks for my next column before you critics let fly again. Coming up: how greenhouser theologians deal with the global water cycle and the highly embarrassing and persistent lag between temperature and subsequent atmospheric CO2 change. After that, I’ll offer a real treat: the nightmare visions of the greenhousers and how many have fallen under the implacable guillotine blade of reality.