Global warming's omitted variable

Copyright Ó 2005, by Alec Rawls

In late January, a spate of alarming global-warming reports hit the newspapers. The International Climate Change Taskforce warned that warming is likely to hit a “point of no return” within ten years. The World Wildlife Fund also warned of imminent climate “tipping.” announced that, by testing a wider variety of initial conditions than other climate modelers, it had arrived at a more radical range of warming predictions.

All of these studies employ the classic ruse of advocacy statistics: they omit key explanatory variables, so that explanatory power gets misattributed to those explanatory variables that are included. The variable that these studies leave out is the solar-magnetic flux. As a result, the warming caused by high levels of solar-wind over the last half-century gets misattributed to greenhouse gases. This exaggerated greenhouse warming effect then gets projected forward into trumped-up predictions of imminent catastrophe if human production of greenhouse gases is not drastically curtailed.

Sunspots and climate

Correlation between sunspot activity and cloudless skies has been observed for over a century. It is also known that the Little Ice Age coincided with a sunspot minimum. What has been a mystery until recently is the mechanisms by which solar activity might affect climate. In the last decade, scientists have finally begun to solve this riddle. Solar flares generate storms of solar-magnetic flux that partially shield the Earth from cosmic radiation. Evidence suggests that this cosmic radiation promotes cloud formation, either by ionizing the atmosphere, or by affecting the atmosphere’s electrical circuit. Thus high levels of solar wind have the effect of blowing away the cloud cover, giving the Earth a sunburn. Add that solar activity has been very high since the 1940's, and the slight global warming observed since the mid 70's could easily be due to this effect.

None of the global warming alarmists take this effect into account. All of the recent alarmist studies are based on the GCMs (General Circulation Models) employed by the IPCC (the International Panel on Climate Change). These IPCC GCMs have never included the effects of cosmic rays on cloud formation. Back in 1996, at the time of the IPCC’s Second Assessment Report, this omission was marginally tenable. Sunspots generate a slight increase in solar luminosity (the relatively cool spots are surrounded by super-hot “faculae”) but this increase in radiance is not enough to create significant global warming. The correlation between sunspots and cloudiness was also known, but since no one had any idea what the causal link might be, they did not built it into their models.

The situation had changed drastically by 2001, when the IPCC’s Third Assessment Report came out. By then the cosmic ray theory had been formulated and evidenced and could be modeled. There were still some difficulties with the theory. In particular, direct measurement of the effect of cosmic rays on cloudiness was complicated by volcanic activity and other influences on cloud formation, but evidence of the long term correlation between cosmic radiation and climate was piling up impressively. In sum, the mechanism was strongly evidenced, but the available correlations were to the output of the climate models (global climate), not to the inputs that drive the models (the amount of solar energy getting reflected back into space by cloud cover).

The scientific thing to do in this circumstance is go with the best available estimate of the relation between solar-flux and the Earth’s reflectivity, then vary the parameters of the relation looking the model specification that best fits the historical temperature data. Instead, the IPCC just continued to omit solar-magnetic effects, calling them “unproven” ( This from a climate-prediction enterprise that is nothing but speculation from top to bottom. The entire enterprise is driven by best estimates, but here a strongly evidenced key determinant of global climate was left out entirely. No mention was even made of how failing to account for solar-magnetic warming effects causes any such effects to be misattributed to greenhouse warming.

Environmental religion

The fact is, global warming alarmists are not scientists, they are propagandists. Instead of trying to incorporate solar-magnetic effects into their models, the alarmists regard the solar-magnetic theory of warming as a competitor to their preferred greenhouse gas theory. As evidence for the impact of cosmic radiation on clouds continues to roll in, the alarmists are still concocting excuses to ignore this mechanism that undercuts their preferred conclusions.

NASA climatologist Gavin Schmidt recently justified leaving cosmic radiation out of NASA models on the grounds that the effect is not needed. “[T]here is no obvious need for ‘new’ or unknown physics to explain what [is] going on,” he explains to science fiction writer Jerry Pournelle (at Pournelle’s website). Earth to NASA: it isn’t enough to tweak your model to fit the historical temperature record. You have to fit ALL the data, including the evidence that cosmic radiation produces cloud cover. If you leave out a real effect, your model is WRONG. Warming that ought to be attributed to solar activity gets misattributed to greenhouse gases, and whatever predictions you make on the basis of those exaggerated warming effects are lies.

These lies are intentional. The goal is to have a grounds for demanding the curtailment of human activity. That is the founding stone of environmental religion. Environmentalists see man as displacing nature, and in this contest, they side with nature. As the self-appointed representatives of a natural world that cannot speak for itself, they see all human impacts as by definition bad, and the interdiction of human impacts as necessarily good, regardless of whether the pretext for curtailing human activity is honest or dishonest.

Gavin Schmidt’s rejection of proper scientific principles is just one example. In the sixties and early seventies, when global temperatures seemed to be falling, Stanford climatologist Stephen Schneider claimed that fossil fuel burning was causing global cooling and needed to be curtailed. When temperatures started rising, he switched to claiming that that fossil fuel burning is causing global warming, and needs to be curtailed. If sunspot activity falls off and cooling returns, he will presumably again claim that human activity is causing cooling, and needs to be curtailed. Schneider seems to be starting with his preferred conclusion (human impact bad), then picking and choosing from the available reason and evidence to fashion the best case he can for this conclusion.

This kind of behavior is why we see today a continued refusal by the global warming alarmists to incorporate well documented solar-magnetic effects into their models. If the implications of honest science do not condemn human impact, these opponents of human impact will find excuses to reject honest science.

Rational environmentalism

Those who study the cyclical patterns in sunspot activity predict a solar minimum by 2030. There is lots of evidence that if such a minimum does occur, increased cloud cover will block the sun and cool the Earth. In this case, the slightly warmer jacket of greenhouse gases created by fossil fuel burning will turn out to be a good thing, not a bad thing. More generally, until we can predict the course of natural variation, we have no idea whether a particular human impact will turn out to be good or bad.

There are valid reasons to limit fossil fuel consumption, but they have nothing to do with global warming. One is to limit pollution. Another is to conserve limited resources. Most important is strategic national interest. Our economy is terribly vulnerable to any kink in the oil supply pipeline. This vulnerability can be reduced by taking four steps. A hefty tax on fossil fuels (with all proceeds returned to taxpayers in the form of lower other taxes) would reduce demand, driving the world price of oil down to the cost of producing the easiest to produce oil. This would create a net gain for our economy while at the same time taking the stress off of production and distribution facilities. We should also fill the strategic oil reserve and we should drill and cap enough domestic reserves to be able to make up any temporary shortfall in imports. Lastly, we should switch over to nuclear generation.

Any decade now, breakthroughs in solar electric generation and in battery technology are likely to place much of our energy production and distribution beyond the reach of any kink in oil supplies. Until then, reducing our vulnerability to supply kinks will require substantial reductions in fossil fuel consumption. It is possible that the associated reduction in greenhouse gas emissions will send us into an ice-age that higher levels of emissions would forestall, but we don’t yet understand climate science well enough to proceed sensibly on this kind of concern. That would be as nutty as paying a high price today in order to gamble that we will want to be wearing a slightly lighter jacket of greenhouse gases fifty or a hundred or two hundred years from now, when we have no idea where natural temperature variation is headed.

At some point, climate science may have clear prescriptions to offer, but not today. The best we can do now is to strive for rapid economic, scientific and technological advance, in order to best be able to deal with whatever threats await.

This article was published in The Stanford Review, 2/15/2005. Similar ground, but with links to the referenced information, is covered in THIS post at Alec's Error Theory blog.

Alec Rawls wrote a chapter on global warming for World Ahead Publishing’s recent book Thank You President Bush. He is currently writing a book on republicanism. Contact

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