"Do the math!" says American climate activist and campaigner Bill McKibben who has just visited New Zealand to spread the global warming gospel. Doing the 'math' on global warming will supposedly prove we are on the brink of climate catastrophe, about to encounter the much-touted "tipping point".

On the strength of his arithmetic, McKibben puts an upper limit on the amount of fossil fuels that can be burned before the carbon dioxide (CO2) they release into the atmosphere causes 'global temperature' to rise by more than 2°C. "Anything more than that," he asserts, "risks catastrophe for life on earth."



According to McKibben and others, the so-called "safe" limit for CO2 is just 350 parts per million (ppm). But readings from the monitoring station on Mt. Mauna Loa in Hawaii indicate we are already close to 400 ppm, if not beyond.



However 'doing the math' proves nothing at all about nature. Mathematics is merely a tool with which to carry out science once we properly understand the science.



Saying "Do the math" is equivalent to saying "shoot the guns" or "drop the bombs" when fighting a war. If your strategy is poor, firing off guns and dropping bombs achieves nothing. The same goes for science. The mathematics is useless if the underlying science is wrong.



An excellent historical example of misplaced faith in the power of mathematics to prove questionable science is the case of the Wright brothers. The same year they achieved their first powered flight, the most celebrated mathematician in America, Simon Newcomb, professor of mathematics and astronomy at Johns Hopkins University, 'did the math' and proved that heavier-than-air powered flight was impossible because it required some as yet unknown force in nature. Scientific American, that bastion of sound science, labeled the Wrights "hoaxers".



So the best mathematics of the era crumbled before the reality of the Wrights' first flight. The experts 'did the math', but it meant nothing because the science of flight was not yet understood. Similarly, until we understand the science of climate change far better than we do now, the mathematics that supposedly 'proves' humans are causing it is meaningless.



It would make more sense to "do the science" because then at least we would be able to account for the now obvious divergence between computer-based climate models (supporting the IPCC and McKibben's 'math') and the actual satellite-measured temperatures. Global temperatures have gone in one direction while CO2 and the IPCC's computer models have gone in the other for nearly twenty years, with no sign of anything changing in the foreseeable future as the divergence becomes more and more pronounced. Obviously then, something is seriously wrong with the science despite the 'math' used to prove it.



It is well known that CO2 and temperature do not change in direct lockstep, with temperature obediently following, as activists would have us believe. The relationship is much like painting a window-the first coat blocks out most of the light. Successive coats take out less and less light until adding more does next to nothing. CO2 in the atmosphere works the same way.



It is also well known that historical 'global temperature' changes have always preceded similar changes in atmospheric CO2 by hundreds of years. This suggests that CO2 rise is the consequence of temperature rise, not the cause. This is the exact opposite to what is assumed in the theory of 'dangerous manmade global warming' that McKibben holds so dear.



Ironically we are near the lowest level of CO2 in Earth's history. During a multi-million year period around 440 million years ago, CO2 was about 1400 percent today's level while Earth was stuck in the coldest period of the last half-billion years. So the climate models' assumption that temperature is driven by CO2 is clearly wrong.



It is also important to recognise that commercial greenhouse operators routinely run their internal atmospheres at up to 1500 ppm CO2. This is more than four times McKibben's so-called "safe" limit. Yet there is no hint of any consequent temperature rise, while the plants inside grow far more efficiently than at the 400 ppm in the outside atmosphere. This is not surprising. Grade school students understand that CO2 is plant food and so anything but "climate pollution" as former Vice President Al Gore wrongly labels it. In fact, CO2 concentrations on submarines can reach levels well above 10,000 ppm, thirty times the "safe" limit, with no harmful effects to the crew.



McKibben should think about all of this as he flies home aboard a fossil fuel-powered aircraft, a feat that math 'proved' impossible.



Joe Fone is the Christchurch-based author of Climate Change: Natural or Manmade?

Tom Harris is the Ottawa, Canada-based Executive Director of the International Climate Science Coalition.