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GLOBAL WARMING

STANLEY FELDMAN

We have to ride the theory of global warming, even if it is wrong.

—Timothy Wirth, ex-president,

United Nations Foundation

Solutions to climate change must be based on firm evidence, not dubious ideology… Policies must be based on science rather than the dogma of the environmentalist movement.

—Pope Benedict XVI,

December 2007

DOGMA

Manmade CO₂ is causing global warming, which will cause catastrophe.

SINCE THE INVENTION of the telescope, the possibility that there was life on other planets has excited astronomers. As we learned more about our galaxy we soon came to realise that most planets are such inhospitable places that life, in any recognisable form, is improbable. One of the most compelling arguments against there being life on most of the planets is the extremes of temperatures that occur on their surface. When they are exposed to the full effect of the sun the temperatures soar, but once the sun sets the cold is so intense that most forms of life would freeze.

The reason why Earth is not subjected to these extremes of temperature is the presence of its peculiar ‘atmosphere’, which provides a protective blanket of gases, containing nitrogen, oxygen, water, argon and a tiny amount, 0.038 per cent, of carbon dioxide. Without this atmosphere the average temperature on the planet would be about minus 18ºC. It is thanks to their effect that our planet is habitable.

It was the observations of the French mathematician Baron Joseph Fourier in 1822 that led to our understanding of the importance of the atmosphere in making our planet habitable. He suggested that it was the presence of particular gases in the atmosphere that moderated the extreme heat produced by the sun. Some years after Fourier, John Tyndall – the Irish physicist who described the Tyndall effect caused by refraction of light – demonstrated that, of the various gases in the atmosphere, only a few of them had a significant effect in preventing the full force of the sun’s energy reaching the surface of the Earth, causing it to become unbearably hot and, by preventing the warm surface losing its heat at night, they prevented it from freezing. He suggested that these gases captured and stored the sun’s energy that made the Earth warm. As a result, they acted as a buffer for solar energy. He studied some of the gases that occur in the air and found that, of the gases he investigated, CO₂ was the most important buffer.

In fact, molecule for molecule, water is a much more potent greenhouse gas than CO₂, since it absorbs energy over a far wider energy-wave spectrum. One has only to consider the effect of supplying energy, in the form of heat, to water in a kettle, or in the form of microwaves in an oven, to appreciate its ability to absorb energy. It is this energy-absorbing property that makes it useful in dowsing fires.

Methane is also about 20 times more potent than CO₂ as a buffer of energy because it absorbs energy over a larger energy-wave spectrum than CO₂, but it is present in only minute amounts in the atmosphere and its overall contribution to this effect is very small. In spite of their high concentrations, nitrogen and oxygen do not absorb energy in the infrared energy spectrum and do not contribute significantly to this buffering effect.

Birth of the greenhouse analogy

It was the Swedish polymath Svante Arrhenius (1859–1927), who in his dissertation in 1896,‘The influence of Carbonic Acid in the Air on the Temperature on the Ground’, first used the greenhouse analogy. He prepared the way for our understanding of the ‘greenhouse-gas effect’. In his experiments he confirmed the importance of CO₂ in preventing the Earth from cooling rapidly when the sun goes down. He believed the effect was so powerful that, as a result of the large amount of wood burned in winter in Sweden, sufficient CO₂ would be given off to increase the greenhouse effect and to produce a warm, productive climate all the year round. Using the Stefan–Boltzmann equation, he calculated that doubling the amount of CO₂ in the atmosphere would increase the temperature on the ground by an overall 4–4.8ºC. At the time he made his observations there was no way of measuring the concentration of CO₂ at the very low levels present in the atmosphere. As the actual concentration of CO₂ is less than 0.038 per cent, it is easily doubled by what, in global terms, is a very small increase in CO₂. It is the fear that in the next hundred years human activity will add significantly to the CO₂ concentration in the atmosphere that has provoked the present global-warming panic.

Although the term ‘greenhouse-gas effect’ has come to be used to describe the total effect of all elements in the atmosphere on the temperatures we enjoy on the surface of our planet, it was only the part played by CO₂, methane and sulphur dioxide, in preventing Earth from freezing when the sun sets, that was highlighted by Arrhenius.

The sun is the only major source of heat on our planet. When it shines it warms us up. Some of that energy is absorbed by the Earth’s crust, warming it up. Some of that heat diffuses from the surface into the soil and rock below. This is geothermal heat and it can be tapped into by the heat pumps that are used to supplement domestic heating. As the surface of the Earth gets hotter, it acts like a radiator, dispersing its heat back into the atmosphere. Because this radiation is in the infrared, invisible spectrum, we cannot see it happening, although we can feel its effect as it warms us up. It is the infrared radiation given off by the planet once it has been warmed that is buffered by the greenhouse gases in the atmosphere. They do it by absorbing the energy within their molecules. It was Arrhenius who pointed out that it was those gases that had the capacity to absorb energy with a wavelength in the infrared spectrum that could buffer heat energy in this way. He studied CO₂, methane and sulphur dioxide, all of which share this property. However, it is water molecules that are the most potent of the greenhouse gases because they absorb energy over a very wide range of wave bands, from infrared to visible light.

Were it not for the blanket of greenhouse gases in the atmosphere the temperatures on the earth would be boiling hot during the day and freezing at night. It is the result of the presence of these gases in our atmosphere that some of the infrared energy that would otherwise reach the surface of the Earth when the sun is shining is absorbed, reducing the extreme heat that would otherwise ensue.

Because of the greenhouse gases, much of the Earth’s warmth, acquired during the day, is prevented from being dissipated into space at night. The proponents of the theory of anthropogenic global warming (i.e. global warming caused by humans) point out that, as a result of this effect, increasing the amount of greenhouse gases in the atmosphere will reduce the amount of heat dissipated into space at night and therefore, over time, it is likely to cause the earth’s temperature to rise.

Arrhenius failed to persuade the climatologists of his era of the significance of his theory. The wood burning in Sweden did not produce the warm winters he forecast. His predictions, based on the greenhouse-gas effect of CO₂, turned out to be wrong. The theory did not explain the recurrent swings in temperature that have occurred since the Earth was born. It failed to answer the question of why, in the not-too-distant past, his Scandinavian ancestors had been able to live, farm and colonise Greenland and the frozen north of his country but had been forced to abandon their settlements due to the encroaching ice in the 16th and 17th centuries, without evidence to suggest there had been any reduction in the atmosphere’s CO₂ concentration. It seemed more likely, to the climatologists, that the explanation lay with the small deviation that occurs in the axis of Earth as it circles the sun and the flattening of its slightly elliptical circuit, the so-called Milankovitch effects.

A new ice age?

In 1938, a British scientist, G S (Guy) Callendar, drew attention to the potential beneficial effect on the agriculture and farming of a rise in temperature as a result of an increase in CO₂ in the atmosphere, but his views were largely ignored. His predictions were based on the observations of Dr Keeling’s team of scientists on the CO₂ content of the atmosphere at the top of a mountain in Hawaii. They had demonstrated that the level of CO₂ in the atmosphere in the Pacific was slowly rising each year. Callendar’s words went unheeded as, in spite of his prediction of a warmer world, it was followed by a 35-year period, from 1940 to 1975, of progressively colder times. Before we accept that an increase in CO₂ causes warming of the planet, the fall in temperature that occurred in this period in spite of a documented incremental rise in CO₂ must be explained.

It is almost certain that the levels of atmospheric CO₂ would have increased rapidly during World War II and the post-war reconstruction period, and that this should have caused a rise in temperature due to the greenhouse-gas effect. But the temperatures actually fell by 0.3–0.4ºC. The effect was sufficiently worrying for climatologists, at that time, to warn of the advent of a new ice age.