Table 3.1
How the scare started
It was the burst of warming following the cold spell that ended in 1975 that gave rise to the global-warming panic. Statistically, a hundred years of ups and downs of less than 1ºC represents too little change over too short a period to know whether or not this is just another blip on the temperature chart or whether it represents the beginning of a new, potentially dangerous change in the world’s weather. Much of the present anxiety is less to do with the actual increase in world temperature – after all, 0.5ºC is less than the variation between town and countryside – but it is the rate of this increase in the 1980s and 1990s that alarmed the weather watchers and started the global-warming panic.
The question that faces us is this: does the recent increase in global temperature represent a departure from the recurring ups and downs of our weather and presage a permanent and increasingly rapid shift towards a warmer world? If so, can we or should we try to counter the effect?
It is like the problem of asking, ‘How long is a piece of string?’ that is at the core of our present confusion. There are those who paint a frightening picture of totally improbable ‘tipping points’ based on a speculative extrapolation of the most extreme predictions. They see the piece of string as being very short. They tell wild stories of cities under water, an ice-covered Britain and imminent global catastrophe. Every storm, drought or flood is proclaimed to be evidence of global warming.
Few of these claims stand up to scientific scrutiny. Climate changes have occurred from the beginning of time. There have been floods, drought and storms ever since the world began, they are recorded in the Bible and are present in the folklore of the first farmers who settled in Mesopotamia at the very beginning of civilisation.
Others take the view that the string is very long and point out that the world has seen the present changes over and over again during its history. They argue that a modest rise in temperature provides us with an extra source of energy at relatively little cost and, like Arrhenius and Callendar, they see the potential benefit to mankind. To them the string is very long. Unfortunately, good news does not sell newspapers or generate research grants, so one seldom hears their side of the story.
The majority take the view that the changes we are seeing are real and they may possibly be made more severe by industrialisation. They advocate caution, suggesting that we should do what we can to moderate the effects of any anthropogenic changes by anticipating any adverse effects that may ensue.
To claim that anyone, or any organisation knows whether the rise in global temperature in the past century is the result of human activity or just another blip in the history of our planet is tantamount to claiming that they have the answer to the conundrum: how long is a piece of string?
Carbon dioxide
Carbon dioxide, or CO2, is a colourless odourless gas that is heavier than air. It dissolves in water, which is why the oceans of the world are such an important buffer against a rapid rise in CO2. The amount that will dissolve in water depends upon its concentration in the atmosphere and the temperature of the water. As the temperature of the seas increases, their capacity to dissolve CO2 decreases. The effect is similar to warming up a bottle of champagne: it causes the fizz of CO2 to come out of the wine, causing it to froth.
When the world was formed, many billions of years ago, it came packaged with a finite content of minerals and gases, which have changed very little over all those years. What change there has been is the result of accretion from cosmic dust, asteroids and comets and as a result of radioactive transformation. These are believed to have produced a large addition to the total amount of water and minerals on the planet. As Earth cooled from the primitive molten mass, violent volcanic eruptions occurred during which vast extra amounts of carbon, in the form of carbon dioxide and carbon monoxide, were spewed into the atmosphere from the depths of the planet. Had nothing happened, the concentration of carbon dioxide in the atmosphere would have remained high, possibly reaching 20 per cent, approaching that found on other planets.
What has changed since that time is the chemical form in which the carbon is found. Over the ages, huge amounts of carbon dioxide have been taken out of the atmosphere and transformed into chalk and coral, into the hydrocarbons of coal, peat, methane and oil, into graphite, diamonds and charcoal. We are not producing any new carbon when we burn fossil fuels We are merely recycling atmospheric carbon dioxide in various chemical guises. The atmospheric CO2 is constantly being taken up by plants in the process of photosynthesis. The plants are then eaten by animals and the carbon they contain is then given off when the animals metabolise fuels, such as sugar and fat, in order to produce energy. The energy used by a person on a bicycle is produced by burning a carbon-based fuel in the same way as a car burns petrol (but man is less efficient as a machine than an internal-combustion engine).
Carbon dioxide is not a pollutant (although the US Supreme Court ruled by five to four that it is). Like oxygen, it is part of our atmosphere and it is essential for life. Without CO2, plant life would cease to exist and most species of animal life, including man, would die out. Ignoring the effects of industrial activity, the amount of CO2 in the atmosphere is, in biological terms, a balance between animal and plant life. An increase in the amount of animal life, relative to plants, will increase the CO2, while a relative increase in plant life will reduce it. The giant rainforests of the world take up some 30–40 per cent of carbon dioxide produced. Contrary to what has been portrayed in the media by pressure groups, 85 per cent of the Amazonian rain forests are intact and a further 12 per cent are in a state of ‘recovering’. In the recovering state, the rapidly growing saplings are more efficient sinks of CO2 than mature trees. Human activity and industrialisation contribute 2.5–3 per cent to the total CO2 output. There is no doubt that this amount is increasing.
The concentration of CO2 in the atmosphere is, in geological terms, historically low at 380 parts per million (0.038 per cent). As a result of this low concentration, it requires only very small additional amounts of CO2 to cause a large percentage increase in its concentration. There is evidence to suggest that even at this tiny level it is about 0.008 per cent higher than it was a hundred years ago. Some of this increase is due to CO2 that is given off by the oceans as their surface waters warm up, and a little comes from volcanoes,
