You know, it is a big "IF". We could waste zillions for nothing. Indeed, a zealot called Lord Stern has estimated that it would be worth spending a few trillion dollars each year to avoid a possible disaster in 200 years' time. Because he is associated with the London School of Economics he is believed - by those whose experience of insurance is limited. It is not worth insuring against something that might happen in 200 years time - we will all be dead and beyond caring.
So I decided to examine the hypothesis from first principles. There are five steps to the hypothesis:
- The observation that the carbon dioxide (CO2) content of the atmosphere is rising.
- The observation that the rise in CO2 in the atmosphere is largely paralleled by the increase in fossil fuel combustion. Combustion of fossil fuels clearly results in emission of CO2, so it is eminently reasonable to link the two increases.
- The observation that CO2 can scatter infra-red over wavelengths primarily at about 15 µm. Infra-red of that wavelength, which should be carrying energy away from the planet, is scattered back into the lower troposphere, where the added energy input should cause an increase in the temperature.
- The expected increase in the energy of the lower troposphere may cause long-term changes in the climate and thermosphere, which will be characterized by increasing frequency and/or magnitude of extreme weather events, an increase in sea temperatures and a reduction in ice cover.
- These phenomena may make areas of the globe uninhabitable either through extreme drought or flooding in the worst cases, but perhaps more subtly through impacts on the biosphere as a whole to which mankind is unable to adapt.
The observations of the increase in CO2 in the atmosphere are incontrovertible. There is a continuous record from the Mauna Loa observatory since 1958:
The annual rise and fall is due to deciduous plants growing or resting, depending on the season. But it is clear that the long-term trend is ever-increasing levels of CO2 in the atmosphere.
Before 1958, there were only sporadic measurements of CO2. Nevertheless they give a clear indication that there was minimal change in the atmosphere before about 1850:
The conclusion is clear - there has been an increase in the carbon dioxide in the atmosphere since 1950. Next, we will consider what has caused it.