The terms ‘global warming’ and the ‘greenhouse effect’ are frequently interchangeable, and for very good reason. Though transparent to visible light, carbon dioxide blocks radiation from the invisible infra-red area of the electromagnetic spectrum. As visible light from the sun penetrates the atmosphere and warms the planet’s surface, infra-red radiation is returned to the atmosphere as heat. But the ‘blocking’ effect of excess atmospheric CO2 means this thermal radiation is prevented from escaping back into space. Heat is trapped, and the planet is subjected to a process similar to that of a greenhouse.
Clearly the heat of the Earth is linked to the atmospheric volume of CO2 (and other greenhouse gases, or GHGs, such as methane and chlorofluorocarbons); a concentration which for the last few million years has been comparatively stable.
Within the last century, however, CO2 concentration has risen sharply with the burning of fossil fuels such as oil, gas, coal and petrol – the carbon-based commodities on which economic growth has been based.
If the Earth’s equilibrium is upset by the failure of its natural processes – evidence for which is before us almost daily – rising CO2 levels will result in an increase in the planet’s average surface temperature. Even a rise of merely a few degrees will be catastrophic, leading to extreme climate change, melting polar icecaps, raised global sea-levels and the flooding of vast areas of low-lying and coastal regions. The impact on humans, animals and plantlife will be enormous.