Читать книгу Global Warming and Other Bollocks - Stanley Feldman - Страница 18

Information about the levels of CO₂ and temperature dating back hundreds of thousands of years has come from cores drilled in the ice in the Antarctic. Bubbles of air trapped in the ice at the time it was formed give surprisingly reproducible measurements of the CO₂ levels. The temperature at those times is calculated from probes inserted into the ice which measured isotope ratios.*

They reveal that, for the past 500,000 years, the level of CO₂ has been roughly stable at around the present levels of less than 0.04 per cent. Over this period of 100,000 years the Earth has cooled slightly, although from time to time the temperatures have fluctuated through swings of 3–4ºC.

In order to get some idea of what the conditions were like further back in time we have to make assumptions based on the changes that we know took place. Primitive cellular animal life evolved between 500 and 300 million years ago. As life developed and photosynthesis occurred, large amounts of the CO₂ were rapidly sequestrated from the atmosphere by plant and animal life and deposited as chalk, peat, shale, coal and oil. This produced a fall in CO₂ concentration from a high of 4.0 per cent to the 0.038 per cent found today. The white cliffs of Dover were made of their calcified carcasses, and they contributed to many of our hills and to the coral of tropical islands. Throughout this time, the Earth was cooling and, although the CO₂ levels were falling, they were many times higher than today.

The CO₂ produced today when we burn fossil fuels is merely returning into the atmosphere a minute part of the CO₂ sequestrated by plant and animal life over hundreds of thousands of years. It is not new CO₂ that we have produced. It is CO₂ that is being recycled. If we were to hold a huge bonfire and burn all the available fossil fuel, coal, oil and gas in the world at one go, it would raise the atmospheric CO₂ by only a small amount, to nowhere near the level it was 500 million years ago, when global cooling caused much of the Earth’s surface to be covered with ice.