Читать книгу Global Warming and Other Bollocks - Stanley Feldman - Страница 19

It was almost entirely due to the apparent link between the temperature and CO₂ levels over the past few hundred thousand years, revealed by the analysis of ice cores drilled in the ice caps, that the present concern about the effect of human activity on the CO₂ levels in the atmosphere has been given some scientific credence (see Figure 3.3).

Figure 3.3: Ice-core date from Vostok, Antarctica (after Raynaud et al., Science 259, 1993)

The indirect information obtained from the ice-core samples in the Antarctic give us a picture of the CO₂ levels and temperatures over the past 600,000 years. However, they can tell us only about the CO₂ levels and temperatures locally; they do not tell us what was happening to the rest of the world. While it is likely that the CO₂ levels measured in one place, such as Mount Mauna Loa in Hawaii, will not differ significantly from that in the rest of the world, the same cannot be said for the temperature. It would be a nonsense to suggest that a period of hot summers in Manchester meant that there was also a period of excessive heat in Botswana. It is unlikely that the relative hot and cold spells found in the Antarctic ice-core samples accurately reflect what was happening in the rest of the world.

Although the results are largely reproducible, their absolute accuracy cannot be verified, as there are no standard measurements with which to compare them. However, we have direct and anecdotal historical evidence of the temperature changes in the past 1,000 years from various areas around the world (see Figure 3.4).

Figure 3.4: Over 1,000 years there is little change in the temperature of northern Europe

Nevertheless, it is only in the past 50 years that advances in technology have allowed us to measure the change in CO₂ levels accurately and record temperatures continuously. In the past 15 years, thanks to the use of Earth-orbiting satellites, we are now able to obtain accurate, reproducible data on ocean levels, global temperatures and the behaviour of clouds.