Given the recent publication of the Intergovernmental Panel on Climate Change Report detailing the physical scientific basis for its wholly reasonable recommendations, it is difficult to understand how Dr Wilson Flood (Letters, June 27) can make the claims which he does. While it may be somewhat disingenuous to infer global trends from local rainfall figures, his suggestion that global temperatures have fallen since 1990 is simply not borne out by the above report; a report which, by the way, is endorsed by the overwhelming majority of serious independent scientists. Furthermore, the IPCC graph of methane concentrations in the atmosphere shows no falls that I can discern, which would support Dr Flood's other claim.

By quoting a chief executive of a Shell company on a global warming issue, he reveals his probable sources.

A N Taylor (Letters, June 28) adds to the disinformation by suggesting that a book by the well-known populariser of science, Nigel Calder, should represent the font of wisdom on this matter. I suspect that even Dr Calder would be aghast that his speculative take on the global warming evidence, with its emphasis on the role of cosmic rays, should become "compulsory school reading".

That Shell or any other oil giant expresses doubt about emission reduction targets of the order of 80% is hardly surprising given that the oil industry is unlikely to support any of the drastic initiatives which will be necessary to achieve such a target - for example, getting people out of gas-guzzling cars and aircraft.

It is perhaps worth noting that global temperature did drop slightly (0.10C) between 1945 and 1975. Scientifically, there is little doubt that this "glitch" was largely attributable to the accumulation of CFCs in the atmosphere. The worldwide ban on aerosols and other CFC-producing agents (a salutary reminder of what worldwide cooperation against global pollution can achieve) has restored the upward temperature trend and the graphs show no reversal since 1975.

Alan J Sangster, 37 Craigmount Terrace, Edinburgh.

How appropriate that a Dr Flood should be writing on the subject of (absence of) climate change in this week of all weeks when it seems that half of England is submerged. It is a pity that he prefers to stick to short-term observations instead of the ones which really matter - perhaps not so much to us, but to future generations.

It is a fact that atmospheric levels of fossil carbon emissions have risen from practically zero in 1850 (around the time of the Industrial Revolution) to about 6500 million tonnes of carbon per year in 2000. When the figures are plotted graphically, there is hardly anything to show until 1850. At 1950, however, the curve really takes off in a parabolic shape so that it is almost vertical today. A graph of global mean surface temperature has almost an identical shape. While this may not prove the "cause and effect" hypothesis that Dr Flood mentions, it is surely enough to make a reasonable person consider the possibility of a link.

Again, Dr Flood states that global temperatures "have shown no statistically significant rise since 1990". That's only 17 years. The average annual temperature for 2007 is expected to be 0.54C above the 1961-90 average of 14.0C. It is important that we always take the long view.

Barry Lees, 12 Denholm Street, Greenock.