Readers letters
The consequences of acting on the assumption that carbon dioxide produced by human activity has a significant impact on global warming will have adverse economic effects on every country, and particularly on the poorer countries. However, there are grounds for reasonable doubt about the validity of the claim that carbon dioxide is a significant factor in global warming and any organisation which could contribute to a resolution of the issue, one way or the other, would put the world in its debt.
In a TV programme broadcast in 2007 entitled “The Great Global Warming Swindle”, a number of established climate scientists presented reasons for their view that carbon dioxide is not a significant contributor to the small increase in global temperature which has occurred in recent years. The programme was heavily criticised but, as far as I can tell from information provided on the Internet, only peripheral matters were attacked and there was no effective challenge to the two key observations cited in support of their thesis. These observations were:
- The main greenhouse gases are water vapour, carbon dioxide and methane, with water vapour being the dominant contributor. They operate by absorbing radiant heat from the earth surface and radiating some of that heat back to earth. Together they add about 33°C to average global temperature. If the global temperature is increasing due to greenhouse gases the rate of increase in temperature of the troposphere should be greater than that near the surface. However, measurements show that the rate of increase at troposphere level is no greater than that at surface level, indicating that the increase in global warming is not being caused by greenhouse gases.
- From ice cores it is possible to determine a history of the variations in temperature and carbon dioxide concentrations over thousands of years. There is a strong correlation between these two parameters which shows that the temperature peaks precede the carbon dioxide peaks by a few hundred years. The implication here is that it is the change in temperature which causes the change in carbon dioxide content and not the other way round. The explanation of the long delay between the temperature peak and the carbon dioxide peak is that the change in ocean temperature lags behind the change in atmospheric temperature and as the water temperature increases carbon dioxide solubility decreases.
Unless it can be shown that the data on the temperature at troposphere level is faulty or that the associated theory is incorrect, the first observation above is very convincing. At the very least it calls for a response from those who claim that global warming is a consequence of the industrial generation of carbon dioxide.
The climatologists who contributed to the scientific content of the TV programme cited included:
Professor Tim Bell, Dept of Climatology, University of Winnipeg
Professor Ian Clark, Dept of Earth sciences, University of Ottawa
Professor John Christy, Dept of Atmospheric Science, University of Alabama
Professor Phillip Stott, Dept of Biogeography, University of London
Professor Paul Reiter, Pasteur Institute , Paris
Dr Roy Spencer, Weather Satellite Team Leader, NASA
Professor Patrick Michaels, Dept of Environmental Science, University of Virginia
Professor Frederick Singer, Former Director, US National Weather Service
David Linning, Warrington