Reason clouded by carbon

Although there are many doubters of man-made climate change, I am not yet one of them. But I remain unconvinced that carbon dioxide is the sole bête noire. Two decades ago, I pored over the spectral properties of the infra-red radiation of this gas, which is essential to plant life, and found that it was almost completely overshadowed by the radiative properties of water vapour, which is vital to all forms of life on earth.

Repeatedly in science we are reminded that happenings in nature can rarely be ascribed to a single phenomenon. For example, sea levels on our coasts are dependent on winds and astronomical forces as well as atmospheric pressure and, on a different time scale, the temperature profile of the ocean. Now, with complete abandon, a vociferous body of claimants is insisting that CO2 alone is the root of climatic evil.

I fear that many supporters of this view have become carried away by the euphoria of mass or dominant group psyche. Scientists are no more immune from being swayed by the pressure of collective enthusiasm than any other member of the human race. I do not believe for one moment that undisciplined burning of fossil fuels is harmless, but the most awful consequence of the burning of carboniferous fuels is not the release of CO2 but the large-scale injection of minute particulate pollutants into the atmosphere.

Detailed studies led by internationally acclaimed cloud physicist Daniel Rosenfeld of the Hebrew University of Jerusalem have revealed that the minute water vapour droplets that form around some carbon particles are so small as to be almost incapable of being subsequently coalesced into larger precipitable drops. In short, the particulates prevent rainfall.

Rosenfeld's research group has shown that humans are changing the climate in a much more direct way than through the release of CO2. Rather, pollution is seriously inhibiting rain over mountains in semi-arid regions, a phenomenon with dire consequences for water resources in the Middle East and many other parts of the world, including China and Australia.

Rosenfeld is no snake-oil salesman. As an American Meteorological Society medallist, he has an internationally endorsed research record in cloud physics that no living Australian can claim to emulate. It is more than 20 years since Australia was a knowledgeable force in cloud physics and cloud seeding. CSIRO's relevant division has long been disbanded and its cloud-seeding techniques based on the use of expensive silver iodide have been superseded by the Israelis using an inexpensive and far more natural product: sea salt.

Chinese and Israeli researchers have shown that the average precipitation on Mt Hua near Xi'an in central China has decreased by 20 per cent amid increasing levels of man-made air pollution during the past 50 years. The precipitation loss was doubled on days that had the poorest visibility because of pollution particles in the air. This explains the widely observed trends of decrease in mountain precipitation relative to the rainfall in nearby densely populated lowlands, which until now had not been directly ascribed to air pollution.

Some of the most chilling evidence was presented by Rosenfeld's Australian-based research associate Aron Gingis in a 2002 submission to the House of Representatives standing committee on agriculture, fisheries and forestry concerning future water supplies for Australia's rural industries and communities.

The US National Oceanic and Atmospheric Administration's satellite map of southeast Australia, enhanced by Rosenfeld, shows the frightening persistence and longevity of pollutant trails across vast areas, including the all-important Snowy Mountains catchments. It may well be concluded that the increasing emissions from the phalanx of brown coal-burning power stations at Hazelwood and other locations in Gippsland, Victoria, have substantially wrecked the natural precipitation processes over the once hydrologically rich Australian Alps.

If Rosenfeld's scientific interpretations are correct, then southern Australia would greatly benefit from the application of his discoveries. At the very least, Rosenfeld's conclusions should be accorded appropriate evaluation and testing by an unprejudiced panel of peers.

Yet his work so far has been ignored in Australia because it does not fit in with the dominant paradigm that holds CO2 responsible for reduced rainfall in semi-arid regions.

Scientists, like all other people, need to remain open to competing views and avoid the danger of being locked into tunnel vision through group obsession, which is what global warming seems to have become.

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