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Millions of tonnes of soot, poured into the atmosphere from a conflagration of the Kuwaiti oilfields in a Gulf War, would have a substantial effect on the world’s climates, according to a leading climate modeller.

Richard Turco of the University of California at Los Angeles, a pioneer of models of the ‘nuclear winter’, told New ÐÓ°ÉÔ­´´ that ‘Gulf oil fires burning for one month could release 3 million tonnes of black smoke into the upper atmosphere, shading up to 100 million square kilometres, more than a fifth of the planet’s surface.

The clouds would contain large amounts of soot, almost pure carbon, which is exceptionally good at absorbing the Sun’s heat. Smoke clouds spread out across India and Southeast Asia and ‘substantially upset the energy balance’, he said. One possible effect would be to disrupt the Asian monsoon.

Once established, such clouds could take many months to disappear. The Kuwaiti oilfields could burn for up to nine months, suggested a senior oil industry executive. If this happens, Turco warned, then a layer of black cloud would build in the atmosphere, up to 25 kilometres from the ground.

The present standoff in the Gulf is the first occasion during which a serious debate about the possible environmental effects has begun in advance of a potential war. Past consequences of war, such as the loss of rainforests in Southeast Asia after the use of defoliants during the Vietnam War, were addressed only after the event.

The present concern stems from the widespread belief in the US and among its allies that Iraq has mined most if not all of the 300 to 400 oil wells in Kuwait and that, in the event of war, they will be detonated. The possible consequences for the planet were first raised by King Hussein of Jordan during the World Climate Conference in Geneva last November. King Hussein warned that the resulting fires could trigger global ecological catastrophes, ranging from a ‘nuclear winter’ over the tropics to accelerated super-acid rains and global warming from the greenhouse effect.

Last week in London, Hussein’s chief scientific advisor, Abdullah Toukan, introduced a meeting organised by members of the Green Party and the Campaign for Nuclear Disarmament to highlight the risks if up to 100 million barrels of oil burn over many months. The smattering of scientists present told the rather larger contingent of journalists that global catastrophe was highly improbable, but some said that regional damage to the environment could be as dangerous to people as the effects of the war itself. The biggest danger arose from the climatic effects of smoke.

Their case was bolstered by Basil Butler, a managing director of BP and former chief engineer for the Kuwait Petroleum Corporation. He told the meeting that, if Iraq blows up wells, the ensuing fires could take up to a year to put out.

After the meeting, Turco said that he had been contacted last week by scientists from the Lawrence Livermore Laboratory, in California, a government centre for defence research, to collaborate on an investigation of the effects of fires in the Gulf.

Besides the military interest, Turco had also been encouraged to attempt a study by the physicist Carl Sagan, with whom he collaborated to develop the early theories of nucleur winter a decade ago. For the moment, the calculations were conjecture, but he believed that the dry, stable air over the Gulf would provide near perfect conditions for the creation and stabilising of vast smoke clouds.

In Britain, the Meteorological Office, which is part of the Ministry of Defence, is best placed to model the effects of a large smoke cloud. A spokesman for the Met Office said this week that it had been asked by an unnamed government department to look into the possible environmental effects of fires in the Gulf. ‘It will not be a modelling exercise. We do not have enough data to put into a model,’ he said. ‘A number of our experts will report on possible problems, such as climate change and alterations to atmospheric chemistry.’ The request to the Met Office came as the energy secretary, John Wakeham, asserted last week that ‘suggestions of a global environmental disaster are entirely misplaced’.

The centrepiece of the London conference last week was a paper delivered by John Cox, a chemical engineer, consultant to a large state oil company in the Gulf and vice-president of the CND. Cox’s paper is to be published by the Institution of Chemical Engineers in its Environmental Protection Bulletin later this month.

Cox estimates that if Kuwait’s oil wells were detonated by the Iraqis, their fires could burn almost 3 million barrels of oil per day, roughly the production of the oilfields before Iraq’s invasion in August last year. The fires would continue, fed from underground by an oilfield containing some 10 per cent of the world’s known oil reserves, until extinquished.

Despite the scale of the fires, they would add less than 5 per cent to world emissions of carbon dioxide, the main greenhouse gas. Fears of a massive escalation of global warming were clearly wrong, said Cox. ‘In reality, the main dangers arise from the major by-products of uncontrolled combustion – carbon monoxide, sulphur dioxide, nitrogen oxides and, above all, smoke.’

Cox’s estimate of the output of smoke is lower than Turco’s, at around 500,000 tonnes per month. But both agree that it would be very much less than the 50 to 100 million tonnes estimated from a major nuclear exchange.

The latest predictions of a nuclear winter, published by Turco and others in Science last year (vol 246, p 166) suggest that enough of the Sun’s radiation would be blocked out to cause cooling of daytime temperatures in the mid-latitudes in summer of 10 to 20 °C. The effect of fires in the Gulf would be regional rather than global, affecting the Middle East and the Indian subcontinent in particular.

Cox anticipates that perhaps 6 per cent of the fuel burned in oilfield fires would be converted into smoke. This figure could be doubled if the fires, especially perhaps those in the centre of an oilfield, were starved of oxygen. Other studies, including those by Turco, assume lower rates of smoke creation, typically from 3 to 4 per cent.

Butler from BP agreed with Cox that, with several hundreds of oil wells ablaze, it might take between six months and a year to put them all out. The conventional method of blowing the flame away with an explosion and then capping the well would not work, because fires from neighbouring wells would reignite the escaping oil. However, drilling a new well and diverting the oil away from the fire may work.

But Butler disagreed with Cox about the likely production of smoke. He remembered that a fire at the Burqan field in Kuwait in 1964 burned with a 150-metre flame for six weeks until it was extinquished, ‘but it produced very little smoke’.

Jom McKay from BP’s health and safety staff said that the company had not conducted modelling studies into the environmental consequences, including smoke production, of multiple fires in an oilfield. ‘We have only looked at the immediate safety aspects,’ he said.

Cox told last week’s meeting that ‘within 1500 kilometres of Kuwait, the pall of smoke could be as great as predicted by nuclear war scenarios’ for the region. Even a small reduction in surface temperatures in the region of the Gulf and the Indian subcontinent might trigger serious climatic consequences, especially for the formation of the summer Indian monsoon, he said.

The summer monsoon wids that sweep north across India during the summer, bringing rain that sustains agriculture to feed perhaps a billion people, are effectively a giant sea breeze. They arise because the air temperature above the Asian land mass heats up faster in summer than the air over the surrounding ocean. The hot air rises, sucking in cooler oceanic air. A pall of smoke over the Indian sub-continent during next summer could reduce the temperature gradient and shut down the monsoon, bringing drought to hundreds of millions of people. This is not idel conjecture. Most models of the impact of smoke from a nuclear war predict the failure of the Asian monsoons on the basis of smoke loads in the region’s air similar to those predicted by Cox and Turco for Gulf oil well fires.

‘A year-long oil well conflagration within this sensitive microclimatic region could influence the onset, duration and character of the monsoons,’ Cox told last week’s meeting. ‘Even a partial failure could cause more deaths than the total population of Iraq, Kuwait and Saudi Arabia combined.’

Cox, who is a chemical engineer, criticised climate modellers for failing to test such ideas. ‘It would cost only a few tens of thousands of pounds and could be done in a matter of days,’ he said.

One sceptic at the meeting was Richard Scorer, a meteorologist from University College London. He doubts people’s ability to influence climate. ‘Nuclear winter is a very erroneous theory. It would be impossible to achieve, even if you deliberately tried to,’ he said. He was more worried about the effect of oil spills in the Gulf on marine life.

But other British specialists are more positive. Peter Jonas at the University of Manchester Institute of Science and Technology says that the models of nuclear winter are an appropriate ‘first attempt’ to look at the effects of fires in the Gulf. But, he says, there are a number of key variables which could make nonsense of the analogy. They relate to the composition of the smoke, how far up in the atmosphere it penetrates and how fast it can be removed from the atmosphere, expecially by rainfall.

Smoke or dust that disperses at a low level in the atmosphere has less effect on temperatures below, and will persist for a shorter time than smoke that penetrates into the upper troposphere or even the stratosphere. Richard Small, director of fire research at the Pacific-Sierra Research Corporation in the US, says that ‘fire intensity has a profound influence on smoke injection’. More intense fires, such as those involving hydrocarbons, create convective currents strong enough for the smoke to penetrate into the upper atmosphere easily.

Alan Thorpe, a climate modeller at the University of Reading, Britain’s leading centre in this field, says: ‘These fires would get extremely hot and the air above them would act like one vast thunderstorm system. The smoke would undoubtedly travel very high up.’

Turco says that as the smoke clouds began to rise, their dark particles would absorb large amounts of solar heat, greatly increasing their buoyancy and taking them up to perhaps 25 kilometres, where the clouds would stabilise. Once there, ‘only very deep convective processes in the atmosphere, such as monsoon systems, if they got going, could remove the clouds,’ he said.

A critical element for the severity of the cooling beneath the clouds is the soot content. A very intense fire might create more soot, which has quite distinct optical properties that allow it to absorb far more of the Sun’s radiation than dust or clouds containing little soot. One gram of soot can block out about two-thirds of the light falling over an area of 8 to 10 square metres.

Models of impact of a nuclear winter are very sensitive to the amount of soot in smoke clouds. The presence of soot is the principal reason why smoke clouds can cause much greater cooling than veils of volcanic dust caused by major eruptions. Nonetheless, past volcanic eruptions have had serious global consequences.

The eruption of the island of Krakatoa in the East Indies in 1883 caused a 20 per cent reduction in the intensity of sunlight in France for several months. That of Mount Laki in Iceland in 1783 created what Benjamin Franklin, writing from Paris, described as ‘a constant fog over all Europe and a great part of North America’. Much of the world subsequently suffered an unusually severe winter.

A closer anology with oil well fires may be large forest fires. Major fires in Siberia in 1915 probably generated between 20 and 40 million tonnes of smoke. They appear to have depressed daytime temperatures by between 2 and 5 °C over much of Siberia.

Another factor is the amount of smoke that will survive in the atmosphere. In temperate climates most smoke swiftly falls to the ground either under its own weight or in rainfall. But Turco’s studies show that, in a dry desert atmosphere, smoke particles will be less liable to coalesce and drop under their own weight. Moreover, the lack of rain means that smoke is unlikely to be ‘rained out’. The stable air over deserts, says Turco, also provides ideal conditions for fast cooling of land surfaces shaded from sunlight. ‘You can see the effect every night in the desert, where temperatures fall far further than in other environments,’ he said.

Fred Pearce is the author of Green Warriors, published by The Bodley Head this week.