Science: Prescott's Earth-saving policy doesn't hold up

In unilaterally setting an aim of cutting carbon dioxide emissions by 20 per cent by 2010, Britain may have inadvertently damaged the cause it is trying to to promote, says an expert in atmospheric science who contributed to the Intergovernmental Panel on Climate Change. Hugh Aldersey- Williams spoke to him.

Sometimes, grand gestures turn out to be just that - gestures. At the Kyoto climate summit last December, the European Union called for 15 per cent cuts in a cocktail of six greenhouse gases including carbon dioxide, increasingly accepted as Man's main contribution to global warming. In the end, it agreed an 8 per cent cut.

Britain, represented at the conference by John Prescott, Deputy Prime Minister and Secretary of State for the Environment, held out for a 20 per cent cut.

Not that his stance was hugely effective. The US, where petrol costs less than a third in real terms what it does in most European countries, took the opposite tack, volunteering to cut emissions by only 7 per cent.

Yet research published in the science journal Nature two years ago by a scientist at the US National Center for Atmospheric Research (NCAR) in Boulder, Colorado - one of the world's top centres in the field - suggested that the cautious approach may the right one for the long term. The scientist is Dr Tom Wigley, and the Kyoto agreement effectively endorses his thinking, seeking to find a middle path between environmental idealism and political and economic reality.

But that is not why Dr Wigley has been making headlines recently. At Christmas, Nature reported that he would no longer be participating in the IPCC's regular reviews of research into climate change. His stepping down carries an implied criticism of the increasing bureaucracy surrounding this crucial field of research.

NCAR is keen to play down the story. "He hasn't resigned; he's going to continue to work with and support the IPCC," a spokeswoman said. "It's just that his role has become so time-consuming that he hasn't been able to do the science he wants to do. I have heard the same complaint about time from others involved with the IPCC reports. It does become a pretty overwhelming commitment." Dr Wigley feels that the need now is to get more results rather than write more reports. Only then might overwhelming evidence be gathered that rising levels of greenhouse gases actually do increase global warming. Meanwhile, the IPCC report that formed the basis of the Kyoto discussions merely states that the "balance of evidence" is that the human release of carbon dioxide and other gases into the atmosphere is causing global warming.

But what evidence - short of obvious damage to our surroundings - could be produced that would be sufficiently unequivocal to convince hard-line sceptics? At the moment, the doubters and prevaricators are exploiting the fact that two sets of scientific measurements - those taken on the earth's surface and those obtained from satellites - disagree somewhat.

Dr Wigley believes that setting challenging targets for greenhouse gas cuts could do more harm than good. For one thing, it could simply harden the attitude of already sceptical politicians and industry against change.

More importantly, it could also be a fundamentally bad way of tackling the problem because of the costly disruption caused by demanding rapid and large-scale changes to the way industry, transport and other energy- intensive activities are run.

Even the targets set at Kyoto - modest by the standard of initial demands from environmentalists and the European Union - may be too painful and too focused on short-term change.

Dr Wigley reached his conclusion by projecting hypothetical concentrations of carbon dioxide in the atmosphere and accompanying levels of man-made emissions of the gas using computer models of the global carbon absorption and emission due to all known causes. The graphs showed that carbon dioxide levels could be brought down to the 1990 level of 354 parts per million, or a range of compromise levels above that, by 2150.

Further, they showed that even having "wasted" 10 years between 1990 and 2000 during which time carbon emissions continued to increase on a "business as usual" footing, it is still possible in principle to stabilise the greenhouse gas at any of those levels.

"The point of the illustration was to say not `let's not do anything', but `don't despair, we can still get there'," Dr Wigley says.

Now comes the realpolitik. Yes, there will eventually have to be substantial and permanent reductions in the emission of carbon dioxide. And yes, the lower we want to stabilise concentrations eventually, the sooner we will have to act.

But having shown that it is possible to achieve a range of desired levels from a variety of initial policies for action, Dr Wigley's co-authors, economists from the Electric Power Research Institute and Battelle's Pacific Northwest Laboratory, then examine the matter from their own perspective.

For economic rather than purely environmental or scientific reasons, their calculations suggest that the best course might be to do rather little at first. "The pathway can be just as important as the concentration stabilisation level in determining the ultimate cost," they write in Nature. "Pathways involving modest reductions below a business-as-usual scenario in the early years followed by sharper reductions later on were found to be less expensive than those involving substantial reductions in the short term."

They give three reasons for building up our efforts to reduce carbon emissions gradually rather than immediately launching an all-out assault. The first is simple economics: the further off the expenditure, the less the pain of budgeting for it now. The second recognises that capital equipment used in energy production is long-lived. Time in which to plan for its replacement could make the transition smoother and more affordable. The third is the Micawber option - the hope that our ingenuity will turn up something in the way of energy-efficient alternative technologies.

Some will take comfort from the apparent stay of execution. But Dr Wigley warns against complacency. "Even from the narrow perspective of a cost- effectiveness analysis, our results should not be interpreted as a `do nothing' or `wait-and-see' policy."

Which is why Dr Wigley is going back into the laboratory. For scientists the priority now should be to "prove conclusively that there is a substantial anthropogenic climate change effect", he says. "We need to quantify the effect better."

But what has Mr Prescott's bold gesture got us into? "I guess each individual country makes decisions on the basis of their own particular circumstances," Dr Wigley says. "The British government wouldn't be foolhardy, and I don't think they're that subservient to the environmentalists. So they must think there's a good reason. From the point of view of reducing the effect on the planet, what one country does has virtually no effect at all. But in terms of acting as a leader and gaining economic advantage from developing new technologies, there may be long-term benefits although in the short term you might reduce your competitiveness."

There is little advantage in taking a very different view of our predicament from that held in other countries of what is, after all, a global phenomenon. As Dr Wigley observes, "to take the lead on an issue doesn't require going to a real extreme; you can just step a little ahead, and you're still leading." Ten per cent might have done the trick.