London

Bjørn Lomborg was vilified by the green movement when he published The Skeptical Environmentalist, a 2001 book that questioned the validity of several widely held beliefs about the state of the planet. A furious activist went so far as to thrust a pie in his face, on at least one occasion. But his next big venture could see him rouse the ire of an equally passionate group: the international aid movement.

As part of Lomborg's latest scheme, nine eminent economists will gather in Copenhagen on 24–28 May to rate solutions to the developing world's ten largest problems, from financial instability to communicable diseases. The panel intends to use cost–benefit analyses to evaluate between three and five rival approaches to each problem. The result, says Lomborg, will rank the most cost-effective ways of doing good.

It could also be the recipe for a major row. International charities say the scheme ignores established targets, such as those developed by the United Nations. Some economists say that Lomborg is overstating the usefulness of cost–benefit analysis — a technique that has long been used by conservative economists to support arguments against everything from clean-air rules to development aid for the poor. “To believe the problems of the world can be solved like this is absurd,” says Eric Neumayer, an expert in environment and development at the London School of Economics.

The economists planning to take part in the assessment mostly reside in élite universities in Europe and the United States, and four of them are Nobel laureates. They will each assign numbers to potential solutions, of which there are around 30; the numbers will represent the size of the benefits that come with the approach, such as fewer cases of disease, minus the costs of implementing it.

Cost–benefit analyses have become more common in aid planning over the past decade, but remain controversial nevertheless. Economists have to assign values to variables in the analyses, such as human life, and the numbers they use can vary widely. Critics such as Neumayer say that for some problems, such as climate change, the variability is far too great for the results to be meaningful.

Others point out that the quantitative approach, if it were adopted by aid agencies, would inevitably push effort away from the toughest problem areas — such as war-torn southern Sudan. “There is little chance of effective use of money there,” says Roger Riddell, international director of Christian Aid, a London-based charity. “But it should not be abandoned.”

Lomborg acknowledges that some countries could lose out, but argues that we already prioritize aid funding and that this is simply a better way of doing it. “There's never an easy answer,” he says. “But if there are places where we can do relatively little then we should consider achieving more elsewhere.”

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