TWO years ago, a Danish environmentalist called Bjorn Lomborg had an idea. We all want to make the world a better place but, given finite resources, we should look for the most cost-effective ways of doing so. He persuaded a bunch of economists, including three Nobel laureates, to draw up a list of priorities. They found that efforts to fight malnutrition and disease would save many lives at modest expense, whereas fighting global warming would cost a colossal amount and yield distant and uncertain rewards.

That conclusion upset a lot of environmentalists. This week, another man who upsets a lot of people embraced it. John Bolton, America's ambassador to the United Nations, said that Mr Lomborg's “Copenhagen Consensus” (see articles) provided a useful way for the world body to get its priorities straight. Too often at the UN, said Mr Bolton, “everything is a priority”. The secretary-general is charged with carrying out 9,000 mandates, he said, and when you have 9,000 priorities you have none.

So, over the weekend, Mr Bolton sat down with UN diplomats from seven other countries, including China and India but no Europeans, to rank 40 ways of tackling ten global crises. The problems addressed were climate change, communicable diseases, war, education, financial instability, governance, malnutrition, migration, clean water and trade barriers.

Given a notional $50 billion, how would the ambassadors spend it to make the world a better place? Their conclusions were strikingly similar to the Copenhagen Consensus. After hearing presentations from experts on each problem, they drew up a list of priorities. The top four were basic health care, better water and sanitation, more schools and better nutrition for children. Averting climate change came last.

The ambassadors thought it wiser to spend money on things they knew would work. Promoting breast-feeding, for example, costs very little and is proven to save lives. It also helps infants grow up stronger and more intelligent, which means they will earn more as adults. Vitamin A supplements cost as little as $1, save lives and stop people from going blind. And so on.

For climate change, the trouble is that though few dispute that it is occurring, no one knows how severe it will be or what damage it will cause. And the proposed solutions are staggeringly expensive. Mr Lomborg reckons that the benefits of implementing the Kyoto protocol would probably outweigh the costs, but not until 2100. This calculation will not please Al Gore. Nipped at the post by George Bush in 2000, Mr Gore calls global warming an “onrushing catastrophe” and argues vigorously that curbing it is the most urgent moral challenge facing mankind.

Mr Lomborg demurs. “We need to realise that there are many inconvenient truths,” he says. But whether he and Mr Bolton can persuade the UN of this remains to be seen. Mark Malloch Brown, the UN's deputy secretary-general, said on June 6th that: “there is currently a perception among many otherwise quite moderate countries that anything the US supports must have a secret agenda...and therefore, put crudely, should be opposed without any real discussion of whether [it makes] sense or not.”