Eight of the sharpest minds were given a $50 million budget and told to rank the world’s worst crises, then put emotion aside to prioritize spending.

If you could spend $50 billion to help solve some of the world’s greatest problems – and no, your car-repair and health care bills don’t count – how would you spend the money?

Ambitious Danish statistician and environmental maverick Bjorn Lomborg recently put the question to eight of the world’s sharpest minds in economics, including three Nobel Prize winners.

Based on a list of global challenges identified by the United Nations, Lomborg instructed them to name the world’s top 10 worst problems, then rank more than 30 proposed solutions to those problems in terms of spending priority. Never mind politics and cultural differences, he said. Instead, use cost-benefit analysis: Crunch the numbers, and weigh benefits against costs to determine how to get the most bang for a buck.

Many of the eight economists who tackled Lomborg’s challenge – each of whom was paid $30,000 for the effort – said they did so in part to demonstrate that it is possible to work without input from hordes of lobbyists to reach a mutual agreement about how best to spend the world’s money.

Efforts to control the spread of AIDS, estimated at $27 billion, should be tackled first to avert 30 million new infections by 2010, the economists said. Next, $12 billion should be spent on dietary supplements to fight malnutrition. Improving the world’s health would dramatically increase its productivity, the economists said.

Relatively cheap policy reforms promoting free trade ranked third.

“Put a group of economists in a room, and the only thing they will absolutely agree on is that anything making trade among countries easier is good, and anything making trade more difficult is bad,” said Jeff Thredgold, an economist for VectraBank Colorado.

The fourth and final expense to win endorsement as a “very good project” was $13 billion to prevent malaria.

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