A tax of one-hundredth of a percentage point on global financial transactions could provide hundreds of billions of dollars for developing countries facing the challenges of soaring commodity prices and climate change, the United Nations heard this week.

The food price crisis that has sparked unrest in some of the world’s poorest countries also spurred mainstream interest in the concept of micro-contributions from the financial markets when UN officials and experts from the World Bank and IMF gathered for a special session in New York.