Contributor(s): Professor Jeffrey D Sachs | Jeffrey Sachs argues the need a new economic paradigmQglobal, inclusive, cooperative, environmentally aware, and science basedQbecause we are running up against the realities of a crowded planet. The alternative is a series of cascading threats to global well-being, all of which are solvable but potentially disastrous if left unattended. Prosperity must be maintained through new strategies for sustainable development that complement market forces, spread sustainable technologies, stabilize the global population, and enable the billion poorest people to escape from the trap of extreme poverty. This event marks launch of Professor SachsU new book Common Wealth: economics for a crowded planet (Allen Lane, March 2008). Jeffrey D Sachs is director of the Earth Institute at Columbia University. He served as special adviser to former United Nations secretary general Kofi Annan on the Millennium Development Goals.