Suppose they held an international summit and nobody came? The Brazilian organizers of the annual United Nations climate conference are close to finding out. They pulled out all the stops, including bulldozing tens of thousands of acres of rainforest to clear a new highway to the host city, Belém. International business leaders flocked to earlier summits, and 150 heads of government attended the one in Dubai two years ago. The moguls are steering clear of Brazil, though, and only 53 national