Small island nations throughout the world are threatened by climate change, toxic waste, and excessive tourism, island leaders said yesterday during a U.N. session in New York focusing on their problems. The 43 members of the Alliance of Small Island States say they want an end to industrial fishing and the transport of nuclear and toxic waste in their waters, but they are running into opposition from larger powers such as France and Japan on the waste issue. The alliance plans to adopt a resolution today calling for more action by industrialized nations to cut down on their greenhouse gas emissions. Island nations are particularly vulnerable to the sea-level rises and storms that are caused by climate change, and they have been highly vocal in calling for international action to address the problem. Island leaders also said yesterday that richer nations have not done nearly enough to live up to commitments of assistance that they made in 1994.