OSLO (Reuters) - It sounds insignificant alongside the Indian Ocean tsunami, yet an almost imperceptible annual rise in the world's oceans may pose a huge threat to ports, coasts and islands by 2100. Leaders of 37 small island states meet in Mauritius this week to discuss an early warning system to protect against tsunamis and a creeping rise in ocean levels, blamed widely on global warming. Rising sea levels, now about 0.08 inch a year, could swamp low-lying countries like Tuvalu in the Pacific or the Maldives in the Indian Ocean if temperatures keep rising. They could also lead to...