InsideClimate: The world needs to invest tens of billions of dollars a year in beefing up shoreline defenses against rising oceans or it will face mind-boggling costs in the decades to come, according to new research published this week in the Proceedings of the National Academy of Sciences. If nations don't build up dikes, levees and sea walls, harden existing infrastructure, and preserve natural sponges like wetlands and barrier islands--and if they also do nothing to cut the emissions of greenhouse gases that...