One of the world's top climate scientists has written a personal new year appeal to Barack and Michelle Obama, warning of the "profound disconnect" between public policy on climate change and the magnitude of the problem. With less than three weeks to go until Obama's inauguration, ProfessorJames Hansen, who heads Nasa's Goddard Institute for Space Studies, asked the recently appointed White House science adviser Professor John Holdren to pass the missive directly to the president-elect.