A panel of scientists advising the federal government says the world needs to worry more about hard-to-predict sudden changes from global warming than it does about the bigger but more gradual impacts. The National Academy of Sciences looked at warming problems that can occur in years instead of centuries. The panel said Tuesday that melting ice in the Arctic Ocean and mass species extinction are already here and worse than predicted. It says the melting ice could be more of a wild card than originally thought. However, the report said two other abrupt climate threats worried about earlier likely won’t be so sudden. Study co-author Richard Alley compared the threats to the random danger of drunk drivers: If you see them coming, you can get out of the way. © 2013 The Associated Press . All rights reserved. This material may not be published, broadcast, rewritten […]