Avoiding global climate chaos will require a major transformation of society and the world economy that is "unprecedented in scale," the UN said Monday in a landmark report that warns time is running out to avert disaster. Earth's surface has warmed one degree Celsius (1.8 degrees Fahrenheit) -- enough to lift oceans and unleash a crescendo of deadly storms, floods and droughts -- and is on track toward an unliveable 3C or 4C rise.
