Alaska, a land of pristine wilderness, sparse population and unimaginable resource riches. It is also the corner of our planet which is experiencing the most dramatic effects of climate change. The carbon economy which made Alaska rich now threatens its delicate ecosystem, presenting the US with a challenge. In the second of two programmes, Stephen Sackur explores whether the world’s second largest carbon emitter is getting serious about climate change.(Image: A sea otter sits on a chunk of ice near Whittier, Alaska. Credit: AFP)