I was lucky enough this week to be able to hear foremost climate scientist Prof James Hansen give evidence in support of 6 greenpeace activists who are arguing that they are not guilty of causing criminal damage to the kingnorth chimney last october, by painting the prime minister's name down the chimney in huge letters, because they were acting to prevent greater property damage from climate change. Hansen is, like many academics, softly spoken, modest but truly impressive. His confidence comes from nearly 3 decades studying the earth's climate and he is absolutley clear about coal and the UK, US and germany's special responsibility in slowing the return to coal by 'drawing a line in the sand'