It’s been fascinating to watch climate change emerge again as a political issue in the US, with President Barack Obama taking potshots at Republican Tea Party favourite and presidential candidate Rick Perry over his denial of climate science.

"You've got a governor whose state is on fire denying climate change," Obama said this week, revelling in the opportunity of engaging a debate he might actually win. Perry’s camp said the jibe was outrageous. But such was the impact that most US political commentators agreed on one thing: climate change is now back on the political agenda, and will be a key battleground in the 2012 presidentials.