AAP: Climate change is set to be a big issue at the 2010 poll – but it’s not clear whether it will hurt or help Prime Minister Julia Gillard’s chances. The issue was central to the 2007 election and helped deliver a win to Labor. Times have changed. Global warming has been one of the toughest issues for Labor in its first term, and it could cost the government votes. Former prime minister Kevin Rudd famously declared climate change was “the great moral challenge of our time”, …