‘Climate change is our moon landing.’ So said Sir Martin Rees, Astronomer Royal and President of the Royal Society, at the end of 2006. According to Rees the task of avoiding catastrophic climate change should be an inspiring and galvanising challenge for the scientists of today and tomorrow. In February 2007, at the press launch of the Summary for Policy Makers of the Intergovernmental Panel on Climate Change’s 4th report on climate change, we were told that the human impact on the climate is ‘unequivocal’ and that urgent action is needed.

The issue of the negative effects of climate change is rarely out of the media and is increasingly portrayed in alarming terms. Politicians of all persuasions attest to the seriousness of the situation and are competing to present their green credentials, alongside business, local government and pretty much every major public organisation.

But what does science tell us about how we should respond to climate change? Are scientists becoming involved in campaigning for particular political responses, and, if so, is this a good or bad thing? Is the time for debate really over, or are political choices being obscured by talk of scientific consensus? Are the threats so great and the science so certain that there really is only one course of action?