Lord Stern, author of the eponymous report on the economics of climate change mitigation, brings the zeal of the converted to this contentious debate. An interview with him is given a two-page spread in yesterday's  Times together with a front page story encouraging us all to turn vegetarian to save the planet. He claimed on the Today programme that such a headline was unfortunate and that it did not represent the main thrust of his interview. Nevertheless, it was said, and the contribution of farming to emissions of so-called greenhouse gases is likely to become a matter for high-profile debate following whatever fudge emerges from the climate change summit in Copenhagen in December.

In his interview, Stern calls for President Obama and other political leaders to attend this conference to ensure agreement is reached. There is little chance of this. The last time the President went to the Danish capital his presence did nothing for Chicago's bid to host the 2016 Olympics and the chances of a similar outcome are high, especially as the US will take no steps on climate change legislation until the top priority of healthcare reform is settled. It is far more likely that he will address the issue when he receives the Nobel Peace Prize in Oslo, following his ill-advised acceptance of this dubious honour.

In the Today interview, Lord Stern claimed that climate change 'deniers' were a small and declining group. Like many statements about climate change, this was put forward on the basis of no evidence. There are signs that the public is becoming increasingly sceptical (hence the government's decision to run the bedtime story propaganda ads on TV). This mood is only likely to strengthen if meat eating, energy and driving all become more expensive. And politicians are surely aware that unpopular policies do not lead to re-election.

Martin Livermore is the director of The Scientific Alliance.