Sir

The irreconcilable differences between David S. Reay's Book Review of The Hot Topic (Nature 452, 31; 2008) and mine, expressed in Nature Reports Climate Change (see http://www.nature.com/climate/2008/0804/full/climate.2008.23.html), go to the heart of why there is now a crisis in climate policy. Reay seems to believe that agreement with a normative agenda precludes the need for rigorous evaluation of evidence or of proposed policy actions, and so falls into the same traps as Gabrielle Walker and David King, the authors whom he praises.

These authors have no doubt that the Kyoto Protocol is the road to follow. They consider that anyone, particularly an American, who doesn't agree is wrong — and perhaps even corrupt.

However, the Kyoto approach is broken, as my colleague Steve Rayner and I have pointed out (Nature 449, 973–975; 2007). The 'bigger and better Kyoto' formula promoted by the authors — and by Al Gore, the European Union and the British Government — was defeated in Bali in December.

Instead, the geopolitical centre of gravity moved from Europe into the Pacific. There, four major powers will determine the future shape of global climate policy: China, India, Japan and the United States, supported by Canada and Australia (once that country recovers from the excitement of the symbolic act of 'signing Kyoto').

The framing concept for future climate policy must now shift, recognizing the failure of Kyoto to manage demand by imposing output targets. The reduction of energy intensity across all economies, including those of China and India, focusing first upon those primary sectors with the heaviest energy use, is emerging as the most robust replacement.

This approach not only preserves competitiveness but also has a demonstrated capacity to deliver results. It is now being promoted with increasing vigour outside Europe.

The reality is that we are at a tipping point for climate policy. Now is a moment where new ideas and new options arising from a radical rethink of the dismal record so far could have a dramatic and positive effect. Instead of welcoming such a discussion, the authors of The Hot Topic seem to wish to prevent it by continuing a tired political campaign for an approach that has not worked and cannot work.

Where climate change is concerned, it is not enough to identify good guys and bad guys — we must also be able to discern good policies from bad. The authors and reviewer of The Hot Topic conflate their judgements of the former with the latter.