Copenhagen Climate Change Conference

It is pleasure to take part in this short debate on climate change. The fact that it is a short debate indicates that more immediate problems tend to come ahead of climate change in our consideration—I do not intend to undermine the importance of the debate on Afghanistan in any way. I look forward to a longer debate on climate change in the autumn. My right hon. Friend the Secretary of State for Energy and Climate Change is correct that we must be consistent in trying to meet the targets that climate change science tells us we ought to meet if we are to stay within a 2° temperature increase. I would like to talk about those numbers, because policy based on scientific analysis is quite new in politics—policy of such magnitude based on science is extremely new. I address my comments not only to Government Members but to Opposition Members, because the point would be a crucial one to miss. The numbers are terribly important, and the Government are far more candid on them than they were two or three years ago, which I welcome. I draw Members' attention to page 35 of the "Road to Copenhagen" document, which for the first time provides an honest assessment:""It is estimated that stabilising the concentration of greenhouse gases in the atmosphere at 450 ppm CO2 equivalent gives around a 50 per cent. chance of keeping temperature levels below 2°C and reduces the chance of increases of between 3 to 4°C. Higher concentrations would reduce the chance of staying below 2°C significantly and increase the chances of much higher temperature rises."" That is a major step forward from the publication of the Stern review two and a half years ago, when the range of targets discussed went up to 550 parts per million, on the basis of which one could plan one's policy, prepare one's budgets and so on. Nick Stern has now reduced his estimate of where we should be to, I think, 450 parts per million. Around the world, others are saying it should go much lower. Jim Hansen, for example, has suggested that 350 parts per million, which is less than where we are today, ought to be our longer-term target. Those numbers may seem arcane to most people outside this Chamber, and I suspect that that is an inevitable consequence of a science-based policy. However, it is essential that we base our policies on numbers based on the science. I fear that in some cases we are still not managing to do that. The Committee on Climate Change's recommended budgets, for example, appear to be based on some modelling that rather ignores the impacts of coupled models, in which the impact of positive feedbacks and carbon sink failures are calculated. The Hadley centre, which contributed evidence to the fourth assessment report of the Intergovernmental Panel On Climate Change, has examined the differences between coupled and uncoupled modelling, and shown that if we followed the coupled model, global carbon emissions would have to be reduced by 80 per cent., not the 50 per cent. that many people are now talking about. That is a radical step change in the budgets that we should consider. Should anyone care to look at it, that evidence from our own Hadley centre is repeated authoritatively in the IPCC AR4 work group 1 report, chapter 10, page 791. There is already a big change in Government, which is welcome, and my right hon. Friend the Secretary of State should be congratulated for shaking things up. However, we always seem to be chasing our tail on climate change policy, and the science seems to be pointing south—even more so than six months ago. In March, the Copenhagen congress on science suggested that the impacts of climate change will be worse than many people thought.