The debate on action over climate change is stuck. Despite copious words and many international conferences, including a UN summit in New York this week, emissions of greenhouse gases continue their upward march. Could this change? One can at least identify the necessary conditions. One is leadership. But the most important one is evidence that tackling climate change is compatible with prosperity. The possibility of combining the elimination of runaway climate change with rising living standards could help transform the debate.

All but the most obdurate sceptics must recognise that the probability of irreversible climate change is much greater than zero. But the cost of buying insurance against that risk also matters. Fortunately, these costs might be quite low and, in some respects, even negative: eliminating reliance on coal-generated electricity, for example, would produce health benefits. So would building more compact cities.

These examples both come from an important new report from the high-level Global Commission on the Economy and Climate. It makes five fundamental points. First, the nature of the infrastructure we build over the next 15 years or so will determine the chances of keeping average global warming to less than 2C, the level above which many scientists think change might prove catastrophic. Second, to achieve such a change, the world must start changing its behaviour now. Third, over this period huge investments will be made in the infrastructure that is going to shape urban development, land use and energy systems. Fourth, by making the right investment decisions, the world could achieve at least half of the reductions in emissions needed by 2030. Finally, shifting the pattern of investment and innovation in the desired direction would add little economic cost and bring many benefits.