Abstract

A global target of stabilizing greenhouse-gas concentrations at between 450 and 550 parts per million carbon-dioxide equivalent has proven robust to recent developments in the science and economics of climate change. Retrospective analysis of the Stern Review suggests that the risks were underestimated, indicating a stabilization target closer to 450 ppm CO2e. Climate policy at the international level is now moving rapidly towards agreeing an emissions pathway, and distributing responsibilities between countries. A feasible framework can be constructed in which each country takes on its own responsibilities and targets, based on a shared understanding of the risks and the need for action and collaboration on climate change. The global deal should contain six key features: a pathway to achieve the world target of 50 per cent reductions by 2050, where rich countries contribute at least 75 per cent of the reductions; global emissions trading to reduce costs; reform of the clean development mechanism to scale up emission reductions on a sectoral or benchmark level; scaling up of R&D funding for low-carbon energy; an agreement on deforestation; and adaptation finance.