Coping with climate change also poses important questions about equity and how to work together internationally. Historically the bulk of accumulated emissions have come from the pioneers of the industrial revolution — essentially Europe and North America. But their demand for energy is now, on average, relatively slow-growing.

Tomorrow’s high emitters are the fast-growing and highly populated developing countries, such as China and India. Ambitious targets will drive the new markets which will channel financial flows from the private sector to the large-scale investment needed for low-carbon energy in these countries.

The additional costs to developing countries of adapting to climate change makes it more urgent than ever for developed countries to honour their commitments — made in Monterrey in 2002, and strengthened at the G8 Gleneagles meeting in 2005 — to double aid flows by 2010.

Despite the size of the challenge ahead, the findings of the Review are essentially optimistic. If we act now, and work internationally, we can reduce the risks drastically at modest cost. But if we delay just 10 or 20 years, the costs will be much higher, and the risks much greater. With strong and urgent action, governments, businesses and individuals, working together, can safeguard our future growth and prosperity. We must not waste this opportunity. Our childrens’ future depends on what we decide now.

Sir Nicholas Stern is head of the UK Government Economic Service, and a former chief economist of the World Bank.