A main thrust will be to draw the US, the world’s largest emitter of greenhouse gases blamed for global warming, into the process. Washington did not ratify the Kyoto Protocol, arguing that mandatory cuts in emissions would harm the economy and calling into question the veracity of global warming science.

Speakers on Monday said the world had more to lose by inaction than by taking some of the costly steps needed to cut emissions.

“One of the stumbling blocks so far has been the fear of economic hardship,” said Indonesian Environment Minister Rachmat Witoelar, the host of the Bali meeting. “Though the cost will be significant... it’s insignificant compared to the damage that uncontrolled climate change will wreak.”

Among the most contentious issues ahead will be whether emission cuts should be mandatory or voluntary, as the US favours. Also to be tackled will be to what extent up-and-coming economies like China and India will have to rein in their skyrocketing emissions, and how to help the world’s poorest countries adapt to a worsening climate.