US energy secretary Steven Chu arrives in China today for the latest in a series of trips by high level US officials to Beijing in the lead up to the Copenhagen meeting in December. Although neither country is pursuing a bilateral deal, a good part of the success of Copenhagen will depend on whether the two biggest emitters of greenhouse gases can both make concrete concessions and commitments. But after the optimism over last week’s G8 commitment, this week is looking decidedly grim.

Many countries, including China, say they want the US to legislate for carbon emission cuts before making their own commitments at Copenhagen in December. But in an increasingly familiar scene of climate change chicken, some US political constituents want China to make its own commitments before supporting legislation in their own country – and that is something that China has so far resolutely refused.