The bill for an American Power Act is full of compromise. Earlier plans for a cap-and-trade program - a tool designed to achieve emission reductions at the lowest economy-wide cost - have been watered down and industrial sources will not be covered by the "national pollution reduction plan" until 2016. To protect US manufacturers from carbon leakage, a controversial border tax will apply to imports from countries that have not taken action to limit emissions to a comparable amount, unless there is a global agreement to address climate change.

Unbridled support for new nuclear power stations is not matched by equivalent measures to promote renewable energy. A Renewable Portfolio Standard requiring a share of electricity to be produced from renewable sources is missing.

However, the Bill would amend the Clean Air Act to establish performance standards for new coal-fired power plants permitted from 2009 onwards. And it's a start. Hopefully the Senate will pass it before the UN climate talks in November/December. Otherwise, international climate change policies are likely to remain uncertain and fragmented.