It sees the US pledging to cut emissions by 17% (below 2005 levels) by 2020, and 83% by 2050.

Make no mistake – wherever you stand on the rights or wrongs of this Bill - it was a hard won victory for the Bill’s proponents, and it seems likely that President Barack Obama’s personal intervention with some of the wavering voters may have saved the day (not to mention ferocious and overt last-minute deal making between various interests in the House.)

In reality though, the provisions in the final Bill accepted by the House are in themselves a shadow of the barnstorming ambition that Obama’s earlier rhetoric promised.

One of the biggest bones of contention lies in the Cap and Trade provisions, for example. Yes, emitters will be capped and have to amass buyable and sellable ‘credits’ equal to their pollution, but as happened with the European Emissions Trading Scheme (ETS), 85% of these permits will be given away (as opposed to 100% auctioning), effectively leading to windfall profits for those that receive and are able to sell them.

This was one of a number of important compromises that Obama had to make. Environmental organisations also reacted angrily to the fact that the benchmark year for emissions reductions is “2005 levels”. This compares with the EU for example, which uses much more challenging “1990 levels” as its own benchmark for reducing Carbon emissions.

The Bill also has a RES (renewable electricity standard) of 15% by 2020.

Critics have lambasted this for being too low, but it’s worth remembering that many States and Cities have their own renewable standards – many already go above what the new national RES will mandate – so the fact that wavering States also need to comply is no bad thing.

Investors in renewable energy always cite the need for long-term incentives and commitments to be put in place. A RES must fall into that category, and will hopefully see the US emerge as a strong market for the renewables industry as previous stars like Spain fade away (of course we’ll need to see the details, and whether there will be set-asides for various technologies for example).

Overall, though, this Bill is just a start of the process of change.

It reflects a fundamental departure from the Bush years in how the US administration regulates energy consumption and the environment, and therefore must be seen as a positive step.

And it will also provide a certain amount of direction to other countries in the run up to make or break climate legislation that needs to be thrashed out at Copenhagen (COP 15) later this year (imagine going into that with no US domestic commitments – unthinkably bad).

And despite its shortcomings, Obama fought tooth and nail to drag this Bill through the House, and must be applauded for his efforts. Now it’s on to the Senate, where passage will be even more precarious, and where he’ll need every ounce of his persuasive magic.