The Environmental Protection Agency’s decision that carbon dioxide and five other gases contribute to climate change, and should therefore be regulated, sparked predictable excitement from the green movement and outrage from groups representing carbon emitters.

As we pointed out on Friday, it won’t be clear for quite some time what this means in terms of regulation.

But John Kemp at Reuters believes that administration officials are talking up that lengthy time frame to reassure legislators and business organisations, while telling green groups that they are prepared to go ahead with measures to regulate greenhouse gases even if supporting legislation is not passed.

Part of the complexity of the decision, he says, relates to the components of the Clean Air Act, which is in fact a series of laws passed over three decades. They divide into Title I of the Act, Air Pollution Prevention and Control, and Title II, Emission Standards for Moving Sources.Title I covers all sources of pollution, but Title II applies primarily to motor vehicle.

The UK’s total investment in renewable energy has fallen sharply in 2009, research from New Energy Finance shows, which meant it fell in NEF’s international rankings from 5th place in 2008 to 15th place, behind Bulgaria and Peru. After investment of £2.5bn last year, the UK saw only £138m of investment in the first quarter of 2009.

The figures show it is Spain that has something to boast about; it has gone from second to first place, pushing aside the US, where congressional hearings on  a clean energy draft bill begin tomorrow.

There was scepticism from NEF that the UK would reach its target of achieving a 26 per cent reduction in emissions from 1990 levels by 2020, and from Cambridge Econometrics that the UK would reach its EU target of 15 per cent of energy coming from renewable sources by 2020. And this is despite the recession which is expected to take about 3 per cent per year off emissions with no effort from policymakers.