Rudd offers a possible 25 per cent cut, but only if comprehensive global agreement on emissions reduction is reached in Copenhagen in December.

This won't happen, and he knows it.

So the original, inadequate, 5 per cent reduction target remains. But now there's a delayed start, a price for carbon too low ($10 a tonne) to drive real behavourial change, and even more free permits for big polluters.

In practice, this means all the "reductions" in Australia's emissions are likely to come from buying permits from developing nations to offset emissions, under schemes such as the Clean Development Mechanism.

This is certainly what the Government expects to happen. Treasury projections show Australia's actual emissions rising by 2020, not falling.

The dilutation of the CPRS was condemned by most environmental organisations and generally met with approval from the big fossil fuel polluters.

And, in case you missed it, the big emitting industries scored another win last week when they were exempted from the Mandatory Renewable Energy Target (MRET) scheme.

What's surprising is that two of Australia's largest environmental organisations, the ACF and WWF, have given Rudd's latest announcement a qualified tick of approval.

It's still unclear whether the CPRS even in this watered down version, will pass the Senate. With the independents and Greens opposed, it depends on whether the Coalition support it.

I've previously speculated that Rudd wants the Opposition to vote down the CPRS. That gets him off the hook: he can avoid the tough job of implementing a complex, unpopular and useless scheme but still go to the next election portraying himself as a climate change crusader with the Opposition as die-hard climate deniers.

On the other hand, Rudd would love to present himself at Copenhagen as a "world leader" on climate change - hence the mention of a higher 25 per cent target.

For a more detailed critique, here's David Spratt of Carbon Equity.