Following today's announcement of Chris Huhne's environmental tax plan The Green Switch, I have to say that it is both worth the wait and delivers all of his promises from the leadership campaign.

The £2,000 Vehicle Excise Duty for Chelsea Tractors Policy has caught the eye of the press - the BBC picked it up almost straight away, and I imagine most of tomorrow's broadsheets will carry it - the Grauniad reports here.

Better still, the Friends of the Earth put out a friendly press release within hours of the announcement, stating: -

"Greening the Budget is crucial if the UK is to reap the economic benefits of responding early and decisively to climate change. After an encouraging start Gordon Brown has gone cold on the green tax agenda. The Liberal Democrats appear to have more fully grasped the potential benefits of green taxation for the economy and the environment."

With any luck, this should follow our announcement into some of tomorrow's papers. I suspect that there might be something of a backlash over this - funny as it is:

"Green taxes can help change behaviour in a way that hugging a husky cannot. Tory hot air won't help cool the climate."

One wonders how our partners in Cross-Pary Approach to Climate Change will react...

Back to the policy: The Green Switch delivers everything you want from a policy announcement - it's innovative, it's ethically sound, and it's a vote-winner. Sadly, the local elections came too soon for it, but if anything it's an indication of how much of a handicap Ming and the party had for these elections, having somewhat perilously changed horses mid-stream. If this is an indication of the sort of quality we're going to be getting in the Campbell era, then I remain optimistic that we can win over the electorate in time for the next election.

I'm particularly pleased by Huhne's suggestion to reform the way we implement the EU Emissions Trading Scheme, a programme that has come in for a fair amount of criticism recently. I'm a firm believer in free-market environmental programmes like carbon trading, but the EUETS has an number of shortcomings, not least the disappointingly high level of the overall emissions cap and the tendency of firms to pass carbon costs on to their customers - the latter is particularly disappointing behaviour, given that these firms were given a large portion of their allocations for free! The EU needs to correct this topsy-turvy situation, not only making companies pay for more of their carbon but stamping out anti-competitive price-gouging. I'm glad to see Huhne is taking a strong lead on this.

I'd like to elaborate on this point, as this is something I've been mulling over for a while. I think that a reformed, properly-run EUETS could be expanded to cover non-EU countries, allowing eventually for a global emissions trading structure. The way to incentivise this would be in exactly the same way that membership of the EU itself is incentivised - by having specific external "green" tariffs and internal market liberalisation. (Yes, that is Gladstone turning over in his grave that you can hear.)

I suggest this, because it ties in with a topic to which countless Lib Dem blogosphere column inches have been devoted since the local elections, and that is the apparent rise of the Green Party at our expense. I believe that this is the defining issue that sets us apart from the Greens - this issue of trade and globalisation. Green opposition to globalisation verges on the fanatical (see mad ranting here) but exposes one of the core contradictions in Green Party philosophy - the rejection of truly global solutions to solve a global problem.

Unilateral green action on the scale being suggested would do little besides dismantling the British economy - and as we retreated back into the Stone Age, we would watch helplessly as the Americans continued to drive cars the size of houses and the Chinese built more coal-fired power stations.

What we need to solve the CO2 problem is an emissions trading scheme with everyone on board - a World Carbon Bank if you like. The problem with efforts thus far is that they have failed to get key players like the Americans signed up. It's easy (and a cop-out) to blame Bush for this, but it's worth bearing in mind that the US Senate voted against Kyoto by 95 votes to nothing - this is highly unlikely to change under a different administration!

The problems that the Americans had with Kyoto were that it did not include developing nations and that, while it had limited emissions trading provisions, it was not free-market enough - a World Carbon Bank has the potential to solve both of these problems. Expanding the EUETS could provide the first tentative steps towards this goal - and controversial as it may seem, I would be much happier if Wall Street bankers were getting rich selling carbon emissions than oil shares!

I mention all this in the hope linking the environment and trade (a traditional Liberal hot topic) can become one of the Big Ideas that help to sustain our party in this new century. Alex Wilcock has already suggested linking the environment and health, which has the potential to be a Big Idea - Huhne's environmental tax plans certainly feel like Big Idea territory as well.

Were I writing the brochure tomorrow, this is how I'd be tempted to sum it all up:

• Environment and Health - Clean air, clean water, clean food
• Environment and Trade - Building a world environmental community through free and fair trade
• Environment and Wealth - Green taxes to lift the poorest out of poverty

Doesn't sound too bad to me!

Now go and read Alex's post, if you haven't already.

Edit: And check out Joe Otten's analysis of the announcement, too.