The target is to cut the territory's emissions of global warming gases by more than half of what they were in 1990 by the middle of the next decade and to achieve zero net emissions by 2045.

This is a very ambitious target, demanding a re-engineering of the city (and a re-engineering of our attitudes - or, as the government puts it, "behavioural change").

The cornerstones of the strategy are phasing out the use of gas, getting people to switch to electric cars and the planting of tens of thousands of trees.

The aim is admirable. But the means are fraught with difficulty.

Firstly, no cost has been put on the change. It's true that the government has allocated $17 million towards the strategy but there is no single, headline figure spelt out for implementing the whole plan.

The scheme involves some tax rises, albeit internal ones within government departments so that high emitters of carbon dioxide would pay a "carbon tax" penalty as an incentive to get output down.

And there will be a cost of converting existing homes away from gas. The ACT government said it would pay to install electrical appliances in public housing units to ensure a "just transition" to zero emissions - but the majority of Canberrans who are not in public housing would foot the bill for that transition.

There would also be a cost to householders and public buildings if they were forbidden from using their existing gas appliances. Already weary from the growing financial load of increasing rates, many Canberrans will be alarmed at the prospect of having to convert their households.

To counter the obvious objections, the government emphasised that the transition would not be overnight. Chief Minister Andrew Barr stressed that Canberrans would not "wake up one morning and everyone is going to be driving electric cars".

Ministers believe that the public is behind them. "I think there is an appetite in the broader Canberra community for this sort of partnership approach and there is certainly a lot of distress at the lack of action at a national level," Mr Barr said.

This may be true - but you don't need to be the most cynical observer of politics to think that good intentions sometimes go out of the window when the bill comes in.

The government is to be applauded for its good intentions. If you aren't ambitious, you won't achieve.

Cities can transform themselves. The government wants Canberra to emulate the Danish capital, Copenhagen, where cycling is now one of the main means of transport - and the heartening story from Copenhagen is that policy plus money can change attitudes and patterns of behaviour.

But now the government needs to be forthcoming about how its good intentions might become reality.

There is a danger with the most ambitious plans that they stir up strong opposition early.

These plans take Canberra way beyond the current or even the next electoral cycle. Today's politicians will be long gone before the bills roll in.

If the government can't convince the voters - and tax-payers - that their strategy will be worthwhile, the risk is that hardening doubts will scupper it.