This is a reasonable article, but I think the notion of the ETS being a potential wedge on the Greens is overstated. I also believe the Democrats' fatal GST decision doesn't really fit the notion of wedge politics either - at least in terms of it being an action or aim of John Howard's.

There are differing views between environment groups about the best strategy for getting an ETS which is strong enough to make the necessary cuts in emission reductions, but there is no disagreement about needing to make those cuts. ETS is core business for the Greens. Their only problem would be if they signed up to something widely seen as useless, which they won’t.

John Howard didn’t use or plan the GST to wedge the Democrats – he never expected to have to deal with the Democrats in the first place. The Democrats basically wedged themselves.

The ‘progressive vs centrists’ categorisation of those Democrats who voted against or for the GST doesn't accurately reflect what happened and why.

It was much more about keeping election (and post-election) promises and keeping to party policy, as well as not needing to rush a decision.

I think 'honest vs dishonest' is a better framework to use than 'progressive vs centrist'. When honesty was THE core brand of the Democrats over the 30 years they existed, it was much more damaging to be perceived to be acting dishonestly than it is for most political parties

At the time, the Democrats had the Greens as their main minor party competitor. When the Democrats angered much of their voter base by backing the GST - and refusing to acknowledge or accept the reality of this anger - many of their voters had the option of going to the Greens, as well as back to major parties.

With the Democrats now gone, the Greens don't have to worry about being wedged or threatened by another minor party competitor. They can afford to disappoint some of their more purist supporters, (not that I'm saying they're planning to) because these people have nowhere else to go.

Bit out of my depth here on party politics but I make this observation.
The split in the opposition might be a symptom of the revision of
CO2 climate change science that seems to be in full flight even if it
is somewhat under the covers.
Just like in the peak oil case pollies do not have the courage to take
an unpopular stance. Remember Sir Humphrey's saying ?
Yes Minister, very courageous if I might say so.

A split like this will not be obvious in the Labour Party because
to oppose the party policy and vote against the government legislation
is a capital offense and would lead to loss of nomination at the next
election.

If my observation is anywhere near correct there might be people in
the labour party who would be pleased to see some delay.

If labor isn't careful, this could be a reverse wedgie.

If in the senate it is rejected by everyone other than labor, it will just look like the bad legislation that it is.

The greens are rejecting it because it will have little impact on emissions and the coalition because it will cost businesses to manage.

a far more lethal 'wedge' or rather pin is the question to Bob Brown: does your party subscribe to anti-population policies and what level do the Greens want to see the Australian population by 2020?

And what about the negative double whammy-jeopardy effects of a very slow growth starving private sector, saddled with a deeply over prescriptive state, sustainably feeding the ever growing bloated public sector. Just look at green labor state governments over the past 10-15 years as an example! Its not who is driving miss daisy, but will she arrive in one piece and does she remember where she wanted to go in the first place or is it another magical mystery tour?