I'll await Dazz's reply for the Official reason on what the purpose of the CT was/is - from one who actually knows.
I'm not in a position to do that Bayview, but can offer some fairly obvious turning points that is public knowledge.
A hell of a lot in all of these public debates hinges on the language used.
The groundwork was done to create these "dirty polluters".....the so called big bad 500 companies that for many months / years the list identifying these companies was kept a secret by the Labor Govt. Of course, before the "dirty polluters" label, they were simply power companies and mining companies and transport companies that everyone in society relied upon for cheap power, cheap building products and cheap logistics.
Suddenly....if you subscribe to a certain ideology.....they are re-badged as "big dirty polluters". If you don't subscribe to a certain ideology, they are simply providing useful products society demands at a minimum of cost. Critically, many many many members of society believe the price of the products, based on electricity cost, and the flow through effect it has within society, is waaay too high as it is and want it to come down....not go higher.
Those who subscribe to the first ideology couldn't give a rats about the cost and are happy to spend whatever it takes to convert society to their way of thinking. Crucially - the struggling battlers - who vote en masse - are not happy with this philosophy and are not prepared to sacrifice the extra money.
Turning points
6 days prior to Aug 2010 federal election, both Labor and Liberal commit to their being no Carbon Tax.
17 days after the Aug 2010 federal election.....due to the result of the lower house, and the 9 senate seats the Greens control, Julia realises that without getting into bed with the Greens, she will have presided over the only first term loss of Govt since Whitlam. She gets into bed and pays whatever price is necessary.
The necessary price extracted by the Greens is a Carbon tax.
The price is paid.
Without the hung parliament result, we would not have a Carbon tax. It's a thought bubble from the 10 or 11% of the population that vote Green. Like most of their thought bubbles, when practically implemented, they usually turn to custard. The Greens come up with all sorts of ideas, but because they never have the heavy burden of implementing responsible governance, they have no clue what damage their ill thought out plans can inflict.
Liberals call the Carbon tax for what it is, a lie foistered on them without their consent. Liberals run a campaign centred around this lie. It becomes the first ticket item on the Liberal agenda if they are successful at the election.
Sept 2013, the first chance the Australian public actually get to have a say on what they actually think of the Carbon tax. The Australian public unequivocally give their decision through the ballot box. The majority of people do not want a Carbon tax. It's utterly rejected by a 53 / 47 majority, which more importantly translates to a 90 / 55 seat majority on the floor.
Of course, life is far more complicated than that, and there are a multitude of reasons on why people vote. The Carbon tax wasn't everything, but it was a significant difference between the two major parties.
Labor is kicked out of office. They'll be the opposition for a very long time. What their ideology is on the subject and what the Greens ideology on the subject is, has been kicked to the back blocks for a good while.
I suspect however, in the mean time, whilst they sit and twiddle their thumbs in the backblocks, the zealots will continue to push their ideology, completely ignoring the will of the people as demonstrated convincingly at the ballot box.