Labor proposes a cap and trade system - not a carbon tax (which is quite different). The Greens' policy is more structured around outcomes but they will support a cap and trade if the larger (by mass) polluters are not subsidized by the issuance of free certificates. It was the issuance of free certificates that almost killed the EU cap and trade system.
Ironically the Liberal Party was proposing a carbon tax if I remember correctly. Now they are proposing something called "Direct Action" which, I suspect, means no action.
The cap and trade system has a lot to recommend it. It has worked brilliantly in the US over the last 20 years for sulfur dioxide and nitrogen oxide reduction. The US did not issue any free certificates but did phase in reducing targets. It is hard to see why this system will not work for carbon dioxide as well.
In summary, if you wish to do something positive for climate change then it is probably best to vote for the Green Party. If you wish to ignore the problem then it is best to vote for the Liberal Party.
With respect to Essendon Airport its existence, as I have said previously, is a matter of legitimate public interest. That the airport meets the regulatory conditions is a necessary, but insufficient, requirement for its continuing existence. It also needs the support of the community.