By effectively agreeing to the continued use of fracking by the mining industry this week, the Parliamentary Commissioner for the Environment has also highlighted a potentially tricky area of difference between future coalition partners Labour and the Greens.
Labour warmly welcomed the Commissioner's report - which rejected a moratorium on fracking and signalled the need for tighter standards.
The Greens on the other hand seemed stunned by the decision, and maintained that the mining technique was not safe and it should be banned until it is proven that it is.
It's a sharp divide, but in fact one that may only be the tip of the iceberg when it comes to differences in opinion on environmental issues for these two parties.
Take for example National's reforms of the Resource Management Act which are likely to see a much bigger emphasis in the legislation placed on development over sustainability.
My understanding is that some members of Labour will be pretty comfortable with these changes, particularly those MPs in depressed regional areas desperate for new jobs and development.
The Greens on the other hand will hate them and be pretty hostile towards any change, particularly if there is any significant loss of community, say, in major developments.
Exactly how Labour approaches the RMA changes due early next year will be fascinating.
If the enthusiastic response for fracking shown by leader David Shearer is anything to go by, then they may well offer some conditional support for the changes. We will have to wait and see.
But if Labour's pro-development MPs did win out and the party backed National's RMA changes, it would create another awkward division between Labour and the Greens.
One that its opponents would no doubt look to exploit.
Outside an election year differences in view between the Greens and Labour are not too much of a problem and in fact probably suit both parties to an extent as they compete for swinging left wing voters.
The Greens quietly backing themselves that they can syphon off Labour party activists who feel that under David Shearer the party is too right wing. Whilst Labour will be quietly happy to see the Greens show a more extremist anti-development face to the public in the hope of winning the centre ground.
However as the next election nears these two parties will need to start highlighting their unity not their divisions.
If they are to present as a credible alternative left wing block at the next election, the public will need to be confident that they can work together in a stable manner.
Having divisions and differences of opinion on issues is OK, but the leaders of both parties must communicate to the public how they would overcome these and work together in government.
Of course much will also would depend on the support levels of each party. In other words where the power balance lies between the two.
On current polling it still looks like Labour would be the dominant partner in any coalition. However don't expect to see the Greens being pushed around by Labour as they were during the Helen Clark years.
In fact I suspect we could yet see a stronger showing from the Greens in 2014.
Labour's recent conference exposed a party still searching for what it stands for, with a leader yet to completely win over his base.
The Greens on the other hand have two very accomplished leaders, a growing membership and an impressive media and support team.
They are fast to respond, seem focused and on top of their game.
The only thing close to a gaffe (and that is debatable) this year being Russel Norman's call for New Zealand to follow the lead of the US and UK and print money to help stimulate the economy.
Next year both parties will need to start producing more new policy.
As they do so it should become a lot clearer as to whether the parties are heading in the same direction and how well they will co-exist in future.