UPDATED 7.07am: The Government's climate change ambitions are being challenged ahead of an upcoming UN conference on the issue in Paris.

It's looking to back a target that restricts global temperature increase to no more than two degrees.

Labour Leader Andrew Little Little doesn't think it helps that the bid New Zealand's putting forward on what it'll commit to is pretty low compared to that from the Europeans.

He thinks we can afford to do something more ambitious.

"But if getting a deal means we're just going to low ball it, and take a lesser outcome then its not going to address the long term problem of climate change and rising sea levels, which is important to us and our Pacific neighbours."

But John Key sees things very differently.

The Prime Minister's optimistic the UN Climate Change Conference in Paris will see some steps taken to address global warming.

Key said no system's perfect, pointing out some countries pulled out of the Kyoto Protocols while others used cheap carbon units from developing states.

But he thinks we're seeing an acceptance by a wide range of countries that climate change needs to be dealt with.

"I don't think it'll be absolutely plain sailing in Paris, but I do think you're going to get progress."

'We could be doing more'

A leading climate change academic says Kiwi households shouldn't be too quick to congratulate themselves on cutting greenhouse gas emissions.

Research released this morning shows the carbon footprint of the average New Zealand household is getting smaller.

But he said greenhouse gas emissions from New Zealand households were bad to start with, and now they are only marginally better.

"We're still driving big cars and we're still wasting food and we're still not turning our lights off."

Sims said we're still not pulling their weight on the world stage.

"We've got a long way t come to reduce our greenhouse gas emissions per persona and therefore compare with other countries in Europe and elsewhere in the world that are much lower than we are."