The government's plan for combating climate change is already being condemned as toothless.

Photo: RNZ / Dom Thomas

The proposed legislation sets a new emissions reduction target for greenhouse gases like carbon dioxide to net zero by 2050, and establishes an independent Climate Commission.

It sets a lower target of 10 percent reduction for methane emissions by 2030, aiming for cuts of 24 percent to 47 percent by 2050.

The plan is in line with New Zealand's commitments under the Paris Agreement but there are questions about how it will be enforced. Courts cannot impose legal sanctions on those who drag their feet, they can only issue a determination.

Greenpeace New Zealand chief executive Russel Norman, a former Green Party co-leader, said the bill was toothless.

"What we've got here is a reasonably ambitious piece of legislation that's then had the teeth ripped out of it. There's bark, but there's no bite," he said.

Watch Russel Norman's interview on Checkpoint:

"The bill sends some good signals, until you get to the section at the end that negates everything else you've just read. This section states there is no remedy or relief for failure to meet the 2050 target, meaning there's no legal compulsion for anyone to take any notice.

"The most anyone can do is get a court to make a 'declaration' that the government isn't achieving its climate goals, but this declaration doesn't make the government actually do anything."

Photo: Supplied

James Young-Drew from youth-led climate change group Generation Zero said that needed to change. He will be pressing for amendments at the select committee.

"That includes giving the courts the power to impose legal sanctions. The carbon budgets and the targets that we are signing onto, absolutely must be legally enforceable," he said.

Prime Minister Jacinda Ardern was downplaying any concerns about compliance, and said it was clear industry was taking its obligations very seriously.

"The commission will be involved in helping us budget across industries, they will be factoring in whether or not the technology exists for us to be able to set an expectation that's reasonable of different sectors as well," Ms Ardern said.

Under the bill, methane will be treated differently to other greenhouse gases, in response to push back from the agricultural industry.

Federated Farmers said the legislation sent the message New Zealand was willing to abandon pastoral farming.

Spokesperson Andrew Hoggard said the provisions calling for the sector to reduce biological methane emissions was "frustratingly cruel".

Climate Change Minister James Shaw said the government had tried to balance the need for action, against the impact on farmers.

Mr Shaw said there was collective responsibility for reducing emissions.

"It is patently unfair for those of us who live in cities to ask the farmers who we depend on for our food, to go through a steeper transition, if we choose to continue to drive around in fossil-fuelled cars, when we could be switching to cleaner options," Mr Shaw said.

The prime minister also highlighted the $20 million government investment in agricultural research.

Fonterra's director of sustainability Carolyn Mortland said much more research was required.

"There needs to be significant investment in innovation and research. We have jointly partnered with the government and will continue to do so, but we will be looking for continued and significant investment from the government," she said.

The aviation industry was among the worst greenhouse gas emitters.

Christchurch Airport chief executive Malcolm Johns said alternative technology would play a key part in improving performance.

"There are electric planes in development, they're not commercial yet and you can't get in an electric plane and go to Shanghai or Los Angeles yet. By 2035 - 2040 it's highly likely that we will start to see different technologies come into all parts of transport," he said.

"What this bill says is that we have to get on and be part of that journey," he said.

It was not clear from today's announcement what the cost to the country would be, but the chair of the climate change iwi leaders group, Mike Smith, said it was time other sectors assumed their fair share.

"Māori took a real haircut over our treaty settlements, in order to preserve the health of the economy and we settled for less than one cent in the dollar basically our historical grievances and the cost of those to the economy. So I think if we're prepared to do that we have an expectation that other sectors need to assume their share of the responsibility as well," Mr Smith said.

The public will have a chance to have their say on the bill when it goes before a select committee next month.