The New Zealand Government is accused of ripping off future generations by not taking action on climate change while it's still relatively cheap to do so.

Law student Sarah Thompson, 26, is suing the Government over its climate change targets, alleging it's not doing enough.

Her lawyer, Davey Salmon, today argued in the High Court at Wellington that the National Government was looking for reasons to delay taking action.

"No one wants to be the first nudist at the beach," he said.

Advertisement

"We shuffle along with the crowd, but no one takes the first brave step.

"But every country needs to be bold and brave, even if the other countries aren't yet. By behaving like this, we're exacerbating delays from others.

"We must not hide behind the way in which our wealth is secured, or our relative size. Every city and country in the world can break it down into reasons why it should not act."

Salmon said that the Government was wrong in its approach to the Paris Climate Accord, by treating two degrees of warming as a target rather than an absolute upper limit.

He argued that as a developed country New Zealand had a responsibility to take the lead, and do more than the global average in responding to climate change.

"If the real cost is $1 now and $2 then, we must do it now.

"If the cost is $1.99 now and $2 then, we must do it now.

"If we do it all right now, we don't have to hope we invent an apparatus or time machine that somehow removes carbon from the air. We can still plant trees.

"You could think the reason for action is we need some target, let's get a cheap one. But we're not buying baked beans at the supermarket.

"The reasons for action are that the costs of inaction are terrifying.

"It is such an illogical approach. In saying how much should we do to avoid this bad thing, they are avoiding saying how bad this bad thing is."

Peter Gunn, defending the case on behalf of the Government, said the legal action wasn't realistic.

"[New Zealand has] an agricultural sector that is very efficient, based on many metrics.

"Some might take issue with those metrics, but that's certainly the defendant's proposition, that New Zealand is a very efficient agricultural producer.

"Getting rid of cattle is a potential step towards reducing emissions.

"But you impact on food in the first instance, and the demand for food is still out there. Then you transfer that burden to a less efficient producer, with a consequent impact on emissions levels."

Gunn said there were no quick fixes and the Government needed to ensure its action on climate change was sustainable.

"New Zealand has to be part of a global movement because of the fact of New Zealand's emissions profile.

"If New Zealand reduced its emissions down to zero, there is going to be no noticeable change in the impacts of climate change.

"We must rely on the efforts of others and the global community to achieve appropriate action. The point is New Zealand cannot do it on its own."

Supporters showed up in large numbers yesterday to support the first day of the court case, with several waving banners outside the High Court.

The public gallery was packed with supporters again today, for the second day of arguments.

The hearing is expected to wrap up tomorrow.