Former prime minister John Key once described it as "a joke" - but now a Hamilton student's climate-change lawsuit against the Government is about to get an airing.

In a case thought to be the first of its kind, Sarah Thomson has taken Climate Change Minister Paula Bennett to court over what the 26-year-old claims is a lack of action over the issue.

Bennett says she's comfortable that New Zealand's target, pledged as part of the Paris Agreement ratified last year, is fair and ambitious.

Thomson filed papers with the High Court ahead of the UN conference in Paris in 2015, in an unusual suit that John Key then dismissed as a joke, pointing out that climate targets by the US and Australia aimed lower.

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But the young law student has remained serious about the action, and was recently notified the case is to be heard at the Wellington High Court next month.

It challenged a claimed failure to review climate targets after the UN's Inter-governmental Panel on Climate Change (IPCC) released its Fifth Assessment Report in 2013.

The suit further challenged the Government's target to slashing domestic greenhouse gas emissions by 11 per cent below 1990 levels and 30 per cent below 2005 levels by 2030, which Thomson argued was "unreasonable and irrational" against the seriousness of the issue.

The suit was filed when Ambassador to the US Tim Groser was Climate Change Minister.

"I'm arguing that the Minister failed to take into account relevant considerations when deciding the target - the Minister considered the cost of reducing emissions, but not what climate change will cost us if we fail to act," Thomson told the Herald today.

"I'm also arguing that the target is irrational because it's well below what's needed to strengthen the global response to climate change.

"I'm taking the case because action on climate change is urgent, and it's going to affect everyone and every aspect of our lives."

Thomson argued a failure to reduce emissions would result in more extreme weather events, which would put peoples' homes and health at risk, make food prices rise, and have a significant impact on the economy.

"At the very least, I would like to see the court order that the target is unlawful and needs to be reviewed."

Bennett, whose lawyers have prepared a Statement of Defence in response to the challenge, said she was limited in what she could say as the case was before the court.

"However, we are very comfortable that our Paris target is fair and ambitious, and that it was set only after a thorough process of consultation."

Other actions being led by the Government included phasing out the "one-for-two" Emissions Trading Scheme credit measure and reviewing the ETS to ensure it was fit for purpose, phasing down the use of hydrofluorocarbons by 80 per cent, spending $2 billion on public transport, increasing renewable electricity to 90 per cent by 2025, eliminating fossil fuel subsidies, investing $20 million a year in agricultural greenhouse gas research, and the planting of more than 5.5 million trees this winter.

Further, the Government had pledged up to $200 million in international aid for climate-related support, $1.3m to support Fiji's presidency of the UN Climate Change Conference and $31 million on research into understanding climate change and its impacts.

Elsewhere, the Government had set up three new expert groups to look at adaptation, agriculture and forestry to address climate change, signed the Climate Change Action Plan with China, begun joint discussions with Korea on developing carbon markets and started toward doubling the number of electric vehicles registered every year to reach 64,000 by 2021.