The government was told its climate target for 2035 was "below expectations" for a developed country and unlikely to meet the expectations of key partners and the international community.

Officials laid out their assessments to Cabinet for a range of possible climate targets, starting from cutting emissions by 51 percent by 2035 and topping out at 65 per cent reductions.

The lowest possible starting point was 51 per cent, because the Paris Agreement requires each country's new target to be a step up on its previous one - and New Zealand's target for 2030 is 50 percent.

That was the figure the government went with.

As well as being the lowest, it was also rated by officials as the cheapest and most feasible to achieve.

However, the government left open the possibility of achieving a 55 per cent reduction if the technology for reducing livestock emissions and other developments go well.

When Climate Change Minister Simon Watts announced the 51-55 per cent target, he described it as "ambitious".

However the assessment he showed Cabinet - which the Ministry for the Environment proactively released this month - rated a 51 per cent target as having "low alignment" with the principle of fairly sharing climate efforts between rich and poor countries. It was described as "less likely to to be considered sufficient by key partners and the global community" compared with any other target. A 55 per cent target was rated slightly better but still not strongly on the Paris Agreement's principles of equity.

The lowest target was, however, also rated most feasible to implement and least likely to involve spending money.

Under the Paris Agreement, each country's target is supposed to represent the "highest possible ambition" in light of national circumstances.

As a developed country, the advice says New Zealand is expected to do more towards global efforts.

In a Cabinet paper, Watts told other government ministers that a target range of 51 per cent to 55 per cent "represents our highest possible ambition given our national circumstances."

He said it was "a relatively small progression over the 50 per cent reduction [for 2030]".

"Other countries are likely to progress their [Paris] commitments by more."

However, he noted it could be achieved inside New Zealand, unlike the current target, which requires overseas help.

"Officials estimate that achieving a reduction of 51 per cent to 55 per cent will reduce GDP by 0.1 per cent to 0.3 per cent in 2035, and cost the average household $80-$195 per year or about $1.50-$3.75 per week," Watts advised his colleagues in the Cabinet paper.

He also noted that the government was already legally required under the Zero Carbon Act to reduce emissions in line with a 51 per cent cut by 2035, so this did not require any extra work.

However, the government is currently 9 million tonnes short of meeting its obligation under the Act, based on policies today, a gap Watts said would be addressed closer to the time.

Achieving a 55 per cent target would require an extra 10 million tonnes of emissions cuts on top of what was already required of the government in domestic law, he said.

"There is uncertainty about what levels of emissions reduction will be feasible in the 2031-35 period," he said.