New Zealand has made a step forward with the passing of the Zero Carbon Act, but lax enforcement and an unwillingness to tackle agricultural emissions has seen New Zealand once again slapped with an "insufficient" grade from the Climate Action Tracker.

The independent scientific group rates how governments are progressing towards the Paris Agreement aim of "holding warming well below 2°C, and pursuing efforts to limit warming to 1.5°C."

This is the sixth time in a row New Zealand has been marked "insufficient".

The group gave the government credit for passing the world's second-ever Zero Carbon Act, though they pointed out that the Act was simply a framework and doesn't include any policies to actually cut emissions.

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The Zero Carbon Act was criticised for a lack of ambition, due to the fact that methane, which makes up 40 per cent of New Zealand's greenhouse gas emissions, was only included under a separate target.

The emissions trading scheme, which is meant to be the government's primary way of reducing pollution from large companies, was also labelled as ineffective.

The scheme requires companies to buy carbon credits to offset their emissions, but the scheme has been gutted by a series of half-measures.

JOE LLOYD/STUFF New Zealand's climate policies have been labelled 'insufficient'.

Agriculture, which makes up 47 per cent of all emissions, is exempt from the scheme, and many of the largest emitters in the country - including the Rio Tinto aluminium smelter - receive massive subsidies that cover 95 per cent of the cost of credits.

The government was also admonished for a backdown on electric car policies. Transport is New Zealand's second-largest source of emissions. The government had previously announced a target that all government-owned vehicles would be electric by 2025, but this has now been pulled back to all new vehicles bought by the government being electric by 2025.

The report warned that New Zealand was not on track to meet the Paris 2030 targets and that if every country followed similar practises it would lead to global warming upwards of 3 degrees Celsius.