“We think that the December quarter of 2022 may have been the lowest levels of pollution this century,” he said, clarifying that was gross emissions.

Robert McLachlan, distinguished professor in Applied Mathematics at Massey University’s School of Fundamental Sciences, says the latest emissions data from the Ministry of Business, Innovation and Employment (MBIE) were “stunning”.

“Climate policy is working - slowly.”

IMAGE: Robert McLachlan

The 12-month renewable share of electricity topped 90% for the first time since December 1981 and emissions from burning fossil fuels are now at their lowest level since June 1999. “Electricity and gas emissions remain at record lows. Oil is equal to pre-Covid [2019].”

While emissions from fossil fuels are a big chunk of gross emissions, McLachlan says they are also the most important part. “We have to stop burning fossil fuels and agricultural methane doesn’t have to go to zero, it just has to reduce a bit. Although fossil fuels is only half the emissions, it’s more than half of the needed reductions.”

He says the numbers are “very, very good indeed. But the question is, can the government take the credit for that?”

McLachlan believes the government can take credit for the Zero Carbon Act, low-emissions investment, and the Clean Car Discount all working to drive down emissions.

“The government can take credit for a big chunk. But it’s also the mood in the country - for example, Fonterra deciding to take action.”

He says it is a pity the National Party would scrap the Clean Car Discount if elected. “That’s been very successful.”

The Ministry for the Environment has advised that we are now on track to meet the first carbon budget to 2025 - after formerly being set to miss the target, with high uptake of EVs and high petrol prices making up for dropping the biofuel mandate.

But McLachlan says it is “very hard” to predict if emissions will stay low. “But I don’t think we’ll go back to the record highs.”

He says that maintaining low emissions will take strong action on fuel efficiency standards, including heavy vehicles, as well as increasing electrification and public and active transport.

“Let's hope that those four years with oil emissions over 5 million tonnes CO2 each are never repeated.”

However the Electricity Authority has said supply is looking tight for the next three winters. “Depending on the lakes we might have to rely on fossil fuels again for generation,” he says.

However, “the trends are good.”

In an aside, McLachlan said he was disappointed that National Party leader Christopher Luxon wrongly stated, during last night’s leaders’ debate, that Huntly power station was burning Indonesian coal. “That hasn’t been the case for three or four years. They mostly use their own coal from a coal mine in Waikato.”

Climate Change Minister James Shaw also called out Luxon's comments on Twitter, pointing out that coal imports are at their lowest since 2013.