The empty New Zealand roads amid lockdown put a slight dent in greenhouse gas emissions last year, just-released statistics show.
But as normal life returned, climate pollution from households soared again over the rest of the year, and hit their highest-recorded level in the last quarter.
Experimental figures published by StatsNZ today show emissions were down 4.8 per cent - or by nearly 4000 kilotonnes of carbon dioxide equivalent (CO2-e) - over the year.
They showed that, despite a strong rebound in emissions across most sectors in the September quarter, emissions were down overall because of drops in the March, June and December quarters.
"The fall in emissions in the December quarter mirrors the fall in economic activity, which followed the September rebound," Stats NZ environmental economic accounts manager Stephen Oakley said.
Emissions were down 1.7 per cent in the December 2020 quarter, compared with gross domestic product (GDP), which was down one per cent.
It was the second time Stats NZ had put out quarterly estimates of New Zealand's gross emissions, using a special economic and environmental system that drew heavily on data from the official greenhouse gas inventory.
In the December 2020 year, only emissions for the transport, postal, and warehousing industry remained well below pre-pandemic levels, because of the ongoing border closure.
Their emissions were down 38 per cent, and their GDP also dropped by 26 per cent.
"On the whole, transport, postal, and warehousing services emissions were down but domestic aviation and road transport emissions picked up slightly in the second half of the year, as national restrictions eased," Oakley said.
Direct emissions from households dropped 5.7 per cent over 2020.
However, after a 23 per cent drop in the June quarter - including the national lockdown - emissions increased in the September and December 2020 quarters.
As a result, household emissions reached their highest quarterly level in the December 2020 quarter since the emissions series began in 2014.
"With international borders closed and overseas travel restricted, households' use of road transport picked up at the end of 2020," Oakley said.
Emissions from other industries such as manufacturing fell last year, despite Covid-19 having less of an impact on the industry.
Manufacturing emissions fell 10 per cent compared with the December 2019 year, largely driven by decreases in gas and coal consumption, and a decrease in steel production.
By comparison, the sector's contribution to GDP only fell 3.1 per cent.
"We can see manufacturing emissions and GDP growth have been diverging slightly since 2018," Oakley said.
New Zealand's most recent inventory showed the country produced 78.9 million tonnes of carbon dioxide equivalent (Mt CO2-e) in 2018 - a 1 per cent decrease on the year previous, but a 24 per cent increase on 1990 levels.