Greenhouse gas emissions rebounded in the three months following last year's lockdown from the end of March to the beginning of June.

Data from Stats NZ showed emissions fell by 8.1 per cent over the lockdown period, but then sharply rose by 9.1 per cent in the three months after.

The seasonally adjusted figures showed emissions fell from 20,134 kilotonnes of carbon dioxide equivalents in the first three months of the year, down to 18,494 kilotonnes in the next.

That decrease showed the impact the lockdown had on emissions. Level 4 lockdown began on 23 March, and social distancing measures continuing until level 1 arrived on 8 June.

But for the three months following that period, emissions returned to the status quo. Between July and September last year, 20,176 kilotonnes of carbon dioxide equivalents were emitted.

They are now at a similar level as they were at the start of 2020.

"Recent global events have highlighted the need to see short-term impacts on both the economyand emissions, and to be able to make comparisons between the two," says Stats NZ environmental-economic accounts manager Stephen Oakley.

The dip and rise followed closely the fluctuations of GDP, which suffered an 11 per cent downturn due to the lockdown, but then increased by 14 per cent in September.

Different trends within industries

The pattern of emissions across industries was different.

Primary industries (agriculture, forestry, fishing and mining) - which is New Zealand's biggest contributor to emissions - remained stable through it all, experiencing negligible decline and growth.

The services industry (transport, postal, warehousing etc) meanwhile experienced the biggest drop in emissions. Greenhouse gas emissions dropped by 811 kilotonnes over lockdown (-34.9 per cent) but that then went back up by 305 kilotonnes (+20.2 per cent) afterwards.

Emissions from households, meanwhile, experienced a significant drop in emissions, but then rocketed back up, to levels higher than at the start of the year.

The goods-producing industries (manufacturing, construction and electricity, gas, water and waste services) however, had hardly any decline over lockdown (in fact, emissions actually increased), but then emissions increased by more than 11 per cent in the three months after.

That was in large part driven by the electricity, gas, water and waste services part of the industry.

Dry weather over July, August and September meant that hydro inflow was down, and so there was a stronger reliance on fossil fuels for electricity generation.

"Household use of road transport and increased fuel use for heating were the main causes of this increase in emissions between the June and September quarters," says Stephen.

About the data:

This is the first time this type of data has been released by Stats NZ. Official data on greenhouse gas emissions runs with an 18-month lag.

As such, this more frequent, and up-to-date data is still considered experimental, and is not official.

"Once we receive external feedback, we hope to make them official statistics," says Stephen.

"Recent global events have highlighted the need to see short-term impacts on both the economy and emissions, and to be able to make comparisons between the two."

Stats NZ is inviting feedback on the methodology used to produce these new experimental estimates.

Harry Lock,/RNZ.