New Zealand has now cut its planet-heating gases for three years in a row, with the latest drop the biggest since climate change efforts began.
A major reason was burning less coal and gas to make electricity, helped by plenty of rain in the country's hydro dams.
Watts says the positive result backs the Government's commitment to doubling New Zealand's renewable energy capacity.
He says he wants New Zealanders to benefit from affordable, clean energy.
However, the former minister, Green MP James Shaw, says it's important to remember that if there's another dry year, Huntly power station will need to increase coal use again.
More efficient vehicles also contributed, with road transport burning less fuel despite similar kilometres travelled.
Other factors included closure of Marsden Point oil refinery and a slight drop in sheep, beef cattle and fertiliser use by farmers.
The figures come from New Zealand's latest Greenhouse Gas Inventory, which covers 1990 to 2022.
Gross emissions fell to 78.4 million tonnes, four per cent lower than in 2021, the third year running in which emissions have dropped.
The annual drop was 3.4 million tonnes - or around three times the emissions produced by all domestic flights in 2022, according to the Ministry for the Environment.
That was the biggest drop since the tally officially began in1990.
2.5 million tonnes of this saving was from the energy sector, which used more renewables and less fossil fuels to make electricity in 2022. That was mostly due to a boost to hydro generation because of wet weather, although increased wind power also helped.
Forestry fluctuations meant trees removed less carbon dioxide than the year previous, however the long-term trend was towards more tree planting.
The only sector of New Zealand's economy not to decrease gross emissions was the nation of Tokelau, whose emissions are counted towards New Zealand's.
However, Tokelau's emissions are small.
