In a small coastal settlement, shrouded by the dense forest ranges of Te Urewera on New Zealand’s North Island, three hydropower stations are hungrily fed from a lake that is filled to the brink.

Over the past year, heavy rainfall has kept the clear waters of Lake Waikaremoana full and the lights of homes in the local district on. Thanks to extreme flooding from Cyclone Gabrielle earlier this year, the reservoir has exceeded its usual levels.

The scenario has been repeated across New Zealand’s north island, where record levels at hydropower stations have contributed to a decline in national Greenhouse Gas Emissions.

Provisional government data shows that seasonally adjusted greenhouse gas emissions decreased 1.8% in the December 2022 quarter. During that same period, electricity, gas, water, and waste services emissions fell to their lowest recorded level, and the share of renewable energy sources increased to 94.7%, “a level not seen in decades”, according to Stats NZ.

While some are heralding the decline in emissions, which began during the pandemic and has since continued, climate scientists have cautioned against placing too much optimism in the decrease driven by hydropower, given the sector’s dependence on high volumes of rain that may reverse with dry conditions borne by the El Niño pattern forecast for summer 2023.

‘Provisional good news’

The past year has been marked by record rainfall, including official reported rainfall of more than 149% above seasonal norms in some regions, says Malcolm Johns, chief executive of Genesis Energy, which manages four hydropower schemes and a wind farm. But while the country’s energy supply has benefited from a wet 2023, he says, New Zealand’s electricity grid is driven by weather, and weather has cycles.

“We could have a dry year next year, New Zealand’s need for thermal generation will increase, and so will emissions. Emissions reduction will not be a straight line but a trend over time.”

Sam Dean, a principal scientist at the National Institute of Water and Atmospheric Research (Niwa), attributes the decline in emissions to natural climate variability and warns that one data point is an insufficient measure of proof that New Zealand is poised to pass peak pollution, as some might believe the data suggests. New Zealand can not rely on a rain strategy to reduce emissions in the long term, he says.

“It’s really important that we reduce emissions and it could be very easy to think we’ve got the situation under control, when I very much don’t think we do.”

While New Zealand has consistently met its targets and obligations to reduce emissions under various protocols, Dean says, “throughout that time we really haven’t changed our net emissions at all. I don’t see evidence yet in the data that we can be hopeful we’ve turned a corner – we need to see emissions dropping constantly, year on year”.

Climate change expert Prof James Renwick of Victoria University says that one of the difficulties they face is there is no comprehensive monitoring of emissions across the country from each sector. “We have estimates based on the amount of fossil fuel and energy use, but all estimates have quite large uncertainty ranges so it may be hard to pin down.

“It’s one of the frustrating things – the emissions of greenhouse gasses globally are not really monitored precisely at the points they’re released. We can infer what’s happened from looking at the global concentration of carbon dioxide, but it can be pretty hard to trace the emissions back to a particular source beyond bulk statistics.”

Overall it was good news, Renwick says, “but it’s provisional good news. The forefront is that total emissions appear to have gone down, given the uncertainty we have around the measurements.”

‘We have all the power we need’

The figures come as the government announces a major deal with Fonterra, one of the world’s largest dairy manufacturers. The company – the country’s largest exporter, responsible for about 30% of global dairy exports – is one of New Zealand’s largest emitters. It is partnering with the government to cut coal use at six of its factories, halving its manufacturing emissions by 2030. The reduction is set to cut about 2.1m tonnes of earlier CO2e reductions, the equivalent of taking some 120,000 cars off the road.

The minister for climate change, James Shaw, says the deal, which follows a significant emissions reduction project with NZ Steel, will put New Zealand in a better position to reach net zero by 2050, but adds that the country can’t be complacent.

“We have to do everything we can to radically reduce our reliance on fossil fuels, in order to avoid the worst of the climate crisis”.

The government has a 2050 target to reach net zero for long-lived greenhouse gas emissions and a reduction in biogenic methane emissions, and has established a number of climate change initiatives to support this goal.

Johns, of Genesis Energy, says New Zealand’s electricity generation is around 85% renewable and projected to be 96-98% renewable by 2030, due to a pipeline of upcoming wind and solar farms and new geothermal plants.

With a general election looming in October, Niwa’s Dean says politicians need to present their vision on climate change measures clearly, and urges the public to ask questions of respective parties’ positions on the issue.

“There’s only one more election, in 2026, that can meaningfully affect our emissions trajectory before 2030. We’ve got a commitment to a target of 50% by 2030 – that’s only seven years away.

“At election time, politicians are listening. In a democracy like New Zealand, they do end up reflecting quite well how people prioritise climate change relative to any other issue.”

Renwick agrees it’s a “race against time”.

“Governments need to play the big role – make it possible for people who don’t have an electric car to get one, and have available public transport that’s reliable and convenient enough to use all the time..

“Having hope and not despairing is crucial – we have all the power we need to take action to stop emitting greenhouse gasses.”