New Zealand’s climate ‘entering uncharted territory’ as greenhouse gases hit record highs

New Zealand's climate is entering "uncharted territory" as greenhouse gas concentrations hit record highs and extreme weather intensifies, according to a new government report.

The report, published on Wednesday, revealed that the Baring Head monitoring station near the capital Wellington had recorded the highest concentrations ever of carbon dioxide, methane, and nitrous oxide in 2025.

New Zealand's annual average temperatures have risen by 1.36C since records began in 1909 and as many as seven of the 10 warmest years on record have come in the last decade.

"The climate we have known is entering uncharted territory,” the report stated, adding that "while the climate has been like this before, it is the ability of ecosystems and our society to adapt to the speed of this change that matters".

The concentration of carbon dioxide at Baring Head touched 423 parts per million in December 2025, about 51 per cent higher than the pre-industrial level of 280 parts per million, according to the report released by by the environment ministry and the statistics agency Stats NZ.

Methane peaked at 1,902 parts per billion in September, around 163 per cent above its pre-industrial level, and nitrous oxide reached 338 parts per billion in December, about 25 per cent above that level.

The country's glaciers shrunk from a peak volume of 56 cubic km in 1997 to 30 cubic km in 2023. Modelling in the report suggests they will likely lose between 14 and 86 per cent of their volume by 2100 under a low-emissions scenario, and between 69 and 100 per cent if emissions remain high.

Heatwaves will very likely become more frequent, longer and more intense, particularly in the northern half of the North Island, and the number of days above 25C is very likely to rise by 2050.

The report projects heavier extreme rainfall, with the most intense one-day falls rising 8-28 per cent by the end of the century under the high-emissions scenario.

Dr Suzie Greenhalgh, principal researcher at the Bioeconomy Science Institute, said the report offered "sobering realisations with some hopeful trends."

She said it was "clear climatic patterns are changing and that extreme events are becoming the new norm."

The report found the seas around the country were warming 34 per cent faster than the global average, and linked marine heatwaves to sponge bleaching in Fiordland and the loss of southern bull kelp in parts of Canterbury.

"We are prone to both worsening droughts and flood events with rising global temperatures, not just one or the other," Dr Luke Harrington, a senior lecturer in climate change at the University of Waikato who served a science adviser for the report, said while discussing its findings on more extreme heat, flooding and droughts.

He said researchers now knew more about heat risks, including "how drying soils can accelerate the rate of warming on our hottest days of the year, a process we thought was limited to regions like the Mediterranean rather than New Zealand, even as recently as the last IPCC report".

New Zealand has been struck by several climate disasters in recent years which have cost the country billions. Cyclone Gabrielle and the Auckland Anniversary floods in 2023 alone led to around £1.6bn in insured losses. Around 10,000 coastal properties in Auckland, Christchurch, Wellington and Dunedin could become difficult or expensive to insure as soon as 2035, the report noted.

Some 750,000 people live in homes exposed to inland flooding in a 1-in-100-year event, a flood with a 1 per cent chance of happening in any given year, and that figure is projected to rise to around 825,000 by 2050.

New Zealand makes up 0.06 per cent of the world's population but produces 0.17 per cent of its emissions. On a per capita basis, that make New Zealand one of the biggest emitters in the world, roughly on a par with the US, according to Dr Joel Rindelaub, senior lecturer in chemical sciences at the University of Auckland.

“This report indicates that New Zealand is not a leader in climate sustainability,” he said.

Modelling by the Climate Change Commission cited in the report suggests that if everyone in the world emitted at New Zealand's per person rate, warming would peak at 5C.