Scorcher: 2022 was NZ’s hottest year on record, climate expert says

2022 was NZ's warmest on record according to climate scientist Jim Salinger. Photo / Mark Mitchell

New Zealand and Auckland may have had their hottest ever year since records began, according to one climate scientist’s calculations.

Veteran climate scientist Professor Jim Salinger told the Herald that, according to his analysis, the year finished with a record average temperature of 13.77C, or 1.16C above the average for 1981-2020 based on his “seven stations” temperature series calculations.

This beats 2021, which was the warmest year on record with a mean land surface temperature of 13.56C.

His calculations were based on the standard seven stations temperature series that he helped develop.

This series draws on more than a century’s worth of climate records taken from stations in Auckland, Wellington, Masterton, Nelson, Hokitika, Lincoln and Dunedin.

Climate scientist Professor Jim Salinger. Photo / File

Salinger also uses a 22-station series that captures more climate stations, and this series also showed 2022 as the hottest year coming in at 1.06C above average.

According to his calculations across that specific dataset, temperatures have increased by 1.4C since the 1870s.

When Salinger looked across the 22-station series, several New Zealand cities also recorded their hottest years including Kaitaia (1.53C above average), Auckland (1.48C above average) Hamilton (at Ruakura, 1.53C above average) New Plymouth (1.33C above average) Nelson (1.16C above average) Hokitika (1.59C above average) and Milford Sound (1.47C above average).

Eight of the past 10 years have been among New Zealand’s warmest on record, and Salinger said this trend is consistent with the overall pattern of global warming.

However, he said climate change was not the only thing that influenced the warm temperatures, but also a mix of the effect of La Nina and the Southern Annular Mode.

“We’re in La Nina, which is bringing warm Northerlies in the winter and Northeasterlies in the summer,” Salinger said.

NZ land and sea temperature anomaly. Image / Supplied

“It’s basically global warming, La Nina which makes it warm in New Zealand and the Southern Annular Mode combined that’s causing the rising temperatures.”

A marine heatwave forecast to hit the bottom of the South Island this week is also expected to bring sea surface temperatures 4C or more above average.

Sea temperatures in the NZ region were also 0.82C above average for 2022, and when he combines the sea temperature data and land data the overall reading was 0.84C above average.

“The sea temperature is just remarkable, and the warmest reading on record yet,” Salinger said.

He said the Southern Annular Mode pushes “as we see now” the anti-cyclone south of New Zealand.

NZ land temperature anomaly 22-stations. Image / Supplied

“In the next day or two you will see a lot of rain in the north of the North Island, and it’s going to be hot and dry in Southern New Zealand,” Salinger said.

Salinger said the continuing rise in temperatures was “extremely concerning”.

“We’re seeing snow melting off very quickly down south, and that means you get permanent snow and ice melting and you see all the fisheries are migrating south which mucks up fishing quotas,” he said.

MetService oceanographer Joao de Souza said marine heatwaves are expected to reach a new high tomorrow with coastal patches off the West Coast forecast to reach 4.7C above average for this time of year.

Souza warned that persistent marine heatwaves may cause problems for marine life.

“Abnormally warm sea temperatures can potentially harm marine life,” he said.

“Last year, a similarly warm marine heatwave in Fiordland reached great depths and caused widespread bleaching of sea sponges, and recent West Coast kelp disappearance has also been attributed to marine heatwaves.”

Niwa meteorologist Seth Carrier confirmed that 2022 was one of the top three warmest years on record, since 1909, but that the final ranking was still being determined.

Niwa, the custodian of the National Climate Database, will be releasing its 2022 climate summary on January 11.