Nelson was flooded in an August "atmospheric river" that came at the tail-end of New Zealand's warmest, wettest winter. Photo / George Heard
Nelson was flooded in an August "atmospheric river" that came at the tail-end of New Zealand's warmest, wettest winter. Photo / George Heard
This year is likely to prove among New Zealand’s very warmest – and perhaps our hottest ever – says a climate scientist who’s been tracking the data.
So far, 2022 has delivered a winter that was the country’s wettest in 50 years of records, but also the warmest for a third consecutive year, finishing up with an average of 9.8C, or 1.4C above the 1981-2010 normal.
Niwa’s seven-station temperature series, built on climate measurements spanning back to 1909, also showed the first six months of 2022 to be our second hottest.
That series’ architect – Professor Jim Salinger – now expected this year to place in the top three warmest ever recorded for the wider New Zealand region.
Using forecast land and sea temperature data from the European Centre for Medium-Range Weather Forecasts (ECMRWF) for the remainder of the year, Salinger calculated our year-end average land temperature could sit as high as 1.15C above average.
That would be even hotter than last year – our warmest to date – which finished up with an average 13.56C, or 0.95C above normal.
But Salinger said 2022 had also proven a remarkably warm year for some four million square kilometres of ocean around New Zealand, which he projected would average out at 0.85C above average.
“That gives us a grand total of 0.87C above average for our combined land and sea area – which would be the second-highest value we’ve recorded.”
Niwa forecaster Chris Brandolino said that, as at late October, land temperatures for the year were tracking at 1.06C above average.
“We’re basically assured a top-three finish for the year... I don’t want to say it’s guaranteed, but there’s a very high probability.”
Salinger said his projections served as another reminder – if we still needed one – that our planet was warming at an alarmingly fast rate.
In just 111 years, the average has risen by more than 1C, but the starkest changes have come within the past three decades, when the pace of warming has tripled.
“And the last five years have clearly been the warmest period in our records dating back to 1870.”
This graph shows combined land and sea temperatures in the New Zealand region, with data for the remainder of 2022 calculated using projections from the European Centre for Medium-Range Weather Forecasts. Source / Jim Salinger
That’s little different to the global trend, which showed the seven warmest years had all been since 2014, while the 10 warmest years have occurred since 2005.
Salinge noted climate change wasn’t the only ingredient in the mix.
One big driver had been a La Niña climate system – expected to again contribute to another unusually warm summer – while another was a Southern Annular Mode that had trended positive throughout most of the year.
“At this time of the year, this tends to push big blocking highs to the east and south of New Zealand, adding to more regional warming.”
As well, sea surface temperatures around our coasts have been persistently warm – the Bay of Plenty recently marked one year of marine heatwave conditions – which in turn drove up temperatures on land.
Brandolino similarly cited those key influences in the year’s climate trends, adding that it was notable in itself September and October’s temperatures came in closer to average.
The last time New Zealand recorded a month of below-average temperatures, relative to the 1981-2010 baseline, was 70 months ago, in January 2017.
“We’ve certainly had a lack of southerlies for a good chunk of the year.”
The year has also brought some of the most extreme weather observed here.
In July, Christchurch was drenched with more rain than the city’s entire monthly average – and more than anything measured over a single day in 157 years.
The winter season eventually finished with a dramatic climax: the strongest “atmospheric river” measured in an August month, and the second-most powerful recorded over winters going back to 1959.
The forecast comes as leaders have been meeting in Egypt for this year’s UN climate negotiations, where secretary-general António Guterres warned the world was on “a highway to climate hell with our foot on the accelerator”.
