Die massive Hitzewelle hinter Neuseelands heißestem Sommer könnte in den 2040er Jahren zu einer „fast jährlichen“ Hitzewelle werden. Zwischen 2017 und 2021 verloren die Südalpen 20 % ihres Eisvolumens – der bedeutendste Rückgang in einem Fünfjahreszeitraum seit Beginn der Aufzeichnungen –, da der saisonale Schnee früher und schneller schmolz.

Regional heatwaves like that which fuelled our hottest summer on record have become 12 times more likely under climate change – and could become almost annual events within the next few decades.

That’s the stark message of a major new study that comes as delegates from nearly 200 nations meet to thrash out new climate deals, with another Kiwi summer of above-average warmth lying beyond.

Summers in our region have been warming up at an unprecedented rate, on the back of global climate change and combined ocean and land heatwaves.

Further back in our past, there’d been just one significant compound heatwave – the historic drought summer of 1934/35 – which set a record for summer warmth unbroken until 2017/18.

In that season, and also 2018/19, 2021/22 and 2022/23, scientists observed unusually high sea surface temperatures in the region around New Zealand.

“The spatial patterns for 2017/18 and 2018/19 are very similar, with the largest temperature anomalies over a west-to-east across the southern Tasman Sea and to the Chatham Islands,” study co-author and Niwa ocean modeller Dr Erik Behrens said.

“Most of this warming has been attributed to blocking high-pressure conditions to the east [of] New Zealand, which reduced the wind-driven ocean mixing and enhanced incoming solar radiation – causing the near-surface waters to warm rapidly.”

[https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.8667](https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.8667)

Could? What is the trajectory in which it would not?