NZ Experiencing 5 Times More Temperature Extremes Than Expected

Temperature extremes in Aotearoa New Zealand are happening far more often than expected, according to NIWA.

Researchers have analysed 70 years’ worth of weather data across the whole country to see how frequently extreme events, such as record-breaking heatwaves, are happening. They found that they are increasing at a much faster rate than the mean average temperature.

In the last decade, there were on average four to five times more extreme high temperatures than would be expected in a climate with no long-term warming. Even with climate change considered, New Zealand still experienced two to three times more extreme high temperatures than expected.

Scientists also looked at rainfall. They discovered that New Zealand is experiencing dry conditions twice as frequently than expected on the east coast.

Lead author of the study, NIWA climate database scientist Raghav Srinivasan, says this work provides the data to back up the anecdotal evidence seen and heard about over the past few years.

"We instinctively know that we’re experiencing more hot, dry days and record-breaking weather events, especially as they’re often reported in the news. This study has given context to this by showing the frequency of these extremes and how they have changed over the last seven decades in New Zealand," he says.

NIWA publishes monthly climate summaries which report on the occurrence of extreme climate and weather events.

"In the last decade, NIWA has reported many record-setting high temperature extremes. We did this work to quantify those patterns and we can say much more confidently that climate change is no longer a thing of the future. It is happening to us now. The extreme events that we were once warned about are playing out across the globe, with droughts, storms and forest fires happening a lot more often than even just a couple of decades ago," says Mr Srinivasan.

The global climate has changed, and human activities are estimated to have caused approximately 1.09°C of global warming above pre-industrial levels. According to the record of global land and ocean temperatures spanning 1880-2020, the seven warmest years have all occurred since 2014, while the 10 warmest years have occurred since 2005.

The study was published in Weather and Climate, New Zealand, co-authored by Dr Trevor Carey-Smith and Gregor Macara.

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