Heat not necessarily climate change related - expert

Yesterday's hot weather may have been record-breaking, but it was not necessarily extraordinary.

"It's summer - it gets hot. Yes, it is hot," Niwa forecaster Chris Brandolino said yesterday.

"Tomorrow, it'll be cooler."

Mr Brandolino said temperatures definitely were rising across the globe, and that rise was definitely due to climate change.

But the rise was a subtle one, he said. The Intergovernmental Panel on Climate Change (IPCC) said in a recent report New Zealand temperatures had risen about .9degC since 1900.

The highs yesterday, more than 2degC above the 50-year record at Dunedin airport, could not be directly attributed to that temperature rise, Mr Brandolino said.

The IPCC report also predicted New Zealand would have up to 60 more days where temperatures broke 25degC by 2090. But the prediction was for "northern areas" - not the South Island, which was most affected by yesterday's heat wave.

That prediction did go "in stride" with another commonly-cited prediction, that "more extreme weather events are likely in the coming years and decades as the climate continues to change and evolve," Mr Brandolino said.

The heat yesterday might fall into that category, but, again, it was impossible to know for sure without doing the research.

Niwa was involved in "emerging research" looking at the effect of climate change on extreme weather events.

"But that's not done, as the situation is unfolding," he said.

"[It] takes many months - if not years - of research, to go through the data."

Climate change has also been widely credited with record high temperatures globally, including the recent confirmation 2015 is on track to be the hottest year on record.

But Mr Brandolino cast doubt on the validity of that correlation, too.

El Nino might be more responsible for 2015's high temperatures than climate change, he said.

"Whenever there's an El Nino, it tends to accentuate warmth [globally]."

And, in any case, Niwa had predicted an average summer for the South Island, temperature-wise, Mr Brandolino said.




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