The record-breaking heatwave that hit parts of eastern Australia earlier this month was made twice as likely by climate change, according to researchers.

At its peak on February 11, temperatures soared to 47 degrees in Richmond, 50km northwest of Sydney.

NSW was the hottest place on Earth, and almost 100 bushfires raged across the state.

In an article for The Conversation, researchers Sarah Perkins-Kirkpatrick, Matthew Hale (both University of NSW) and Andrew King (University of Melbourne) argue climate change has made such extremes much more likely.

“Let’s be clear, this is not natural,” the article says. “What’s more, in just a few decades’ time, summer conditions like these will be felt across the whole country regularly.”

The heatwave was “all the more noteworthy” because the El Nino of 2015/16 is long gone and conditions are “firmly in neutral”.

“This means we should expect average, not sweltering, temperatures.”

The researchers say detailed analysis shows heatwaves “at least as hot as this one” are now twice as likely to occur.

“In the current climate, a heatwave of this severity and extent occurs, on average, once every 120 years, so is still quite rare. However, without human-induced climate change, this heatwave would occur only once every 240 years.

“In other words, the waiting time for the recent east Australian heatwave has halved.

“As climate change worsens in the coming decades, the waiting time will reduce even further.”