A summer heatwave scorched the most populated parts of Australia over the weekend, with temperatures topping 107 degrees Fahrenheit in Sydney and 96 degrees in Melbourne, with readings up to 117 degrees farther inland.
As wildfires raged and several weather stations reported all-time and monthly record highs, climate scientists warned that this summer's extreme heat, super-charged by climate change, is becoming Australia's new normal.
Nearly every week has brought extreme heat this summer, but the latest surge was exceptional by encompassing nearly all of New South Wales, home to the capital Sydney and 7.5 million people. The average maximum temperature hit 111.2 degrees Fahrenheit Saturday across about 300,000 square miles, similar to an area the size of the southeastern U.S.
Temperatures were even hotter during the Great Heat Wave of 2013, but those extreme readings were concentrated in the less-populated, central area of the country.
The Australian Bureau of Meteorology reported that a weather station at White Cliffs, in the Southeast, recorded the warmest-ever nighttime low temperature in Australia, at 94.3 degrees Fahrenheit. Overnight temperatures are especially important in terms of human health impacts, because if nights don't cool down, people don't have a chance to recover from the extreme daytime temperatures.
Some spots in Queensland, in the Northeast, broke the 40 degree Celsius mark (104 degrees Fahrenheit) for the first time ever—another sign that heatwaves are broaching new frontiers, according to Sarah Perkins-Kirkpatrick of Australia's Climate Change Research Center at the University of New South Wales.
The heat has helped fuel large wildfires and as of late Sunday, 48 fires were burning out of control in New South Wales. Tens of thousands of people were being evacuated in some rural areas, with officials saying the conditions are worse than during the deadly Black Sunday fires that killed 173 people in 2009, Australian media reported. The Australian Bureau of Meteorology expects above-average heat to persist through February and into March.
The state of New South Wales was 6 degrees Fahrenheit above average in January, making it the third-warmest January record. Several towns west of Sydney had record-setting streaks of temperatures above 104 degrees Fahrenheit, with the trend continuing into February, according to a recent post on NOAA's Climate.gov website.
Based on records going back to the late 1800s, there's no question that heatwaves have become more frequent, with some regional nuances, Perkins-Kirkpatrick said.
"In Canberra, Australia's capital, the number of heat wave days has doubled in the past 60 years. In that same time, the beginning of the heatwave season in Sydney has advanced by three weeks, and in Melbourne, heatwaves are hotter," she said.
The buildup of heat-trapping greenhouse gas pollution in the atmosphere means things will get much worse. By the end of the century, Australia's tropics will see an additional 40-50 heatwave days, while Sydney and Melbourne will see 2030 more days of extreme heat annually.
"What's really interesting about this event is that all the physical mechanisms that drive heat waves are not in place," Perkins-Kirkpatrick said, explaining that normal climate cycles like El Niño and hemispheric wind patterns are not influencing Australia this summer.
"So we should have had average conditions, but what we have had is dominating high pressure systems keeping temperatures persistently hot."
Extreme heat has killed more Australians than any other type of natural disaster in the last 100 years, according to the Australian Climate Council.
Australia has always been prone to hot weather, but long-time researchers like forest and fire ecologist David Bowman said human-caused global warming is now having a noticeable effect.
"In the last few years it has crossed a line—the anomalous weather has become consistently anomalous. I am confident we are seeing climate change play out in bush fires," he said, citing a number of extreme and deadly fires that have blazed across Australia in the past 10 years.
"We are therefore in a period where talk about adaptation is moving from the academic futuristic realm to the real world of now. Unfortunately, individuals and societies are lagging in this adaptive process—there is a huge amount to do and we have frittered away precious time debating abstractions or missing the point entirely. Numerous extreme events, seem unfortunately, the only things to spur broader social change."
Australia's current heatwave is just the latest in a series of extreme heat events around the world that are increasingly being linked with the buildup of greenhouse gases in a world that has set a global temperature record three years in a row.
Parts of South America have also warmed to record levels this year, including Chile, where 12 different weather stations set all-time temperature records above 110 degrees Fahrenheit in late January, as the largest wildfires on record in that country swept across more than 300,000 acres, according to Weather Underground.
And 2016 ended with a record heat wave and drought in the Southeast, where conditions also contributed to unusually large and intense wildfires, in some cases in normally moist hardwood forests that don't see much fire.