Have you noticed the bizarre weather lately? Sweltering heat when we were promised a cool, wet spring? It seems an Antarctic phenomenon is to blame, and it has climate scientists deeply concerned.
For those of us in New South Wales (NSW) and Victoria, the forecast pointed to a La Nina weather pattern, typically bringing lower temperatures and above-average rainfall. We were all set for a mild, damp spring. But instead, we've been hit with heatwaves and early-season bushfires, even on the Central Coast and Mid North Coast of NSW. What gives?
Scientists are pointing to a freak weather event that unfolded way back in September: a sudden stratospheric warming (SSW) over Antarctica. Imagine temperatures in the stratosphere, high above the South Pole, skyrocketing by a staggering 50 degrees Celsius! This rarely happens.
And this is the part most people miss... This isn't just some isolated event. Similar occurrences were recorded in 2002 and 2019. Guess what followed those events? Some of Australia's worst bushfire seasons. That's a pretty worrying pattern, right?
This Antarctic phenomenon has been recorded only twice before, in 2002 and 2019, and in each instance months of warmer, dry conditions preceded some of Australia’s worst bushfire seasons.
A dry spring could make things much worse this summer, but, as of now, there aren't any widespread warnings of heightened bushfire risk in eastern Australia. Why? Two years of above-average rainfall have left us with increased soil moisture, which reduces the chance of high-risk fire days with extremely low humidity.
However, rainfall deficiencies have emerged in large pockets of the country, and the Australasian Fire and Emergency Service Authorities Council (AFAC), the peak body for fire, land management, and emergency services, is warning of increased bushfire risk. This includes parts of Victoria. They also point out that there are high fuel loads in central northern NSW, contributing to the bushfire danger. So, while we're not in full-blown panic mode, vigilance is key.
So, how does a heat spike above Antarctica affect our weather here? It all comes down to something called the polar vortex.
Think of the polar vortex as a band of strong winds that usually spins tightly around the Earth's poles. In the Southern Hemisphere, these winds, known as westerlies, form a tight circle around Antarctica from autumn until the start of summer. They act like a barrier, keeping the cold air locked up down south.
The stratospheric heat spike disrupts this system. It causes the polar vortex to weaken, and the circle of winds above the South Pole to fan out. The westerlies then spread northwards, and this has a knock-on effect for Australia.
These winds end up blowing across the southern end of Australia, bringing hot, dry air from the arid interior to the eastern seaboard. That's why we're experiencing this unseasonably warm and dry weather.
Emeritus Professor Mark Howden of the Australian National University, a vice chair of the United Nations’ Intergovernmental Panel on Climate Change, explains it this way: "Leading into summer, in NSW and Victoria the odds were tilted towards higher than average rainfall and cooler than recent temperatures by a combination of a La Nina in the Pacific and by conditions in the Indian Ocean. The prevailing conditions indicated a good chance of a wetter than average spring across eastern Australia, and it was probably the sudden stratospheric warming that helped disrupt that." He also notes that Tasmania, interestingly, was wetter than expected.
Martin Jucker, a senior lecturer at the University of NSW Climate Change Research Centre, admitted to being surprised by the change in weather patterns since the stratospheric heat spike. "I was actually pretty cautious at the time in saying it might have an impact. But now I’m quite surprised how much of an effect there probably has been," he said.
He goes on to say, "Linking a particular heatwave to the breakdown in the vortex is very difficult. But if we measure several months in a row that are drier than usual, then we can start saying, yes, this is probably because of the polar vortex."
But here's where it gets controversial... While scientists are increasingly confident in linking the SSW to our current weather patterns, definitively attributing individual heatwaves or bushfires to this phenomenon is still a challenge. Some argue that focusing solely on the SSW might distract from other important climate drivers.
So, what do you think? Are we seeing the direct consequences of this Antarctic event, or are there other factors at play? And more importantly, what can we do to prepare for a potentially dangerous fire season? Share your thoughts and concerns in the comments below.
