Last season’s bushfires directly killed 34 people and devastated more than eight million hectares of land along the south-eastern fringe of Australia.
A further 445 people are estimated to have died from smoke-induced respiratory problems.
The burned landscape may take decades to recover, if it recovers at all.
Watch: Make a bushfire survival plan. Post continues below.
So will the 2020 fire season kick off this month? And is last summer’s inferno what we should expect as a normal fire season? The answer to both questions is no. Let’s look at why.
Last fire season
First, let’s recap what led to last year’s early start to the fire season, and why the bushfires became so intense and extensive.
The fires were so severe because they incorporated five energy sources. The most obvious is fuel: live and dead plant material.
The other sources bushfires get their energy from include the terrain, weather, atmospheric instability and a lack of moisture in the environment such as in soil, timber in houses and large woody debris.
The June fires in Queensland resulted from a drought due to the lack of rain coming from the Indian Ocean. The drought combined with unusually hot dry winds from the north-west. By August the bushfires were burning all along the east coast of Australia and had become large and overwhelming.
Ahead of the fire season, environmental moisture was the lowest ever recorded in much of eastern Australia. This was due to the Indian Ocean Dipole – the difference in sea surface temperature on either side of the ocean – which affects rainfall in Australia. The dipole was in positive mode, which brought drought. This meant the fire used less of its own energy to spread.
Fire weather conditions in south-eastern Australia were severe from August 2019 until March 2020. Temperatures reached record highs in places, relative humidity was low and winds were strong due to high-pressure systems tracking further north than normal.
High atmospheric instability, often associated with thunderstorms, enabled large fire plumes to develop as fires grew to several thousand hectares in size. This increased winds and dryness at ground level, rapidly escalating the damaging power and size of the fires.
Fuel levels were high because of the drying trend associated with climate change and a lack of low-intensity fires over the past couple of decades, which allowed fuel levels to build up.