Climate: Australia hoped to dodge wildfires. El Niño has other plans

A warming climate is sharply increasing the frequency of El Niño and positive dipole events.

The declaration of El Niño conditions in the middle of a spring heatwave is the sort of news that can cause dread in Australia.

The climate cycle brings warm water to the tropical Pacific Ocean and hot, dry conditions to much of the globe, raising the risk of wildfires in theAmazon and Southeast Asia while tending to reduce them in the western US. In Australia, the conflagrations can be particularly devastating: the 1983, 2003, 2007, 2010 and 2015 fire seasons, some of the most damaging in the country’s history, all occurred during El Niño.

This year, many hoped for some respite. Less than four years ago, more than 10,000 fires swept through 24 million hectares. The Black Summer catastrophe burned a fifth of its forests, killed 33 people and more than 1 billion animals, destroyed nearly 2,500 homes, and released as much as 1.06 billion metric tons of carbon dioxide into the atmosphere, equivalent to three years’ worth of Australia’s normal CO2 emissions.

One consolation was that the destruction itself would reduce the risk of repeat events. Wildfires depend on fuel — leaf litter and bark carpeting the ground. A major disaster like that of 2019-2020 acts like a broom sweeping this away.

Things are different this time around. The fires released as much as 3 million metric tons of particulates into the atmosphere, causing parts of the tropical Pacific to cool as the floating dust blocked out the sun’s rays. That helped contribute to the extraordinary three-year La Niña cooling event that began in September 2020 and ended in March this year. La Niña brings heavy rainfall to Australia, and the floods that resulted caused the country’s worst natural disaster in insurance terms, at $4.3 billion of covered losses.

Burnt-out vegetation recovered at prodigious rates as parched ground became saturated. The wheat crop over the season ended in January rose to a record of nearly three times the tonnage produced in 2019-2020. As El Niño dries out the ground in the coming months, that regrowth is primed to be turned into a new load of fuel.

“What we’re seeing is this flickering between tropical, luxuriant plant growth and arid conditions, and then you get the absolutely worst conditions” for fire, says David Bowman, a professor of fire science at the University of Tasmania.

The state of the oceans and atmosphere could add a spark to this dry tinder. Australia’s worst fires have come in years when El Niño coincides with a positive Indian Ocean Dipole, a similar system that causes Southeast Asia, Australia and eastern Africa to flip between drought and flood years.

A warming climate is sharply increasing the frequency of El Niño and positive dipole events, according to a 2021 study led by Nerilie Abram, a professor of climate science at Australian National University. “Fire-promoting phases are now occurring more often than any other time in the last several centuries,” they wrote.

A relatively dry southern hemisphere winter means the ground is already more parched than you’d expect coming out of three years of downpours. Root-zone soil moisture was well below average across a swath of southeastern Australia in August, a situation that’s likely to spark grass fires in arid inland farming areas. Conditions are closer to average in the deep layers of soil that matter most for the coastal forest fires that catch international news headlines, says Rachael Nolan, a bushfire ecologist at Western Sydney University, who expects forests to retain enough moisture this year to avoid fires on the scale of 2019’s Black Summer.

Even so, the way unprecedented fires have struck Canada and Hawaii in recent months gives her pause. “With these very hot conditions it is almost new territory,” she says.

The warmer atmosphere itself means it’s hard to count on landscapes remaining as damp as they did in the past. Hotter air acts like a sponge, sucking water more readily from plants and soils than if it was cooler. “It’s quite possible that because the atmosphere is getting thirstier we will see more rapid drying,” says Abram.

Australia likes to see itself as the victim of these global forces. That’s not quite right. As the largest fossil-fuel exporter after Russia, Saudi Arabia and the US, it’s contributing every year to a warming climate that risks turning its lush woodlands into savannahs and its Great Barrier Reef into a bleached boneyard.

The benefits of those exports accrue largely to the businesses that produce them, and the governments that tax them. The cost is paid by every citizen: through  inhaled smoke and the health problems that result, and through insurance premiums that leapt 50 percent last year in high-risk areas, leaving one in 10 households struggling to pay them.

Australians tend to view their environment as a national treasure, and the summer as an opportunity for carefree enjoyment of its glories. Increasingly, our carbon emissions and the fires that result are turning this blessing into a threat.

David Fickling is a Bloomberg Opinion columnist covering commodities, as well as industrial and consumer companies. Views are personal, and do not represent the stand of this publication.

Credit: Bloomberg