Greenhouse gases drive Australia’s bushfires

What remains of much of Australia’s breadbasket, November 2019. Image: Courtesy of Andrew Burgess

Australia’s bushfires are feeding on heat from the climate change happening in the tropics, but its government doesn’t want to know.

NEW SOUTH WALES, 14 November, 2019 − Australia has earned a formidable reputation for being the driest and most agriculturally disappointing continent on Earth. Droughts and floods have followed each other like day and night, spawning a laconic and resilient breed of agriculturalists known for taking climatic adversity and variability in their stride.

Everyone in the industry believes both good and bad times are cyclical, each replacing the other. The continent is surrounded by three oceans which, depending on their temperature fluxes, deliver or deny precious rainfall, as moisture-bearing ocean winds blow either toward the continent or away.

A knowledge of the state of each ocean can help farmers to understand how long it will be before the situation changes. Preparation for the next drought in good times is a no-brainer and is supported with Government policy. Water supply augmentation systems, fodder storage and stockpiling money are modern tricks used by graziers to abate the ravages of drought.

That’s been the traditional pattern. This year, though, after three consecutive failed springs in eastern Australia, there’s a level of despair which is taking an enormous toll on families, businesses and ecosystems. Farming communities are suffering mental anguish as they run out of options.

We haven’t seen the usual cyclical return to wetter seasons. No-one has ever seen the likes of this drought and no-one knows when it will end. We are out of tricks, out of water and out of feed.

Livestock breeding herds  and flocks that have taken generations to build are now depleted because the only option is to send them to slaughter. It’s unclear anyway whether there’ll be sufficient fodder-grade grain to keep them alive.

Breadbasket on fire

Modern cropping systems are designed to store soil moisture until the next crop can be planted. But in the bread basket of the nation, soil moisture is now at record lows, and severe bush fires ravage the landscape.

As I write this in the second week of November, we’re in the third day of gale-force winds, high temperatures and low humidity. The sky is full of dust, smoke and fire-fighting aircraft, when we should be planning what to do with excess stock feed.

Yesterday the government announced further assistance to farmers, in the billions. But the problem is that the federal government will not acknowledge there is a climate problem at all, let alone a catastrophe.

Deputy prime minister Michael McCormack aroused anger when he dismissed the possibility of climate change causing the crisis as the ravings of “pure, enlightened and woke capital city greenies” who were ignoring the needs of rural Australians. “We’ve had fires in Australia since time began”, he said.

Our understanding of the climatic drivers of this drought has been severely challenged. The Pacific Ocean is in a neutral phase, so ENSO is not a major issue. The Southern Ocean is in a negative mode, which should bring rain-bearing westerlies at least to southern Australia. But the Indian Ocean is in a phase which prevents tropical moisture inflow.

“The only way the climate models can simulate the depleted rainfall observations is to include the effects of greenhouse gases”

None of these by itself is enough to produce a drought as long and intense as this. In some places it is in its eighth year, and mostly at least the third. On our farm less than half of the annual rainfall of the previous worst year so far has been recorded. Apart from an intense La Niña in 2010-2011 there have been no significantly wet or average years this century.

In 2010 a report was released by a government agency, the Centre for Australian Weather and Climate Research, which showed conclusively that there has been a serious and persistent decline in rainfall in southwestern and more recently southeastern Australia. It is clearly visible, it is anthropogenic in nature, and its mechanism can be easily understood by non-scientists. The Australian Bureau of Meteorology published an update on this year’s drought in September.

Superimposed on the oceans’ tableau is a natural phenomenon known as the Sub-Tropical Ridge (STR). This is a belt of high atmospheric pressure which encircles the planet at about 35 degrees of latitude in both hemispheres, where many of the world’s deserts occur. This high pressure is caused by the descent of cool dry air at these latitudes.

This air originated in the tropics, rose, rained out and then descended, depleted of moisture. Meteorologists call this cycle the Hadley Circulation.

The trouble is that the dry high pressure cells are becoming more frequent and more intense because of growing heating in the sub-tropics, which are increasing in aridity.

Heat blocks rains

Until now, though, it was happening slowly enough for no-one to notice. However, recent analysis can now detect the signature as far back as the World War Two drought.

The STR is like a string of pearls under high pressure, with the gaps allowing rain-bearing systems to penetrate from either the tropics or the poles. But now the extra heat caused by climate change in the tropics is making the highs more frequent and more intense.

It is now a regular feature of Australian weather that rain-bearing fronts are pushed to the south and rarely penetrate the persistent highs. Similar changes have been seen in the northern hemisphere in southern Europe and California.

There is a direct linear relationship between these changes and the level of carbon dioxide in the atmosphere. The only way the climate models can simulate the depleted rainfall observations is to include the effects of greenhouse gases.

This should have been front-page news at least in the agricultural press, but instead the news is about government handouts to needy farmers.

Worse in store

So it looks as if the plight of Australian agriculture is set to worsen because of the tropical oceanic heating. The strengthening STR is not an oceanic phenomenon, but an atmospheric one, so its effects are not as apparent to the casual observer. Nevertheless, it seems to be putting the already nasty changes of the oceans on steroids.

Somehow we need to persuade the government that as well as providing welfare, and mitigation strategies, we have to stop venting novel carbon dioxide and avoid exposing Australian agriculture to the ravages of an angry atmosphere.

Yet there are now two strong reasons why governments in Australia will not acknowledge that the drought is attributable to climate change. Firstly, at the last election, there was an enormous voter backlash against proponents of the closure of coal mining.

Secondly, there is political mileage to be grafted out of massive welfare payments to the agricultural community. There is no doubt that there is enormous hardship in the sector, but you need to wonder whether they can see a connection between budgetary pain and carbon policy, or whether any government has sought briefing on the matter.

Clearly courage and leadership matching that required in warfare is needed to address this dreadful situation. Instead we have cowardice and schizophrenia. − Climate News Network

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Andrew Burgess is a sheep farmer in New South Wales whose family has raised animals in the same area for more than a century. He has now sold his farm because he finds the drought has made his work and survival there impossible.