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The truth about fires in Australia

Among the most told and discussed the news of the last few weeks are those on the great fires in Australia. As was the case with the fires in the Amazon rainforest last summer, the way in which some newspapers dealt with the issue, in some cases by disseminating incorrect information, was also much discussed.

1) How much territory is on fire?
The fires have traveled approximately 8 million hectares of land between New South Wales, Victoria, South Australia, and Queensland since October – a surface area twice that of the 2019 fires in Siberia and the Amazon combined, and equal to four-fifths of all the Italian forests. In just four years, in the past 50 years, the burned surface in New South Wales has exceeded one million hectares, and today it has almost reached double the second most dramatic year (1974 with 3.5 million hectares traveled).

Another unprecedented aspect is the simultaneity of the fires on huge territories, which usually alternate in being subject to fires. And we are only at the beginning of summer (the seasons in Australia have shifted six months compared to ours, so now it is as if it were the beginning of July), therefore these figures will rise again, potentially up to 15 million hectares covered by fire. Australia is 769 million hectares large, so we cannot say that it is “burning a continent”. In addition, in the central-northern savannahs, on average, 38 million hectares of grasslands burn (20 percent of the total) every year in the dry season, which in that part of the country is April-November. But it is an entirely different ecosystem from what is now on fire.

2) Which vegetation is burning?
These are mainly eucalyptus and bush forests, a semi-arid savannah with low, dense or scattered trees, made mainly of herbs and shrubs and similar to the Mediterranean scrub. It is a vegetation that was born to burn: the climate of central Australia has been very arid in the last 100 million years (since Australia made its journey from Antarctica to the position it currently occupies), and fires caused by lightning have been so frequent as to force plants to evolve to overcome them in the best way: letting themselves be burned! In fact, if on the one hand, the fire destroys the existing vegetation, on the other it opens new spaces for the plants to reproduce and renew themselves. Many bush species contain highly flammable oils and resins, so they burn well and with very intense flames when the fire comes. Since the seeds of these species are almost completely impervious to fire, this ploy is the only way to “beat” the competing vegetation and successfully reproduce by exploiting adverse environmental conditions to your advantage. However, this time the drought conditions are so extreme that forest ecosystems traditionally more humid and rarely affected by the fire are also on fire.

3) What caused the ignitions?
In Australia, half of the ignitions are caused by lightning, and half by humans for both culpable and malicious causes (in Italy, on the other hand, 95 percent have anthropogenic causes, mainly culpable). The largest fires, however, tend to be caused by lightning, because they affect the most remote and uninhabited areas, where human activities are less likely to arrive (with the possible exception of accidents at power lines, which have also been responsible for the devastating fires in California of 2017 and 2019). According to Ross Bradstock, of the University of Wollongong, a single fire caused by lightning (the Gospers Mountain Fire) has already covered over 500,000 hectares of bushes since October and today and could be the largest fire ever recorded in the world in historical times.

News is circulating about the arrest of alleged arsonists. In part, false news has been shown to be widespread to deny the climate problem. It is also not an arsonist, in English, the definition of arson includes both willfulness and guilt. However, it is clear that the problem here is not what ignites the flame, but what makes it spread once it is lit – they are two different and distinct phases.

4) What is causing the spread of the flames?
2019 was the hottest and driest year ever in Australia from 1900 to today. In the last year, the average temperatures have been 1.5 degrees higher than the average 1961-1990, the maximums over 2 ° C more, and more than a third of the rain that usually falls on the continent has been missing. A wave of terrestrial and marine heat recorded record temperatures in the country in December (42 ° C national average, with peaks of 49), while the drought has been going on for two years now. When the air is hot and dry, the vegetation quickly loses water by evaporation and dries up. The longer the drought, the larger the size of the plant parts that dry out. When even the largest parts (stems and branches) lose water, which happens very rarely, fires can last longer just like in a fireplace: the small “pieces” are those that make the firelight, and the large ones are those who burn for longer.

Forest fuels are in fact classified as “one-hour fuels”, “ten hours”, “one hundred” or “one thousand hours” depending on their size and how long they can sustain combustion. What spreads the flames, however, is the wind, which pushes the hot air generated by the flame onto nearby plants. Normally, the largest fires occur in fact on very windy days. Very large and intense fires are even able to create the wind on their own: the hot air rises so quickly as to leave a “void”: to fill it, more air rushes from the surrounding areas. The result is a firestorm, the “wind of fire”, with which the fire sustains itself until the fuel available runs out.

5) How come the fires can’t be put out?
To extinguish a fire it is necessary to eliminate the fuel. The water and the retardant launched by air vehicles can only slow down combustion (by cooling the fuel or chemically delaying the combustion reaction), but to eliminate the fuel, ground crews are needed. Intense canopy fires such as those that are developing in Australia can generate tens of meters high flames, proceed at speeds above ten kilometers per hour (the running speed of an average man) and develop a power of one hundred thousand kW per meter in front (! !). Ground crews cannot operate safely at an intensity of 4,000 kW per meter (25 times less than that of the most intense fires).

6) What are the effects of fires?
The Australian bush is an environment that wants to burn with all its strength, and burning improves its health and biodiversity – with its times, regenerating over the years or decades. Even animals know the danger and many know how to respond: the estimate of half a billion animals involved (or even a billion) relaunched by the media is a rough and somewhat alarmist estimate, which for example also considers birds – which obviously can fly and move away from the area – with the important exclusion of babies and eggs. Smaller and less mobile animals (koalas, but also amphibians, micro-mammals and reptiles) may actually fail to escape, and these habitats will be radically altered for many years to come – many animals will no longer find suitable conditions.

Others, on the other hand, will even find better ones. It is a known phenomenon in Australia that some hawks are able to transport fiery twigs to actively spread fires to new areas, thus freeing the view of new hunting grounds.

Fires, on the other hand, can create strong threats to rare species of plants (such as the Wollemi pine) and are above all very problematic for humans: already 25 victims for a total of 800 deaths from 1967 to today, the smoke that makes the air dangerous to breathe, properties and businesses destroyed for billions of dollars in damage. In addition, fires create erosion, increase hydrogeological risk and risk making the climate crisis even more serious both globally, contributing to the increase in atmospheric CO2 (306 million tons emitted so far according to NASA, almost equal emissions from the whole country in 2018), which local, depositing their residues on the New Zealand glaciers which, made so darker, risk melting more rapidly.

7) What does climate change have to do with it?
The extraordinary Australian drought was generated by a rare combination of factors. Normally the first link in the chain is El Niño, a periodic warming of the South Pacific that causes major changes in Earth’s meteorology, but El Niño is not active this year. Instead, another climatic phenomenon has occurred with unprecedented intensity, the Indian Ocean Dipole (IOD) – a configuration that brings humid air to the African coast and dry air to the Australian coast. Global warming has been shown to triple the frequency of extreme events in the IOD.

To this was superimposed, in September 2019, an event of sudden heating of the stratosphere (over 40 degrees of increase) in the Antarctic area, also extraordinary, for “natural” causes, which brought further hot and dry air to Australia. The third phenomenon was a northward shift of western (or anti-trade) winds, winds that blow constantly from west to east between 30 and 60 degrees latitude on the seas of the two terrestrial hemispheres. The northward movement of the anti-trade winds (Southern Annular Mode) brings dry and warm air to Australia and seems to be favored both by climate change and, think a little, by the ozone hole. Climate change, therefore, has something to do with it, both in its direct action (the Australian air has warmed on average by at least one degree in the last century) and indirectly through its influences on the large meteorological structures of the southern hemisphere.

8) What does Australian politics have to do with it?
Much criticism has focused on the Australian government, responsible for not doing enough to achieve the already modest commitments (28 percent emissions reduction from 2005 to 2030) that the country had voluntarily contracted with the Paris agreements. The main problem is that Australia’s economy is heavily based on the extraction and export of coal (especially to Japan – 40 percent of exports -, China and India), a fossil fuel whose extraction is not compatible. with the achievement of the Paris objectives to contain the Earth’s temperature below 1.5 ° C compared to the pre-industrial era.

The coal industry employs nearly 40,000 Australian workers and is heavily subsidized by the government. The current conservative government, as in other parts of the world, tends to be reluctant to decarbonize the national economy. However, there is no need to get confused: every nation is connected to every other. The fires in Australia are not only the responsibility of Prime Minister Morrison or whoever elected him, but of all the activities that continue to contribute to the increase in atmospheric CO2 worldwide – energy production and consumption (30 percent), transportation (25 percent), agriculture and livestock (20 percent), domestic heating and cooling (15 percent) and deforestation (10 percent) – all of which you are also responsible for reading, and I also write (yes, also tropical deforestation).

9) Could it have been foreseen or avoided?
All the latest reports from the IPCC, from Australian research institutions on the environment, and from the government itself, agree to report an increase in the danger of fires in Australia due to climate change, with a “virtually certain” degree of probability. The arrival of highly dangerous weather configurations is also monitored and known well in advance. The alarms have been branched and the evacuations correctly carried out, as far as I know. But the challenge of fire-fighting services, also valid in Italy, is how to keep a system operating that needs to be activated on a very large scale only once every decade.

The other tool to prevent fires is prevention, which is carried out over large areas with the “prescribed fire” technique, which eliminates fuel using a low and scientifically designed flame (a type of intervention also approved by many Australian ecologists, and practiced for forty thousand years by Aboriginal peoples). In 2018-2019 140 thousand hectares of land were subject to this treatment, the application of which is however severely limited by the lack of funds and, again, by climate change, which reduces the number of days with suitable weather conditions to carry it out. It must be said that the intensity of the drought and the fires in progress would probably have put even the most prepared services and communities in difficulty.

10) What can we do?
Reduce our emissions with collective and high impact behaviors. Strive to see the footprint of climate change and our productions and (above all) our consumption in what is happening. The biggest problem we have is this. Koalas are hit hard, but tomorrow it will be up to other animals, other ecosystems … other men. And maybe to us too.

For those who live in contact with a forest, inquire about the fire hazard and the self-protection practices necessary to minimize the risk to your property: fires will strike again in Italy, with increasing intensity, and possibly in places where there you would wait for them. Knowing how to protect is extremely important.

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