October 22, 2020

The Australian fire that extinguished 85% of its megafauna



Australia is a land of fire and global warming is causing it to suffer more than ever. Since they began, the last fires have burned 10 million hectares, a larger area of ​​the Netherlands. Twenty-seven people killed, more than 2000 homes have been reduced to ashes and it is estimated that two thirds of the koalas in the affected areas have died in the fires.

It is a true catastrophe and we better solve it before it gets worse, because Australia has a long history with fire and it is believed that, once, it was the cause of one of the worst mass extinctions in recent history.

Sleep time

Australian mythology tells stories about the time of sleep, a fantasy space populated by huge and wonderful beasts. The rainbow snake, creator of everything, may seem like the fabulation of a mind drunk with some kind of substance, but not so long ago that a five-meter snake crawled across Oceania.

It is thought that many of the monsters that describe the Australian aborigines in their songs are memories of extinct animals that once walked their continent. From a genus of carnivorous kangaroos to marsupial lions, through a turtle the size of a small car, a 270 kilos kangaroo and the endearing diprotodon: a beast of almost 3 tons, a relative of the current uombats.

Marsupials of hundreds of kilos and varied forms of which, mysteriously, there is none. We have invaded Australia with cattle and pets, but of its native fauna, the heaviest mammal is the red kangaroo that barely reaches 85 kilos. Africa and Asia have elephants, America and Europe moose of half a ton What happened to the great Australian mammals? Where is your megafauna?

A story of pollen and ashes

There are many things we don’t know about this story, but something is clear. Between 100,000 and 50,000 years ago Oceania was very different. Far from being the driest continent on the planet, it was covered with meadows and forests.

We know this because pollen rarely lies and is perfectly preserved for thousands of years. Thanks to the remains of pollen found in archaeological excavations, we know more or less the flora of that time and we know that something made it change, because at the end of this period, the pollen of many plants began to be scarce. In fact, there is a less orthodox place where the change in flora was also reflected: the feces of herbivores. As we get closer to our time we can see how the remains of feces have fewer and fewer spores of the fungus Sporormiella. Something was ending the vegetation and it is very likely that the same motive will destroy the megafauna in a matter of a few thousand years.

The reason could be any, if it were not that there is a second witness that has come fully to our day. Analyzing the layers of sediments formed at that time reveals the cause: fire. The decrease in pollen is accompanied by a significant increase in ashes that tell us about a burned Australia. Most likely, the fire made a sort of sieve, eliminating the most sensitive plants and giving an advantage to resistant species, such as eucalyptus or acacias. The fires forever changed the landscape of Australia transforming it from forest to garriga and extinguishing 85% of species over 45 kilos, but why did they occur?

Of marsupials and men

It is difficult to be sure what a fire like this could produce, but for decades experts have considered a wild hypothesis. It is possible that the fault is ours.

The explorer Ludwig Leichardt discovered in 1847 that the Australian aborigines used fire to hunt animals. The strategy was to burn the land irregularly, generating small islands of vegetation surrounded by black seas of ash. In this way, the dams ended up meeting in one place, making their hunting easier. Arsons that, until recently, were still being carried out, and not only for hunting, but for agriculture. There is evidence of the burning of swamps, specifically the reeds that grow in them, fertile the Earth with its ashes, making them much more cultivable.

If we add to this its ritual use, such as lighting, for cooking, for heating, or even to suffocate bats in a cave, the constant presence of fire around human settlements makes us especially suspicious of the fires of tens of thousands of years. In this way, by altering the vegetation, we could have compromised the food of herbivores and therefore carnivores.

And there is more, because to all this must be added the hunt itself. Gifford Miller speaks of an “imperceptible extermination”, since the slow gestation of the marsupials and their low number of young per litter make their repopulation difficult, making them very sensitive to hunting, however controlled. Specifically, Miller’s calculations indicate that, with each person killing one juvenile per decade, the species could become extinct in a matter of a few hundred years.

However, as logical as it may seem, we cannot be sure that this was the reason, because we cannot specify the date much more. The truth is that we do not know when exactly the first human beings arrived in Australia. Although most studies state that we reached around 60,000 or 40,000 years, others suggest that it could be much more recent, after the change in vegetation. Moreover, other studies suggest that the burning carried out by the aborigines kept the mountain clean of dry leaves, preventing spontaneous fires. But then, if it wasn’t us, what could cause such a catastrophe?

Climate change

What if it was the other way around? What if the vegetation first changed, drying up in large quantities causing huge fires across the continent? This is the second most shuffled option among experts. Geological records indicate that Australia, at that time, experienced a change in climatic conditions. This could change the rules of the game for many plants and animals, unable to survive in more barren environments. When the great herbivores died, there was no one left to clean the stubble, and the dried plants began to accumulate. This, Australia’s dry climate and natural flammability did the rest.

However, most likely, the reality was mixed, a mixture of the two hypotheses that brings us back to the present, where the protagonists are the same: the human being and global warming.

Global warming is a fact, experts have no doubt. However, many will say that climate change is something natural, that there are cycles with glaciations and thaws, and the truth is that they will be right. Change is not our fault or the real problem, it is the speed at which it changes. Every year there is more scientific evidence of this: human action is accelerating climate change.

Australia’s climate is becoming increasingly extreme and burning as it had rarely done. Now we know its history and we know what that land of fire is capable of. In our hands is putting a brake.

DON’T KEEP IT UP:

  • We do not know for sure if the extinction of the Australian megafauna was due to the action of man. Most likely, it was the combined effect of hunting fires and climate change.
  • Global warming is a reality of which we have objective scientific evidence that goes beyond any political, economic or ideological interest.
  • The cyclical changes in the weather are natural and, in fact, we are still emerging from an “ice age.” However, they are accelerating because of human action, being too fast for many species to adapt to them.

REFERENCES (MLA):

.



Source link