- Tweeter
republish
The states of Victoria and New South Wales, in the south-east of Australia, have been devastated since the end of September by gigantic fires, an extreme phenomenon which had not occurred for several decades. Are these fires, which have become uncontrollable, due to global warming?
The starting ingredients for these fires are dry land and temperatures well above seasonal averages. The link with the weather is pretty clear. Temperatures have broken records since the start of summer in Australia.
On the plain of Nullarbor, a vast flat region, almost treeless, located south of the island and north of the Great Australian Bay, the temperature climbed to 49.9 ° C on Thursday December 19, 2019, a record historical.
The climate, jointly responsible
It is more difficult to establish a clear link between these mega-moles and the climate. However, the Australian weather has noted temperature averages since 1910. These averages began to increase in the 1980s. Then from 2013, there was between 1 and 3 ° C on average more across the country, with a very sharp peak in 2019.
Robert Vautard, a researcher in the laboratory of climate and environmental sciences at the CNRS, remains cautious about the attribution of these fires to climate change, but he notes a marked increase in heat waves. Conditions are therefore more favorable for this type of fire than they were a few decades ago.
The Australians were confronted with pyrocumulonimbus. These are gigantic "clouds of fire" or "dragon breath", which are created above the plumes of smoke.
The heat given off by a violent forest fire creates a very fast updraft, of ultra hot air. This air rises and when it arrives in the upper layers of the atmosphere, it is brutally cooled and turns into a huge cloud of water vapor from which flashes of lightning and tornadoes burst.
NASA observers say there are so many this year that they could be listed in the Guinness Book of Records.
Smoke goes around the planet
The immense plumes of smoke that emanate from these mega-lights have already traveled half the globe. By the way, they notably deposited ashes on the glaciers of New Zealand . The ice is therefore now darker there, it reflects the sun's rays less well, which will accelerate its melting. But this smoke will disappear in the coming months. On the other hand, the greenhouse gases which are released in quantity during the combustion of forests will themselves remain in the atmosphere for a very long time.
► Read: Fires in Australia: toxic fumes pollute up to New Zealand
" In the future, these trends towards stronger and more intense droughts in Australia are quite clear and we expect fire episodes of the same intensity ", explains Robert Vautard, researcher at CNRS. Even if we stopped emitting greenhouse gases now, global warming could not be reversed.
The study of 57 scientific articles by researchers from the University of East Anglia (United States), published on Tuesday, January 14, shows a clear link between climate change and both the frequency and the intensity of fires in several regions, with a 20% extension of the fire season.
It therefore seems necessary to think about forest management and land use, the co-responsible parameters of these fires, but on which we can act.