Some 3,859 outbreaks were recorded by the country’s National Space Research Institute (Inpe) in the 48 hours following the 60-day prohibition on setting trees alight.
Some 2.000 of those blazes were in the Amazon rainforest.
The figures come as the latest blow in an environmental crisis that has caused panic across the world and which led the agenda at the recent G7 summit in France.
More than 72,000 fires had already been detected across Brazil between January and August – the highest number since records began in 2013 and an 83 per cent increase on the same period last year.
Because it is the world’s largest rainforest, the fate of the Amazon – often called the “lungs of the world” – is widely considered by climate change experts as key to the future of the planet.
It is a vital carbon store that slows down global warming while providing some 20 per cent of the world’s oxygen. Its destruction – deliberate or otherwise – reduces the ability of nature to suck carbon from the atmosphere.
But Brazil’s far-right president, Jair Bolsonaro, who came into power promising to clear vast tracts of the rainforest for development, had, until last week, remained unmoved.
He has systematically weakened institutions designed to protect the rainforest, while offering moral support to farmers wishing to turn the land into cattle ranches.
And, although he has now placed a 60-day ban on burning and deployed 44,000 troops to fight the ongoing blazes, critics fear it is too little too late.
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Tasso Azevedo, who runs the deforestation monitoring group Mapbiomas, said the legislation’s focus on fire means developers clearing the forest would continue to legally chop down trees – and then simply burn them after the prohibition period ended.
Writing in O Globo newspaper, he called for the ban on the use of fire to be extended until the end of the dry season in November.
He said: “What we are experiencing is a real crisis, which can turn into a tragedy that will feature fires much larger than the current ones if not stopped immediately.”