Thousands of fires are ravaging the Amazon rainforest in Brazil – the most intense blazes.

The northern states of Roraima, Acre, Rondônia and Amazonas have been particularly badly affected.

The National Institute for Space Research (Inpe) says its satellite data shows an 85% increase on the same period in 2018.

The official figures show more than 75,000 forest fires were recorded in Brazil in the first eight months of the year – the highest number since 2013. That compares with 40,000 in the same period in 2018.

Forest fires are common in the Amazon during the dry season, which runs from July to October. They can be caused by naturally occurring events, such as by lightning strikes, but also by farmers and loggers clearing land for crops or grazing.

The fires have been releasing a large amount of carbon dioxide, the equivalent of 228 megatonnes so far this year, according to Cams, the highest since 2010.

They are also emitting carbon monoxide – a gas released when wood is burned and does not have much access to oxygen.

The Amazon basin – home to about 3 million species of plants and animals, and 1 million indigenous people – is crucial to regulating global warming, with its forests absorbing millions of tonnes of carbon emissions every year.

But when trees are cut or burned, the carbon they are storing is released into the atmosphere and the rainforest’s capacity to absorb carbon emissions is reduced.

Organizations, activists, and social media users worldwide have reacted to the news with alarm. #PrayForTheAmazon and other variations of the hashtag are trending globally on Twitter, with hundreds of thousands of tweets. As images and news of the fire spread, many are demanding accountability from Brazilian President Jair Bolsonaro.