Forest fires in Indonesia last year released 11.3 million tonnes of carbon per day, researchers have found. This figure exceeds the daily rate of 8.9 million tonnes of carbon emissions from the whole of the European Union, the study says.The 2015 fires were the worst since 1997, when a strong El Niño also fanned widespread fires, says the study, published in the journal Scientific Reports.Fire is widely used in South-East Asia to clear vegetation and maintain land for the growing of crops, the paper explains. Last year, fires were exacerbated by extended drought associated with El Niño, releasing 857 million tonnes of carbon dioxide from September to October 2015, the authors say. This represents 97 per cent of the country’s annual carbon emissions.