Amazon fires spread as drought brings hazardous smoke to Manaus

Fires are spreading through parts of the central and eastern Amazon after months of drought, with smoke severely worsening air quality in the Brazilian city of Manaus, NASA says. Satellite monitoring detected a sharp rise in fire activity from September, and scientists warn the region may be at the start of a prolonged fire season. [1]

An image captured by NASA’s Aqua satellite on 12 October showed smoke from fires on both sides of the Amazon River. Manaus officials reported fine-particle pollution above 135 micrograms per cubic metre that day. Schools closed, and public events and children’s sports leagues were cancelled, NASA reported, citing news coverage. [1]

Douglas Morton, an Earth system scientist at NASA’s Goddard Space Flight Center, describes the Amazon fires as part of a wider tropical pattern linked to El Niño. Research published after the 2015–16 El Niño, and observations in 2023, found a sequence of elevated fire activity beginning with drought and peat fires in Indonesia before moving to the central and eastern Amazon. Morton says the current fires follow a similar pattern.

He expects fire risk to increase farther north in November and December, including in parts of Brazil, Venezuela, Guyana and Suriname. In the southern Amazon, including areas of Brazil and Paraguay, he expects drought and fire risk to peak around August and September 2027. These are forecasts, and the timing and severity will depend on conditions, including rainfall. [1]

NASA says rainfall in Manaus was 95 per cent below normal in August and 60 per cent below normal in September, citing Brazil’s National Institute of Meteorology. Morton said most fires in the Brazilian Amazon are started by people rather than lightning. He said many begin as land-management burns, such as clearing pasture or fields, but can escape into the dry forest understorey.

The scale may be undercounted by standard satellite monitoring. Shane Coffield, a University of Maryland researcher working with NASA Goddard, estimates that 50 to 70 uncontrolled fires are burning in the Santarém area. His analysis of additional satellite observations identified about 40 per cent more fires there than appear in active-fire counts from NASA’s Fire Information for Resource Management System. Smoke, clouds and tree cover can prevent satellites from detecting fires, particularly those burning at lower intensity beneath the canopy. [1]