When El Niño develops in the Pacific, its effects reach thousands of kilometers away, into tropical forests. NASA satellite observations show that the strong 2026 El Niño has already set off a "cascade" of fires, starting in Indonesia's drought-stricken peatlands and reaching the Amazon. Research by Douglas Morton, an Earth system scientist at NASA's Goddard Space Flight Center, has shown this sequence is predictable: in satellite data for 1997\u20132016, fire emissions in pan-tropical forests were on average 133% higher during and after El Niño than during La Niña.

Since September, satellites have detected a sharp rise in fires and smoke emissions across the central and eastern Amazon, from the forests around Manaus and Santarém to the river's mouth. On October 12, an image from NASA's Aqua satellite showed dense smoke blanketing Manaus, a city of more than 2 million people, where fine particle levels exceeded 135 \u00b5g/m\u00b3 and schools closed. Brazil's Amazon recorded 9,045 fire hotspots in the first half of October, 62% more than a year earlier, even as deforestation fell to a record low. Lightning ignites less than 1% of fires there, so nearly all are started by people, but drought has made them hard to control. A team led by Shane Coffield, of the University of Maryland and NASA Goddard, estimates there are about 40% more fires around Santarém than official counts show, because smoke, cloud and canopy hide low-intensity fires creeping through the understory.

Morton expects the fires around Manaus and Santarém to burn until the rains return in December 2026 or January 2027, with a further wave possibly hitting southern Brazil and Paraguay. These are researchers' expectations, not a probability forecast. The scientist's message is simple: this is the year to avoid burning at all costs.

Sources:
NASA Earth Observatory, NASA Science, Nature Climate Change, Reuters, MercoPress, ScienceDaily