El Niño Is Setting the Amazon on Fire, and Scientists Say the Worst Is Still Ahead

Keypoints:

• Brazil's Amazonas state recorded 1,679 fires in the first two weeks of October, a 253% jump from a year earlier
• At least 36 municipalities declared states of emergency
• NASA scientist Douglas Morton describes a chain of El Niño fires that moved from Indonesia to the Amazon
• Burning is expected to continue until rains arrive in December or January
• Forests that burned during the 2015 and 2023 El Niño events are burning again

Fires are surging across Brazil's Amazon as one of the strongest El Niño events on record dries the region. According to the state's monitoring system, Amazonas state recorded 1,679 fires in the first two weeks of October. That is 253% more than the same period last year. At least 36 municipalities have declared states of emergency, and smoke has caused respiratory problems for residents.

The timing is unusual. August and September are normally the height of the dry season. Rains typically bring relief in October. This year the rains have been slow. Carlos Durigan of the Amazon Environmental Research Institute says intense water stress and heat stress, combined with human activity, threaten biodiversity, health and productivity.

NASA scientist Douglas Morton of the Goddard Space Flight Center describes a pattern. El Niño changes rainfall over many months, so fires tend to move across the tropics in sequence. Indonesia's haze came first this year. The Amazon is the second domino. Morton warns that more fire-prone regions could follow into 2027.

Human choices matter. Fires in the Amazon are rarely natural. They are usually set to clear land for farming or ranching, and officials suspect many of these were set on purpose. Smoke has covered Manaus, where schools closed and outdoor events were cancelled. Satellites have recorded rising fire counts and smoke since September in the central and eastern forest, from near Manaus and Santarém to the mouth of the river.

Rainforest fires are especially damaging. Most plants and animals in a tropical forest have not evolved to withstand frequent burning. Morton also notes that areas burned in 2015 and 2023 are burning again. His advice is clear. Given the intensity of this El Niño, this is the year for people to avoid burning at all costs.