BRASILIA, Brazil

The Negro River, Brazil’s second largest tributary, reached its lowest level since official measurements began near Manaus 121 years ago, confirming the Amazon’s worst drought. The river drains about 10% of the Amazon basin and is the world’s sixth largest by water volume.

The Madeira River, another main tributary of the Amazon, has also recorded historically low levels, causing the halt of the Santo Antonio hydroelectric dam, Brazil’s fourth largest.

Throughout Brazil’s Amazon, low river levels have left hundreds of riverine communities isolated and struggling to access drinkable water. The drought has disrupted commercial navigation that supplies Manaus, the largest city and capital of Amazonas, the state hit hardest by the drought. In late September, 55 of 62 municipalities in the state entered states of emergency due to the severe drought.

Manaus and nearby cities are experiencing high temperatures, heavy smoke from deforestation-caused fires, and drought, potentially leading to river dolphin deaths in Tefe Lake near the Amazon River.This is a startling contrast to July 2021, when Negro River waters took over part of the Manaus downtown area, causing a historic flood that ruined crops of hundreds of riverine communities.

The Negro River, which converges with the Amazon River in Brazil, is expected to worsen due to increasing frequency and severity of similar events with climate change. The eastern equatorial Pacific Ocean is now warmer than during the “Godzilla” El Niño of 2015-2016 and is expanding, leading to droughts in the northern part of the Amazon.

A warm water patch in the tropical North Atlantic Ocean is also causing drought in the southern part of the Amazon, similar to 2005 and 2010. The forecast is for the start of rains to be delayed compared to normal and for a drier-than-normal rainy season, potentially resulting in extreme low water levels this year and in 2024. The situation is expected to worsen until the rainy season begins in the basin.