MANAUS, BRAZIL—Jochen Schöngart darts back and forth along an escarpment just above the Amazon River, a short water taxi ride from downtown Manaus, Brazil. It’s still early this October morning in 2023, but it’s already hot and his face is beaded with sweat. “Look, there’s a piece of ceramic!” he says, nodding to a worn shard lodged between boulders, likely a relic of an earlier civilization. It’s not the only one.

       Schöngart, a forest scientist at the National Institute of Amazon Research (INPA), stoops and stares at the bedrock at his feet. Well below the river’s normal level for this time of year, the rock bears a gallery of life-size faces, perhaps carved during a megadrought 1000 years ago. Now, they have been exposed again by a new drought, the worst in the region’s modern history.

        In the previous 4 months, only a few millimeters of rain have fallen in this city of 2 million at the confluence of the Negro and Amazon rivers. Normally it gets close to a half a meter during the same period. The Amazon sank steadily beginning in June, as it does most years during the dry season. But by mid-October, the port’s river gauge reached the lowest level observed since the record began in 1902. Freighters coming up from the Atlantic Ocean—the city’s primary supply line—were blocked by shoals. Factories furloughed workers.

     Making matters worse, the drought coincided with a series of week-long heat waves. In September and October, withering conditions persisted across the Amazon, and temperatures here peaked at 39°C, 6°C above normal. Desiccated jungle set ablaze by farmers enveloped the city in choking smoke. Then, in the season’s most freakish episode, a sandstorm blotted out the Sun.

       Drought and heat are only half of the story of the changes unfolding in the heart of the world’s largest rainforest. Schöngart and collaborators’ research on the river here has shown that for decades, while dry-season low water has been plummeting, rainyseason high water has been rising. The city has experienced frequent major flooding in recent years because of heavy rains across much of the Amazon Basin, forcing the officials to erect temporary wooden walkways above streets of the historic waterfront.

    Schöngart and other researchers expect such changes to intensify as global climate warms. The current drought provided a grim preview, killing river dolphins and fish, and threatening livelihoods for communities along the river. If the combination of higher highs and lower lows becomes the new norm, the ramifications could extend throughout the Amazon Basin and even beyond, threatening the very existence of the forest—which harbors much of the planet’s biodiversity, has a far-reaching influence over regional and global climate, and sustains millions of people.

    “We are undergoing massive changes in the hydrological cycle” of the Amazon Basin, Schöngart says. The question now, he says, is whether its ecosystems and people can adapt.

Adapted from: https://www.science.org/content/article/amazon-river-may-alteredforever-climate-change