On paper, the The Amazon rainforest is a still land: always wet, impenetrable, always buzzing with biology. But in reality, the region suffers from periodic droughts as rainfall dwindles, trees weaken, and wetlands dry up. Boom and bust. As with forests around the world, it is part of the natural order.
One of the causes of drought in the Amazon could soon flare up, potentially putting additional strain on an ecosystem already ravaged by deforestation and fires caused by human intervention. The El Nino-Southern Oscillation is a Pacific phenomenon in which a growing stretch of water off the coast of South America turns from neutral to extremely cold or warm. Cold conditions “La Niña” for the past few years is weakeninglikely to give way to warming “El Niño” conditions later this year, according to model by the National Oceanic and Atmospheric Administration. And for the Amazon, that could trigger a drought.
It is still too early to know when El Nino will arrive and how severe it will be. But scientists recall bad things that happened during El Niño eight years ago. “In the year 2015-2016, we Was observed Juan Carlos Jiménez-Muñoz, a physicist and remote sensing expert at the University of Valencia, said the air temperature in Amazonia was probably the highest in the last century. “Especially, on Amazonia [El Niño] prevent rain, and in general you can expect a widespread drought.” However, Jiménez-Muñoz cautions, “every El Niño is different—you can have different regional or local impacts.”
That’s because El Niño widely alters the atmospheric circulation. As that warm body of water formed in the Pacific Ocean, it created more evaporation, sending moist air into the sky. That water ends up falling like rain on the ocean. This messes with pedestrian traffic, sending relatively dry, sunken air over the land of South America, resulting in less rainfall over the Amazon. “In general, more rain falls over the ocean,” said James Randerson, an earth system scientist at the University of California, Irvine. “It’s just that it doesn’t rain much on land. Continents lost water, especially South America.”
When El Niño is inactive and conditions are normal, moisture evaporates from the Amazon and rises into the sky before falling into the forest as rain. Amazon can recycle up to half of its rain this way. “The Amazon is a factory that produces moisture in the atmosphere,” said Paola A. Arias, a climate scientist at the University of Antioquia in Colombia. “When you have these drought events, you usually reduce this recycled rainfall as well.”
Because El Niños vary in intensity, they vary in how well they block rain on the Amazon. They also differ in where exactly they spawn and for how long. If El Niño growth is more concentrated in the central Pacific Ocean, it tends to produce drought centered in the northeast of the Amazon. If it were more concentrated in the eastern Pacific, the drought could be more widespread and last a little longer. But by 2023, it’s too early to say how any of this will play out — Randerson says scientists should have a better idea this spring. “The fact that we are in here La Nina lasts “I think you’re more likely to go into a stronger El Niño,” Randerson said.
