on paper, The Amazon rainforest is a static expanse: perpetually wet, impenetrable and constantly humming with biology. are stressed and wetlands dry up. boom and bust. Like forests around the world, it is part of the natural order.
One of the drivers of the Amazon drought could begin soon, putting even greater strain on ecosystems already devastated by human-induced deforestation and fires. The El Niño-Southern Oscillation is a Pacific phenomenon in which bands of water develop off the coast of South America, transitioning from neutral to very cold or warm conditions. Models from the National Oceanic and Atmospheric Administration show that the cool ‘La Niña’ conditions of the past few years may weaken and transition to warmer ‘El Niño’ conditions later this year. And for the Amazon, it could cause drought.
It is still too early to tell when El Niño will occur and how severe it will be. But scientists remember how bad things happened during El Niño eight years ago. “From 2015 to 2016 he observed that the temperature in Amazonia was probably the highest in the last 100 years,” said Juan Carlos Jiménez Muñoz, a physicist and remote sensing expert at the University of Valencia. said. “Especially over Amazonia [El Niño] Controlling rains and generally widespread drought is expected. But Jimenez Munoz warns, “Each El Niño is different. It can affect regions and regions in different ways.”
This is because El Niño changes the atmospheric circulation. As warm water masses form in the Pacific Ocean, they evaporate more, sending moist air into the sky. The water eventually falls into the sea as rain. This disrupts the Walker Circulation, sending relatively dry air that sinks over land in South America and reduces precipitation in the Amazon. “In general, more rain falls on the oceans,” says James Landerson, an earth system scientist at the University of California, Irvine. .”
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 could recycle up to half of its precipitation this way. “The Amazon is a factory for atmospheric moisture,” says Paola A. Arias, a climate scientist at the University of Antioquia in Colombia. “When these droughts occur, this precipitation recycling is also typically reduced.”
Because El Niños vary in size, they also vary in how well they hold back Amazonian rain. They also differ in the exact location and duration of drought. When El Niño outbreaks are concentrated in the central Pacific, droughts tend to be concentrated in the northeastern part of the Amazon. If concentrated in the eastern Pacific, the drought could be more widespread and last a little longer. But as of 2023, it’s too early to tell how this will play out. “I think the fact that we’re in this persistent La Niña for so long makes it likely that we’ll transition to a stronger El Niño condition,” says Landerson.
