LIMA, PERU — The transition of the Amazon rainforest into a drier, savanna-like ecosystem often termed the Amazon’s “tipping point”—is being driven by the disruption of crucial atmospheric moisture pathways, known as “flying rivers,” according to a new report from Amazon Conservation’s Monitoring of the Andes Amazon Project.
The report aims to clarify the misconception that the tipping point will be a single, sudden event, stressing instead that it is a gradual process happening at varied rates across the region. The fate of these flying rivers, which transport and recycle moisture from the Atlantic Ocean across the Amazon basin, is identified as a critical factor influencing this transition.
Deforestation Disrupts Water Recycling Hundreds of Miles Away
Flying rivers are the primary source of water for huge swaths of the western Amazon. In this ecosystem, at least 75% of rainfall is recycled through evapotranspiration, going through up to six cycles before the air currents hit the Andes and turn south.
\text{MAAP}’s analysis found that deforestation interrupts this vital process. When the forest is cleared, more than 50% of the water runs off instead of being recycled, leaving the downwind forest without the necessary moisture to survive. This effect is not localized the report shows that deforestation in one part of the Amazon can cause permanent damage to distant parts hundreds of miles away.
Regions like Southern Peru and Northern Bolivia are particularly dependent on this recycled moisture, placing them at a higher risk of collapse.
While flying rivers appear intact during the wet seasons, scientists have detected significant disruptions during the dry months of July and August. During this time, moisture cycles are shifting farther south and hitting stretches of deforestation, interrupting the moisture transfer and leading to less rain in the western nations.
Need for Transboundary Conservation
The report warns that these interruptions will intensify as deforestation spreads, citing the proposed \text{BR-319} federal highway in Brazil as an “especially serious threat.” Conservationists have already dubbed the project the Amazon’s “tipping point road” because it could block flying rivers from reaching the western Amazon.
The team stressed the urgent need for a more regional and transboundary approach to conservation. Experts warn that even if conservation initiatives succeed in countries like Peru and Bolivia, “if Brazil’s forest gets annihilated, in the long term, these forests could be doomed,” as they depend on their eastern neighbors for the continuity of the hydrological cycle. The report recommends reduced deforestation in the eastern Amazon and strategic restoration projects to repair moisture recycling pathways.