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Deforestation linked to irreversible transition in the Amazon

The Amazon rainforest is one of the most biodiverse places on Earth. As the world’s largest tropical rainforest, it also plays an important part in regulating the planet’s oxygen and carbon cycles. Yet, the harsh reality is that this vital ecosystem may not be able to survive the pressures of deforestation and human-induced climate change. 

Many scientists believe that the Amazon may soon reach a tipping point – a critical threshold beyond which it can no longer sustain rainforest. Some experts predict that the Amazon rainforest is being irreversibly transformed into dry savannah. Until now, however, the inception of this transition has not been supported by observations.

In a new study from the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences, experts have revealed how deforestation is triggering an irreversible transition in the Amazon hydrological system. According to the researchers, the consequences could trigger a tipping point to a treeless Amazon.

“Here we show that reduction in evapotranspiration from 20 years of deforestation dried the atmosphere persistently and caused moisture decoupling, i.e. an opposite sign of moisture change between the lower and middle troposphere. Increased deforestation exacerbated the lower troposphere drying and caused it to penetrate deeper into the middle troposphere in the dry and transition seasons over monsoon forests and savannas,” explained the researchers.

“Deforestation induced warming-enhanced buoyant updrafts, elevated hot and dry air and thereby reduced downward mixing of water supplies from the tropical Atlantic that normally moisten the Amazon forests.”

Study co-author Dr. Gensuo Jia said that the severe atmospheric desiccation cannot be compensated by enhanced water supplies from the Atlantic Ocean, demonstrating an emerging transition in Amazon hydrological cycle.

Despite the grim findings, the study has also produced some hopeful results. The experts determined that the drying over the northern part of Amazon rainforest has just recently occurred, which indicates that there may be an opportunity for preventing ecosystem collapse with forest conservation. 

“Large scale forest conservation and ecological restoration are still promising and offer opportunities for reversing the drying trend and preventing ecosystem collapse,” said Dr. Jia. 

The study is published in the journal Environmental Research.

By Chrissy Sexton, Staff Writer

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