Nature & Environment

Amazon rainforest could turn into grasslands

By T.K. Randall
October 5, 2020

Image: Amazon Rainforest in Tena, Ecuador
Credit: Jay / CC BY 2.0 (adapted) There's no denying the impact that mankind has had on the Amazon basin - a vast region of South America containing more than 2 million square miles of tropical rainforest.

Over the last few decades, this diverse and critical biome has been gradually destroyed by deforestation, human construction projects and climate change.

Now scientists at the Stockholm Resilience Center have warned that much of the Amazon is now on the verge of permanently switching from rainforest to open savannah - a process that can take decades to happen but which is extremely difficult to reverse once it gets going.

Chief among the reasons for this is climate change which has brought about less rainfall and longer periods of dry, hot weather which in turn has brought lengthy droughts and more frequent wildfires.According to the study, at least 40% of the Amazon is now at the tipping point at which it could exist as either rainforest or savannah and more is reaching this state all the time.

"As forests grow and spread across a region, this affects rainfall," said study lead author Arie Staal.

"Forests create their own rain because leaves give off water vapour and this falls as rain further downwind. Rainfall means fewer fires leading to even more forests."

If enough trees are lost however, the balance is tipped and the forest is no longer sustainable.

"Drier conditions make it harder for the forest to recover and increase the flammability of the ecosystem," said Staal.

"It is harder to return from the 'trap' caused by the feedback mechanism in which the open, grassy ecosystem is more flammable, and the fires, in turn, keep the ecosystem open."

Source: The Guardian

Tags: Amazon