Up to 40% of the Amazon at risk of becoming savannah

Posted by Storm Simpson on 6 October 2020

Up to 40% of the Amazon rainforest is at risk of transforming into a totally different, much drier, savannah-like ecosystem if rainfall levels continue to decline because of climate change, according to new research.

Rainforests are very susceptible to changes that affect the rainfall for extended periods of time. If rainfall drops below a certain threshold, large swathes of the forest may shift into a savannah state, permanently.

Sectors of the Amazon region are currently experiencing less rainfall than previous years. As greenhouse emissions increase, even more sections of the Amazon rainforest are at risk of losing their natural resilience, becoming unstable and are likely to dry out, according to researchers from the Stockholm Resilience Centre (SRC).

The SRC is an independent international research centre that focuses on resilience and sustainability science.

Arie Staal, the lead researcher of the study published in the peer-reviewed journal Nature Communicationsand his team used mathematical modelling to evaluate how rising temperatures, induced by climate change, would affect tropical rainforests around the world.

‘In around 40 percent of the Amazon, the rainfall is now at a level where the forest could exist in either state – rainforest or savanna,’ said Staal.

The findings are concerning because the trend is expected to worsen. According to the study’s introduction: ‘Tropical forests are important regulators of the global climate – and the effects of their loss could cascade through the Earth system.’

In their modelling and simulations, the team investigated the resilience of tropical rainforests by considering two questions. Namely: what if all the forests in the tropics disappeared, where would they grow back?

And its opposite: what would happen if rainforests covered the entire tropical region of Earth?

These extreme scenarios help scientists understand the resilience and sustainability of real rainforests and give us an idea of how forests will react to changing precipitation patterns because of climate change, according to Science Daily.

After running three different models the researchers concluded that as greenhouse emissions continue to grow, more parts of the Amazon will lose its natural resilience and become a savannah-like ecosystem. They note that even the most resilient part of the rainforest shrinks.

‘We understand now that rainforests on all continents are very sensitive to global change and can rapidly lose their ability to adapt,’ says Ingo Fetzer, a co-author of the study.

‘Once gone, their recovery will take many decades to return to their original state. And given that rainforests host the majority of all global species, all this will be forever lost.’

The devastating loss of the Amazon rainforest may already be underway, according to EartherIn email correspondence with the publication, Arie Staal said: ‘There is evidence that in some places it is occurring,” citing the Amazon’s rainforest floodplains as an example.

Picture: Unsplash.

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