Climate crisis: Amazon to reach critical tipping point ‘by 2064’, study suggests

The ‘lungs of the world’ are on fire and academics’ warnings are becoming increasingly fervent, writes Harry Cockburn

A burning wasteland in what used to be part of the Amazon rainforest (Getty)

The Amazon, the world’s largest rainforest and one of the most diverse ecosystems on the planet, could cross a tipping point within 50 years which will put it on course to become an inhospitable dry plain, a University of Florida professor has predicted in an academic journal.

The “collapse of environmental governance in Brazil and other Amazonian nations”, along with rampant deforestation has already “radically altered” the Amazon Basin’s environment over the last 50 years, resulting in the region being “on the verge of a tipping point”, according to Professor Robert Walker, writing in Environment: Science and Policy for Sustainable Development.

As agricultural use in the forest expands, fire seasons worsen amid rising temperatures, and levels of rainfall decline, the collapse of the “Earth’s lungs” as the ecosystem is known, could be fully underway by the year 2064.

The lengthening dry seasons will mean that over the coming decades the rainforest canopies will no longer have the five years they need in between dry seasons to fully recover from fires, a change which could allow flammable grasses and shrubs to take over.

Using climate models, Professor Walker predicts that once around 30 to 50 per cent of the forest is lost in the south, the amount of rain in western parts of the Amazon could fall by up to 40 per cent - hastening the region’s overall demise.

“Southern Amazonia can expect to reach a tipping point sometime before 2064 at the current rate of dry-season lengthening,” Professor Walker said.

In the article, Professor Walker notes that water recycling accounts for 25 - 50 per cent of Amazonian precipitation, and is essential to the forest’s long-run sustainability.

Speaking to news agency UPI, he said: “The best way to think of the forest ecosystem is that it's a pump. The forest recycles moisture, which supports regional rainfall.

“If you continue to destroy the forest, the rainfall amount drops ... and eventually, you wreck the pump.”

The research provides scientists with the most specific date yet for the demise of the Amazon rainforest.

But the research outlines various future scenarios which could unfold as the ecosystem breaks down, which involve both deforestation and the impact on the forest of the global climate crisis.

“A tipping point need not only lead to tropical savanna,” writes Professor Walker.

“Other terminal possibilities include transition to an open, deciduous system or to what has all the appearances of a degraded, secondary forest with low biomass.

“In either case, the tipping mechanisms would be the same, processes of tree mortality arising from water and thermal stress. Such stress, reflecting changes in the regional hydroclimate, might result from global warming induced by greenhouse gas emissions.

“Alternatively, deforestation could alter land-surface albedo and the flux of latent heat, thereby compromising the forest’s ability to recycle moisture and sustain the amount of precipitation it needs to survive.”

The rainforest has already shrunk by around 20 per cent since development in the Amazon began in earnest in the 20th century.

Despite some “effective environmental policies” affording the forest in Brazil some respite at the turn of the millennium, Professor Walker says they “began to unravel at almost the same time they proved effective, and the deforestation numbers started to climb after reaching a low point in 2012.”

He writes that Brazilian president Jair Bolsonaro's administration “appears intent on scrapping all remaining restraints on the unfettered exploitation of Amazonia's natural resources.”

Ultimately the lack of water the scenario describes will not only impact the tens of millions living in the Amazon basin, but have a far wider impact, with tens of millions of people across South America going hungry and thirsty, he says.

The dire prediction follows an equally alarming report in the journal Nature Communications which warned the Amazon is on track to reach a critical tipping point within our lifetimes when the ecosystem’s ability to absorb excess carbon will fail and flip from being a vital carbon sink to a vast source of carbon by as soon as 2035.