<
https://www.theguardian.com/environment/2024/feb/14/amazon-rainforest-could-reach-tipping-point-by-2050-scientists-warn>
"Up to half of the Amazon rainforest could hit a tipping point by 2050 as a
result of water stress, land clearance and climate disruption, a study has
shown.
The paper, which is the most comprehensive to date in its analysis of the
compounding impacts of local human activity and the global climate crisis,
warned that the forest had already passed a safe boundary and urged remedial
action to restore degraded areas and improve the resilience of the ecosystem.
Bernardo Flores of the Federal University of Santa Catarina, Brazil, the lead
author of the study, said he was surprised by the results, which projected a
potential shift from slow to rapid forest decline earlier than he had expected.
The forest was already becoming weaker and more homogenous, he said. “By 2050,
it will accelerate rapidly. We need to respond now. Once we pass the tipping
point, we will lose control of how the system will behave.”
This requires international action because even a local halt to deforestation
would not prevent collapse without a global reduction in the CO2 emissions that
are disrupting the climate.
For 65 million years, Amazonian forests have withstood climatic variability,
but the region is now exposed to unprecedented stress from drought, heat, fire
and land clearance, which are penetrating even the deep central areas of the
biome. This is altering the functioning of the forest, which in many areas is
producing less rain than before, and turning a carbon sink into a carbon
emitter.
Concerns about an Amazon tipping point have been discussed for the past two
decades, with previous models suggesting this could come when 20% to 25% of the
forest is cleared. The new study, published in Nature on Wednesday, went
further in its complexity, analysing evidence for five drivers of water stress
and identifying critical thresholds that, if crossed, could trigger local,
regional or even biome-wide forest collapse.
It estimated that by 2050, 10% to 47% of Amazonian forests would be exposed to
compounding disturbances that might trigger unexpected ecosystem-wide
transitions and have an adverse knock-on effect for regional climate change.
To prevent this, the study found that a safe boundary, which included a buffer
zone, would be needed to keep deforestation to 10% of the Amazon region, and to
keep global heating within 1.5C above pre-industrial levels.
But overshoot has already happened. The study found 15% of the Amazon had
already been cleared and another 17% had been degraded by human activity, such
as logging, fires and under-canopy extraction. A further 38% of the Amazon may
be weakened as a result of the prolonged droughts over the past decade.
Using recent data collected on the ground, proxy indicators of ancient trends,
and computer modelling that incorporates regional and global climate trends,
the study traced three plausible ecosystem trajectories: a white-sand savanna,
a degraded open canopy and a degraded forest – all of which would bring more
fire and drought."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
