A burnt section of the Amazon rainforest near the city of Porto Velho, Rondonia state, Brazil, on September 15, 2017. MAURO PIMENTEL / AFP
A new study published on Monday, March 7 in the scientific journal Nature raises concerns about the survival of the Amazon. Three researchers from the University of Exeter, UK, the Institute for Climate Impact Research Potsdam and the Technical University of Munich, Germany, studied the phenomenon of resilience, which they define as “the ability of the Amazon rainforest to return to a stable state.” after disturbances such as climatic events or droughts.
The study, titled “Pronounced Loss of Resilience in the Amazonian Forest Since the Early 2000s,” focused on the Amazon due to its key role in climate. The vast rainforest will hold about 90 billion tons of carbon dioxide, mostly in its trees and partly in the soil, which is equivalent to several years of global CO2 emissions.
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“We have been working with satellite imagery over the past twenty years, which were marked by fires and two severe droughts in 2005 and 2010. We then measured the resilience of the forest using metrics that we believe are strongly linked to sustainability,” says the University. Exeter mathematician and geographer Chris Boulton. The co-authors particularly appreciated the availability of water, the evolution of the general condition of vegetation, and the photosynthetic activity of species.
“More carbon dioxide”
Their findings are a new wake-up call for the international community, and in particular for the American South, which will be the first to witness a radical transformation of its climate driven by shocks to the Amazon ecosystem. According to their calculations, 75% of the Amazon rainforest is now losing sustainability. This loss is more pronounced in the most arid areas and where human activity is more intense, which primarily affects the southeast of the forest, an area corresponding to Brazil. “This buckling works without necessarily showing significant changes in biomass or forest cover. Thus, we were able to observe it in places that, nevertheless, have survived, ”adds Chris Boulton.
This reduced ability to regenerate allows researchers to extrapolate other lessons to the overall health of the forest and its future. According to physicist Niklas Burs of the Institute for Climate Impact Research in Potsdam, “These results, combined with IPCC projections [Groupe d’experts intergouvernemental sur l’évolution du climat], which predict less rainfall in the coming decades, means the impact could be even more severe than expected.” And to conclude that the tipping point of rainforest to savannah may also be closer than currently thought.
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