The Amazon and other tropical forests store between 90 and 140 billion tons of carbon; This makes it contribute to climate stability, and the Amazon alone has about 10 percent of the Earth's biomass.
The "El Niño" phenomenon between 2015 and 2016 caused severe drought, and the associated forest fires that resulted in it, in addition to the death of hundreds of millions of trees and plants.
The phenomenon caused emissions of an estimated 495 million tons of carbon dioxide, from an area that makes up only 1.2 percent of the entire Brazilian Amazon rainforest.
El Niño is a global climate phenomenon that occurs when a temperature change in one ocean affects the weather in another remote area, produces massive changes in weather conditions, and can lead to droughts.
The international team, led by scientists from Lancaster and Oxford Universities and the Brazilian Institute of Agricultural Research, worked for more than 8 years on a long-term study of the Amazon region, before, during and after the El Niño phenomenon; They discover shocking findings that have major implications for global efforts to control the carbon balance in the atmosphere.
According to climate predictions: Severe droughts will become more common, and until now the long-term effects of drought and fires on the Amazon rainforest were largely unknown, especially within forests affected by activities such as illegal selective logging.
But when examining the “Amazon Center” of the “El Niño” phenomenon in the Lower Tapagos region of Brazil, located east of the Amazon, and an area about twice the size of Belgium, the international team found that the damage extends for several years.
The study revealed that trees and plants in drought-affected forests, as well as burnt forests, continued to die at a higher rate than normal for up to 3 years after the El Niño phenomenon subsided. As a result, more carbon dioxide remains in the atmosphere.
The total carbon emissions from drought and fires in the lower Tapagos region alone, were higher than full-year deforestation in the entire Amazon.
As a result of droughts and fires, over 3 years, the region has released the equivalent of the annual carbon emissions of some of the world's most polluted countries, surpassing those of developed countries such as Britain and Australia.
After three years, only about a third of the "37 percent" of emissions had been reabsorbed by plant growth in the forest.
This shows that the Amazon's vital function as a "carbon sink" can be impaired for years after these drought events.
Dr Erica Berenger, lead author of the study, said: 'Our results highlight the highly devastating, long-term effects that fires can have in the Amazon, an ecosystem that did not evolve with fires and represents a systemic stress.
The scientists collected the data by regularly reviewing 21 plots of regrown forest land, and forests affected by selective logging.
Although previous research has shown that human-grown forests are more susceptible to fire, it was not known whether there was any difference in the vulnerability and resilience of trees and plants in these forests when exposed to drought and fire.
They found that trees and plants with lower wood density and thinner bark were more likely to die from drought and fire, and these smaller trees are more common in human-growth forests.
The researchers estimate that around 447 million large trees died, while around 2.5 billion smaller trees died across the lower Tapagos region.
Carbon emissions from those forests hit by fires were nearly 6 times higher than from drought-affected forests alone.
These findings highlight that human intervention can make the Amazon forest more vulnerable and underscore the need to reduce illegal logging and other large-scale human activities in the Amazon, as well as the need to invest in the region's firefighting capabilities.
Commenting on the findings, Professor Jos Barlow, of Lancaster University and the Federal University of Lavras, lead author of the study, said: “The need for action has emerged at different levels internationally. We need to take action to address climate change, at a time when the potential for action is rising. severe droughts and fires.
"At the local level 'in the Amazon' forests, forests will suffer fewer negative consequences than fires if they are protected from degradation," Barlow added.