According to the international team of 35 scientists who conducted the study, the four most consequential sources of disruption are "edge effects" (forest changes caused by nearby deforestation and the ensuing habitat fragmentation); "selective logging"; and forest fires and extreme droughts intensified by the fossil fuel-driven climate crisis.
Based on their analysis of existing data on the extent of edge effects, timber extraction, and fires from 2001 to 2018, researchers found that 5.5% of Amazonian forests are degraded. When data on extreme droughts was considered, their estimate of the total degraded area grew to 38%.
The Guardian, which had early access to the full paper, summarized the scholars' findings as follows on Thursday: "Fires, land conversion, logging, and water shortages have weakened the resilience of up to 2.5 million square kilometers of the forest, an area 10 times the size of the U.K. This area is now drier, more flammable, and more vulnerable than before, prompting the authors to warn of 'megafires' in the future."
A substantial chunk of the world's largest tropical rainforest—nicknamed the "lungs of the Earth" due to its unparalleled capacity to provide oxygen and absorb planet-heating pollution—is "less able to regulate the climate, generate rainfall, store carbon, provide a habitat to other species, offer a livelihood to local people, and sustain itself as a viable ecosystem," The Guardian noted.
Degradation, defined as human-induced changes in forest conditions, has led to carbon emissions equivalent to or greater than those from deforestation, the authors note. As an accompanying statement explains: "Degradation is different from deforestation, where the forest is removed altogether and a new land use, such as agriculture, is established in its place. Although highly degraded forests can lose almost all of the trees, the land use itself does not change."
Co-author Jos Barlow, a professor of conservation science at Lancaster Univerity, said that the cumulative impact of the key degradation factors examined "can be as important as deforestation for carbon emissions and biodiversity loss."
In addition, the paper makes clear that Amazon forest degradation is associated with significant socioeconomic harms that require further investigation.
"Degradation benefits the few, but places important burdens on many," said co-author Rachel Carmenta from the University of East Anglia. "Few people profit from the degradation processes, yet many lose out across all dimensions of human well-being— including health, nutrition, and the place attachments held for the forest landscapes where they live."
"Many of these burdens are hidden at present," Carmenta added. "Recognizing them will help enable better governance with social justice at the center."
"Preventing the advance of deforestation remains vital, and could also allow more attention to be directed to other drivers of forest degradation."
Looking ahead to 2050, the paper projects that the four main drivers of Amazon forest degradation "will remain a major threat and source of carbon fluxes to the atmosphere" regardless of whether deforestation is halted.
"Even in an optimistic scenario, when there is no more deforestation, the effects of climate change will see degradation of the forest continue, leading to further carbon emissions," said lead author David Lapola, a researcher at the Centre for Meteorological and Climatic Research Applied to Agriculture at the University of Campinas. However, "preventing the advance of deforestation remains vital, and could also allow more attention to be directed to other drivers of forest degradation."
Luiz Inácio Lula da Silva, the recently inaugurated leftist president of Brazil—home to roughly 60% of the Amazon—has vowed to make "this devastation" of the forest "a thing of the past."
"There's no climate security for the world without a protected Amazon," Lula said during a mid-November speech at the United Nations COP27 summit—the first he made on the international stage after defeating Brazil's far-right ex-president, Jair Bolsonaro.
The Amazon passed a key tipping point at the tail end of Bolsonaro's four-year reign, during which ecological destruction accelerated as logging, mining, and agribusiness companies routinely violated the rights of Indigenous forest dwellers.
Last week, Lula accused Bolsonaro of committing genocide against the Yanomami people, who are enduring a deadly rise in hunger and disease due to a surge in illegal gold mining.
Lula, who drastically reduced deforestation and curbed inequality when he governed Brazil earlier this century, recently launched the first anti-deforestation raids of his new administration.
"There is hope now, but our paper shows it is not enough to resolve deforestation," Barlow told The Guardian. "There is much more work to be done."
As the new paper notes: "Whereas some disturbances such as edge effects can be tackled by curbing deforestation, others, like constraining the increase in extreme droughts, require additional measures, including global efforts to reduce greenhouse gas emissions. Curbing degradation will also require engaging with the diverse set of actors that promote it, operationalizing effective monitoring of different disturbances, and refining policy frameworks."
The authors propose creating high-tech systems to monitor forest degradation and implementing policies to prevent illegal logging and better manage the use of fire.
"Public and private actions and policies to curb deforestation will not necessarily address degradation as well," said Lapola. "It is necessary to invest in innovative strategies."
