Climate change will fuel fires in the Amazon jungle | Science

In 30 years, the burned area of ​​the Amazon jungle will have doubled. A study based on the evolution of fires so far this century shows that the result of the interaction of deforestation and climate change will be a greater number of even more devastating fires. As a consequence, a good part of the Amazon region will become a net emitter of greenhouse gases, which, in turn, would feed back the process. There are experts who start talking about a point of no return and the sabanization from the Amazon.

Brazilian and American researchers have modeled the evolution of the fires on almost 200 million hectares of the southern and southeastern portions of the Legal Amazon. In the model, the number of fires and their main characteristics (moment of ignition, duration, burned area …) were integrated with the evolution of deforestation and climate change between 2000 and 2050. Both processes are independent but, combined, affect the amount and severity of fires, as shown in this work, published in Science Advances.

In the worst of the predicted emission scenarios and keeping the current rate of deforestation relatively low (compared to 2000), the severity of the fires will intensify. In an expected context of higher temperature and lower humidity, the dry season will lengthen, exacerbating conditions for ignition. In 2050, according to this study and in this scenario, up to 15 million hectares of jungle will have been burned.

Increasing temperatures and lower humidity will increase the flammability of the forest

But it is in combination with deforestation in which climate change will fuel the fire to threaten what has been the Amazon in the last 55 million years. In a context of high greenhouse gas (GHG) emissions and increased regional warming, the intensification of deforestation will expose the rest of the forest. The study estimates that, in this scenario, the hectares burned in 2050 will rise to 22 million.

Among the synergies between climate change and logging that explain this increase in the burned area is a general increase in the flammability of the forest. The edges and edges of the forest, more exposed, will have increased. In clear forests, the highest solar radiation reduces humidity, the main natural firefighter. And a less humid environment facilitates the start and spread of a fire and complicates its extinction. In addition, what is left of the jungle will be more difficult to recover.

“Our projections point to an acceleration of fire activity in the southern Amazon,” conclude the study authors, adding, “We show that up to 16% of the region’s rainforests could burn as the weather it gets drier and warmer in a few decades. “

A paradoxical effect of these projections has to do with GHG emissions. The Amazon rainforest is the main sink for COtwo on the Earth’s surface. Fires could upset your balance. According to this research, and in the worst climate and deforestation scenario, the burning of a sixth of the Amazon will release more than 17,000 million tons of CO by 2050.two into the atmosphere, turning much of the southern and southeastern Amazon into net GHG emitters.

Up to 60% of the forest could degenerate into savanna by the end of the century

“Under normal conditions, tropical forests such as the Amazon are very humid, with a short dry season and very resistant to fire,” recalls Carlos Nobre, researcher at the Institute for Advanced Studies at the University of São Paulo (Brazil). “However, climate change has generalized higher temperatures and more extreme droughts everywhere, also in the Amazon. Along with the degradation of man-made tropical forest and the intensive use of fire in tropical agriculture and to clear new ranches and farmland, all of this makes today’s Amazon rainforest exponentially more vulnerable to fire than it was in the past, “adds Nobre, unrelated to this study.

The fire thus joins the cocktail that threatens to change forever what the Amazon is. “We are very close to reaching a point of no return in the sabanization of large portions of the Amazon rainforest, “says Nobre, who wrote an editorial about this risk in the magazine Science Advances last month. “If we exceed this point of no return, more than 60% of the Amazon forests will become a tropical dry savanna. What remains of the jungle will be limited to the western portion of the Amazon basin, at the foot of the Andes. south, east and northeast of the Amazon jungle could disappear, “he warns.


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