Amazon Rainforest Approaching Critical Tipping Point, Study


Scientists added on Monday that the Amazon is losing its ability to recover from disturbances such as drought and land-use changes, adding that the rainforest is approaching a critical threshold where grassland will replace most of its rainforest, with major consequences for biodiversity and land use. climate change.

The scientists said their research has not determined exactly when this threshold, which they describe as a tipping point, will be reached.

“But it’s worth reminding ourselves that if we reach a tipping point where we’re committed to losing the Amazon rainforest, then we’re going to have significant feedback on global climate change,” said Tim Lenton, director of Global Systems, one of the scientists. Institute at the University of Exeter in England.

He said losing rainforests could result in up to 90 billion tons of heat-trapping carbon dioxide being returned to the atmosphere, equivalent to several years of global emissions. This will make limiting global warming more difficult.

Among previous studies, there was great uncertainty about when such a threshold could be reached. But some studies have concluded that deforestation, drying and other factors could lead to significant forest death in the Amazon by the end of this century.

Carlos Nobre, a senior scientist at Brazil’s National Institute of Amazonian Studies and one of the first to raise the alarm about the potential loss of the Amazon more than three decades ago, called the new study “very compelling.”

Not involved in the research, Dr. “This raised my level of anxiety,” Nobre said.

Covering more than two million square miles in Brazil and neighboring countries, the Amazon is the world’s largest rainforest and plays a pivotal role in mitigating climate change most years by taking in more carbon dioxide from the atmosphere than it emits. It is as rich in the diversity of plant and animal species as or more than anywhere else on the planet. And it pumps so much moisture into the atmosphere that it can affect the air beyond South America.

But climate change, along with widespread deforestation and burning for agriculture and ranching, has made the Amazon hotter and drier. One of the wettest regions in the world, the region has experienced three droughts since 2000.

Most previous resilience studies in the Amazon relied on models or simulations of how forest health could change over time. In the new research, the scientists used real observations: decades of remote sensing data from satellites that measure the amount of biomass corresponding to their health in certain areas. By looking only at undisturbed parts of the rainforest, the researchers found that these areas have generally lost resilience since 2000. For example, woodlands took longer and longer to recover from drought after exposure.

“This lack of resilience really shows that there is a lot of blow this forest can take,” said tropical ecologist Paulo Brando at the University of California at Irvine, who was not involved in the study. “It reduces the ability to bounce back.”

However, Dr. Brando said this isn’t necessarily a sign that a tipping point is inevitable, pointing to the need to halt deforestation and deforestation in the area. “These systems are extremely durable, and just because we’ve reduced durability doesn’t mean it’s lost all durability,” he said. “If you leave them alone for a bit, they’ll come back super strong.”

The researchers found that more than three-quarters of the pristine rainforest lost its flexibility during this time, and the loss was greatest in areas that were drier or closer to human activities such as logging. this study It was published in the journal Nature Climate Change.

Chris Boulton, a researcher at the University of Exeter and lead author of the study, said the Amazon is like a giant water recycling network, as moisture from evaporation and tree transpiration is blown away by the winds. Thus the loss of part of the forest and part of the moisture leads to further drying out elsewhere.

Dr. “You can imagine starting to see this resistance disappear more and more quickly as the Amazon dries up,” Boulton said. Forests can then decline and die relatively quickly, becoming more like a savanna with grass and far less trees.

Not only would the loss of forest trees return the carbon stored in their tissues back to the atmosphere, the savannas would also take up much less carbon than the large, broadleaf trees they replace. Savanna habitat will also support far fewer species.

Dr. Nobre said the research shows that the Amazon is “on the edge of this abyss, it’s moving into a different ecosystem.” And if it did, “it would be hundreds, maybe thousands of years of new ecosystems,” he added.

About 17 percent of the Amazon has been deforested in the last half century, and while the pace of deforestation in Brazil has slowed for several years, i just bought itly. The researchers said their study shows that efforts to stop deforestation not only protect certain areas, but have an impact on the resilience of the Amazon as a whole.

“Absolutely true,” said Dr. Nobel. We must achieve zero deforestation, zero forest degradation,” he adds, “We still have a chance to save the forest.”



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