Recently, a study by the University of Exeter found that the resilience of the Amazon rainforest is weakening. Once the critical point is exceeded, the forest may be replaced by grassland. However, experts pointed out that this "critical point" is not inevitable and called for an immediate stop to deforestation of tropical rain forests. According to the report of the New York Times on March 7, the number of droughts in the Amazon rainforest has increased since 2000, and it will take longer and longer to recover. Tim Lenton, one of the researchers and director of the Institute of global systems at the University of Exeter, warned that the loss of the Amazon rainforest could lead to nearly 90 billion tons of carbon dioxide (equivalent to global emissions in recent years) returning to the atmosphere or exacerbate global warming. The replacement of tropical rain forest by savanna will also greatly reduce the habitat of different species. The study did not determine when the so-called "critical point" will be reached. However, it can be predicted that by the end of the 21st century, factors such as deforestation and dry climate may lead to a large shrinkage of tropical rain forests in the Amazon. The study found that more than three-quarters of the unspoiled rainforests have "lost elasticity", which is most severe in drier or more deforested areas. Chris Bolton, the lead author of the study and a researcher at the University of Exeter, pointed out that the Amazon is like a huge water cycle system. The shrinkage of the rainforest will make the area drier, which in turn will accelerate the elastic failure of the ecosystem. Paul Brando, a tropical ecologist at the University of California, Irvine, said the "tipping point" was not inevitable and called for an end to deforestation in the Amazon. He pointed out that the rainforest ecosystem has strong elasticity. The reduction of elasticity does not mean that it is completely lost. If it is not destroyed over time, it is still expected to recover rapidly. Carlos Nobre, a senior scientist at Brazil's national Amazonian Institute, was one of the first scholars to call attention to the protection of the Amazonian rainforest more than 30 years ago. Although he did not participate in the study, he said the latest research results are very noteworthy. "We must achieve zero deforestation and zero forest degradation, and we still have a chance to save the Amazon rainforest." Norbray said. Amazon tropical rain forest is the largest and most diverse tropical rain forest in the world. It is known as the "lung of the earth". It plays an important role in absorbing carbon dioxide, mitigating climate change and protecting biodiversity. In the past half century, about 17% of tropical rain forests have been cut down. Although the cutting rate has slowed down for several years, it has rebounded in recent years. As one of the wettest regions in the world, the Amazon region has experienced drought three times since 2000. (Xinhua News Agency)