Has the Amazon rainforest reached a critical stage?
The Amazon rainforest, the biggest of its kind, is currently under threat due to the effects of climate change. While the tropical rainforest generally manages to deal with less rainfall and droughts quite well, there are some concerning issues in certain regions.
A study published in the "Proceedings of the National Academy of Sciences" ("PNAS") shows that the Amazon rainforest is recovering more slowly from droughts, a phenomenon known as critical slowdown. This refers to when a system, like a natural system or even the climate, recovers more slowly from small disturbances when it's getting close to a tipping point. When this happens, it's a sign that the system could be heading towards a rapid and irreversible decline. For the Amazon rainforest, this could mean it turning into savanna, as scientists are concerned about.
The research notes that in the past 20 years, there have been three "droughts of the century" in the Amazon region. Climate change is predicted to make these extreme events more frequent and severe.
A team of scientists, led by Johanna Van Passel from the Catholic University of Leuven in Belgium, analyzed satellite images from 2001 to 2019 and used a vegetation index to assess plant activity. The vegetation index works by measuring how strongly plants reflect sunlight in the near-infrared range - the more they reflect, the more photosynthesis they're doing.
The investigation revealed that the intensity of a drought has a greater impact than its duration or frequency. Approximately 37% of the area analyzed showed a tendency to recover slowly after a drought, with the south and south-east areas being hit particularly hard. The amount of rainfall in these regions experiences more significant fluctuations throughout the year, making them more susceptible to change than the central Amazon region.
Plants can die in two ways as a result of drought: hydraulic failure, where water-conducting vessels constrict and block, preventing water from reaching the rest of the plant, and carbon dioxide deficiency, where plants close their stomata to prevent evaporation, leading to less carbon dioxide entering the plant for photosynthesis. This means that the plant uses more energy than it generates and eventually dies. The study found that hydraulic failure is more significant during intense droughts, while carbon dioxide deficiency is more significant during long-lasting droughts.
The Amazon rainforest is crucial as it's home to a vast array of unique species, influences the rainfall in South America, and helps prevent greenhouse gases from being released by preserving the forest. However, as more researchers are observing, the forest has now entered a carbon source mode rather than a carbon sink, meaning it's releasing more carbon dioxide than it's absorbing. This is believed to be due to the destruction of the rainforest and the increased impact of the dry season.
As one of the world's largest carbon sinks, the Amazon rainforest has significant global implications. It absorbs carbon dioxide from the atmosphere, impacting rainfall across South America and preventing the release of greenhouse gases into the atmosphere. However, with the rainforest's slow recovery from droughts, its significance could be diminishing, leading to dire consequences for the entire planet.
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1.Global warming and climate change are major factors contributing to the increased frequency and severity of extreme weather events in the Amazon rainforest, posing a significant threat to its recovery from droughts.2.Given the critical slowdown of the Amazon rainforest's recovery from droughts, educating the public about the importance of preserving this global carbon sink and its role in influencing rainfall and preventing greenhouse gas emissions becomes increasingly vital.3.As concerns mount over the Amazon rainforest turning into savanna due to climate change, the international community should invest in sustainable conservation strategies to mitigate the effects of global warming on the world's largest tropical rainforest.
Source: www.ntv.de
