Is the Amazon Rainforest on the Verge of Extinction?
Spanning over 5.5 million square kilometers, the Amazon rainforest is the largest of its kind and home to one in ten of all known species. At Present, at least 40,000 plants, 2,200 fish, 1,200 birds, 400 mammals, 400 amphibians and 375 reptiles are scientifically classified in the region, not to mention the approximately 2.5 million insect species. The Amazon has existed as a dense and humid rainforest teeming with life for at least five and a half million years. But in a new paper, scientists claim that more than 75% of ecosystems are losing their ability to survive since the early 2000s due to climate change.
This process appears to be most prominent in areas that are close to human activity, as well as in areas with low rainfall. The sustainability of an ecosystem – its ability to sustain normal processes such as the regrowth of vegetation after a drought – is a difficult concept for scientists to measure. In this paper, the authors analyzed satellite images of remote areas of rainforest in the Amazon from 1991 to 2016. Using a measurement called vegetation optical depth, they suggested that forest biomass (the total weight of organisms in a given area) is taking longer to repair damage as pressure increases. They argue that this suggests that prolonged dry seasons and drought conditions due to climate change are reducing the ability of rainforests to recover from gradual droughts.
Drought-sensitive tree species turning into drought-resistant tree species
Drought-sensitive tree species are changing to drought-resistant tree species at a much slower rate than the rapid change in regional climate. This could mean that the Amazon is approaching a situation that, if it continues to grow, will result in the collapse of this rainforest into a dry grassland or savanna. Does this new research offer a credible caveat? Here’s what the evidence tells us. When an ecosystem becomes less resilient to sustaining its existence, it is less able to recover from drought and other sources of stress. This is known as a ‘critical slowdown’. If stress continues, it is more likely that the ecosystem will reach a point where it suddenly changes to a new form.
In other words, a critical slowdown can act as an early warning sign of an impending collapse. Instead of losing trees, the patches of rainforest studied by the authors may simply dry out as the dry season extends and droughts spread, which scientists have documented in the Amazon in recent decades. However, research on rainforest plots reported elsewhere supports the new study’s claim that biomass in the rainforest is taking longer to recover from pressure. According to measurements taken over the same period, trees are dying more frequently and growing slower, contributing to an overall reduction in total biomass in the Amazon.
The weather is becoming increasingly dry with frequent droughts
Amazonian vegetation is changing. These changes may indicate that the rainforest is losing its ability to sustain itself or perhaps that the seasons are becoming increasingly drier with more frequent droughts. From these results it is not possible to identify when a significant infection may have occurred, or whether one is already underway. The question remains unanswered whether Amazon is reaching a position that could convert it to another form. This paper studied the effect of climate change on rainforests in the form of long and dry droughts. But scientists know that road construction and expansion of agricultural land are also serious sources of stress.
Even if Amazon has not yet exceeded that level of its collapse risk, these combined effects could mean that that time may come soon, and once the turnaround begins. New research underscores the need to conserve habitats to reverse global greenhouse emissions, reduce local pressure on rainforests, and counter the effects of arid climates. Otherwise, we may be the last generation, privileged enough to share a planet with these ecosystems.
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