More than a third of Amazon rainforest is experiencing a slowdown in recovery from drought, a new study has revealed.
The weakening resilience of the “lungs of the planet” raises concerns that this globally significant ecosystem is irreversibly degrading as a result of persistent droughts.
Climate Change Impacts
The world’s largest tropical forest has experienced four unprecedented dry spells in less than 20 years. This reflects the impacts of climate change on trees and other plants, many of which are dying as a result of dehydration.
In the past, the canopy of the Amazon rainforest would shrink and expand in tandem with the annual dry and rainy seasons. It also showed an ability to recover from a drought, according to the Guardian.
Slow Recovery
In recent years, recovery of the Amazon rainforest has become slower due to the increasing intensity of droughts in the south-east of the tropical forest and their increasing frequency in the Amazon’s north-east.
In a new study, published in Proceedings of the National Academy of Sciences (PNAS), researchers analyzed satellite images on a month-by-month basis to figure out how periods of drought affected vegetation activity from 2001 to 2019. Their main goal was to examine how “the frequency, intensity or duration of droughts contribute to stability loss of Amazon vegetation.”
The results showed a slowing-down trend in 37% of the mature vegetation in the forest. Although patterns varied from area to another, researchers found that the south-eastern Amazon was highly vulnerable to a tipping event, which could lead to a catastrophic decline of the rainforest to more dryness.
Influencing Factor
According to the study results, drought intensity played a bigger role in recovery slowdown than drought frequency. However, the combination of both factors has a more devastating effect.
Johanna Van Passel, the study’s lead author, said that what the satellite images reveal is just part of the true picture, and the situation below the forest’s canopy could be worse. She explained that trees tend to show tipping points later on because they have the longest life cycle and are most able to cope.
“If we are already seeing a tipping point getting closer at this macro forest level, then it must be getting worse at a micro level,” Van Passel said.
Ecosystem Collapse
Last year, the Amazon rainforest, home to the biggest body of freshwater in the world, suffered a severe drought that caused its rivers to decline to record low levels, made forest fires more devastating, and led to the die-off of more than 100 river dolphins. This was part of a broader and ongoing trend.
The Amazon rainforest plays critical role in absorbing carbon dioxide from the atmosphere, as it is home to 1500 tree species. However, burning of trees and fossil fuels undermines this ability, and the forest’s overall resilience.
The study warned that the forest’s slowing recovery rate could be an “early indicator” of large-scale ecosystem collapse. Van Passel expressed concern over the future of the Amazon. She said: “It is a warning sign that a tipping point can be reached in the future if these droughts continue to increase and get more intense.”
Worsening Trends
According to the study, rain seasons are becoming shorter and more intense, hurting the ability of the forest to recover from drought. These trends will grow worse in the future because droughts will become more intense and frequent over the Amazon as a result of global warming.
This is expected to “cause changes in the forest structure and functioning by increasing forest mortality and can potentially bring more areas in the Amazon closer to a tipping point.” Areas that suffer tree cutting and fires are more vulnerable.
The change in the internal rain cycle in the affected areas “may trigger a cascading effect, potentially leading to further slowing down in other parts of the Amazon forest, with implications for global effects on other tipping points,” the study warned.
Researchers urged policymakers to take actions to counter this. Van Passel said: “The message to policy makers is that we must protect the forest that is still there, especially in the south of the Amazon. Farmers should stop cutting forest because they lose out when this reduces rainfall. We must stop climate change. We have all this information, now let’s act on it.”
