Extreme temperatures and humidity exacerbated by climate change could diminish the Amazon rainforest's ability to absorb methane—a potent greenhouse gas—by as much as 70%, according to a recent study.
This alarming finding is a reflection of the potential impact of climate-induced extreme weather on the Amazon's role as a vital carbon sink.
The Amazon rainforest, often referred to as the "lungs of the planet," spans several countries, including Brazil, Peru, Colombia, and Ecuador. It is renowned for its critical role in absorbing greenhouse gases from the atmosphere.
However, researchers from the University of São Paulo, Brazil, caution that changes in the climate may threaten this delicate balance.
The study highlights that approximately 20% of the Amazon remains flooded for nearly half the year, releasing methane instead of absorbing it, thereby counteracting its environmental benefits.
This phenomenon has been documented, with previous studies indicating that flooded areas of the Amazon contribute nearly 30% of global methane emissions from wetlands.
Lead author Julia Gontijo, a postdoctoral researcher at the University of California, Davis, raised concerns about the consequences of climate change on the Amazon's microbial communities.
"Although it's already been shown that factors such as air temperature and seasonal flooding can influence the composition of microbial communities affecting the flow of methane in these environments, what should we expect in the context of climate change and the projected extreme weather?" she stated.
For their study, researchers collected soil samples from two flooded regions of the Amazon and one from elevated forests known for their methane absorption capabilities.
These samples were subjected to extreme temperature conditions of 27 degrees Celsius and 30 degrees Celsius, alongside varying humidity levels.
Findings revealed a significant decrease in methane absorption potential from the elevated forest soil, dropping by 70% under hot and dry conditions.
Conversely, the study noted a surge in methane production during heavy rainfall, as the soil struggled to cope with the extreme humidity.
"Within this (elevated) forest soil, an average decrease of 70% in (methane) consumption potential was observed with temperature increase in dry conditions," the authors wrote.
Gontijo explained that while the floodplain microbiome may adapt to climate change, the upland forest microbiome is more sensitive, potentially disrupting the balance of greenhouse gas emissions in the Amazon.
"In view of the Amazon Rainforest biome's importance in proportion to global levels, this could represent a very serious problem," Gontijo emphasised.
Despite the absence of significant changes in methane emission patterns observed in the floodplains, researchers noted a rise in methane-producing microorganisms, posing a future risk.
The implications of this study are profound, suggesting a need for urgent policy considerations to mitigate the impact of climate change on one of the world's most vital ecosystems.
Gontijo stated that the results could be instrumental in shaping public policies aimed at protecting the Amazon rainforest and its crucial environmental functions.
As the effects of climate change become increasingly pronounced, understanding and preserving the Amazon's capacity to absorb greenhouse gases is essential in the fight against global warming.
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