It’s no secret that the world’s largest tropical rainforest, the Amazon, is under immense pressure, nearing an ecological tipping point, and at risk of collapse.
But the situation is much worse than we may realize, according to new research suggesting the Amazon’s bleak future has arrived after rampant deforestation.
The new study – the most comprehensive assessment of the Amazon’s impact on the global climate to date – found that fires, droughts and land clearance caused the forest to release more heat-trapping gases than it stores in plants and soil.
This means that the Amazon is most likely warming and not cooling the Earth’s atmosphere, and the worrying effect is only expected to intensify, say the group of more than 30 scientists behind this work.
In addition, the jungle can no longer be relied upon to help offset greenhouse gas emissions from human activities, namely the burning of fossil fuels, which are wasting our remaining global carbon budget.
What sets this research apart is that unlike previous studies, this research measures all of the climate-warming gases circulating through the Amazon basin and the atmosphere and assesses the direct impact of human activities on one of the largest carbon deposits on Earth.
“To cut [down] the forest disrupts the absorption of carbon; that’s a problem, ‘said ecologist and lead author Kristofer Covey of Skidmore College in New York National Geographic
“But when you look at these other factors in addition to CO2, it becomes really difficult to see that the net effect is not that the Amazon as a whole is really warming the global climate.”
In general, ecological and climate studies in the Amazon basin have focused entirely on the absorption and storage of CO2 by the forest, and with good reason – CO2 makes up the bulk of humanity’s greenhouse gas emissions, which in the Amazon are largely driven by forest . degradation.
Forest loss in the Amazon is so severe that some scientists estimate that the rainforest could turn from a carbon sink to a carbon source that releases more CO2 than it can hold, once it can hold in 2035.
Researchers are too concerned that with increasing illegal land clearance activities, the region is rapidly approaching a catastrophic ‘tipping point’ where the Amazon is being pushed to the edge and turning into a very different, much drier ecosystem.
But CO2 isn’t the only factor influencing Earth’s climate, nor is the Amazon Basin easy to study, with its mountainous montane forests, mangrove swamps and river systems spanning nine countries in South America.
The two other major agents of climate change are nitrous oxide (N2O) and methane (CH4). These gases don’t stay in the atmosphere for nearly as long as CO2, but they are much more powerful than greenhouse gases – they retain 300 times more heat per molecule than CO2, in the case of N2O.
Globally, emissions of both methane and nitrous oxide have increased significantly over the past decade. And now, with this analysis and the image below, we can understand how these less studied gases are tipping the scale in the Amazon.
(Covey et al., Frontiers in Forests and Global Change, 2021)
Above: greenhouse gases cycling through the Amazon.
By analyzing existing data on greenhouse gas emissions and the combined effects of human influences in the Amazon basin, the researchers showed how the Amazon is likely to exacerbate climate change by emitting more gases than it naturally absorbs.
Never before has a study of the Amazon basin assessed the data to consider the full range of forest-climate interactions, which the study authors called a “ daunting task. ” and the central challenge limiting our understanding of the Amazon’s global climate impact ”.
The ecosystem-wide analysis also goes deep into the grainy details, because Given the size of the Amazon basin, even seemingly small changes in the amount of greenhouse gases absorbed or released by the forest (and its microbial-rich soils) lead to tremendous upheaval in the entire ecosystem.
Prolonged droughts reduce the Amazon’s ability to absorb CO2 and increase the likelihood of wildfires – which burned in record time in 2019. Like the illegal fires lit to clear land, these wildfires turn trees into soot particles that absorb sunlight and raise the dial in atmospheric temperatures.
Meanwhile, industry-driven deforestation, a 60 percent increase in Brazil’s Amazon since 2012, clears thousands upon thousands of square miles of forest every year for mining and agriculture, churning soils, changing rainfall patterns and increasing the amount of sunlight received. the Amazon. in the atmosphere where greenhouse gases await.
Add to that the construction of dams, mining practices, seasonal flooding, severe storms, soil compaction for farmlands and grazing livestock – all of which alter forest and its emissions – and it’s understandable how the researchers came to such a disaster. inference.
The team recognizes a great deal of uncertainty in their results, which they attribute to a lack of data from some parts of the Amazon, particularly the meandering river systems, and the unique ecological features of a forest so large it has its own climate. creates. .
Yet, with the available data, the resounding result of their analysis is that the Amazon is releasing more heat-trapping gases than it is storing, creating a net warming effect in the Earth’s atmosphere.
Protecting the Amazon is now more urgent than ever before and that includes reducing deforestation and restoring indigenous land rights.
The research is published in Borders in forests and global changes.