It’s no secret that the world’s largest rainforest, the Amazon, is under immense pressure, close to an ecological tipping point and is in danger of collapsing.
But the situation is much worse than we realized, according to new research suggesting that the bleak future of the Amazon came after rampant deforestation.
The new research – the most comprehensive assessment of the influence of the Amazon Basin on the global climate to date – found that with fires, drought and land clearing, the forest releases more gases that capture heat than it stores in plants and soil.
This means that the Amazon is most likely warming the Earth’s atmosphere, not cooling it, and the worrying effect is expected to increase, says the group of more than 30 scientists behind this work.
Moreover, the jungle can no longer be counted on to help offset greenhouse gas emissions from human activities, namely the burning of fossil fuels, which waste our remaining global carbon budget.
What differentiates this research is that, unlike previous studies, this research increases all climate warming gases flowing through the Amazon Basin and into the atmosphere and assesses the direct impact of human activities on one of the largest carbon deposits on Earth. .
“Cutting [down] the forest interferes with its carbon sequestration; this is a problem, “said ecologist and lead author Kristofer Covey of Skidmore College in New York. National Geographic.
“But when you start looking at these other factors along with CO2, it becomes very difficult to see how the net effect is not that Amazon as a whole is really warming the global climate.”
In general, ecological studies and climate research in the Amazon Basin have focused directly on the forest’s uptake and storage of CO2, and rightly so – CO2 accounts for most of humanity’s greenhouse gas emissions, which are in the Amazon. led largely by forests. degradation.
The loss of forests is so severe in the Amazon that some scientists have estimated that the rainforest could overturn from a carbon sink into a carbon source that releases more CO2 than it can hold in 2035.
Researchers are also Concerned that, with the increase in illegal land clearing activities, the region is rapidly approaching a catastrophic ‘tipping point’ where the Amazon is being pushed to the brink and transformed into another much drier ecosystem.
But CO2 is not the only factor influencing the Earth’s climate, and the Amazon Basin is not easy to study, with its mountainous forests, mangrove wetlands, and river systems spanning nine South American countries.
The other two well-known agents of climate change are nitrogen oxide (N2O) and methane (CH4). These gases do not last nearly as long in the atmosphere as CO2, but are much stronger than greenhouse gases – capturing 300 times more heat per molecule than CO2 in the case of N2O.
Globally, emissions of both methane and nitrogen oxide have increased substantially in the last decade or two. And now, with this analysis and the chart below, we can appreciate how these less studied gases tip the scales in Amazon, specifically.
(Covey et al., Forest Borders and Global Change, 2021)
Above: Greenhouse gases circulating through the Amazon.
Analyzing existing data on greenhouse gas emissions and the combined effects of human impact on the Amazon Basin, the researchers showed how the Amazon is likely to worsen climate change, emitting more gases than it absorbs naturally.
Never has a study of the Amazon Basin evaluated the data in such a way as to take into account the whole suite of forest-climate interactions, which the study authors called a “daunting task” and a central challenge that limits our understanding of the global climate impact of the Amazon. “
The entire ecosystem analysis is also delved into the bloody details because given how huge the Amazon Basin is, even the seemingly small changes in the amount of greenhouse gases absorbed or released by the forest (and its microbial-rich soils) add to the massive riots across the ecosystem.
Prolonged droughts reduce Amazon’s ability to absorb CO2 and increase the chances of fires – which in 2019 burned at a record speed. Like illegal fires lit to clear the ground, these fires turn trees into soot particles that absorb sunlight and raise the dial to atmospheric temperatures.
Meanwhile, deforestation caused by industry, up 60% from 2012 in the Brazilian Amazon, clears thousands and thousands of square kilometers of forest each year for mining and agriculture, reflecting soils, changing rainfall patterns and increasing the amount of sun reflected by Amazon back in the atmosphere where greenhouse gases are waiting.
Add to this equation the construction of the dam, extractive mining practices, seasonal floods, severe storms, soil compaction for agricultural land and grazing cattle – all this changing the forest and its emissions – and it is understandable how researchers were able to reach such a calamity. conclusion.
The team acknowledges a high degree of uncertainty about the results, which they have reduced to the lack of data in some parts of the Amazon, especially its winding river systems, and the unique ecological characteristics of a forest so large that it creates its own climate.
However, with the available data, the resounding result of their analysis is that the Amazon releases more gases that capture heat than it stores, creating a net warming effect in the Earth’s atmosphere.
Protecting the Amazon is now more urgent than ever, and that includes reducing deforestation and restoring indigenous land rights.
The research was published in Borders in forests and global change.