Amazon could now worsen climate change, scientists warn

It’s no secret that the world’s largest rainforest, the Amazon, is under immense pressure, approaching an ecological tipping point and in danger of collapsing.

But the situation is far worse than we may realize, according to new research that suggests the Amazon’s grim future has arrived as a result of rampant deforestation.

The new research – the most comprehensive assessment of the Amazon Basin’s influence on the global climate to date – found that with fires, drought and land clearing, the forest releases more heat-trapping gases than it does. it does not store it in plants and soil.

This means the Amazon is most likely warming Earth’s atmosphere, not cooling it, and the worrying effect is only expected to increase, according to the group of more than 30 scientists behind this. job.

In addition, the jungle can no longer be relied upon to help offset the greenhouse gas emissions from human activities, namely the burning of fossil fuels, which wastes our remaining global carbon budget.

What distinguishes this research is that unlike previous studies, this research identifies all the gases that warm the climate circulating in the Amazon basin and in the atmosphere, and assesses the direct impacts of human activities on one of the most major carbon reservoirs on the planet.

“Chopped off [down] the forest interferes with its carbon absorption; it’s a problem, ”said environmentalist and senior author Kristofer Covey, of Skidmore College in New York City. National Geographic.

“But when you start looking at these other factors besides CO2, it becomes really hard to see how the net effect isn’t that the Amazon as a whole is really warming the global climate.”

Overall, ecological studies and climate research in the Amazon Basin have focused directly on the uptake and storage of CO2 by the forest, and rightly so – CO2 makes up the bulk of gas emissions. humanity’s greenhouse effect, which in the Amazon, are largely due to forest degradation.

The loss of forest in the Amazon is so severe that some scientists have estimated that the rainforest could shift from a carbon sink to a carbon source that releases more CO2 than it can hold as early as 2035.

Researchers are also fearing that with the increase in illegal land clearing activities, the region is rapidly approaching a catastrophic “ tipping point ” where the Amazon is pushed to the brink and turns into a whole other ecosystem much more dry.

But CO2 isn’t the only factor influencing Earth’s climate, and the Amazon Basin isn’t easy to study either, with its mountainous mountain forests, mangrove wetlands, and river systems spanning nine countries. from South America.

The other two major agents of climate change are nitrous oxide (N2O) and methane (CH4). These gases don’t last as long in the atmosphere as CO2, but they are much more potent than greenhouse gases – trapping 300 times more heat per molecule than CO2, in the case of N2O.

Globally, emissions of methane and nitrous oxide have increased dramatically over the past decade or two. And now, with this analysis and the graph below, we can appreciate how these less studied gases tip the scales in the Amazon, in particular.

(Covey et al., Frontiers in Forests and Global Change, 2021)

Above: Greenhouse gases circulate in the Amazon.

By analyzing existing data on greenhouse gas emissions and the combined effects of human impacts in the Amazon Basin, the researchers showed how the Amazon is likely to worsen climate change by emitting more gases than it does. absorbs naturally.

Never before has a study of the Amazon basin evaluated the data in such a way as to take into account all the forest-climate interactions, that the authors of the study called a “daunting task” and the central challenge limiting our understanding of the global climate impact of the Amazon ”.

The ecosystem-wide analysis also delves into the details, as Given the vastness 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) add up to massive upheavals throughout the ecosystem.

Prolonged droughts reduce the Amazon’s capacity to absorb CO2 and increase the risk of forest fires – which in 2019 burned at a record rate. Much like illegal fires started to clear land, these forest fires turn trees into soot particles that absorb sunlight and raise the air temperature dial.

Meanwhile, industry-induced deforestation, up 60% since 2012 in the Brazilian Amazon, clears thousands and thousands of square kilometers of forest each year for mining and agriculture, stirring up soils, altering rainfall patterns and increasing the amount of sunlight reflected from the Amazon into the atmosphere where greenhouse gases await.

Add to that equation dam building, mining practices, seasonal flooding, severe storms, soil compaction for farmland and cattle grazing – all of which are changing the forest and its emissions. – and it is understandable that the researchers could have arrived at such a calamitous. conclusion.

The team recognizes a large degree of uncertainty in their results, which they attribute to a lack of data on parts of the Amazon, particularly its winding river systems, and the unique ecological features of a forest so large that ‘it creates its own climate. .

Yet even so, with the data available, the resounding result of their analysis is that the Amazon releases more heat-trapping gas than it stores, creating a net warming effect in Earth’s atmosphere.

Protecting the Amazon is now more urgent than ever and this includes reducing deforestation and restoring indigenous land rights.

The research was published in Forest boundaries and global change.