Rainforests help offset emissions from fossil fuel burning because they absorb carbon dioxide from the atmosphere. In recent years, scientists have been worried that deforestation, drought, carbon emissions, and rising temperatures reduce the world’s rainforests’ capacity to absorb CO2 – especially in the Amazon, the largest, most species-rich jungle globally.
And recent studies suggest the situation goes beyond merely not absorbing enough CO2 – some portions of the tropical landscape could be releasing more of the planet-warming greenhouse gas than they’re storing. A new first-of-its-kind analysis from over 30 scientists supported by the National Geographic Society reveals the Amazon rainforest is likely a net contributor to global warming now.
The research is the first broad look at all of the gasses (not just carbon dioxide) that affect how the Amazon works. It reveals a system on the brink of collapse, with its damaged forests worsening the climate crisis.
Fiona Soper, a co-author of the study and assistant professor at McGill University, said:
We have this system that we have relied on to counter our mistakes, and we have exceeded the capacity of that system to provide reliable service.
Natural and human-caused activities can alter the rainforest’s contribution to the global climate in significant ways. Cutting down trees removes a carbon sink and also releases CO2 into the air. When trees die, they release some of the CO2 they absorbed when alive. Deforestation also alters rainfall patterns, heating and drying the forest further.
Many other things can cause the rainforest to warm the air directly or release gasses that do. For example:
- Soil compaction from logging and drying wetlands can increase emissions of nitrous oxide, another greenhouse gas.
- Land-clearing fires release tiny particles of soot called black carbon that absorb sunlight and increase warmth.
- Dam-building and regular flooding release methane, yet another potent gas. Cattle ranching also releases lots of methane, and it’s one of the leading causes of forest destruction.
- About 3.5% of globally released methane comes naturally from the Amazon’s trees.
All these and other factors are swamping the Amazon’s natural cooling effect.
Tom Lovejoy, a researcher, working in the Brazilian Amazon for decades who’s a senior fellow in biodiversity with the United Nations Foundation, said:
As important as carbon is in the Amazon, it’s not the only thing that’s going on. The only surprise, if you can call it that, is how much more there is when you add it all up.
Kristofer Covey, a lead author of the study and a professor of environmental studies at New York’s Skidmore College, said:
Cutting the forest is interfering with its carbon uptake; that’s a problem. But when you start to look at these other factors alongside CO2, it gets tough to see how the net effect isn’t that the Amazon as a whole is significantly warming global climate.
Patrick Megonigal, an associate director of research with the Smithsonian Environmental Research Center, agreed and said:
What the authors do that’s important is to expand the conversation beyond carbon dioxide, which is what 90 percent of public conversation is centered around. CO2 is not a lone actor. When you consider the whole cast of other characters, the outlook in the Amazon is that the impacts of human activities will be worse than we realize.
Fortunately, Covey and his colleagues say we can still reverse the damage. Amazon reforestation and conservation are just as crucial to combating climate change as halting global emissions from oil, coal, and natural gas.
Deforestation in South America, especially Brazil, has sky-rocketed in recent years. It hit a 12-year record high in 2020, increasing almost 10% from 2019. The Amazon has lost the equivalent of 8.4m soccer fields this decade and continues to lose three fields per minute!
As more of the Amazon is cleared away, the rainfall will change, and vast regions could transition to dry savannah forever. Other studies have found this phenomenon is already happening. This is a troubling situation because far fewer trees grow in savannahs, so the planet loses a significant amount of sequestering power.
What happens in the Amazon affects the whole world. It’s very frightening that a few countries hold the world’s fate in their hands.
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