Seen from above, the Amazon in South America is a lush emerald blanket, home to millions of animals and the largest river on the planet by volume. It is also key to protecting our planet from the damaging effects of climate change.
But why? And what could happen to the global climate if we lost it?
The great size of the Amazon: it covers almost seven million square kilometers, or about the area of Australia- makes it shine in the climate scenario. With so many trees covering such a vast swath of land, everything the forest “does” is big and impressive. Some of its actions are downright unique: The Amazon creates its own climate, generating some of its rainfall and staying cool, while also stabilizing regional temperatures. Add that to the greenhouse gas droplets your biomass stores, and you have a natural climate shield. Yet we are constantly dismantling this precious landscape, exacerbating climate change in ways that scientists are only beginning to understand.
giant carbon sponge
All forests on Earth impact the atmosphere. Trees extract carbon dioxide from the atmosphere through photosynthesis, locking that greenhouse gas in leaves, trunks, roots, and nearby soil. The large number of trees in the Amazon makes it one of the largest carbon sinks in the world. “The Amazon today, even with all the deforestation, stores more than 150 billion tons of carbon,” says Carlos Nobre, an earth systems scientist at the University of São Paulo, Brazil, and a longtime researcher on climate effects. and ecological of the Amazon. deforestation. It roughly helped the Amazon’s carbon stock to be found underground in the soil. The other half is in your trees, which contain about 20 percent of all the carbon sequestered by vegetation on the entire planet.
But when humans cut down those trees, that biomass releases its stored carbon back into the atmosphere as CO2, where it has a heating effect. Like other greenhouse gases, carbon dioxide molecules prevent Earth’s heat from escaping into space. The agricultural and mining industries are constantly cutting into the dense web of the Amazon 16,000 species of trees; Taken together, deforestation has stripped 17 percent of tropical forest tree cover since 1970.
Deforestation industries often clear an area by burning, which rapidly releases stored carbon into the atmosphere. Trees that are left unburned but cut down decompose and also release their carbon. The fires help explain why parts of the Amazon rainforest now emits more CO2 of what they absorb. Fires also send up plumes of soot that block sunlight and contribute to warming.
making it rain
The warm atmosphere feeds back into the forest. As the globe warms, the frequency and severity of meteorological phenomena associated with drought they are increasing in South America, says Nobre, who is also co-chair of the Scientific Panel for the Amazon, which supports research and initiatives to save the rainforest. The effects are creating longer regional dry periods and less rainfall, making trees the disadvantages. Dryness and decreased forest cover also increase risk of natural fires.
The loss of trees brings other consequences, says Nobre. During the dry season, the most intense sunlight generates large amounts of water, stored in the trees and in the soil from the wet periods.transpire. That water vapor “reaches the lower atmosphere and turns back into clouds and rain,” explains Nobre. “A molecule of water vapor that enters the Amazon is recycled between five and eight times,” he adds, illustrating the importance of this hydrological engine in recharging regional rainfall. Heavy rains also have a cooling effect, just as sweating can refresh a person off after a workout.
If tree cover decreases, so will the water supply, and with it more of the forest. past investigation led by Nobre showed that a cycle of warming, drying, and forest thinning could push the Amazon to a minimum tree cover threshold, below which forest would irreversibly degrade into simpler grassland habitat.
And if the forest disappears?
Estimates vary on where exactly that threshold is: Nobre and others suggest it could be a loss of only 20 percent to 25 percent of pre-deforestation tree cover in the Amazon (bearing in mind that the forest has already lost 17 percent). There are also varying figures on how quickly the forest could degrade once the threshold is passed. But already, parts of the southern Amazon are transitioning into what Nobre describes as “degraded open-canopy ecosystems.” This is a landscape with sparse tree cover, containing “tremendously reduced biodiversity,” storing a fraction of the carbon of an intact rainforest, Nobre says.
If the forest vanishes and its trees release their huge store of carbon, what does that mean for the global climate?
The Amazon’s estimated carbon bank of more than 150 billion tons is the equivalent of more than 10 years of global emissions from fossil fuels, says Nobre. If the entire Amazon were to degrade into an open savannah-like landscape, local rainfall would decrease by as much as 30 percent, with consequences felt as far as Colombia and Argentina, where rainfall cycles are partly fueled by Amazon moisture. Nobre explains. Without the forest surface-cooling effectregional temperatures would rise in various degrees.
The loss of forests would have repercussions around the world. “If you put [carbon dioxide] in the atmosphere, it spreads rapidly around the world,” says Elena Shevliakova, a physical scientist at the Geophysical Fluid Dynamics Laboratory, part of the US National Oceanic and Atmospheric Administration, who has modeled the climate effects of the loss from the Amazon. Releasing, say, 120 billion tons of CO2 (a more conservative estimate of Amazon carbon stocks) removing forests would warm the planet by about 0.25 degrees Celsius, he explains.
Even if the world reduced human-caused emissions enough to be on track to meet the Paris Climate Agreement, keeping global warming below a 1.5 degree C rise from pre-industrial levels, the sudden loss of the Amazon and its stored carbon would put that goal out of reach. Global emission reductions are currently not on targetwhich should raise concerns about the impact of Amazon degradation, says Shevliakova.
To protect this planetary jewel, Nobre says the international community urgently needs to curb deforestation and greenhouse gas emissions and, where possible, reforest degraded stripes. Saving the Amazon is also intertwined with the rights of indigenous peoples; to growing body research suggests that lands managed by indigenous peoples are less deforested.
Even if the emerald biome seems like a distant world, everyone on Earth is connected to their destiny, Shevliakova says. “Losing the Amazon is going to affect everyone.”