Key Takeaways
- The Amazon Basin covers roughly 2.7 million square miles, about 40 percent of South America, and the broader Amazon region spans nine countries: Brazil, Bolivia, Peru, Ecuador, Colombia, Venezuela, Guyana, Suriname, and French Guiana.
- The Amazon rainforest holds about one in 10 known species on Earth, with an average of 121 tree species per hectare and as many as 357 in a single hectare.
- Amazon vegetation and soils store an estimated 150 billion to 200 billion tons of carbon, and the forest recycles its own rainfall through atmospheric flows that reach far beyond its borders.
- Roughly 17 percent of Amazonian forest has been lost over the past 40 to 50 years, and another 38 percent of what remains is degraded by fire, edge effects, logging, or drought.
- Brazil's deforestation rate is falling. Its national space research institute recorded 5,731 square kilometers cleared in the Legal Amazon in 2025, down 12.07 percent from the year before.
"Everybody said there's nothing to find," Stéphen Rostain, director of research at France's National Center for Scientific Research, told BBC Science Focus about the decades he spent surveying Ecuador's Upano Valley on foot, mapping earthen mounds one at a time and convinced something bigger was under the canopy. Then Ecuador's government flew a lidar survey over the region, and the laser stripped the trees away on screen. "Thirty years after, I saw that there were not hundreds of mounds, but thousands," he said.
What the survey revealed, published in the journal Science in January 2024, was a network of more than 6,000 rectangular earthen platforms across roughly 300 square kilometers, connected by sunken roads up to 33 feet wide and ringed by drainage canals and farm fields. People built it starting around 500 B.C. and lived in it for about 1,000 years. "It was a lost valley of cities. It's incredible," Rostain told CBS News. Part of why nobody found it sooner comes down to building materials. "The Incas and Mayans built with stone, but people in Amazonia didn't usually have stone available to build — they built with mud," José Iriarte, an archaeologist at the University of Exeter, told the outlet.
The Upano cities dismantle the idea of the Amazon as untouched wilderness and replace it with something more accurate: a landscape people have farmed, engineered, and lived in for millennia, and one whose full contents we are still counting. Every year the accounting gets better, and every year the case for restoring what has been lost gets stronger.
What is the Amazon Rainforest?
The Amazon Rainforest is the humid tropical forest covering most of the Amazon biome in South America, and it includes two key overlapping terms it’s easy to confuse: The Amazon Basin is the full drainage area of the river and its tributaries; the Amazon biome takes in the rainforest plus floodplain forests, wetlands, savannas, and bamboo forests.
The region’s size also shifts with those boundaries. The World Wildlife Fund puts the basin at about 2.7 million square miles; NASA describes it as at least 6 million square kilometers, or roughly 2.3 million square miles. "Different research groups use different systems when defining the boundaries of what they are studying," Viviana Zalles, a researcher at the University of Maryland, explained in NASA's account of mapping the region.
Why the Amazon Rainforest matters
The Amazon’s crown jewel is its density of life. A 2023 study of 2,046 inventoried forest plots recorded an average of 121 tree species per hectare and as many as 357 in a single one. These trees anchor jaguars, harpy eagles, giant otters, tapirs, pink river dolphins, macaws, and thousands of fish and insect species, along with the relationships that hold the system together, from seed-dispersing birds to seasonal floodwaters that move nutrients across the basin.
The forest also makes its own weather. Trees pull water from the soil and release vapor through their leaves, winds carry that moisture inland, and the cycle repeats several times over, which is why Brazilian scientists call the flows "flying rivers." Rainfall generated this way reaches past the basin into the La Plata region of southern Brazil, Paraguay, Uruguay, and Argentina. Thin the forest and the cycle weakens. A 2025 analysis in AGU Advances found that a 3.2 percent reduction in Brazilian forest cover between 2002 and 2015 tracked with a 5.4 percent decline in precipitation.
Carbon is the third piece, and where stewardship becomes even more important. Between 2001 and 2021, Amazon forests managed by Indigenous peoples were a net sink of 340 million tonnes of CO2 equivalent per year, World Resources Institute analysis found, while forests outside Indigenous territories were a net source of roughly 270 million tonnes. Around 47 million people live in the Amazon, including nearly 2.2 million Indigenous people from 410 ethnic groups.
The Amazon is often called the lungs of the Earth, credited with 20 percent of the world's oxygen, but the popular claim does not survive scrutiny. "The net [oxygen] effect of the Amazon, or really any other biome, is around zero," Yadvinder Malhi, an ecosystem ecologist at Oxford University, told National Geographic, since respiration and decomposition consume roughly what photosynthesis produces. "There are a number of reasons why you would want to keep the Amazon in place, oxygen just isn't any one of them," Michael Coe, an earth systems scientist then at Woods Hole Research Center, told the same publication.
Threats facing the Amazon Rainforest
Deforestation converts forest into pasture, cropland, roads, and mines, and it has taken about 17 percent of the Amazon over the past 40 to 50 years, more than four-fifths of that for agriculture. Degradation is the other problem. Selective logging, repeated fire, fragmentation, and extreme drought damage the forest without clearing it, and a 2023 review in the journal Science found that 2.5 million square kilometers, or 38 percent of remaining Amazon forest, carries damage from at least one of those four drivers.
Those pressures compound. A 2024 study published in Nature estimated that by 2050, between 10 and 47 percent of Amazonian forests will face combined disturbances capable of triggering abrupt ecosystem shifts. "Compounding disturbances are increasingly common within the core of the Amazon," Bernardo Flores of the Federal University of Santa Catarina, the study's lead author, said in a statement. "If these disturbances act in synergy, we may observe unexpected ecosystem transitions in areas previously considered as resilient, such as the moist forests of the western and central Amazon."
The UN Environment Programme said in a Sept. 3 report that Earth will pass the Paris accord's 1.5 degrees Celsius warming threshold "within the next few years," with warming peaking at 1.8 C mid-century under the most ambitious scenario and 2.6 C by 2100 under current policies.
"If we reach 20, 25% deforestation, global warming close to two degrees, we cross permanently the tipping point," Carlos Nobre, senior researcher at the University of São Paulo's Institute of Advanced Studies and co-chair of the Science Panel for the Amazon, told Democracy Now in November 2025, putting current deforestation near 18 percent and degradation near 30 percent. "We need urgently to get to zero deforestation in all Brazilian biomes, especially the Amazon."
Amazon Reforestation
While the losses are significant, the numbers are moving in the right direction. Brazil's National Institute for Space Research recorded 5,731 square kilometers of clearing in the Legal Amazon between August 2024 and July 2025, a 12.07 percent drop from the year before, with eight of nine Amazonian states reporting declines. Nobre has also pointed to the opportunity sitting inside the damage, telling Yale Environment 360 that "the whole Amazon has at least 500,000 square kilometers either abandoned or degraded" and that "the forest has this ability to regenerate."
Replanting native species on degraded land reconnects fragmented habitat, stabilizes soil, restores water systems, and gives wildlife somewhere to return to. One Tree Planted's Amazon work concentrates on the Western Amazon Headwaters across Peru, Ecuador, and Brazil, where the upper tributaries feed the river system downstream, with a goal of restoring 9,600 hectares and planting 10 million trees by 2035 alongside Indigenous organizations and local partners.
"Latin America and the Caribbean is home to some of the most biodiverse forests in the world, playing a critical role in the health of the planet," Gabriela Gard, regional director for Latin America and the Caribbean at One Tree Planted, said. "Restoring these biodiversity hotspots directly benefits communities, supports unique wildlife and bolsters climate resilience."
