The Amazon basin is the largest tropical rainforest system on Earth, and its importance extends far beyond South America. It stores roughly 123 billion tons of carbon, produces about 20% of all freshwater that rivers discharge into the world’s oceans, and supports more plant and animal diversity than any other ecosystem. Its health directly shapes global climate stability, continental rainfall patterns, and the livelihoods of millions of people.
A Reservoir of Life Found Nowhere Else
The Amazon basin hosts an estimated 50,000 plant species. A verified inventory of just the lowland rainforest floor has cataloged 14,003 seed plant species across 1,788 genera and 188 families. Of those, 6,727 are trees large enough to form the forest canopy, while the remaining 7,276 species are shrubs, small trees, vines, and herbs that fill every available niche beneath it. That’s just the plants. The basin also supports roughly 2.5 million insect species, over 2,000 species of fish, more than 1,300 bird species, and hundreds of mammals, reptiles, and amphibians.
This density of life matters practically. Tropical forests are the planet’s primary engine for generating new species and maintaining genetic diversity, which underpins everything from crop resilience to pharmaceutical discovery. Many of the compounds used in modern medicine trace back to organisms first identified in tropical rainforests, and the Amazon remains the least-explored of them all.
The Amazon’s Role in Regulating Global Climate
Trees absorb carbon dioxide as they grow, locking it into wood, roots, and soil. The Amazon holds an estimated 123 billion tons of carbon above and below ground, making it one of Earth’s most significant terrestrial carbon reserves. For context, global human activity releases roughly 10 billion tons of carbon per year from fossil fuels alone, so the Amazon’s stored carbon represents more than a decade’s worth of total industrial emissions.
For most of recorded history, the forest absorbed more carbon than it released, functioning as a net carbon sink that helped slow the buildup of greenhouse gases. That is changing. Research published in Nature in 2025 confirmed that the combined effects of climate change and deforestation have turned large parts of South American tropical forests from carbon sinks into carbon sources. Southeastern Amazonia, where deforestation and fire are most intense, now emits more carbon than it captures. The rest of the forest still absorbs carbon on balance, but its capacity is shrinking. If the Amazon shifts fully from sink to source, the acceleration of global warming would be significant and very difficult to reverse.
Freshwater Supply and “Flying Rivers”
The Amazon River is Earth’s largest source of liquid freshwater. It supplies about 20% of all freshwater discharged from continents into the oceans and roughly 50% of all freshwater entering the Atlantic. That volume of water shapes ocean salinity, marine ecosystems, and ocean circulation patterns hundreds of miles from the river’s mouth.
What happens above the forest is equally important. Amazonian trees pull water from the soil through their roots and release it as vapor through their leaves, a process called evapotranspiration. This moisture rises, forms clouds, and falls again as rain further inland. A single water molecule can be recycled up to seven times as it moves westward across the basin, creating what scientists call “flying rivers,” atmospheric corridors of moisture that travel thousands of kilometers. These flying rivers deliver rainfall to agricultural regions in central and southern Brazil, Paraguay, and Argentina. São Paulo, a city of over 12 million people, depends partly on moisture that originates in the Amazon. If the forest shrinks enough to disrupt this cycle, rainfall in some of South America’s most productive farmland could drop dramatically.
Home to Hundreds of Indigenous Groups
About 1.5 million Indigenous people live in the Amazon’s forests, spread across roughly 385 distinct groups occupying around 2.4 million square kilometers. Some of these communities have had sustained contact with the outside world for centuries. Others remain voluntarily isolated, with little or no outside contact.
Indigenous territories are not just culturally significant. They also function as some of the most effective conservation zones in the basin. Satellite data consistently shows that deforestation rates inside Indigenous-managed lands are far lower than in surrounding areas, even compared to some government-designated protected areas. The knowledge these communities hold about forest ecology, medicinal plants, and sustainable land use has been developed over thousands of years and represents an irreplaceable resource in its own right.
Ecosystem Services Worth Billions
Economists have tried to put a price on what the Amazon provides for free. A meta-analysis of Brazilian research estimated the combined value of the forest’s ecosystem services, including species habitat, carbon storage, water regulation, and recreation, at roughly $410 per hectare per year. Habitat preservation alone was valued at about $455 per hectare per year. These numbers are almost certainly conservative, since they capture only the services researchers have been able to measure and only within Brazil’s portion of the basin.
Scaled across the Amazon’s roughly 550 million hectares, even a modest per-hectare value translates into hundreds of billions of dollars annually. That figure reflects services no technology can replace at scale: water purification, pollination of crops, flood regulation, and climate stabilization. When the forest is cleared for cattle ranching or soy farming, the short-term economic gain from the land is a fraction of the long-term value lost.
How Close the Amazon Is to a Tipping Point
Around 20% of the Amazon has already been deforested, and an additional 6% is classified as highly degraded. Previous modeling studies suggest that if total forest loss exceeds 40%, the basin could cross an irreversible tipping point where the remaining forest can no longer sustain enough rainfall to support itself. At that stage, large sections would transition into degraded savanna, releasing their stored carbon and permanently losing their biodiversity.
A 2024 study published in Nature found that by 2050, between 10% and 47% of the Amazon forest will face compounding disturbances from drought, fire, and land-use change simultaneously. These overlapping pressures could trigger ecosystem transitions well before the 40% deforestation threshold is reached. The concern is not a single dramatic collapse but a cascading process: losing more forest reduces rainfall, which stresses the remaining forest, which makes it more vulnerable to fire, which accelerates further loss. Each step makes the next more likely.
The Amazon basin matters because it sits at the intersection of nearly every major environmental system on the planet. Its trees regulate atmospheric carbon. Its water cycle feeds agriculture across a continent. Its soils and canopy support more species than any comparable area on Earth. Its Indigenous communities are both its oldest inhabitants and its most effective stewards. Losing it would not just be a regional disaster. It would reshape the global climate, water systems, and biological inheritance that every country depends on.