The Amazon Rainforest: The World's Largest Rainforest

By Rhett A. Butler [Last update Apr 4, 2024]

The Amazon River Basin is home to the largest rainforest on Earth. The basin -- roughly the size of the forty-eight contiguous United States -- covers some 40 percent of the South American continent and includes parts of eight South American countries: Brazil, Bolivia, Peru, Ecuador, Colombia, Venezuela, Guyana, and Suriname, as well as French Guiana, a department of France.

Reflecting environmental conditions as well as past human influence, the Amazon is made up of a mosaic of ecosystems and vegetation types including rainforests, seasonal forests, deciduous forests, flooded forests, and savannas.

The basin is drained by the Amazon River, the world's largest river in terms of discharge, and the second longest river in the world after the Nile. The river is made up of over 1,100 tributaries, 17 of which are longer than 1000 miles, and two of which (the Negro and the Madeira) are larger, in terms of volume, than the Congo river.

The river system is the lifeline of the forest and its history plays an important part in the development of its rainforests.

WHERE THE AMAZON RANKS AMONG GLOBAL RAINFORESTS

The Amazon is the world's biggest rainforest, larger than the next two largest rainforests — in the Congo Basin and Indonesia — combined.

As of 2020, the Amazon has 526 million hectares of primary forest, which accounts for nearly 84% of the region's 629 million hectares of total tree cover. By comparison, the Congo Basin has around 168 million hectares of primary forest and 288 million hectares of tree cover, while the combined tropical areas of Indonesia, Papua New Guinea, Malaysia, and Australia have 120 million hectares of primary forest and 216 million hectares of tree cover.

THE HISTORY OF THE AMAZON RAINFOREST

At one time Amazon River flowed westward, perhaps as part of a proto-Congo river system from the interior of present day Africa when the continents were joined as part of Gondwana. Fifteen million years ago, the Andes were formed by the collision of the South American plate with the Nazca plate. The rise of the Andes and the linkage of the Brazilian and Guyana bedrock shields, blocked the river and caused the Amazon to become a vast inland sea. Gradually this inland sea became a massive swampy, freshwater lake and the marine inhabitants adapted to life in freshwater. For example, over 20 species of stingray, most closely related to those found in the Pacific Ocean, can be found today in the freshwaters of the Amazon.

About ten million years ago, waters worked through the sandstone to the west and the Amazon began to flow eastward. At this time the Amazon rainforest was born. During the Ice Age, sea levels dropped and the great Amazon lake rapidly drained and became a river. Three million years later, the ocean level receded enough to expose the Central American isthmus and allow mass migration of mammal species between the Americas.

The Ice Ages caused tropical rainforest around the world to retreat. Although debated, it is believed that much of the Amazon reverted to savanna and montane forest (see Ice Ages and Glaciation). Savanna divided patches of rainforest into "islands" and separated existing species for periods long enough to allow genetic differentiation (a similar rainforest retreat took place in Africa. Delta core samples suggest that even the mighty Congo watershed was void of rainforest at this time). When the ice ages ended, the forest was again joined and the species that were once one had diverged significantly enough to be constitute designation as separate species, adding to the tremendous diversity of the region. About 6000 years ago, sea levels rose about 130 meters, once again causing the river to be inundated like a long, giant freshwater lake.

Note: Human populations have shaped the biodiversity of the Amazon. See Amazon people for more.

THE AMAZON RIVER TODAY

Today the Amazon River is the most voluminous river on Earth, carrying more than five times the volume of the Congo or twelve times that of the Mississippi, draining an area nearly the size of the forty-eight contiguous United States. During the high water season, the river's mouth may be 300 miles wide and every day up to 18 billion cubic meters (635 billion cubic feet) of water flow into the Atlantic. That discharge, equivalent to 209,000 cubic meters of water per second (7.3 million cubic feet/sec), could fill over 7.2 million Olympic swimming pools per day or supply New York City's freshwater needs for nine years.

The force of the current -- from sheer water volume alone -- causes Amazon River water to continue flowing 125 miles out to sea before mixing with Atlantic salt water. Early sailors could drink freshwater out of the ocean before sighting the South American continent.

The river current carries tons of suspended sediment all the way from the Andes and gives the river a characteristic muddy whitewater appearance. It is calculated that 106 million cubic feet of suspended sediment are swept into the ocean each day. The result from the silt deposited at the mouth of the Amazon is Majaro island, a river island about the size of Switzerland.

The Amazon's influence on the movement of moisture extends beyond the water that flows down the Amazon river. The trees of the Amazon rainforest pump vast quantities of water vapor into the atmosphere every day via transpiration. While much of this water falls locally as rain, some of this moisture is carried by airflows across other parts of the continent, including the agricultural heartland of South America to the south. This movement has been likened to "flying rivers". By one estimate, 70% of Brazil's gross national product comes from areas that receive rainfall generated by the Amazon rainforest.

THE AMAZON RAINFOREST

While the Amazon Basin is home to the world's largest tropical rainforest, the region consists of myriad other ecosystems ranging from natural savanna to swamps. Even the rainforest itself is highly variable, tree diversity and structure varying depending on soil type, history, drainage, elevation, and other factors. This is discussed at greater length in the Amazon rainforest ecology section.

AMAZON BIODIVERSITY

The Amazon is home to more species of plants and animals than any other terrestrial ecosystem on the planet -- perhaps 30 percent of the world's species are found there. The following numbers represent a sampling of its astounding levels of biodiversity:

• 40,000 plant species
• 16,000 tree species
• 3,000 fish species
• 1,300 birds
• 430+ mammals
• 1,000+ amphibians
• 400+ reptiles

THE CHANGING AMAZON RAINFOREST

The Amazon has a long history of human settlement, but in recent decades the pace of change has accelerated due to an increase in human population, the introduction of mechanized agriculture, and integration of the Amazon region into the global economy. Vast quantities of commodities produced in the Amazon — cattle beef and leather, timber, soy, oil and gas, and minerals, to name a few — are exported today to China, Europe, the U.S., Russia, and other countries. This shift has had substantial impacts on the Amazon.

This transition from a remote backwater to a cog in the global economy has resulted in large-scale deforestation and forest degradation in the Amazon — more than 1.4 million hectares of forest have been cleared since the 1970s. An even larger area has been affected by selective logging and forest fires.

Conversion for cattle grazing is the biggest single direct driver of deforestation. In Brazil, more than 60 percent of cleared land ends up as pasture, most of which has low productivity, supporting less than one head per hectare. Across much of the Amazon, the primary objective for cattle ranching is to establish land claims, rather than produce beef or leather. But market-oriented cattle production has nonetheless expanded rapidly during the past decade.

Industrial agricultural production, especially soy farms, has also been an important driver of deforestation since the early 1990s. However since 2006 the Brazil soy industry has had a moratorium on new forest clearing for soy. The moratorium was a direct result of a Greenpeace campaign.

Mining, subsistence agriculture, dams, urban expansion, agricultural fires, and timber plantations also result in significant forest loss in the Amazon. Logging is the primary driver of forest disturbance and studies have shown that logged-over forests — even when selectively harvested — have a much higher likelihood of eventual deforestation. Logging roads grant access to farmers and ranchers to previous inaccessible forest areas.

Deforestation isn't the only reason the Amazon is changing. Global climate change is having major impacts on the Amazon rainforest. Higher temperatures in the tropical Atlantic reduce rainfall across large extents of the Amazon, causing drought and increasing the susceptibility of the rainforest to fire. Computer models suggest that if current rates of warming continue, much of the Amazon could transition from rainforest to savanna, especially in the southern parts of the region. Such a shift could have dramatic economic and ecological impacts, including affecting rainfall that currently feeds regions that generate 70 percent of South America's GDP and triggering enormous carbon emissions from forest die-off. These emissions could further worsen climate change.

PROTECTING THE AMAZON RAINFOREST

While destruction of the Amazon rainforest is ongoing, the overall rate of deforestation rate in the region dropped between the mid-2000s and mid-2010s, mostly due to to the sharp decline in forest clearing in Brazil. However deforestation has been steadily rising in the region in more recent years.

Brazil's decline in its deforestation rate between 2004 and 2012 was attributed to several factors, some of which it controls, some of which it doesn't. Between 2000 and 2010 Brazil established the world's largest network of protected areas, the majority of which are located in the Amazon region. In 2004, the government implemented a deforestation reduction program which included improved law enforcement, satellite monitoring, and the provision of financial incentives for respecting environmental laws. Independent public prosecutors offices played a particularly important role in pursing illegal activities in the Brazilian Amazon. The private sector also got involved, especially after 2006 when major crushers established a moratorium on new deforestation for soy. That soy moratorium was followed by the "Cattle Agreement", which major slaughterhouses and beef processors committed to source cattle only from areas where environmental laws were being respected.

However these conservation initiatives started to break down in the Brazilian Amazon in the mid-2010s. Major cattle producers circumvented the rules through livestock laundering, while financial incentives for conserving forests failed to materialize at the expected scale needed to change landowners' behavior. The Temer and Bolsonaro Administrations dismantled environmental regulations, reduced environmental law enforcement, stripped conservation areas and indigenous territories of protections, and encouraged a wide range of industries (mining, logging, agribusiness) to expand extraction and conversion in the Amazon. In 2019, deforestation in the Brazilian started accelerating rapidly.

THE LATEST AMAZON RAINFOREST NEWS

Amazon deforestation falls to 10-year low in first half of 2026 (Jul 16 2026)
Deforestation in the Brazilian Amazon has fallen to its lowest level in the past 10 years, according to satellite data published by Brazil’s National Space Agency (INPE). Between January and June 2025, a total of 2,090 square kilometers (807 square miles) of deforestation was recorded in the Brazilian Amazon. In the same months of 2026, […]

How Brazil’s federal fiscal policy hinders Amazon Rainforest conservation (commentary) (Jul 15 2026)
- The three Brazilian states whose territory is mostly Amazon Rainforest — and carry the heaviest share of its conservation burden — are among the poorest and most fiscally dependent in the country.
- Amapá, Acre, and Amazonas operate on budgets so dependent on federal funding that they have almost no ability to act on their own, yet they are also precluded from developing their economies within their vast and federally protected swaths of forest.
- “It is a design flaw in Brazil’s fiscal constitution, and it is getting worse,” a new op-ed argues. “Brazil cannot credibly lead global climate diplomacy while its Amazonian states remain fiscally trapped.”
- This article is a commentary. The views expressed are those of the author, not necessarily of Mongabay.

Dark earth: Ancient Amazonian soil can boost forest restoration, study finds (Jul 8 2026)
- Researchers from the University of São Paulo and the Brazilian Agricultural Research Corporation showed in a study that the ancient organic-rich soil known as Amazonian dark earth (ADE) boosted seedling growth under real field conditions.
- The investigation suggests ADE could work as a “biological engineer” by reshaping the soil’s microbiome, increasing beneficial fungal diversity and reducing pathogenic microbes that hinder tree growth.
- With conservation in mind, scientists are now working to isolate these micro-organisms to develop bioinputs for forest restoration without disturbing the original Amazonian dark-earth deposits.

A fraction of promised climate money reaches Amazon communities: Interview with Latimpacto’s leaders (Jul 8 2026)
- Despite major funding pledges for the Amazon, much of the promised capital never reaches Indigenous peoples and local communities, often because funding structures are poorly aligned with on-the-ground realities.
- Latimpacto, a Colombia-based philanthropic network, is working to close this gap through initiatives that train funders, support locally led innovation and integrate Indigenous knowledge into conservation and development projects.
- Mongabay spoke with Latimpacto’s leaders, Carolina Suárez Visbal and Juan David Ferreira, who say the organization is also advocating for stronger domestic philanthropy across Latin America, arguing that better tax incentives, trust-based grantmaking, and patient, flexible capital are needed to complement international funding.
- Suárez Visbal and Ferreira say they see greater collaboration between Latin America and Southeast Asia as a key opportunity, calling for shared funding mechanisms and knowledge exchange to strengthen conservation of tropical forests and broader socioecological resilience.

Targeted conservation in Brazil could help protect the Amazon’s flying rivers (Jul 2 2026)
- The Amazon’s atmospheric moisture flows known as “flying rivers” provide over 70% of rainfall in parts of southern Peru and northern Bolivia, but they are threatened by deforestation in the Brazilian Amazon.
- According to a new report by the NGO Amazon Conservation, the lack of protections for areas known as undesignated public forests and road development projects pose a deforestation risk that would disrupt the flying rivers during dry and transition seasons.
- Research shows that the Amazon is already experiencing longer dry seasons, which in turn affects the forest’s capacity to recycle moisture for the flying rivers.
- Conservation targeting the forests that are most important for recycling atmospheric moisture could help maintain the flying rivers, the report proposes.

Fire surge in 2025 threatened isolated peoples in Brazil (Jun 24 2026)
- In 2025, fires caused a significant spike in forest loss in Indigenous territories in Brazil that are home to peoples living in voluntary isolation: Alto Turiaçu, Uru-Eu-Wau-Wau, and Apiaká do Pontal e Isolados.
- According to data from Global Forest Watch, fires were responsible for nearly all of the forest loss in each of the territories, destroying mostly primary forest.
- Indigenous leaders told Mongabay that fires are a threat to their way of life, including those living in voluntary isolation, negatively impacting health, vegetation, biodiversity, and food security.
- A climate expert warns the upcoming El Niño, predicted to be stronger than the 2023-2024 event, will likely lead to warmer temperatures and drier conditions across the Amazon Basin, making it more prone to fires.

South America’s farms depend, in part, on a healthy Amazon (Jun 22 2026)
- The Amazon is not only a carbon store; it is also a major source of atmospheric moisture that helps sustain rainfall across much of South America.
- A new Nature study finds that deforestation lowers the warming threshold at which large parts of the Amazon could lose stability.
- Recent droughts, El Niño conditions, and fire risk show why degraded forests are less able to withstand climate stress and recover afterward.
- Protecting intact forests, restoring degraded areas, and reducing fire are increasingly important for climate resilience, biodiversity, and South America’s food system.

Death and exile: A war plagues Indigenous Jiw and Nukak in the Colombian Amazon (Jun 19 2026)
- By late May, at least 48 people were killed in rural areas of Colombia following clashes between the FARC guerrilla dissident groups controlled by the aliases “Calarcá” and “Iván Mordisco.”
- Conflicts have displaced 10 Indigenous Jiw families from the municipality of Mapiripán, Meta department. They had to reach the urban area of San José del Guaviare for protection.
- The clashes occurred near the Tomachipán-Cumare road, an illegal trail used by dissident armed cells as a strategic corridor to mobilize and transport drug trafficking supplies in the Guaviare department.
- Experts warn that controlling this disputed area is important for armed groups, as it means dominating strategic zones in the department and also being closer to the Venezuelan border.

Illegal miners adapt their strategies in Yanomami Amazon territory (Jun 17 2026)
- Illegal miners are adapting their tactics in the Yanomami Indigenous Territory in Brazil’s Amazonas and Roraima states to evade efforts in the last few years to remove them, found researchers.
- Miners are fragmenting into smaller groups instead of concentrating near airstrips, going deeper into the middle of the Amazon forest, moving to specific border areas with Venezuela and paying high prices to continue their activities.
- Illegal mining is significantly down in the territory due to the government operation, said Indigenous people and authorities, though concerns remain for the health of isolated Indigenous people.
- Brazil’s government says it is in the phase of “scavenging the territory” to remove miners deep in the forest which are unable to be detected by satellite imagery and require long walks into the Amazon.

Amazon deforestation alerts fall to lowest 12-month level since 2014, show Brazilian data (Jun 14 2026)
- INPE’s DETER alert system detected 370 square kilometers of deforestation in the Brazilian Amazon in May, down from 960 square kilometers in May 2025.
- Over the past 12 months, DETER registered 3,182 square kilometers of deforestation, the lowest total for any 12-month period in the system’s record dating back to July 2014.
- Independent monitoring by Imazon shows a similar downward trend, reinforcing evidence that forest clearing has continued to decline.
- Scientists warn that a likely strong El Niño could still increase drought, fire and forest degradation risks, even if clear-cutting remains low.

Amazon deforestation declines as Brazil reduces forest loss nationwide (Jun 12 2026)
Deforestation in Brazil’s Amazon biome fell by 23.5% in 2025 compared with 2024, according to a new report from MapBiomas, a Brazil-based land-use mapping project. Reductions in deforestation were recorded across the board in all of Brazil’s biomes, culminating in a 21% nationwide decrease in forest loss. In total, nearly 985,000 hectares (2.4 million acres) […]

In Ecuador, an Indigenous community goes thirsty despite its two rivers (Jun 12 2026)
- On the banks of the Puní River’s middle basin, in the Ecuadorian Amazon, illegal mining has increased by 2,700% over seven years, contaminating the main water source for the ancestral Kichwa community of Capirona.
- Residents of Capirona say that, by 2021, the color of the Puní River started to change, turning brownish. Meanwhile, problems such as skin rashes, fungal infections and itching became frequent.
- In samples of mining ore collected by Ecuadorian authorities from an illegal mining camp on the banks of Puní, signs of mercury were found at levels far exceeding the permitted limit for this metal in agricultural soils.
- Industrial farming activity has also polluted the waters of the Shalkana River, another watercourse located within the community. Despite being surrounded by two rivers, residents of Capirona rely on two water tankers sent weekly by municipal authorities, which is enough for barely half of the families for just a few days.

PICTURES OF THE AMAZON RAINFOREST