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

Birds are changing — and Indigenous memory is the longest record we have (Mar 3 2026)
- A global study drawing on Indigenous and local knowledge across three continents finds that bird communities have shifted toward smaller-bodied species over the past 80 years, suggesting a substantial loss of larger birds even in places with little formal monitoring.
- Traditional ecological knowledge, built through daily interaction with landscapes over generations, can reveal long-term environmental changes that scientific datasets — often only decades deep — fail to capture.
- Because larger species tend to be more vulnerable to habitat fragmentation and environmental stress, a shift toward smaller birds may signal deeper ecological restructuring rather than a simple decline in numbers.
- Integrating lived experience with scientific methods offers a fuller picture of environmental change, highlighting that some of the earliest warnings come from people who depend most directly on the natural world.

Agroforestry offers market-based way to boost Amazon rains & farmer incomes (analysis) (Feb 25 2026)
- Since the 1970s, Brazil has cleared a large amount of Amazon Rainforest, and the consequences extend beyond biodiversity loss, carbon emissions and social disruption, because the forest generates its own weather.
- Continued deforestation could push the system past a tipping point where the Amazon can no longer sustain its rainfall regime, threatening the continent’s productive capacity and the economic livelihoods of hundreds of millions of people.
- The economic opportunity that can change this is agroforestry systems that reforest areas to produce global commodities that can also comply with Brazil’s Forest Code, which requires private properties in the Amazonian region to maintain native vegetation on 80% of their landholdings.
- This article is an analysis. The views expressed are those of the author, not necessarily of Mongabay.

A journey from student to Amazon “Junglekeeper”: Interview with Paul Rosolie (Feb 23 2026)
- Conservationist Paul Rosolie published a new book describing his journey from student to Amazon “Junglekeeper.”
- In a wide-ranging interview, Rosolie talks about uncontacted tribes, drug traffickers and the distance he still needs to go to achieve his goal of protecting the Las Piedras River.
- Rosolie also discusses the personal challenges and sacrifices of devoting his life to this slice of the Peruvian Amazon.

The cost of compliance with the EUDR will limit its impact on reducing deforestation (commentary) (Feb 23 2026)
- Many links in agri-commodity supply chains have very narrow profit margins, making them particularly sensitive to additional costs.
- The costs of implementing “zero deforestation” agri-commodity supply chain commitments requiring physical segregation are likely to cause positively engaged companies to avoid commodities grown in regions with active deforestation, leaving companies with no deforestation commitments in their place.
- Contrary to dominant beliefs in adding controls and costs, systemically linking markets and public policy in producer regions enables cheaper, more price-competitive and thus more effective forest-climate strategies; jurisdictional REDD+ is poised to provide such a bridge, argue Bjørn Rask Thomsen, Europe Director at Earth Innovation Institute and former food industry CEO and Daniel Nepstad, Executive Director and President at Earth Innovation Institute in this op-ed.
- This article is a commentary. The views expressed are those of the author, not necessarily of Mongabay.

The Amazon’s most valuable export isn’t timber — it’s rain (Feb 19 2026)
- Tropical forests actively generate rainfall by releasing moisture into the atmosphere, with each square meter producing hundreds of liters of rain annually across surrounding regions. Clearing even small portions can measurably reduce precipitation, especially during dry seasons.
- Much of the rain that falls far inland originates from forests through long-distance moisture transport known as “flying rivers,” meaning farms, cities, and reservoirs may depend on ecosystems located hundreds or thousands of kilometers away.
- Reduced rainfall from deforestation can undermine agriculture, river flows, and hydropower, revealing forests as a form of natural water infrastructure that supports food production, energy systems, and economic stability.
- By assigning a monetary value to forest-generated rainfall, researchers estimate the service in the Amazon alone is worth on the order of tens of billions of dollars annually, underscoring that forest loss threatens not only biodiversity and carbon storage but regional climate systems themselves.

Banks must step in before the Amazon Soy Moratorium collapses (commentary) (Feb 18 2026)
- Finance is often portrayed as distant from environmental destruction, but in reality, it sits at the center: banks and investors decide which business models survive and which harms they will tolerate.
- Right now, a successful agreement called the Amazon Soy Moratorium, which has helped protect millions of hectares of forest by stopping major traders from buying soy grown on Amazon land deforested after 2008, is on the brink of collapse due to industry pressure — but banks can play a role in ensuring these traders stay in the pact and don’t let it unravel.
- “Financial institutions should make continued access to capital conditional on compliance with the moratorium’s core principles: no deforestation after 2008, full traceability, and zero tolerance for forest destruction in the Amazon biome,” a new op-ed argues.
- This article is a commentary. The views expressed are those of the author, not necessarily of Mongabay.

Amazon deforestation on pace to be the lowest on record, says Brazil (Feb 17 2026)
- Near-real-time satellite alerts show Amazon deforestation in Brazil continuing to decline into early 2026, with clearing from August through January falling to its lowest level for that period since 2014.
- Over the previous 12 months, detected forest loss also dropped to a 2014 low, reinforcing a broader downward trend that is corroborated by official annual data and independent monitoring. Clearing in the neighboring Cerrado savanna has also fallen
- Environment Minister Marina Silva attributed the decline to strengthened enforcement and municipal cooperation, saying Brazil could record the lowest Amazon deforestation rate since record-keeping began in 1988 if current efforts continue.
- While the data is positive for conservation advocates, short-term satellite data can fluctuate seasonally, and long-term outcomes will depend on economic pressures, infrastructure expansion, and climate-driven risks such as drought and fire.

Malaria outbreak among Indigenous Pirahã linked to forest loss, satellite data find (Feb 17 2026)
- According to data from Global Forest Watch, the Pirahã Indigenous Territory in Brazil lost 7,000 hectares of tree cover from 2002-24.
- A large spike occurred in 2024, when the territory lost 3,200 hectares of tree cover.
- Government officials told Mongabay that the recently contacted Pirahã people are facing a malaria outbreak, and the deforestation is the result of an effort by Brazil’s Indigenous affairs agency to improve food security.
- The situation is complex, conservationists say, and although the clearings to plant crops may exacerbate the risk of malaria, the Pirahã people need food to improve their ability to fight the disease.

That “butterfly” you saw? It was probably a moth (Feb 17 2026)
Most people think moths are dull, nocturnal, and nothing like butterflies. That couldn’t be more wrong. In the Amazon rainforest, moths come in every color, shape, and size — and many are active during the day. In fact, while there are only about 18,000 species of butterflies worldwide, there are over 160,000 species of moths. […]

Brazil gov’t builds map to help exporters comply with EU anti-deforestation rule (Feb 12 2026)
- Brazil’s National Space Research Institute, INPE, created a new technology to generate deforestation data in polygons of a half-hectare threshold for the first time, following the European Union’s new regulation on deforestation-free products, or EUDR.
- When it comes into effect at the end of 2026 (delayed for the second year in a row), the EUDR will require suppliers to provide geolocalized data and other documentation to prove that their products exported to the EU aren’t sourced from areas illegally deforested after Dec. 31, 2020.
- December is the start of the Amazon rainy season, which poses challenges to track deforestation due to the high incidence of clouds; to tackle this, INPE created the Brazil Data Cube, which captures all remote sensing images of a period and radar to get cloud-free images for that month.
- The map was built per request of the agriculture ministry, which made it available for rural producers in late December 2025 through a platform aimed at integrating information from public and private databases to generate compliance reports to be used by exporters.

Another controversial land deal in Suriname threatens the Amazon Rainforest (Feb 11 2026)
- Critics in Suriname are speaking out against plans to develop 113,465 hectares (280,378 acres) of rainforest for industrial agriculture in the district of Nickerie.
- The plans come from a 2024 public-private partnership between the agriculture ministry and Suriname Green Energy Agriculture N.V., a private company working in agriculture and bioenergy.
- The partnership was inherited from the previous government and allegedly went forward without environmental permits, causing frustration and confusion across several regulatory agencies.
- If the entire 113,465-hectare block is cleared, Suriname could lose its negative carbon emission status and fail to qualify for certain carbon credit programs, experts said.

Indigenous protests force Brazil to suspend Tapajós River dredging plan (Feb 10 2026)
Brazil has suspended a decree on dredging and privatizing the Tapajós River, a major tributary of the Amazon, after protests shut down a grain terminal — but Indigenous groups are pressing for its full revocation. Hundreds of Indigenous protesters have since Jan. 22 blockaded the Cargill grain facility in the Amazonian city of Santarém over […]

PICTURES OF THE AMAZON RAINFOREST