The Amazon Rainforest: The World's Largest Rainforest

By Rhett A. Butler [Last update June 4, 2020]

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

In Suriname’s Amazon, the Wayana community struggling to keep gold miners at bay (Oct 29 2026)
- The government in Suriname has pledged to combat illegal mining and the industry’s use of mercury, maintain 90% national forest cover and preserve its status as one of the few countries in the world that absorbs more CO₂ than it emits.
- But on the border with French Guiana, where the government is largely absent, Indigenous Wayana communities have had to adapt to illegal gold miners, who for decades have cut down the forest and polluted rivers with mercury.
- One Wayana chief controls the only airstrip in the area, giving him some leverage with miners who have no other practical way into the forest. But in some instances, those relationships have led to violence.
- The Mulokot Foundation, an advocacy group, is working to help the Wayana improve education and map its ancestral territory. In the future, these initiatives may help residents move beyond mining to more sustainable activities.

‘Already feeling it’: Northern Amazon waterfall season ends early, hurting livelihoods (Oct 29 2026)
- Driven by a “super El Niño,” reduced rainfall in Roraima has lowered water levels in the state’s main rivers, cutting off the flow of seasonal waterfalls that form in the mountains, including the cascade known as Véu de Noiva.
- By drying up the waterfall earlier than usual, climate change is directly hurting regional tourism, which local residents and surrounding communities rely on for their livelihoods.
- Guides and tourism specialists say the drop in tour bookings has forced the sector to reinvent itself, while the state government operates under a state of emergency to prepare for environmental fallout from El Niño.

Environmental officials fear new wave of harassment if Flavio Bolsonaro wins in Brazil (Oct 23 2026)
- Federal employees in the environmental and Indigenous affairs sectors fear a return to the institutional harassment and dismantling of institutions they faced during the Jair Bolsonaro administration if his son, Senator Flávio Bolsonaro, wins the runoff election Sunday, Oct. 25.
- Complaints of harassment and violence filed with the Federal District Labor Prosecutor’s Office nearly tripled during Jair Bolsonaro’s four-year term.
- The weakening of regulatory agencies has led to record levels of deforestation in the Amazon and intensified violence against Indigenous groups that protect the forest.
- Environmental officials and Indigenous experts have launched campaigns and open letters to mobilize the public to vote for incumbent President Luiz Inácio Lula da Silva and defend them and regulatory agencies.

Amazon communities lose water as mining and deforestation reshape rivers (Oct 23 2026)
- An investigation analyzed 722 micro watersheds that feed the Beni River in Bolivia, the Caquetá River in Colombia, the Madre de Dios River in Peru, and the Caroní River in Venezuela. These areas are home to 74 Indigenous groups spread across 202 territories.
- In all four river basins, natural water resources are under pressure. Mining activity has left behind large pools of artificial or anthropogenic (human-made) water, and where livestock ranching has taken hold, the water has disappeared.
- Over the 25 years analyzed, the four catchment areas lost nearly 33,000 hectares (81,500 acres) of natural water, an area more than double the size of Colombia’s Tayrona National Park. The greatest loss occurred in the Colombian Caquetá catchment area, which crosses a department where extensive livestock ranching has long been the main economic activity.
- In the three basins with mining activity — the Madre de Dios, Beni, and Caroní — artificial water sources appeared: four in every five hectares of these water sources are on Indigenous territory.

What if Flávio Bolsonaro wins? High stakes for the environment in Brazil’s 2026 elections (commentary) (Oct 23 2026)
- If Flávio Bolonaro wins Brazil’s 25 October runoff election the consequences for the environment will be enormous, especially in the Amazon but also for the world, argues Philip Fearnside, a researcher who has worked in the Brazilian Amazon for 50 years.
- Flávio, son of Brazil’s anti-environmental former president Jair Bolsonaro, is slightly ahead of incumbent President Lula in the polls, but the difference is within the margin of error. Flávio, who denies anthropogenic climate change and has supported a series of anti-environmental bills as senator, plans to follow in his father’s footsteps.
- The Amazon rainforest is near a series of tipping points, beyond which risk of the forest collapsing rises sharply. If the forest collapses, the emission of greenhouse gases would push global climate past the point where warming escapes from human control. Flávio’s policies would increase this risk.
- This article is a commentary. The views expressed are those of the author, not necessarily of Mongabay.

Amazon deforestation falls 42% to a record low (Oct 16 2026)
Deforestation in the Brazilian Amazon has fallen to the lowest level on record. Data released today by Brazil’s national space research institute, INPE, shows that forest clearing in Earth’s largest rainforest over the 12 months ended July 31, 2026, amounted to 3,335 square kilometers (1,288 square miles), an area smaller than the Spanish island of […]

In Ecuador, Indigenous youth turn to rap music to defend the Amazon (Oct 9 2026)
- In the Ecuadorian Amazon, young people from several Indigenous nationalities are turning to rap to speak out against the toll extractive industries take on their home territories.
- Each track is performed in the artist’s native language (some of which are on the verge of disappearing), with some incorporating Spanish verses to connect with listeners from other cultures.
- Indigenous rappers include Willan Gualinga (Taki Supay) of the Kichwa nationality of Sarayaku; Misael Elías Criollo Grefa (Misa17), from the A’i Cofán community; Raúl Vargas (Robenban), Kichwa from Pastaza; and Tzitzanu, from Sapara.
- Their music is reaching national and international audiences, with Misa17’s track “Ingi Tsampi” drawing more than 400,000 views on TikTok just a month after its release.

The push for a sustainable artisanal mining in the Peruvian Amazon (Sep 12 2026)
MADRE DE DIOS, Peru — In Madre de Dios, in the Peruvian Amazon, thousands of people depend on gold mining, while the spread of mercury and deforestation are transforming the country’s most biodiverse tropical forest. In La Pampa, one of the region’s main gold mining hubs, a formalized artisanal mining operation is trying to prove […]

Scientists use mining data to build malaria alert system in the Amazon (Sep 1 2026)
- Researchers have found a direct link between illegal mining, miners’ routes, and malaria cases in the Yanomami Indigenous Territory in Brazil.
- Now, they’re working on an alert system that will rely on mining data to warn local health agents about the risk of a malaria outbreak.
- The number of malaria cases dropped sharply after authorities expelled illegal miners from the Yanomami land, but Indigenous people worry the potential return of a right-wing government after October’s election could revive the humanitarian crisis.

For 50 years, Philip Fearnside has calculated the costs of losing the Amazon (Aug 31 2026)
- Philip Fearnside has spent 50 years studying the practical limits of Amazon development, beginning with the agricultural settlements built along Brazil’s Trans-Amazonian Highway. His work repeatedly asked who benefits from projects and who bears their longer-term costs.
- He produced influential research on deforestation, forest carbon, tropical dams, and the wider effects of roads, often challenging official assumptions about emissions and economic viability. He later contributed to the IPCC’s work on climate change.
- Fearnside has paired research with public engagement, publishing in Portuguese, writing for Amazônia Real and Mongabay, speaking to journalists, and testifying on projects including the BR-319 highway. That role has also made him a target of hostility, including at a 2021 public hearing where his microphone was cut.
- Former students and colleagues credit him with generous, exacting mentorship and an unusual command of the scientific literature. At a recent tribute at Brazil’s National Institute for Amazonian Research, he rejected any suggestion of a farewell: he intends to keep working.

PICTURES OF THE AMAZON RAINFOREST