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

Brazil declares environmental emergency ahead of 2025 fire season (Mar 20 2025)
Brazil has declared a nationwide environmental emergency to prevent another devastating fire season in 2025. In 2024, record-breaking blazes scorched millions of hectares of native vegetation in the Amazon Rainforest and other biodiversity-rich biomes. The measure, decreed by environment minister Marina Silva on Feb. 27, gives authorities extra powers and resources to nip wildfires in […]

Ecuador must improve conditions for uncontacted Indigenous communities, human rights court rules (Mar 20 2025)
- The Inter-American Court of Human Rights (IACHR) ruled that Ecuador violated numerous rights of the Tagaeri and Taromenane Indigenous peoples and failed to protect them from violent attacks.
- The nomadic Tagaeri and Taromenane rely on hunting and gathering in the Amazon Rainforest, but the area has also been an attractive location for oil development and logging.
- The court ruled that Ecuador must expand protection zones where the uncontacted Indigenous communities live and improve monitoring of threats in those areas.

Deforestation and airstrip close to isolated teen’s Indigenous land in Brazil Amazon (Feb 24 2025)
On the evening of Feb. 12, a teenager from an isolated Indigenous group voluntarily made contact with people in a fishing village in the western Brazilian Amazon, according to Brazil’s Indigenous agency, Funai. He returned to his land on Feb. 15. The young man is likely part of an isolated Indigenous group in the Mamoriá […]

Randy Borman (1955-2025): An unlikely guardian of the Amazon rainforest (Feb 19 2025)
- Randy Borman, a leader of the Cofan people of the Ecuadorian Amazon, died on February 17th.
- Born to American missionaries in the Amazon, he was raised among the Cofán people and became a lifelong advocate for their land and rights.
- Borman led efforts to gain legal recognition for over a million acres of Cofán territory, ensuring long-term Indigenous control of a vast stretch of rainforest.
- Randy coordinated and helped lead four Rapid Biological Inventories with Chicago Field Museum biologists and local scientists to establish protected areas.

Wild Targets (Feb 17 2025)
The illicit wildlife trade is one of the most lucrative black-market industries in the world, behind only drug trafficking, counterfeit goods, and human trafficking. Wild Targets is a Mongabay video series that explores the cultural beliefs behind the pervasiveness of poaching, as well as the innovative and inspiring solutions that aim to combat the trade. […]

Ecuador’s next debt-for-nature deal falls short of Indigenous involvement (Feb 10 2025)
- Following the success of its first debt-for-nature swap for the Galapagos, Ecuador received $460 million dollars that will be allocated to the conservation of the Amazon.
- The financial organizations involved in the ‘the Amazon Biocorridor Fund’ have publicized the involvement of Indigenous peoples in the process. However, Indigenous leaders have denied these claims and say they have not been involved in full participation.
- On a positive side, the conservation objectives were set based on scientific work by Ecuador’s National Institute of Biodiversity (INABIO), which identified the areas that need to be prioritized based on the richness of their biodiversity.
- The Amazon Biocorridor Fund is set to begin operating this year, and will do so under the supervision of civil society organizations, seeking transparency in the management of resources.

Handcrafted woodwork helps save an Amazonian reserve, one tree at a time (Feb 5 2025)
- A community in the Brazilian Amazon is transforming fallen trunks and dead trees into everyday items and art pieces.
- Household utensils, furniture, miniature trees and jewelry made with forest seeds are some items being produced by women and youth in the Chico Mendes Extractive Reserve. 
- The woodshop sits in a region where rubber tappers have fought for environmental and labor rights for ago, and which still faces deforestation pressure. 

Why is this endangered dolphin being killed to make “love perfumes”? | Wild Targets (Feb 5 2025)
IQUITOS, Peru – The Plight of the Pink River Dolphin is a short documentary investigating the illegal exploitation of endangered pink river dolphins in the Amazon, driven by a myth about their magical properties. The film reveals how pusangas—perfumes made from dolphin oil and body parts—are sold in markets and online, despite the species being protected […]

What’s at stake for the environment in Ecuador’s upcoming election? (Feb 5 2025)
- Ecuador will hold presidential elections on Feb. 9, with incumbent center-right Daniel Noboa facing left-wing challenger Luisa González.
- Both candidates have prioritized security concerns and the economy over environmental issues like climate change, deforestation and water scarcity, but do have some policy proposals that could be promising.
- Noboa and González both promise to increase protections for forests, protected areas and Indigenous communities, but also plan to continue attracting foreign investment in mining, oil and gas, and other activities that threaten Ecuador’s vulnerable ecosystems.

Drop in Amazon deforestation confirmed, but degradation soars 497% in 2024 (Jan 29 2025)
Deforestation in the Brazilian Amazon dropped by 7% in 2024 compared to 2023, according to an analysis by Imazon, a Brazil-based organization that uses satellite imagery to monitor changes in the world’s largest rainforest. However, the news was not entirely positive for conservation efforts: forest degradation skyrocketed by 497%, driven primarily by fires that scorched […]

Probe details the playbook of one of Amazon’s top land grabbers (Jan 20 2025)
- Professional land grabbers operating in the Brazilian Amazon have sophisticated strategies to steal and deforest public lands and get away with it.
- According to the Federal Police, Bruno Heller is one of Amazon’s largest deforesters and relied on legal and technical advice, including a fake contract, bribing police officers, and near-real-time monitoring of deforestation work through satellite imagery, investigators said.
- Low penalties and hurdles faced by federal bodies in seizing back stolen lands from criminals have spurred the land-grabbing industry in Brazil.

Mongabay documentary spotlights Indigenous alliance to protect Amazon headwaters (Jan 16 2025)
Mongabay’s new short documentary The Time of Water premiered Dec. 16 at the Barcelona Center for Contemporary Culture, in Spain. Directed by Pablo Albarenga and produced with support from the Pulitzer Center and OpenDemocracy, the 18-minute documentary explores the Amazon Sacred Headwaters Alliance and its fight to protect one of the world’s most vital sources […]

PICTURES OF THE AMAZON RAINFOREST