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

New agreement aims to streamline Amazon Rainforest protection efforts (Nov 27 2025)
- A new agreement announced at the COP30 climate talks in Brazil intends to unify countries and institutions from around the world to monitor and protect the Amazon Rainforest.
- The Mamirauá Declaration aims to develop a streamlined framework that will unify various long-term efforts to streamline data gathering and analysis.
- The agreement focuses on the active participation of Indigenous peoples and local communities in monitoring; it also calls for more capacity building in countries in the Amazon Basin.

Why are Amazonian trees getting ‘fatter’? (Nov 24 2025)
- A new study has found that the trunks of trees in the Amazon have become thicker in recent decades — an unexpected sign of the rainforest’s resilience in response to record-high levels of CO2 in the atmosphere.
- Nearly 100 scientists involved in the study have stated that old-growth forests in the Amazon are sequestering more carbon than they did 30 years ago, contradicting predictions of immediate collapse due to climate change.
- But the warning still stands: Despite the trees’ capacity to adapt, scientists fear that the extreme droughts and advancing deforestation could invert the rainforest’s balance and threaten its vital role in global climate regulation.

A forest worth more standing: Virgilio Viana on what it will take to protect the Amazon (Nov 21 2025)
The first time Virgilio Viana saw the Amazon up close, he was a 16-year-old with a backpack, two school friends and very little sense of what he was walking into. They arrived by land, drifting along dirt roads that had more potholes than surface, then continued by riverboat as the forest thickened around them. Something […]

Top ethnobotanist Mark Plotkin’s COP30 reflections on Amazon conservation (analysis) (Nov 17 2025)
- The global battle to mitigate climate change cannot be won in the Amazon, but it can certainly be lost there, writes top ethnobotanist Mark Plotkin in a new analysis for Mongabay. Though he’s well-known for investigating traditional uses of plants in the region, he’s also a keen observer of and advocate for Indigenous communities and conservation there.
- Compared to the 1970s, he writes, the Amazon enjoys far greater formal protection, understanding and attention, while advances in technology and ethnobotany have revealed new insights into tropical biodiversity, and Indigenous communities — long the guardians and stewards of this ecosystem — are increasingly recognized as central partners in conservation, and their shamans employ hallucinogens like biological scalpels to diagnose, treat and sometimes cure ailments, a technology that is increasingly and ever more widely appreciated.
- “The challenge now is to ensure that the forces of protection outpace the forces of destruction, which, of course, is one of the ultimate goals of the COP30 meeting in Belém,” he writes.
- This article is an analysis. The views expressed are those of the author, not necessarily of Mongabay.

Strategic ignorance, climate change and Amazonia (commentary) (Nov 13 2025)
- With the support of President Luiz Inácio Lula da Silva, essentially all of Brazil’s government outside of the Ministry of Environment and Climate Change is promoting actions that push us toward tipping points, both for the Amazon Rainforest and the global climate.
- Crossing any of these tipping points would result in global warming escaping from human control, with devastating consequences for Brazil that include mass mortalities.
- The question of whether Brazil’s leaders understand the consequences of their actions is relevant to how they will be judged by history, but the climatic consequences follow automatically, regardless of how these actions may be judged, a new op-ed argues.
- This post is a commentary. The views expressed are those of the author, not necessarily of Mongabay.

After 6 years, trial in Indigenous forest guardian killing pushed to 2026 (Nov 7 2025)
- The trial of the two suspects charged in the killing of Indigenous forest guardian Paulo Paulino Guajajara and attempted killing of fellow guardian Laércio Guajajara in the Brazilian Amazon in 2019 was pushed to 2026, triggering outrage among the Guajajara people and Indigenous rights advocates.
- The trial over the crimes will be a legal landmark as the first Indigenous cases to go before a federal jury in Maranhão; usually, killings are considered crimes against individuals and are tried by a state jury, but these crimes were escalated to the federal level because prosecutors made the case that they represented an aggression against the entire Guajajara community and Indigenous culture.
- A long-awaited anthropological report on the collective damages to the Indigenous community as a result of the crimes was concluded and attached to the court case in August, but the trial is very likely to only happen in early 2026, “given that there is not enough time for it to be held by the end of this year,” the judge’s advisory staff in the case said.
- Paulo’s father, José Maria Paulino Guajajara, said he is “really angry” at white people for killing his son for no reason — and inside the Arariboia territory, where their entrance is forbidden. “We Indians are dying, and the white man won’t stop killing us.”

Brazil can protect its forests while growing its economy, says Arapyaú’s Renata Piazzon (Nov 5 2025)
- Renata Piazzon, CEO of the Instituto Arapyaú, is one of Brazil’s leading voices for aligning conservation with economic development, arguing that protecting forests and improving livelihoods must go hand in hand.
- Under her leadership, Arapyaú has helped catalyze initiatives like MapBiomas and the Forest People Connection, which link data, finance, and connectivity to reduce deforestation and strengthen Amazonian communities.
- As Brazil prepares to host COP30, Piazzon envisions the country shifting from negotiation to implementation—demonstrating global leadership through regenerative agriculture, forest restoration, and a low-carbon economy.
- Piazzon spoke with Mongabay founder and CEO Rhett Ayers Butler in November 2025.

Brazil charges 31 people in major carbon credit fraud investigation (Nov 4 2025)
Brazil’s Federal Police have indicted 31 suspects for fraud and land-grabbing in a massive criminal carbon credit scheme in the Brazilian Amazon, according to Brazilian national media outlet Folha de S.Paulo. It is the largest known criminal operation involving carbon credit fraud to date in the nation. The police probe, called Operation Greenwashing, was launched […]

Beyond deforestation: redesigning how we protect and value tropical forests (analysis) (Nov 3 2025)
- Following his earlier essay tracing possible futures for the world’s forests, Mongabay founder and CEO Rhett Ayers Butler turns from diagnosis to design—asking what concrete interventions could still avert collapse. This piece explores how governance, finance, and stewardship might evolve in a second act for tropical forests.
- The essay argues that lasting protection depends structural reform: securing Indigenous land rights, treating governance as infrastructure, and creating steady finance that outlasts election cycles and aid projects.
- Butler also examines overlooked levers—from restoring degraded lands and valuing forests’ local cooling effects to rethinking “bioeconomies” and building regional cooperation across borders. Each points toward a shift from reactive conservation to deliberate, sustained design.
- This article is a commentary. The views expressed are those of the author, not necessarily of Mongabay.

What might lie ahead for tropical forests (analysis) (Nov 2 2025)
- Heading into COP30, where tropical forests are set to be a central theme, Mongabay founder and CEO Rhett Ayers Butler offers a thought experiment—tracing today’s trajectories a little further forward to imagine where they might lead. What follows are scenarios, some improbable, others already taking shape.
- The essay envisions a world where deforestation gives way to disorder: weakened governance, runaway fires, and ecological feedback loops eroding forests from within even without the swing of an axe. It explores how technology and biology—AI-driven agriculture, gene-edited trees, and microbial interventions—could either accelerate destruction or redefine restoration, depending on who controls them.
- Across these imagined futures, one pattern recurs: forests thinning, recovering, and thinning again, as human ambition, migration, and climate instability test whether nature will be given the time and space to heal.
- This article is a commentary. The views expressed are those of the author, not necessarily of Mongabay.

Heading into COP, Brazil’s Amazon deforestation rate is falling. What about fires? (Oct 30 2025)
- Brazil’s official data show deforestation in the Amazon fell 11% in the 12 months to July 2025, with independent monitoring by Imazon confirming a similar trend—evidence that policies under President Lula da Silva are reversing the sharp rise seen during Jair Bolsonaro’s administration.
- Even as land clearing slows, fires and forest degradation have become major drivers of loss. Exceptional drought in 2024, record heat, and the spread of roads and logging left large areas of the forest dry and flammable, causing 2.78 million hectares of primary forest loss—roughly 60% from fire.
- Burned areas have dropped by 45% over the past year, suggesting some recovery, yet scientists warn the Amazon is entering a more fragile state shaped by climate extremes and the lingering effects of past destruction.
- As Brazil prepares to host COP30 in Belém, attention will center on sustaining recent gains and advancing initiatives like the proposed $125 billion Tropical Forest Forever Facility, even as new roads, gold mining, and policy uncertainty—such as the wavering soy moratorium—continue to threaten progress.

Belém faces its social and natural demons as host to COP30 (Oct 28 2025)
- Deforestation and the city’s historic shift from rivers to roads led to a massive influx of people into low-lying baixadas, where 57% of residents lack services, such as sewage, and are highly prone to flooding.
- The lack of trees in one of the Amazon’s most revered cities, especially in poor neighborhoods, contributes to projections that Belém will face 222 days of extreme heat by 2050.
- Experts argue that the infrastructure projects being implemented don’t offer sustainable solutions, reflecting a long-term failure to address Belém’s water and sewage crises.

PICTURES OF THE AMAZON RAINFOREST