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.
|Tree cover extent
|Primary forest extent
|Tree cover loss since
|Tree cover loss
|Primary forest loss
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.
How large is the Amazon rainforest?
The extent of the Amazon depends on the definition. The the Amazon River drains about 6.915 million sq km (2.722 sq mi), or roughly 40 percent of South America, but generally areas outside the basin are included when people speak about "the Amazon." The biogeographic Amazon ranges from 7.76-8.24 million sq km (3-3.2 million sq mi), of which just over 80 percent is forested. For comparison, the land area of the United States (including Alaska and Hawaii) is 9,629,091 square kilometers (3,717,811 sq km).
Nearly two-thirds of the Amazon lies in Brazil.
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.
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
Major meatpacker JBS misled the public about sustainability efforts, NY lawsuit claims (Mar 1 2024)
- New York Attorney General Letitia James filed a lawsuit against JBS USA Food Company and JBS USA Food Company Holdings for misrepresenting plans to achieve net-zero greenhouse gas emissions by 2040.
- The lawsuit cites numerous instances in which the company’s claims to the public didn’t align with what was happening behind closed doors. Its website and advertisements have boasted claims about reaching net-zero carbon emissions while company executives were making plans to grow.
- The New York attorney general said JBS Group’s greenhouse gas emissions calculations don’t include deforestation in the Amazon Rainforest, making its environmental goals “not feasible given the current scope of [its] business operations.”
New giant anaconda species found on Waorani Indigenous land in Ecuador (Feb 28 2024)
- A new species of giant anaconda has been found in the Bameno region of Baihuaeri Waorani Territory in the Ecuadorian Amazon.
- The largest snake the team found in Waorani territory was a female anaconda that measured 6.3 meters (20.7 feet) long from head to tail, but there are Indigenous reports of larger individuals.
- As apex predators, anacondas play a vital ecological role in regulating prey populations like fish, rodents, deer and caimans.
- Anacondas face a number of threats across their range, including habitat loss from deforestation, hunting by humans and pollution from oil spills.
To reverse deforestation and protect biodiversity, build a bioeconomy in the Amazon (commentary) (Feb 23 2024)
- Slowing and reversing deforestation and land degradation in the Amazon requires not only conservation efforts but also increasing the economic value of standing primary forests through a bioeconomy approach, argues Robert Muggah, co-founder of Instituto Igarapé.
- A bioeconomy involves regenerative agriculture, sustainable energy, and other activities that leverage the forest’s natural assets while ensuring economic benefits for local communities. However, the expansion of the bioeconomy faces challenges, including resistance from extractive sectors, investment risks, and the need for infrastructure, research, and support for local enterprises.
- Despite these hurdles, advancing the bioeconomy is essential for sustainable development and decarbonization in the Amazon and crucial for the world, says Muggah.
- This post is a commentary. The views expressed are those of the authors, not necessarily Mongabay.
Brazil’s BR-319 highway: The danger reaches a critical moment (commentary) (Feb 17 2024)
- A project to rebuild Brazil’s notorious BR-319 highway is quickly moving closer to becoming a fait accompli. Together with planned side roads, BR-319 would open vast areas of Amazon rainforest to the entry of deforesters. A working group convened by the Ministry of Transportation will soon release a report intended to justify approval of the project’s environmental license. Congressional approval of legislation to force granting the license is also looming.
- Despite a constant political discourse claiming that governance will contain deforestation and tourists will admire the forest from their cars as they drive on a “park road,” the reality on an Amazon frontier is very different. Most of what happens once access is provided by road is outside of the government’s control.
- The consequences of unleashing deforestation in the last great block of Amazon forest would be catastrophic for Brazil, threatening the water carried to São Paulo by the winds known as “flying rivers” and pushing global warming past a tipping point.
- An earlier version of this text was published in Portuguese by Amazônia Real. It is a commentary and does not necessarily reflect the views of Mongabay.
Ecuador government weighs delaying closure of controversial ITT oil block (Feb 12 2024)
- The government in Ecuador is considering ways to avoid closing the 43-ITT oil block, located inside Yasuní National Park in the eastern Amazon, despite the results of a national referendum last year to halt drilling.
- Since opening in 2016, the operation has led to numerous oil spills and the construction of a road through the 82,000-hectare (202,626 acre) reserve, threatening biodiversity as well as Indigenous groups, many of them living in voluntary isolation.
- But some officials have said closing the oil block needs to be delayed by at least one year to allow the national economy to respond to what could amount to billions of dollars in losses.
Brazil’s 2024-2027 “Transversal Environmental Agenda”: The elephants in the room (commentary) (Feb 4 2024)
- Brazil’s current 4-year development plan is accompanied by a “Transversal Environmental Agenda,” released last week, to coordinate environmental measures across the different federal agencies.
- While the agenda lists many worthwhile items in the portfolios of the various ministries, it fails in the most basic role such an agenda should play: ensuring that government actions do not cause environmental catastrophes.
- Missing subjects include foregoing building roads that open Amazon forest to deforestation, legalizing illegal land claims that stimulates an unending cycle of land grabbing and invasion, plans for hydroelectric dams in Amazonia, expanding oil and gas drilling and the burning of fossil fuels that must end without delay if global warming is to be controlled.
- An earlier version of this text was published in Portuguese by Amazônia Real. It is a commentary and does not necessarily reflect the views of Mongabay.
Tropical forests share similar mix of common and rare tree species, study shows (Jan 31 2024)
- A Nature study reveals surprising similarities among the most common tree species in tropical rainforests in Africa, the Amazon and Southeast Asia, with 2.2% of tree species accounting for half of the trees in each region.
- University College London (UCL) researchers and 356 collaborators analyzed more than 1 million trees across 1,568 locations, identifying 1,119 prevalent tree species through statistical techniques and resampling.
- Despite diverse environmental conditions, tropical forests on different continents exhibit consistent patterns of tree diversity, suggesting possible universal mechanisms shaping these ecosystems.
- The focus on common tree species could aid predictions of forest responses to environmental changes, emphasizing the importance of balancing conservation efforts for common and rare species.
Grassroots efforts and an Emmy-winning film help Indigenous fight in Brazil (Jan 29 2024)
- The 2022 documentary “The Territory” won an Emmy award this January, shining a light on the Uru-eu-wau-wau Indigenous people and the invasions, conflicts and threats from land grabbers in their territory in the Brazilian Amazon from 2018 to 2021.
- After years of increasing invasions and deforestation in the protected area, experts say the situation has slowly improved in the past three years, and both Indigenous and government officials in the region “feel a little safer.”
- Grassroots surveillance efforts, increased visibility of the problems, and a more effective federal crackdown against invaders have helped tackle illegal land occupiers and allowed the Indigenous populations to take their land back.
- Despite the security improvements, however, the territory still struggles against invasions and deforestation within the region, experts say.
Direct funding of Indigenous peoples can protect global rainforests & the climate (commentary) (Jan 24 2024)
- Indigenous leaders attended the World Economic Forum’s 2024 Annual Meeting in Davos last week.
- Though communities like theirs have the potential to transform global rainforest conservation and climate efforts by delivering proven, scalable, community-based solutions, they require direct funding.
- Governments and donors must increase their direct, flexible, and less bureaucratic grant-making to those who have the profound knowledge and the means to make a real difference in preserving our planet’s future – Indigenous peoples, a new op-ed by Rainforest Foundation argues.
- This article is a commentary. The views expressed are those of the authors, not necessarily Mongabay.
Why the Amazon’s small streams have a major impact on its grand rivers (Jan 18 2024)
- An unprecedented time-series study in the basin of the Tapajós River, a major tributary of the Amazon, assesses the level of degradation of small rivers threatened by agribusiness expansion.
- Researchers from several universities will assess the conservation status of 100 streams spread between the municipalities of Santarém and Paragominas, at the confluence of the Tapajós and the Amazon, which were first analyzed in 2010.
- The impact of dirt roads and their network of river crossings, which causes sediment load, siltation, erosion and changes in water quality, was one of the factors that caught researchers’ attention in the initial time-series study.
- Experts say that local development models should ideally start from water to land, rather than the other way around, given the importance of water for the rainforest, its biodiversity, and the inhabitants who depend on both.
PICTURES OF THE AMAZON RAINFOREST
Blackwater lake and whitewater river in the Amazon
Victoria water lilies
Flowering tree in the Amazon rainforest canopy
Oxbow lake in the Amazon
Blue poison dart frog
Jaguar in the Colombian Amazon
Creek in the Colombian Amazon
Passion flower in the Colombian Amazon
Daybreak over the Amazon
Amazonian wax-tailed fulgorid
Amazon rainforest canopy in Brazil
Rivers in the Amazon rainforest
Squirrel monkey in the Amazon
Leaf-cutter ant in the Amazon
Giant monkey frog
Amazon rainforest canopy in Peru
Orange planthopper in Peru
Oxbow lake in the Amazon
Indigenous man with bird eggs
Indigenous Tikuna man in the Amazon rainforest
Javari river in the Amazon
Mantid in Suriname
Amazon leaf toad
Frequently asked questions about the Amazon, answered
Where is the Amazon rainforest?
Amazon rainforest section contents: