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

‘They will die’: Fears for the last Piripkura as Amazon invasion ramps up (03 Dec 2021 20:48:42 +0000)
- Overflight images show that outsiders have not just invaded the Piripkura Indigenous Territory in the Brazilian Amazon, but are also expanding their illegal cattle ranches in what’s supposed to be the protected land of one of the world’s most vulnerable uncontacted Indigenous groups.
- Deforestation inside the territory surged nearly a hundredfold in the 12 months since August 2020, which Indigenous rights activists attribute to anticipation among would-be invaders that a restriction ordinance banning outsiders won’t be renewed as it has every two years since 2008.
- The invaders are closing in on the parts of the territory inhabited by Pakyî and Tamandua, the last two known Piripkura individuals living in the territory; there may be another 13 there who have chosen to remain uncontacted.
- The Piripkura suffered from at least two massacres since their first contact with outsiders in the 1980s, and now face the risk of extermination again, activists warn.

Meet Magali, the conservation warrior rescuing Peru’s rainforest animals: Video (26 Nov 2021 22:20:43 +0000)
- A new, award-winning short film by Nick Werber follows wildlife rehabilitator and founder of Amazon Shelter, Magali Salinas, as she discusses her work in the Madre de Dios region of the Peruvian Amazon.
- Magali has dedicated the past 16 years of her life to rescuing animals in a region rife with illegal logging, mining, and wildlife trade. Her center cares for up to 80 animals at once (including sloths, tortoises, parrots, monkeys and more) and releases dozens back into the wild each year.
- Amazon shelter specializes in howler monkeys and Magali releases troops of rehabilitated howlers into protected reserves away from other howler troops’ territories. Finding these places can take days to weeks of searching.
- The film builds to the release of 14 howler monkeys into the wild. “It just goes to show the difference that one person can make,” Werber said. “That was what inspired me to make the film.”

In Brazil, an agribusiness haven’s green pivot leaves many skeptical (25 Nov 2021 12:57:47 +0000)
- The Amacro project was conceived in early 2020 as an agribusiness hub in a heavily deforested part of the Brazilian Amazon, but a year later is being touted as a hub for sustainable business.
- Now renamed the Abunã-Madeira Sustainable Development Area (ZDS), it stretches across 32 municipalities in the states of Amazonas, Acre and Rondônia, which last year accounted for nearly a quarter of the total deforestation in the Brazilian Amazon.
- The ZDS project aims to attract investments into a wide range of sectors, from agroforestry and fish farming, to tourism and logistics, as well as the agribusiness, while promising to avoid deforestation through technology to help boost agricultural productivity.
- Despite these green claims, prosecutors and nonprofit researchers say the prospect of new investment is already boosting land grabbing and deforestation in the area, and argue the best way to halt deforestation is to create protected areas — something that’s not included in the ZDS project.

Amazon deforestation unexpectedly surges 22% to highest level since 2006 (18 Nov 2021 23:59:32 +0000)
- Deforestation in Earth’s largest rainforest surged 22% to the highest level since 2006, according to official data released today by the Brazilian government.
- Preliminary analysis of satellite data by Brazil’s national space research institute INPE shows that 13,235 square kilometers (5,110 square miles) of rainforest was cleared in the Brazilian Amazon between August 1, 2020 and July 31, 2021.
- The sharp increase came as a surprise: Data from INPE’s near-real-time deforestation alert system had set expectations for a modest year-over-year decline in the rate of forest destruction.
- Deforestation has been on an upward trend in the Brazilian Amazon since 2012.

Indigenous groups call for gov’t intervention as land grabbers invade Bolivian protected area (12 Nov 2021 19:24:20 +0000)
- Bajo Paraguá – San Ignacio de Velasco Municipal Protected Area was created on February 12, 2021, to protect 983,000 hectares (about 2,429,045 acres) of primary forest in the Chiquitania region of Bolivia.
- But despite its new protected status, residents are reporting invasions and human settlements in Bajo Paraguá, claiming the colonizers were land traffickers.
- On-site investigation and satellite data and imagery show ongoing deforestation.
- Local leaders, including those of Indigenous groups that live in Bajo Paraguá, are calling for government intervention – while also alleging connections between land grabbers and government officials.

The Amazon has highest October forest loss since at least 2007 (12 Nov 2021 19:19:14 +0000)
- On Friday Brazil reported the highest level of deforestation for any October dating back to 2007.
- According to data from Brazil’s national space research institute INPE, 877 square kilometers (339 square miles) of rainforest were destroyed in the Brazilian Amazon, a 5% increase over October 2020.
- It marks the second straight month where the rate of forest clearing has risen, but on a trailing-twelve-month basis, deforestation stands 5% lower than the same time last year.
- Brazil is expected to release its preliminary deforestation for the year ended July 31, 2021 later this month. It will likely show about a 10% decline relative to 2020.

Top Brazil gold exporter leaves a trail of criminal probes and illegal mines (10 Nov 2021 21:26:40 +0000)
- Brazilian gold exporter BP Trading accounted for 10% of the country’s exports of the precious metal in 2019 and 2020, having purchased it from companies prosecuted for buying illegal gold.
- Most of the illegal mines are concentrated in Indigenous territories, where they deforest the land, pollute the rivers, and inflict violence on Indigenous communities.
- The company saw strong growth in recent years, with revenues of $256 million in 2019, more than double what it made in 2018.
- Illegal mining generates $600,000 to $800,000 a year in Brazil, according to Ministry of Mines and Energy estimates.

Indigenous agents fight deforestation with drones and AI in Brazilian Amazon (10 Nov 2021 21:10:15 +0000)
- The rate of deforestation has increased in recent years in the Brazilian state of Acre, which is now in the top five for deforestation risk, according to a forecast by an artificial intelligence tool developed by Microsoft and Brazilian nonprofit Imazon.
- In a study developed especially for Mongabay, the AI tool shows that Acre has 878 square kilometers (339 square miles) of land that is at high or very high risk of deforestation, including inside, 20 conservation units and 29 Indigenous territories.
- Efforts to combat deforestation include training of Indigenous people to monitor their own territories against agriculture-driven invasions.
- One Indigenous agroforestry agent told Mongabay that he and his peers rely on technology such as drones and GPS to monitor forest fires, guard against poaching, and thwart illegal invasions.

Ecuador’s consultation process for Indigenous lands comes under the microscope (04 Nov 2021 09:48:22 +0000)
- Ecuador’s Constitutional Court has selected two previous legal cases, involving the Cofan (2018) and Waorani (2019) Indigenous groups, as a basis to analyze the country’s process of Free, Prior and Informed Consent (FPIC) and how well it adheres to the rights in the constitution.
- Judges ruled in favor of both the Cofan and Waorani in their lawsuits against the state, both of whom sued three government bodies for selling, or trying to sell, their land to oil and mining companies without properly consulting the communities.
- This review, of which the first hearing will be held in Indigenous territory for the first time in Ecuador’s history, could set new standards for FPIC in the country and grant Indigenous communities more autonomy over their land.
- The new conservative government of President Guillermo Lasso has already passed two decrees to double oil drilling and mining in the country to boost its economy, without consulting with communities who live in the regions where these projects will likely be developed.

COP-26: Amazonia’s Indigenous peoples are vital to fighting global warming (commentary) (02 Nov 2021 13:23:44 +0000)
- The United Nations Climate Change summit, the 26th conference of the parties (COP-26), held in Glasgow Scotland through November 12, is important both for the future of the global climate and for Amazonian Indigenous peoples.
- Uncontrolled climate change threatens the Amazon forest on which Indigenous peoples depend, and Indigenous peoples in turn have an important role as guardians of the forest.
- Decisions on how international funds intended to avoid greenhouse gas emissions are used represent both opportunities and risks for the climate, for the forest, and for Indigenous peoples.
- Indigenous voices need to be heard at COP-26, as empowered stakeholders threatened by climate change, and for the invaluable traditional wisdom these peoples can contribute to global warming solutions. This post is a commentary. The views expressed are those of the author, not necessarily Mongabay.

PICTURES OF THE AMAZON RAINFOREST