The Amazon Rainforest: The World's Largest Rainforest

By Rhett A. Butler [April 1, 2019]

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.

The Amazon rainforest in Peru. Photo by Rhett A. Butler.

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 (formerly the Zaire) river. The river system is the lifeline of the forest and its history plays an important part in the development of its rainforests.

The Amazon basin
CountryTree cover extent, 2010
30% tree cover definition
Tree cover loss, 2010-2017
Tree cover loss
as percentage of 2010 cover
Brazil320,902,659 17,784,762 5.5%
Bolivia39,035,889 2,269,636 5.8%
Peru63,290,191 1,654,462 2.6%
Colombia42,332,155 863,678 2.0%
Venezuela29,664,713 273,739 0.9%
Ecuador9,073,694 213,491 2.4%
Guyana15,432,968 109,875 0.7%
Suriname11,338,148 103,967 0.9%
French Guiana6,607,846 35,990 0.5%
Grand Total537,678,393 23,309,605 4.3%



At one time Amazon River flowed westward, perhaps as part of a proto-Congo (Zaire) 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 chapter 3-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.

The world's largest rainforests [more]
1. Amazon Basin, South America
2. Congo Basin, Africa
3. Indonesian Archipelago, Southeast Asia

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.


Today the Amazon River is the most voluminous river on Earth, eleven times the volume of the Mississippi, and drains an area equivalent in size to the United States. During the high water season, the river's mouth may be 300 miles wide and every day up to 500 billion cubic feet of water (5,787,037 cubic feet/sec) flow into the Atlantic. For reference, the Amazon's daily freshwater discharge into the Atlantic is enough to 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.

Protected areas and indigenous territories in the Amazon and adjacent areas. Data accessed via Global Forest Watch.
Tree cover loss in Amazon countries according to analysis of satellite data by Hansen et al 2018.


While the Amazon Basin is home to the world's largest tropical rainforest, the region consists of a number of 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 rainforest ecology section.


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., 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.

Tree cover loss in Amazon countries according to analysis of satellite data by Hansen et al 2018.
Tree cover loss in Amazon countries according to analysis of satellite data by Hansen et al 2018.


While destruction of the Amazon rainforest is ongoing, the overall rate of deforestation rate in the region is slowing, mostly due to to the sharp drop in forest clearing in Brazil since 2004.

Brazil's declining deforestation rate has been attributed to several factors, some of which it controls, some of which it doesn't. Since 2000 Brazil has established the world's largest network of protected areas, the majority of which are located in the Amazon region. Since 2004 the government has also had a deforestation reduction program in place. This includes improved law enforcement, satellite monitoring, and financial incentives for respecting environmental laws. Furthermore, the private sector — especially the soy, logging, and cattle industries — are increasingly responsive to consumer demand for less-damaging commodities. Finally the Brazilian Amazon has been the site of a number of innovative and ambitious conservation experiments, ranging from jurisdictional commodity certification to indigenous led Reducing Emissions from Deforestation and Degradation (REDD+) projects to Norway's billion dollar performance-based payment for cutting deforestation.

Amazon rainforest canopy as seen from above. Photo by Rhett A. Butler



On anniversary of nun’s murder Amazon land rights activists at high risk (Thu, 27 Feb 2020 12:19:15)
- Fifteen years ago this month, land rights activist and Catholic nun Dorothy Stang, “Sister Dorothy,” was brutally assassinated in Anapu municipality, Pará state, Brazil. While her death caused a loud international public outcry, and resulted in Brazil cracking down on such violence, those corrections didn’t last.
- Less than 5% of the more than 550 killings that have occurred since Stang’s murder having gone to court, according to data collected by Brazil’s Pastoral Land Commission (CPT) and analyzed by Mongabay. In Pará, the state where Stang was murdered, just 6 of more than 190 land conflict murders have been judged in court.
- Experts say the majority of such killings are plotted by land grabbers and powerful land owners trying to intimidate peasant farmers seeking land reform, or trying to protect their small land holdings. Local corruption in government, law enforcement and in the courts leads to few prosecutions.
- Analysts fear President Jair Bolsonaro’s polices will worsen the problem. In December, he issued executive order MP 910, which critics say effectively legalizes land grabbing. The decree, supposedly benefiting smallholders, provides a pardon for past large-scale land grabbers and could embolden land grabbing in future.

Amazon Tipping Point puts Brazil’s agribusiness, energy sector at risk: Top scientists (Mon, 24 Feb 2020 16:16:35)
- Scientists are sounding the alarm: the Brazilian Amazon is dangerously close to, or may already be hitting, a disastrous rainforest-to-savanna tipping point, with heightened drought driven by regional and global climate change, rapidly rising deforestation and more numerous and intense wild fires.
- Overshooting the tipping point would not only be cataclysmic to Amazon biodiversity and release massive amounts of forest carbon destabilizing the planet’s climate further, it could also devastate Brazil’s economy by depriving agribusiness and hydroelectric energy production of water.
- Signs of deepening drought are already evident, as are serious repercussions. The $9.5 billion Belo Monte mega-dam for example, is already seeing greatly reduced seasonal flows in the Xingu River, a trend expected to worsen, potentially making the dam economically unviable, while also threatening the proposed Belo Sun goldmine.
- Reduced rainfall and a shorter growing season are also putting Brazilian agribusiness at risk. Even as scientists rush to develop heat and drought-resistant crops, many doubt new cultivars will keep pace with a changing climate. The Bolsonaro government is ignoring the economic threat posed by the tipping point

Brazilian meat giant JBS expands its reach in China (Thu, 20 Feb 2020 07:27:18)
- Brazilian meatpacker JBS has agreed to supply WH Group, a Hong Kong-based meat processor with access to retail outlets across China, with beef, pork and poultry products worth around $687 million a year beginning in 2020.
- Investigations have shown that JBS sources some of its beef from producers who have been fined for illegal deforestation in the Amazon.
- The push for cattle pasture drives most of the deforestation in the Amazon, while soybean plantations to supply pig and chicken feed have replaced large tracts of the wooded savannas of the Cerrado.

Pope makes impassioned plea to save the Amazon — will the world listen? (Mon, 17 Feb 2020 16:46:20)
- In a 94-page document entitled “Querida Amazonia” (Dear Amazon), Pope Francis has made an impassioned plea for world leaders, transnational companies, and people everywhere to step up and protect the Amazon rainforest along with the indigenous people who live there and are its best stewards.
- The Amazon is seeing rapid deforestation in Brazil, Peru, Bolivia and Colombia, while violence against indigenous people is rising. Scientists say climate change and deforestation are forcing a forest-to-savanna tipping point, which could lead to a massive tree die-off, the release of huge amounts of CO2, and global climate catastrophe.
- “We are water, air, earth and life of the environment created by God,” Pope Francis writes in Dear Amazon. “For this reason, we demand an end to the mistreatment and destruction of mother Earth. The land has blood, and it is bleeding; the multinationals have cut the veins of our mother Earth.”
- Faith leaders applauded the pope: “Care for creation and… social justice for indigenous peoples and forest communities are part of one moral fabric,” said Joe Corcoran of the Interfaith Rainforest Initiative. But most media ignored the pope’s message, focusing instead on his verdict disallowing Amazon priests from marrying.

Early deforestation numbers for 2019 reveal trends in the Amazon (Wed, 12 Feb 2020 10:09:56)
- The Monitoring of the Andean Amazon Project, or MAAP, an initiative of the nonprofit organization Amazon Conservation, has published its analysis of preliminary deforestation data for the Amazon in 2019.
- The figures project that deforestation in 2019 tapered, if slightly, or held relatively steady in four of the five Amazon countries included in the study.
- Bolivia’s loss of forest in 2019 rose in comparison with 2018, likely as a result of widespread fires that burned standing forest.
- The researchers used early-warning alerts of tree cover loss in 2019 to estimate total deforestation in the five countries and then compared the figures with historical rates going back to 2001.

Private firms will pay soy farmers not to deforest Brazil’s Cerrado (Tue, 11 Feb 2020 12:27:47)
- The meteoric growth of the soy industry, which cultivates the profitable bean to feed livestock and cultivated fish in both Brazil and internationally (especially in the UK and EU) is rapidly destroying critical biomes like the Cerrado, Brazil’s tropical savanna.
- But in December. Tesco, Nutreco, and Grieg Seafood launched a groundbreaking initiative aimed at reducing deforestation in the Cerrado by paying farmers to conserve native vegetation on their lands.
- The “Funding for Soy Farmers in the Cerrado Initiative” has so far managed to secure around US$13 million in pledges to incentivize farmers to avoid new deforestation, and instead grow on land that has already been transformed for agriculture. A mechanism for distributing the funds has yet to be established.
- The initiative’s goals align with those of the Cerrado Manifesto, a voluntary pact already signed by 60+ organizations to protect the Cerrado. Backers only want soy grown on the 38 million hectares already converted from savanna to agriculture. A sticking point: transnational commodities companies, like Cargill, haven’t signed on.

Deforestation in Brazil continues torrid pace into 2020 (Sun, 09 Feb 2020 12:39:02)
- Deforestation in the Brazilian Amazon continues to rise, according to data from Brazil’s national space research institute INPE.
- INPE’s deforestation alert system DETER shows that deforestation during January 2020 amounted to 284 square kilometers (110 square miles), an area 83 times the size of New York’s Central Park. The loss is more than twice that registered in January 2019.
- January’s numbers put deforestation in the Brazilian Amazon over 9,000 sq km for the past 12 months, an 85% increase over a year ago.
- The various data points suggest that forest destruction in the Brazilian Amazon is currently pacing about double last year’s rate.

Bolsonaro sends Congress bill to open indigenous lands to mining, fossil fuels (Fri, 07 Feb 2020 14:07:33)
- President Jair Bolsonaro has long pledged to open Brazil’s indigenous reserves in the Amazon and elsewhere to commercial mining, oil and gas exploration, cattle ranching and agribusiness, new hydroelectric dam projects, and tourism. This week he sent a bill to Congress that would do just that.
- And while the legislation would allow consultation with impacted indigenous populations, they would lack the power of veto, except in cases of “garimpo” or wildcat mining. Though the bancada ruralista agribusiness lobby is strong in Congress, it remains to be seen whether the bill will be approved.
- The legislation would also allow the use of GM, genetically modified, seeds in agricultural projects, a practice previously banned because of the danger of contaminating native seeds. Royalties would be paid to indigenous communities for the economic activities allowed in their reserves and communities.
- Bolsonaro called his project a “dream” but it has already met with withering criticism from indigenous organizations who see it as a nightmare. Apib, the Articulation of Indigenous Peoples, called it a ‘death project’ which would, under the mask of false good intentions, effectively authorize the invasion of their lands

Carbon uptake slower than expected in Amazon secondary forest: Study (Wed, 05 Feb 2020 12:05:02)
- A secondary forest in a portion of the Brazilian Amazon takes up carbon at only about twice the rate of primary forest, as compared to carbon accumulation at up to 11 times in other parts of the world; that could be bad news if similar findings are confirmed elsewhere in the Amazon and the tropics, according to scientists.
- The Bragantina region of Pará state where the study occurred has been used agriculturally for hundreds of years, until today, almost no primary forest remains. It is unlikely these degraded forests will return to their original levels of carbon storage and biodiversity on “politically meaningful timescales,” the researchers said.
- The results indicate that future researchers should be more cautious in estimating the absorption capacity of atmospheric carbon by regenerating tropical forests to mitigate the impacts of climate change, as that capacity is variable depending on multiple factors and may be overestimated.
- The findings could also put in doubt Brazil’s plan to meet its Paris Climate Agreement carbon reduction pledges by replanting forest. The nation promises to restore 12 million hectares of forest by 2030. But the actual carbon storage value of these new secondary forests, including tree plantations, could be far lower than expected.

Upset about Amazon fires last year? Focus on deforestation this year (commentary) (Tue, 04 Feb 2020 12:43:56)
- Satellites reveal the true story of the 2019 Brazilian Amazon fires, and how to avoid a repeat in 2020.
- The common media narrative, and resulting public perception, is that large uncontrolled fires were raging through the Brazilian Amazon rainforest, causing vast destruction and deforestation. Subsequent analysis of extensive satellite imagery archives, however, has quietly revealed the opposite scenario: many of the fires were actually burning the remains of areas that were recently deforested.
- That is, the recent deforestation surge fueled the 2019 Brazilian Amazon fires. The fires were in fact a lagging indicator of recent deforestation. Such information provides a much more focused target for the world’s outcry and related policy actions than just focusing on the fires alone.
- This post is a commentary. The views expressed are those of the author, not necessarily Mongabay.


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