Image: Instagram/The Boiling River Project

The steamy Amazon rainforest represents a wilderness of phenomenal power and beauty. Here, copious rainfall and blazing tropical sunshine sustain a one-off natural wonder teeming with life and mystery. Indeed, in terms of scope, scale, biodiversity and ecosystem services, the Amazon rainforest has unrivaled global significance. And the following 20 facts explain why…

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20. The Amazon rainforest encompasses half of the world’s remaining tropical forests

Once upon a time, tropical rainforests covered 14 percent of the surface of the Earth. Today, though, they are known to cover less than six percent. And approximately half of what remains can be found in the Amazon as the world’s largest tract of unbroken rainforest – Indonesia and the Congo Basin harbor much of the rest.

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19. The Amazon rainforest harbors 10 percent of Earth’s biodiversity

The Amazon rainforest is teeming with biological life. To date, its spectacular flora and fauna includes approximately 1,294 species of birds, 427 species of mammals, 2,200 different types of fishes, 428 varieties of amphibians, 378 reptile species, 40,000 plants and no less than 2.5 million insect species. All that amounts to one in five of the world’s bird and fish species and one in ten of all species on the planet.

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Image: Ministério da Cultura

18. The Amazon is the world’s largest – and perhaps longest – river

The Amazon is the world’s largest river in terms of watershed, tributaries and volume of discharge, running for an incredible 4,000 miles from source to sea. However, it falls short of being the world’s longest river – that accolade goes to the Nile, at least according to traditional measures. In recent years, though, this has become a point of contention: according to teams of Peruvian and Brazilian scientists, the Amazon may actually be up to 65 miles longer than the Nile.

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17. The Amazon rainforest is as large as the United States

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To get an idea of the astonishing scale of the Amazon, imagine a rainforest spanning the entire land mass of the U.S. from New York to California. That’s right: this incredible natural feature is roughly the size of the 48 contiguous United States, as it covers more than two million square miles – or 40 percent of the South American continent. And it’s not all in Brazil, either: nine different countries can claim part of the Amazon, in fact.

Image: Agência de Notícias do Acre

16. The Amazon is home to dozens of “uncontacted” tribes

According to Survival International, a non-governmental organization dedicated to indigenous rights, the Brazilian Amazon may be home to as many as 100 “uncontacted” tribes. And little is known about these groups, other than their avoidance of contact with outsiders and other tribes. It is thought, though, that at least some of them may be descended from refugees who fled the atrocities committed by colonists during the 19th century rubber boom.

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15. The Amazon rainforest produces 20 percent of the world’s oxygen

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The Amazon rainforest is often called “the lungs of the Earth” because it produces approximately a fifth of the world’s total oxygen supply. Microorganisms in the ocean produce the rest. Meanwhile, the rainforest also plays a vital role in many other natural systems by regulating global weather systems, absorbing heat and sequestering carbon.

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14. Only one percent of the sun’s energy reaches the forest floor

The Amazon’s multi-storied canopies of vegetation are so dense that practically no light at all reaches the ground. In fact, rain can take as long as ten minutes to percolate to the soil. Unsurprisingly, then, with the exception of vines and seedlings, there is little flora on the dark forest floor. However, plants known as epiphytes have nevertheless adapted to these conditions by colonizing tree branches.

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13. The Amazon River discharges approximately 46 million gallons of water every second

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The Amazon River discharges ten times more water into the Atlantic Ocean than the Mississippi River. That is, 46 million gallons per second, 2.76 billion gallons per minute, 166 billion gallons per hour and four trillion gallons per day. What’s more, in a single 24-hour period the Amazon empties as much water into the ocean as the U.S. consumes in one month.

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12. A single patch of Amazon rainforest can contain more tree species than in all of North America

Studies of native tree populations in the Amazon paint a picture of incredible diversity. According to a 2001 survey of the Ecuadorian rainforest by Joseph Wright, for example, a single 62-acre area contained 1,100 tree species – approximately ten percent more than can be found in the entire North American continent. Furthermore, the total number of tree species in the Amazon is thought to be at 16,000 – approximately 16 times greater than the number of species found in North America.

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11. Around nine feet of rain falls on the Amazon every year

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With a staggering nine feet of annual rainfall, the Amazon rainforest is certainly one of the wettest places on Earth. And like all tropical regions, it is known for having only two seasons: wet and dry. In practice, however, it never dries out completely, so its seasons might be better described as “wet” and “wetter.” And during the wettest months, the river can rise by an incredible 40 feet.

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10. Tree leaves and tissues contain 90 percent of the Amazon’s energy

In temperate regions, soil and leaf litter contain a considerable share of a forest’s energy and biomass. By contrast, in the Amazon some ninety percent of the forest’s energy still remains locked up within the trees. This is because organic decay occurs at a much faster rate in the warmth of the tropics, allowing nutrients to be rapidly recycled by decomposers and then used again by the plants.

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9. The Amazon River once flowed from east to west

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In 2006 geologists from the University of North Carolina presented astonishing evidence that, approximately 145 to 165 million years ago, the Amazon River flowed in the opposite direction. They stumbled upon the discovery while studying the movement and distribution of sediment from the Andes to the Atlantic. In addition, they have claimed that the river’s change in direction is connected to the break-up of the South American and African continents.

Image: Neil Palmer (CIAT)

8. The Amazon impacts weather systems in the northwest U.S.

The Amazon rainforest creates up to three-quarters of its own precipitation through the natural process of transpiration. Moreover, the moisture it produces is believed to impact weather systems as far away as the Western U.S. Indeed, a study from Princeton University has predicted 20 percent less rainfall in the coastal northwest of the United States in the event of the Amazon’s complete deforestation.

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7. The Amazon rainforest contains 86 billion tons of carbon

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The Amazon rainforest is one of the world’s most important carbon sinks, holding as it does some 86 billion tons of carbon according to a 2007 study by Global Change Biology. Furthermore, of all the atmospheric carbon absorbed by the world’s forests, the Amazon accounts for 25 percent. However, recent research by the U.K.’s University of Leeds suggests that the forest’s capacity for sequestering carbon is now diminishing due to deforestation.

Image: Neil Palmer (CIAT)

6. There are 390 billion trees in the Amazon

There are an astounding 390 billion trees in the Amazon – that’s more than 50 for every man, woman and child on the planet. This mind-boggling estimate was published in 2013 by the journal Science as part of a ground-breaking study into the abundance and distribution of Amazonian tree species. And, according to the data, approximately 6,000 species have populations of fewer than 1,000 individual trees there.

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Image: NASA Earth Observatory

5. The Amazon discharges 106 million cubic feet of sediment daily

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The Amazon River dumps approximately 106 million cubic feet of sediments into the Atlantic Ocean every day, including material that has traveled all the way from the Andes Mountains. Even more incredibly, the accumulation of sediments at the mouth of the river has also created an island the size of Switzerland. Majaro Island, as it is known, sees 13-feet high waves, making it a popular destination with surfers.

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4. Twenty five species of hot pepper can be found in the Amazon

The Amazon rainforest is a storehouse of exotic edibles, including no fewer than 25 species of hot peppers. Moreover, cacao, the base ingredient in chocolate, is also believed to have originated in the tangled jungles of the Amazon. Not surprisingly, then, the rainforest is considered a valuable pharmacopeia; it is also thought to hide scores of medicinal plants still undocumented by science.

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3. Annual floodwaters can extend 12 miles from river banks

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Approximately four percent of the Amazon rainforest is flooded during the wet season each year. In fact, the resulting rainfall at that time can submerge surrounding land for up to 12 miles from the river banks. And typically the total area under water is around 100,000 square miles – an area larger than the United Kingdom.

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2. The width of the Amazon River can swell to 24 miles in the wet season

The Amazon River still stretches on average an impressive seven miles across during the dry season. However, during the torrential downpours of the wet season, its width can more than triple to 24 miles. Moreover, its yawning estuarine outlet is just as vast. This measures approximately 202 miles wide – that’s more than 50 miles greater than the Sea of Cortez at its largest point.

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Image: The Boiling River Project

1. One of the Amazon’s tributaries is a “boiling river”

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In 2014 Peruvian geoscientist Andrés Ruzo documented a so-called “boiling river” in the Amazon rainforest. And even though with an average temperature of 188°F it was, in fact, not quite boiling, it did still cook any animal unfortunate enough to fall into it. Ruzo believes that the river is heated by a vast underground hydrothermal system – if true, it would be an unprecedented phenomenon.

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