Amazon Rainforest: The Lungs of the World

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The Amazon Rainforest, also known as Amazonia or the Amazon Jungle, is the largest tropical rainforest in the world. It covers approximately 2,500,000 square miles in South America across nine countries. That is bigger than a billion football fields!

• What is a rainforest actually?

Rainforests are dense forests that receive a large amount of rainfall every year, usually at least 80 inches. This constant rain creates a warm, humid environment where plants grow quickly and thickly.

Rainforests are made up of layers. The tallest trees form the emergent layer, rising above the rest of the forest. Below that is the canopy, a thick “roof” of leaves and branches where most animals live.

Under the canopy is the understory, a darker layer with smaller plants that can survive with limited sunlight. At ground level is the forest floor, where fallen leaves and plants decompose, recycling nutrients back into the soil.

Because sunlight is limited beneath the canopy, plants and animals have adapted in unique ways to survive. Some plants grow large leaves to capture more light, while animals may climb, glide, or camouflage to move through the dense environment.

Rainforests are the richest and oldest ecosystems on Earth. They are home to over half of all the planet's plants and animals. Many of those plants, which are used for food and medicine, cannot be found anywhere else.

Rainforests also regulate global temperatures, the water cycle, and the levels of carbon dioxide and oxygen in the atmosphere.

• But what does all that really mean?

Some of these facts are easy to understand. Golden lion tamarins only live in the Amazon Rainforest. If the rainforest were not there, these monkeys would no longer exist.

The bark from cinchona trees is the key ingredient in quinine, which is the only drug that continues to be effective against malaria. More than 3 billion people are at risk of this disease. If cinchona trees disappeared, we would be unable to prevent the spread of malaria.

Harder to grasp is how a rainforest in South America influences the water cycle and climate both inside and outside of its ecosystem.

Rainforests act like giant water pumps for the planet. Trees pull water from the soil through their roots and release it into the air through their leaves in a process called transpiration. This water vapor rises into the atmosphere, forms clouds, and eventually falls back to Earth as rain.

In the Amazon, this process happens on a massive scale. Water is constantly recycled—rain falls, trees absorb it, and then release it back into the air again. This creates a continuous cycle that helps maintain rainfall not only in the rainforest but also in surrounding regions.

These moisture flows are sometimes called “flying rivers” because they carry water across continents. This means the Amazon Rainforest can influence weather patterns far beyond South America, helping regulate climates around the world.

• Finally, why is the Amazon Rainforest called the lungs of the world?
• What does that mean?

The Amazon is called the “lungs of the world” because of the way its plants interact with the atmosphere. Just like lungs exchange gases in your body, the rainforest exchanges gases with the air around it.

Trees and plants absorb carbon dioxide, which is a gas that contributes to global warming, and store that carbon in their trunks, branches, and leaves. At the same time, they release oxygen through photosynthesis.

The Amazon contains hundreds of billions of trees doing this work simultaneously. Together, they act like a massive natural system that helps clean the air and maintain the balance of gases in the atmosphere.

However, unlike human lungs, the rainforest is not just producing oxygen—it is also storing huge amounts of carbon. This makes it one of the most important systems on Earth for slowing climate change.

The Amazon Rainforest is so large and home to so many trees that it produces more than 20% of the world's oxygen. Take five big, deep breaths right now. One of those was made possible by the Amazon Rainforest. That is what 20% means.

• Does that also mean that without the Amazon, you would need to skip every fifth breath you take?

Not literally, of course, but it helps us understand how important a number like 20% is.

• How does the Amazon Rainforest produce this much oxygen?

You know that plants use photosynthesis to survive. This process absorbs carbon dioxide from the atmosphere and releases oxygen. Now, imagine 390 billion trees and even more plants acting like one big factory pumping out oxygen into the atmosphere. Oh, and they do it for free.

• Sounds like a pretty good deal, huh?

And don't forget about all that carbon they absorb from the atmosphere. This process cleans the air and actually cools its temperature.

• What happens if those trees are destroyed?

The Amazon Rainforest has always been plagued by deforestation, which is just a fancy word that means cutting down all the trees and killing all the animals. Initially, local farmers were responsible for deforestation as they made room to grow crops to feed their families. Over time, the industrialization of countries such as Brazil has led to mass deforestation, often for cattle ranching.

Destroying the trees in the Amazon Rainforest not only prevents them from removing future carbon dioxide from the air, but it also releases the carbon previously absorbed and stored within those trees. If those trees are destroyed by fire, the carbon returns to the atmosphere. 

Deforestation is happening all over the world, but it is especially severe in tropical rainforests. These forests contain some of the highest levels of biodiversity on Earth, yet they are being cleared for farming, logging, and development.

When forests are removed, animals lose their habitats, plant species disappear, and the balance of the ecosystem is disrupted. Forests also play a major role in controlling weather patterns, so removing them can reduce rainfall and increase extreme heat.

By now, you should have a better grasp of why the Amazon Rainforest is so important. Time to head over to the Got It? section and review those facts while delving a little deeper.