Why Is the Amazon Called 'The Lungs of the Earth'?

The nickname is famous — but what's actually happening inside all those trees?

The Amazon rainforest is enormous — it stretches across parts of nine countries in South America and covers an area larger than the entire European Union. But its famous nickname, "the lungs of the Earth," is about more than just its size.

How trees actually "breathe"

Plants take in carbon dioxide from the air and, using sunlight, convert it into energy — releasing oxygen as part of the process. This is called photosynthesis. With so many trees packed into one place, the Amazon produces an enormous amount of oxygen and absorbs a huge amount of carbon dioxide.

Because of that, some people describe the Amazon as functioning a bit like a giant set of lungs for the planet — constantly cycling gases in and out on a massive scale.

It's more complicated than "lungs," though

Scientists actually debate the nickname a little. Recent research suggests the Amazon's trees use up a large portion of the oxygen they produce through their own natural processes at night, meaning the net amount of oxygen the Amazon adds to the world's air supply may be smaller than the nickname suggests.

What's not debated, though, is the Amazon's other massive role: it stores a huge amount of carbon inside its trees and soil. When forests like the Amazon are cut down or burned, much of that stored carbon gets released back into the atmosphere — which is a major reason deforestation there is such a widely discussed environmental issue.

An enormous home for life

Beyond gases, the Amazon holds an almost unbelievable amount of biodiversity — scientists estimate it's home to about 10% of all known species on Earth, many of which live nowhere else.

A question to think about

If a forest that far away can affect air and climate everywhere else on Earth, what do you think that tells us about how connected different parts of the planet really are?