Why do people call the Amazon rainforest the ​“lungs of the earth”?

For three weeks the Amazon rainforest has been on fire, with 73,000 separate fires recorded – the highest number since records started in 2013.

Emmanuel Macron has called it ​“an international crisis”, while German Chancellor Angela Merkel has backed the French president’s call to action, much to the disdain of their Brazilian counterpart, the far-right Jair Bolsonaro. Bolsonaro, for his part, has attempted to deflect blame for the devastation.

Yesterday, environmentalist Nick Rose posted a photo to his Instagram of the fires in the Amazon rainforest with a caption: ​“Terrifying to think that the Amazon is the largest rainforest on the planet, creating 20% of the earth’s oxygen, basically the lungs of the world, has been on fire and burning for the last 16 days running, with literally NO media coverage whatsoever! Why?”.

Thanks to Leonardo DiCaprio, Camila Cabello and Instagram’s most followed person Cristiano Ronaldo, who all quickly regrammed the post, the phrase ​“lungs of the earth” quickly gained traction. But what exactly does it mean?

The Amazon rainforest has long been referred to as the ​“lungs of the earth”, and it’s easy to see why.

The largest and most diverse tropical rainforest on Earth, covering a staggering 5.5m square kilometres, the trees within its stretch have the ability to draw in carbon dioxide and breathe out oxygen – just like the human lung.

It’s a natural phenomenon called ​“carbon sinking” and without it, we’d be in some deep shit. Seriously – roughly a third of the world’s primary forests are housed in the Amazon basin, which accounts for roughly 90 to 140b tonnes of CO2 being taken out of the atmosphere yearly.

And with fires raging through this important ecosystem – endangering both the one million indigenous people, as well as the three million species of plants and animals who call the rainforest home – the planet will be affected in many ways.

According to @theintercept, losing ​“another fifth of Brazil’s Amazon will trigger the feedback loop known as dieback, in which the forest begins to dry out and burn in a cascading system collapse, beyond the reach of any subsequent human intervention or regret.”

@ShannonGSims tweeted: ​“the sky randomly turned dark today in São Paulo, and meteorologists believe it’s smoke from the fires burning *thousands* of kilometers away, in Rondônia or Paraguay. Imagine how much has to be burning to create that much smoke(!). SOS”.

While @WMO (World Meteorological Organization) shared a harrowing map. ​“Produced by @CopernicusEU​’s atmosphere monitoring service, it shows the smoke reaching the Atlantic coast and São Paulo”.

This really is an international crisis. With the world’s climate crisis reaching a state of emergency and the point of no return fast approaching, we cannot ignore what’s going on in Brazil right now. The earth’s lungs are on fire. If we lose them, the body could be next.

Act now: here are eight ways you can help save the Amazon rainforest.