The African Desert that Helps the Earth Breathe

If you’ve ever been caught in a dust storm you’ll know how scary it can be and how it can feel like you are going to choke to death. So you might be surprised to learn that we wouldn’t have enough oxygen on the planet to breathe if it wasn’t for Saharan dust storms.

Every year winds whip up huge dust storms on the African continent. These dust storms are absolutely massive.  

The scale of them cannot be truly appreciated, unless you view them from space. 

NASA astronaut Jerry Linenger has seen them first hand.

“You know, I had seen little dust storms blowing and you kinda look hard. This you didn’t need to look hard. It was a continent of Northern Africa basically obscured by thick brown dust. And as I orbited, I couldn’t wait to come back. And then when I did, I saw that dust storm that was over Africa now over the Atlantic Ocean. And my next orbit I see it hitting the coast of South America.”

dust storm from space
A huge dust storm off the West coast of Africa, seen from space.

These huge Saharan dust storms are carried by wind from Africa across the Atlantic until they eventually hit the Amazon basin.

Every year about 27 million tonnes of that African dust we can see from orbit drops out of the sky into the Amazon Basin.

This 6000 mile trans-continental journey of dust is extremely important for the health of the planet, because of what is in the dust.

It turns out, that African dust  is the perfect fertiliser.

The dust is picked up from the Bodélé Depression in Chad, an ancient lake bed where rock minerals composed of dead microorganisms are loaded with phosphorus. Phosphorus is an essential nutrient for plant proteins and growth, which the Amazon rain forest depends on in order to flourish.

“The Sahara Desert is huge, hot, and full of sand and dust. The Amazon basin is huge, warm, but full of greenery and wildlife. And one can’t live without the other. The Amazon, it seems, depends on the Sahara for its very survival. ….Even tens of millions of years after South America separated from Africa, the two continents are still inextricably linked, like an older brother and a younger brother,” says Charlie Zender, a climate scientist at the University of California, Irvine.

The African Desert that Helps the Earth Breathe
Animated image of the dust cloud traveling from the Sahara to the Amazon.

The dust from the Sahara is essential for the health of the Amazon’s tree and plant life, and as they grow, the plants and the trees turn carbon dioxide…into oxygen.

The Amazon produces a huge amount of oxygen, but contrary to popular belief almost none of that oxygen is used by us humans, almost all of the Amazon’s oxygen is consumed by the rainforest itself. 

The Amazon rainforest does help us breathe, but not because of the oxygen it produces. But because of water. 

There’s a river in the Amazon, no, not that one, there’s another river, a river in the sky.

The Amazon has approximately 390 billion trees. Now if you were able to look inside the trees you’d see that they are all sucking up water from the forest floor.

This water travels all through the trees distributing nutrients.

When the water hits the top of the forest canopy the combination of sun and wind evaporates it, turning it into a mighty river.

A flying river. A river in the sky that is larger than the river Amazon below. 

The River Amazon, is  the largest river on Earth, One fifth of all the fresh water that leaves the continents of the whole world and ends up in the oceans comes from the Amazon. It dumps 17 billion tons of water a day in the Atlantic Ocean. Comparatively, 20 billion tons of water is transpired by the rainforest per day. This river of vapor that comes up from the forest and goes into the atmosphere is greater that the Amazon River.

Now this river in the sky, this river of cloud, flows across South America, obscuring everything beneath it… Until it hits a stone wall 5,500 miles  long and up to 4 miles high. The Andes.

When the clouds hit the Andes they condense into raindrops, which then race down the slopes, stripping nutrients from the rocks as they go, and flow directly back into the Amazon Basin…

…until all those nutrients are dumped into the ocean where they are essential for feeding diatoms – a strange organism that you may not have even heard of but that supplies the world with vast amounts of oxygen 

Diatoms are an extraordinary organism, four times thinner than a human hair.

The African Desert that Helps the Earth Breathe
Diatoms seen under the microscope.

Diatoms are the secret to the Earth’s oxygen supply.

They use silica from the ground up rock washed down from the Andes to create new shells, which allows them to reproduce.

Their population can double each day. 

Diatoms are photosynthesising algae.

And as they photosyhtheszie they produce oxygen.

Approximately 20% of the worlds oxygen comes from marine diatoms.  

Huge dust clouds from the Sahara travel thousands of miles across the Atlantic Ocean and then fall on the Amazon, where they fertilize the forest, whose trees create a huge river in the sky, which travels to the Andes, turns into rain. The rain, strips rocks of their nutrients, which flow into the sea, feeding huge diatom blooms which produce huge amounts of oxygen which helps the planet breathe. 

It is an incredible interconnected cycle and just goes to show how interlinked our planet is. 

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