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  • Writer's pictureLuiza Ribeiro

How Dust Changed the World

Sometimes, the most insignificantly small things are the ones with the most significant impacts. Dust is hard to see but its secrets are even more invisible; space lasers, the Amazon, and how everyone is alive today can be impacted by these tiny particles floating around our immense world.

The Fossilized Fish

Chad, the dustiest place on Earth, specifically in the Bodelé Depression, has something very important that will help resolve the secrets of dust: a fish. A fish in one of the driest and hottest deserts ever seems quite odd, but the world wasn't the same before as it is now, and a long long time ago, the whole section of the Bodelé Depression was submerged in a lake. This lake was called Lake Mega-Chad and in its prime, it was the size of modern-day Germany and as deep as the Washington Monument is tall. As time passed, however, it dried up, and all the life that was once there vanished, but the fossils did not. In the middle of the dried lake, a catfish’s fossil lays but, and I know what you're thinking, what does that have to do with dust? Well, not only the fish but everything that has been fossilized due to the drying of the lake has been having a pretty interesting afterlife.

The Abundance of Dust in the Sahara

The wind of the deserts grinds the fossils into little particles of dust and it kicks them into the air. Where this dust goes will impact deadly hurricanes, nut packages, and oxygen we all breathe. Chip Trepte, the dust specialist from NASA, states that dust can go up to 4 kilometers high, and with that, it’s easier for dust to be picked up and carried to the west. This dust leaves the African continent entirely and heads to the Atlantic Ocean. There is so much dust leaving Africa that astronauts can see it from space with their naked eye, but it has only been recently that they were able to study it from space. The 'CALIPSO Satellite' is a satellite that orbits earth (from the poles) every 90 minutes and is able to track dust by shooting 20 lasers every second. In the end, the data is registered like this:

And according to CALIPSO, the Sahara desert produces out 150 million tons of dust every year, which is equivalent to half of the entire population's weight; so what happens to all of this dust? Scientist Jason Dunion wonders that too; he is so curious, in fact, that he and his team will be flying directly into the path of a hurricane to find out.

Hurricanes' Relationship with Dust

These hurricanes that are significant in size start as baby hurricanes at, you guessed it, the Sahara desert. Water pressure and warm water are what Africa's coast provides and they are everything a hurricane needs to form its size. Dunion shows a dust storm in the Sahara and he places the U.S. on top of it to compare the size in relation to the dust. Surprisingly, the dust storm is almost the entire size of the United States. Because of this surprising abundance of dust, Dunion says it's worth analyzing it. When they are right on top of the storm they launch an interesting device called a dropsonde. Dunion describes them as mini weather stations with parachutes, and it provides them with crucial information about the atmosphere, temperature, humidity, pressure, and the wind. They dropped this device into the storm and it appears that it is a mile and a half to two miles thick. The reason this is so important to hurricanes is that it penetrates holes into the clouds, consequently suffocating the hurricanes. This doesn't mean that dust storms always prevent hurricanes, but it for sure limits the amount; if it wasn't for dust, there would be many more severe hurricanes destroying parts of the world.

Oxygen's Relationship with Dust

Dust, however, doesn’t only stay in one place, it travels all the way to the Atlantic, and, as the saying goes, whatever is up must come down, down to the ocean in this case. Jan-Berend Stuut is a marine geologist at the Royal Netherlands Institute for Sea Research, and he wants to find out the effects of dust on the ocean. To sample these effects, Stuut's team strategically placed 3 buoys across the ocean used to collect material from the atmosphere and another instrument made to collect material that is sinking down on the ocean. The buoys stay a year around in the ocean and when they are picked up, scientists can see lots of residues of dust in its panels. The scientists, however, aren't interested in finding the dust, they are interested in finding out what it does to the ocean, and what they found out prompted astonishment. They discovered that this dust actually carries various nutrients that help planktons nourish and use as a nutrients source. But why are random plants getting nutrients so interesting you ask? Well, these plants are able to suck in a lot of carbon dioxide from our atmosphere, which can be one of our best hopes in curbing climate change. It works as the following; the dust drags carbon down to the ocean floor (which doesn't affect the greenhouse effect), serving as a literal carbon sink. These plants that suck in this carbon can also do something extremely important apart from sucking CO2, and that photosynthesizes. When they suck in sunlight, they return it with one of the most crucial things a human needs in order to survive, oxygen. About half of all the oxygen in our atmosphere comes from the ocean phytoplankton, and scientists believe all of that is thanks to the Saharan dust. Nevertheless, the dust doesn't only contribute to our human lives by stopping hurricanes and bringing us oxygen, it can also be the harbinger of death.

The dust that does manage to cross the entire Atlantic Ocean, can go all the way to Florida. Scientists of that area were speculating that microalgae called Karenia Brevis trigger something awful. Karenia Brevis forms something called Red Tide. Red tides concentrate millions of cells, and they wouldn't be a problem if they weren't extremely toxic. They produce neurotoxins that are prejudicial to dolphins, turtles, and manatees. But it's not only the marine life that gets affected, humans do too. When the tide hits the beach, that sea spray is full of red toxins, which humans can breathe in making it hard for them to breathe and the symptoms can be even worse for people with respiratory problems. But who would have thought that a simple fossilized fish could stop hurricanes, impact our oxygen levels and at the same time make it hard to breathe? But don't worry, we still haven't arrived at the best part yet, the Amazon rainforest.

The Amazon's Relationship with Dust

It is a bit crazy to think that the dust from the Sahara desert would finally reside in a place so distinct from where it originally started. According to scientists 27 million tons of dust arrive at the Amazon basin every year. All of this is equivalent to the Burj Kalifa, Beijing National Stadium, Hoover Damn, Sydney Opera house, and The Great Pyramid of Giza, doubled, of dust that arrives every year. All of this dust gets picked up by different types of trees and the soil, which acts as a nutrient. is extremely important because the soil of the Amazon is unfertile. Yes, believe it or not, Amazon's soil isn't great at all because the constant rain washes down the nutrients of their soil. Nutrients like phosphorus, but you know what else has phosphorus? The fossilized fish in the middle of the desert of Lake Mega-Chad.

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