Two different parts of the world. Two different landscapes. Two different places. Can they ever be connected? Surprisingly, the answer is, yes!

The dry Sahara was the lifeblood for the vibrant and verdant Amazon. This is the story of a destiny that started long, long ago, when the Sahara was gushing with deep blue water.

Six thousand years ago, the Sahara Desert was nowhere near a desert that today takes up one tenth of Africa. It was a lake. Not just any lake, but the world’s largest freshwater lake. The Sahara is covered with ancient plankton. This plankton, which lies on the floor of the old lake, is called diatomite. It is extremely old, when an ocean existed in the region.

NASA’s Landsat 7 satellite is studying the composition of rocks from 400 miles above the Earth. It takes high resolution pictures of the Bodele Depression, where the diatomite is, in many different wavelengths of different light.

The lake used to be over a 1,000 kilometres, or about 621 miles, long and 600 kilometres, or about 373 miles, wide. Using Landsat 7, scientists can put together the pictures the satellite takes and see the entire bed of the lake at one time using a computer. Landsat 7 shows more than 24,000 square miles of the sediment from the lake bed. Not just any sediment though. Every single square mile is diatomite.

Scientists have mapped where the diatomite is using the satellite’s images. The diatomite, which comes from the plankton, is a large source of phosphorus. Phosphorus is needed by all living things. It is used by living things to produce energy. The Sahara has now come in play, but what about the Amazon?

To get to the Amazon, the wind lifts some diatomite into the air. The diatomite gets crushed into a powder and then flies along with the breath of the Earth. The wind flows around the Sahara, forming a gritty dust storm. Up in space, 22,000 miles above the Blue Marble, a European weather satellite by the name of Meteosat 8, looks down.

Sitting in its geostationary orbit, Meteosat 8 observes and records the daily pulses of dust rising from the Bodele Depression. The dust appears as a whitish cloud on the satellite. As “observed by Meteosat 8, the dust rises at noon each and every day,” Charlie Bristow, from the Birkbeck University of London, tells us. “The individual dust particles are minute … there are such vast clouds of this dust that you can see it on satellite images.”

The dust clouds are over a hundred stories high and about 200 miles wide. The dust then blows west across Africa. When it reaches the coast of the Atlantic Ocean, the dust flies up many miles high. Next, prevailing winds take the dust 3,000 miles west and south, 7,000 tonnes of dust can be up in the air, at one time alone.

After the 3,000 miles tiresome flight, the diatomite has reached its destination, the South American Amazon jungle. The dust which also contains phosphates, is being carried all this way, but for what?

Surprisingly, this dry dust will be used to fertilise the lush Amazon. The minerals that are in the dust combine with the clouds and turn into water droplets, to fall as rain. The soil in the Amazon is very dry and depleted of necessary nutrients, including phosphate, which the Sahara’s sand dutifully delivers.

During the wet season in the Amazon, the rain falls continually, never pausing. It delivers thousands of tonnes of phosphate, enriching the soil. The reaction of all this nourishment can be seen all the way from space.

Terra, another satellite, circles the Earth not just every day, but every 99 minutes. It sees how fast vegetation is growing. Terra uses a colour scanner to monitor the effect the Sahara’s dust has on the Amazon’s soil, comparing the beginning and the end of the rainy season. The satellite sees that the Amazon takes on more of the specific green of chlorophyll.

Two things so different, yet so connected. The Sahara has nourished the Amazon like no other force could. For every leaf that exists now, three more will be growing soon. This happens not only in the Amazon, but everywhere on Earth. Humans just can’t see something so mind-blowing, yet so common in nature. The Earth has an intricate and powerful system that we are just beginning to discover.

Published in Dawn, Business & Finance weekly, October 1st, 2016