How the Sahara Desert Fertilizes the Amazon Rainforest Across the Ocean

What do the Sahara Desert and the humid Amazon rainforest have in common? It turns out that one fertilizes the other. Scientists have found that massive amounts of Saharan dust that are blown by winds across the ocean actually fertilize the dense vegetation in the rainforest.

In this case, the researchers studied how much phosphorus makes the trans-Atlantic journey from the desert to the rainforest. This phosphorus accounts for just .08 percent of the 27.7 million tons of Saharan dust that settles in the Amazon each year. Yet it impacts the growth of the forest immensely.

"We know that dust is very important in many ways," said Hongbin Yu, the lead author of the new study, in a news release. "Dust will affect climate and, at the same time, climate change will affect dust."

The researchers analyzed dust transport estimates based on data collected by NASA's Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite between 2007 and 2013. More specifically, they focused on Saharan dust transported across the Atlantic Ocean to South America, because it's the largest transport of dust on the planet.

The researcher then estimated the phosphorus content of the Saharan dust by studying samples from the Bodele Depression and form g round stations on Barbados and in Miami. They then used this estimate to calculate how much phosphorus gets deposited in the Amazon basin.

It turns out that from year to year, the dust pattern is highly variable. In fact, there was an 86 percent change between the highest amount of dust transported in 2007 and the lowest in 2011.

The findings reveal how these two systems are connected. This, in turn, shows that things that impact one side of the globe can also impact the other.

The findings are published in the journal Geophysical Research Letters.

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