The Amazon Rainforest is Fed by Saharan Desert Dust

The crossing of Saharan dust to South America is the largest transport of dust on the planet. Image: NASA

At first glance the Amazon rainforest and the Sahara desert might not seem to have much in common — but according to NASA, the lush jungles of the Amazon are actually fed by dust from the desert located an entirely separate continent.

The Amazon rainforest is a dense, broadleaf forest that covers most of the Amazon basin in South America, comprising one of the biggest and most biodiverse expanses of tropical rainforest on the earth. Phosphorus is one of the primary minerals the forest needs to survive and flourish. Organic matter releases phosphorus into the soil upon decomposition, but many of the nutrients are washed away by rainfall, unable to feed the Amazonian plants.

Instead, the forest gets its phosphorus fix from an unlikely place — tons of Saharan dust are transported across the ocean every year. Scientists studied the amount of dust transported on a yearly basis using a lidar instrument on NASA’s Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation, or CALIPSO, satellite.

They studied data spanning the years from 2007 to 2013 and found a huge variation in the amount of dust transported on a yearly basis — as high as 86%. While the reason for the variation is not exactly known, it is related to the yearly amount of rainfall in the Sahel, an expanse of land on the southern border of the Sahara.

Image: Wikimedia Commons

The data shows an estimated average 182 million tons of dust each year are transported across the ocean. This is the first time a NASA satellite has been able to quantify this data in three-dimensional form.

“We know that dust is very important in many ways. It is an essential component of the Earth system. Dust will affect climate and, at the same time, climate change will affect dust,” states lead author Hongbin Yu. “First we have to try to answer two basic questions. How much dust is transported? And what is the relationship between the amount of dust transport and climate indicators?”

This research is a step in the right direction for understanding the relationship of dust with the climate. The full study is published in Geophysical Research Letters.

The video below, from NASA, explains the findings from the first multi-year study measuring the 3-D distribution of dust travelling from the Sahara Desert to the Amazon basin. This video features Hongbin Yu, lead author of the study. Watch: