Is Sahara Desert Dust Secretly Feeding the Amazon? The science behind a 10,000-mile journey
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In 2015, scientists reported evidence that vast plumes of dust from the Sahara Desert help replenish phosphorus in the Amazon rainforest, linking the world’s largest desert to its largest rainforest in what researchers described as one of the planet’s most important natural nutrient transfers. the conclusions were detailed in the papers. Led by atmospheric scientist Hongbin Yu of the University of Maryland’s Earth System Science Interdisciplinary Center (ESSIC), who is working with NASA’s Goddard Space Flight Center in Greenbelt, Maryland. results published in a geophysical research paper and in a related study on remote sensing of the environment.
10,000-mile-long atmospheric river
Scientists have known for decades that large plumes of Saharan dust travel thousands of miles across the Atlantic Ocean, creating giant grey clouds visible from space before settling over South America. In April 2015, NASA described this connection as a “10,000-mile-long intermittent atmospheric river of dust” connecting Africa and the Amazon basin. Using data from NASA’s Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation Satellite With CALIPSO, launched in 2006, Yu and colleagues first quantified how much dust completes the trans-Atlantic journey. According to the team, an average of 182 million tonnes of dust comes out of the Sahara every year. Of that, 27.7 million tonnes, about 15 per cent, are deposited annually in the Amazon basin. Another analysis reported the region to be 28.8 million tonnes. NASA compared the total to approximately 689,290 semi-truckloads of dust coming out of the desert and 104,908 semi-trucks full of dust dumped into the Amazon each year.
The lidar instrument aboard the Calypso satellite sends pulses of light that bounce off particles in the atmosphere and back to the satellite. It separates dust from other particles on the basis of optical properties. Credit: Scientific Visualization Studio, NASA Goddard Space Flight Center
CALIPSO, which stands for “Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation,” uses a laser to look at the atmosphere and check how dust and other tiny particles are spread out vertically, allowing it to track the movement of the Sahara-Amazon plume in three dimensions from 200
Phosphorus: a missing nutrient
The Amazon rainforest is famous for its biodiversity, but it is also characterised by nutrient-poor soils. About 90 per cent of Amazon soil is deficient in phosphorus, a nutrient essential for plant growth. Heavy rainfall and river systems leach thousands of tonnes of nutrients, including phosphorus and nitrogen, out of the basin each year. Across the Atlantic, the Sahara has significant phosphorus reserves, particularly in the Bodele Depression in Chad, an ancient lake rich in the remains of long-dead microorganisms. Frequent dust storms from this region lift phosphorus-containing particles into the atmosphere. In a 2015 geophysical research paper, Yu and colleagues provided the first satellite-based estimate of how much phosphorus is transported within that dust. After analysing CALIPSO data with dust samples collected from research stations in Chad, Barbados and Miami, the team concluded that about 22,000 tonnes of phosphorus reach the Amazon annually from the Sahara.
An aerial view of fishing boats of the Caju Una community fishing in Porto Stream, Marajó Island, Pará state, Brazil, Saturday, Nov. 1, 2025. (AP Photo/Eraldo Perez)
This figure closely matches the estimated amount of phosphorus lost each year from the rainforest through hydrological processes. “It’s a small world, and we’re all connected,” Yu said at the time. The researchers wrote in the paper, “This suggests that African dust may have a significant impact on maintaining the health of the Amazon rainforest over the long term. Without phosphorus input from African dust, hydrological losses would greatly reduce soil phosphorus reserves on time scales of decades or centuries and affect the health and productivity of the Amazon rainforest.” However, he cautioned that uncertainties remain, noting that they still do not know “the amount of dust needed to provide enough phosphorus to maintain the productivity of the Amazon rainforest.”
Extreme Variability and Sahel Link
The researchers also found that the amount of dust transported across the Atlantic fluctuates rapidly from year to year. Between 2007 and 2011, there was an 86 per cent difference between the largest dust plume recorded in 2007 and the smallest dust plume in 2011. Yu and colleagues identified a possible link between precipitation and dust transport in the Sahel, a semi-arid region south of the Sahara. When rainfall increased in the Sahel, the amount of dust transported across the Atlantic was reduced.
Dust and sand blown from the Sahara Desert covered parts of Europe, turning the sky and snow orange.
The exact mechanism remains uncertain. Yu suggested that increased rainfall could promote vegetation growth in the Sahel, thereby reducing exposed soil available for wind erosion. Alternatively, the rainfall pattern may be related to wind systems that lift dust into the upper atmosphere, which acts as a transportation corridor toward the Americas. “We know that dust is very important in many complex ways,” Yu said. “Dust affects climate and at the same time, climate change will affect dust as well.” He added, “As researchers, we ask ourselves two basic questions: ‘How much dust is transported? And how does climate change affect the amount of dust traveling across the Atlantic?'”
a global earth system connection
Each individual dust particle measures only a fraction of the width of a human hair, yet collectively they create one of the largest intercontinental material transfers on Earth. The work of Yu and colleagues highlighted the extent to which distant ecosystems remain interconnected through atmospheric processes. By measuring the total amount of dust and its phosphorus content, studies from 2015 showed that the Sahara helps keep the Amazon rainforest’s nutrients balanced over time, even as scientists look into how changes in climate might impact this important exchange across the Atlantic.
