News / Science & Technology

Dust From Farming May Affect Rainfall

Dust storm in the Sahara (Parc National du Banc d'Arguin)
Dust storm in the Sahara (Parc National du Banc d'Arguin)

Multimedia

Audio

New research suggests agriculture has greatly increased the amount of dust blowing off of West Africa, the world's largest source of atmospheric dust, and may have been one factor driving the decrease in rainfall in the region over the past several centuries.

Dust is more than a housekeeping nuisance. To climate scientists, dust is a force of nature. It's the most abundant particle in the atmosphere, and it reflects sunlight and heat.

Africa's Sahel region
Africa's Sahel region

The world's largest source of dust is the Sahara and Sahel region of West Africa. And its influence on the environment is surprisingly wide-ranging, according to Stefan Mulitza, a marine geologist at the University of Bremen in Germany.

"It probably interacts with cloud formation; people think that it has an influence on the quantity of precipitation; hurricane activity through the cooling of the sea surface is probably affected; and last but not least, the quality of the air we breathe" is also affected by dust, Mulitza says. Dust from severe West African dust storms can blow all the way across the Atlantic Ocean to the U.S. state of Florida.

3,000 years of dust

But it's been hard for scientists to unravel what impact human activity has had on dust production in West Africa, in part because good data from satellites and ground stations has only been available for the last few decades.

Saharan dust blowing off Northwest Africa to the Atlantic Ocean
Saharan dust blowing off Northwest Africa to the Atlantic Ocean

In a new study in the journal Nature, Mulitza and his colleagues studied ocean sediments off the coast of Senegal and Mauritania. They constructed a record of West African dust production stretching back more than three thousand years.

For nearly that entire period, dust generation followed a predictable pattern: more dust in drier years, less in wetter ones. But then, beginning in the 19th century, something surprising happened: dust production increased dramatically.

Mulitza says that increase in dust coincides with a major economic change in the Sahel region.

"In the 19th century groundnuts were introduced into Senegal, just as one example," he says. "And there was a very widespread commercial agriculture to fuel the groundnut oil industry."

Unintended consequences

Farmers in the Sahel cleared forests to produce groundnuts and other cash crops. He says that disrupted the sandy soil and led to a sharp rise in the amount of dust blowing off the Sahel.

Mauritanian landscape. The photo was taken on a field trip to Mauritania led by Jan-Berend Stuut in November 2009.
Mauritanian landscape. The photo was taken on a field trip to Mauritania led by Jan-Berend Stuut in November 2009.

And that dust may have been one factor behind the drier climate in the region over the past few centuries. Although the effects of dust on climate are complex and not fully understood, it may cool surface temperatures, which can shift precipitation patterns away from the region.

Atmospheric scientist Charlie Zender at the University of California at Irvine says this is the first study to link farming with increased dust generation in the world's largest source of dust. And he says there may be lessons for farmers elsewhere in the world.

"In those regions where rainfall isn't plentiful and abundant, this study suggests that using those surfaces for agriculture, using that land, will lead to these types of unintended consequences, whether that's in Africa or not," he says.

Cooling dust

Cornell University climate researcher Natalie Mahowald says if future studies confirm Mulitza's findings, it could have larger implications for climate change research.

"It would mean that there has been a cooling from dust over the 20th century that we haven't really been thinking about previously," she says. "And this cooling could be hiding some of the increase or the warming that should be happening from carbon dioxide."

Mahowald says that could mean the Earth is more sensitive to the warming effects of carbon dioxide than previously thought.

Mulitza says his findings may not be all bad news. He notes that increased dust over the tropical Atlantic may have lowered ocean surface temperatures, which may have reduced hurricane activity. "The climate system is coupled," he says. "And if you change something in the tropics, and you change something in the African dust source, it has global consequences" – although, he says, more research will be needed to quantify exactly what those consequences are.

You May Like

Mali's Female Basketball Players Rebound After Islamist Occupation

Islamist extremists ruled northern Mali for most of 2012, imposing strict Sharia law, and now some 18 months later, the region is slowly getting back on its feet More

Video Vietnamese Staging Chinese Product Boycott After Oil Rig Spat

Many Chinese-made products go unsold, for now, with numerous Vietnamese consumers still angry over recent dispute More

Koreas Mark 61st Anniversary of War Armistice

Muted observances on both sides of heavily-armed Demilitarized Zone that separates two decades-long enemies More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Students in Business for Themselvesi
X
Mike O'Sullivan
July 26, 2014 11:04 AM
They're only high school students, but they are making accessories for shoes, fabricating backpacks and doing product photography - all through their own businesses. It's the result of a partnership between a non-profit organization that teaches entrepreneurship and their schools. VOA's Mike O'Sullivan and Deyane Moses met the budding entrepreneurs near Los Angeles.
Video

Video Students in Business for Themselves

They're only high school students, but they are making accessories for shoes, fabricating backpacks and doing product photography - all through their own businesses. It's the result of a partnership between a non-profit organization that teaches entrepreneurship and their schools. VOA's Mike O'Sullivan and Deyane Moses met the budding entrepreneurs near Los Angeles.
Video

Video Astronauts Train in Underwater Lab

In the world’s only underwater laboratory, four U.S. astronauts train for a planned visit to an asteroid. The lab - called Aquarius- is located five kilometers off Key Largo, in southern Florida. Living in close quarters and making excursions only into the surrounding ocean, they try to simulate the daily routine of a crew that will someday travel to collect samples of a rock orbiting far away from earth. VOA’s George Putic has more.
Video

Video Not Even Monks Spared From Thailand’s Junta-Backed Morality Push

With Thailand’s military government firmly in control after May’s bloodless coup, authorities are carrying out plans they say are aimed at restoring discipline, morality and patriotism to all Thais. The measures include a crackdown on illegal gambling, education reforms to promote students’ moral development, and a new 24-hour phone hotline for citizens to report misbehaving monks. Steve Sandford reports from Bangkok.
Video

Video Virtual Program Teaches Farming Skills

In a fast-changing world beset by unpredictable climate conditions, farmers cannot afford to ignore new technology. Researchers in Australia are developing an online virtual world program to share information about climate change and more sustainable farming techniques for sugar cane growers. As VOA's Zlatica Hoke reports, the idea is to create a wider support network for farmers.
Video

Video Airline Expert: Missile will Show Signature on Debris

The debris field from Malaysia Airlines Flight 17 is spread over a 21-kilometer radius in eastern Ukraine. It is expected to take investigators months to sort through the airplane pieces to learn about the missile that brought down the jetliner and who fired it. VOAs Carolyn Presutti explains how this work will be done.
Video

Video Treatment for Childhood Epilepsy Heats up Medical Marijuana Debate

In the United States, marijuana is classed as an illegal drug by the federal government. But nearly half the states have legalized it, to some degree. Proponents say some strains of marijuana might have exceptional health benefits, for treating pain or inflammation in chronic conditions such as cancer, multiple sclerosis and epilepsy. Shelley Schlender reports on a strain of medical marijuana developed in Colorado that is reputed to reduce seizures in childhood epilepsy
Video

Video Airbus Adds Metal 3D Printed Parts to New Jets

By the end of this year, European aircraft manufacturing consortium Airbus plans to deliver the first of its new, extra-wide-body passenger jets, the A350-XWB. Among other technological innovations, the new plane will also incorporate metal parts made in a 3-D printer. VOA's George Putic has more.
Video

Video AIDS Conference Welcomes Exciting Developments in HIV Treatment, Prevention

Significant strides have been made in recent years toward the treatment and prevention of HIV, the virus that causes AIDS. This year, at the International AIDS Conference, the AIDS community welcomed progress on a new pill that may prevent transmission of the deadly virus. VOA’s Anita Powell reports from Melbourne, Australia.
Video

Video IAEA: Iran Turns its Enriched Uranium Into Less Harmful Form

Iran has converted its stockpiles of enriched uranium into a less dangerous form that is more difficult to use for nuclear weapons, according to the United Nations’ Atomic Energy Agency. The move complies with an interim deal reached with Western powers on Iran's nuclear program last year, in exchange for easing of sanctions. Henry Ridgwell reports for VOA from London.

AppleAndroid