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

Egypt's Suez Canal Dreams Tempered by Continued Unrest

Seen as a potential driver of recovery, Cairo’s plan to expand waterway had been raising hopes to give country much needed economic boost More

Ebola Maternity Ward in Sierra Leone First of its Kind

Country already had one of world's highest maternal mortality rates before Ebola arrived, virus has added even more complications to health care More

Malaysia Flight 370 Disappearance Ruled Accident

Aircraft disappeared on March 8, 2014; with ruling, families of 239 passengers and crew can now seek compensation from airline 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.
Groundbreaking Hand-Painted Documentary About Van Gogh in Productioni
X
George Putic
January 29, 2015 9:43 PM
The troubled life of the famous 19th century Dutch painter Vincent van Gogh has been told through many books and films, but never in the way a group of filmmakers now intends to do. "Loving Vincent " will be the first ever feature-length film made of animated hand-painted images, done in the style of the late artist. VOA’s George Putic reports.
Video

Video Groundbreaking Hand-Painted Documentary About Van Gogh in Production

The troubled life of the famous 19th century Dutch painter Vincent van Gogh has been told through many books and films, but never in the way a group of filmmakers now intends to do. "Loving Vincent " will be the first ever feature-length film made of animated hand-painted images, done in the style of the late artist. VOA’s George Putic reports.
Video

Video Rock-Consuming Organisms Alter Views of Life Processes

Scientists thought they knew much about how life works, until a discovery more than two decades ago challenged conventional beliefs. Scientists found that there are organisms that breathe rocks. And it is only recently that the scientific community is accepting that there are organisms that could get energy out of rocks. Correspondent Elizabeth Lee reports.
Video

Video Paris Attacks Highlight Global Weapons Black Market

As law enforcement officials piece together how the Paris and Belgian terror cells carried out their recent attacks, questions are being asked about how they obtained military grade assault weapons - which are illegal in the European Union. As VOA's Jeff Swicord reports, experts say there is a very active worldwide black market for these weapons, and criminals and terrorists are buying.
Video

Video Activists Accuse China of Targeting Religious Freedom

The U.S.-based Chinese religious rights group ChinaAid says 2014 was the worst year for religious freedom in China since the end of the Cultural Revolution. As Ye Fan reports, activists say Beijing has been tightening religious controls ever since Chinese leader Xi Jinping came to office. Hu Wei narrates.
Video

Video Super Bowl Ads Compete for Eyes on TV, Web

Super Bowl Sunday (Feb. 1) is about more than just the NFL's American football championship and big parties to watch the game. Viewers also tune in for the world famous commercials that send Facebook and Twitter abuzz. Daniela Schrier reports on the social media rewards for America’s priciest advertising.
Video

Video Theologians Cast Doubt on Morality of Drone Strikes

In 2006, stirred by photos of U.S. soldiers mistreating Iraqi prisoners, a group of American faith leaders and academics launched the National Religious Campaign Against Torture. It played an important role in getting Congress to investigate, and the president to ban, torture. VOA's Jerome Socolovsky reports.
Video

Video Freedom on Decline Worldwide, Report Says

The state of global freedom declined for the ninth consecutive year in 2014, according to global watchdog Freedom House's annual report released Wednesday. VOA's William Gallo has more.
Video

Video MRI Seems to Help Diagnose Prostate Cancer, Preliminary Study Shows

Just as with mammography used to detect breast cancer, there's a lot of controversy about tests used to diagnose prostate cancer. Fortunately, a new study shows doctors may now have a more reliable way to diagnose prostate cancer for high risk patients. More from VOA's Carol Pearson.
Video

Video Smartphones About to Make Leap, Carry Basic Senses

Long-distance communication contains mostly sounds and pictures - for now. But scientists in Britain say they are close to creating additions for our smartphones that will make it possible to send taste, smell and even a basic touch. VOA’s George Putic reports.
Video

Video Former Sudan 'Lost Boy' Becomes Chess Master in NYC

In the mid-1980’s, thousands of Sudanese boys escaped the country's civil war by walking for weeks, then months and finally for more than a year, up to 1,500 kilometers across three countries. The so-called Lost Boys of the Sudan had little time for games. But one of them later mastered the game of chess, and now teaches it to children in the New York area. VOA’s Bernard Shusman in New York has his story.
Video

Video NASA Monitors Earth’s Vital Signs From Space

The U.S. space agency, NASA, is wrapping up its busiest 12-month period in more than a decade, with three missions launched in 2014 and two this month, one in early January and the fifth scheduled for January 29. As VOA’s Rosanne Skirble reports, the instruments being lifted into orbit are focused on Earth’s vital life support systems and how they are responding to a warmer planet.
Video

Video Crowded Republican Presidential Field Off to Early Start for 2016

It seems early, but the 2016 U.S. presidential election campaign is already heating up. Though no one has officially announced a candidacy, several potential Republican contenders have been busy speaking to conservative groups about making a White House run next year. Many of the possible contenders are critical of the Obama administration’s foreign policy record. VOA national correspondent Jim Malone reports.

Circumventing Censorship

An Internet Primer for Healthy Web Habits

As surveillance and censoring technologies advance, so, too, do new tools for your computer or mobile device that help protect your privacy and break through Internet censorship.
More

All About America

AppleAndroid