News / Science & Technology

Study: Pollution Led to African Drought

FILE - Through the 1980s, rainfall in the African Sahel declined more than anywhere else in the world, causing increased aridity, as evidenced by this dust storm in Senegal.
FILE - Through the 1980s, rainfall in the African Sahel declined more than anywhere else in the world, causing increased aridity, as evidenced by this dust storm in Senegal.

Related Articles

Unapproved US Wheat Sparks Trade Concerns

Some countries are suspending imports of U.S. wheat after unapproved genetically modified variety turns up in in northwestern state of Oregon

Video South Sudan Hopes New Mining Law Will Unearth Treasures

New nation seeks to attract foreign companies to eastern region to uncover natural resources that could transition country off its oil dependency

Ethiopia: Halting Dam's Construction Unthinkable

Tensions between Egypt, Ethiopia rising after Ethiopia began diverting water of a Nile River tributary to build continent’s biggest hydroelectric power plant
Decades of drought in central Africa may have had a surprising cause, according to new research that challenges the notion that the severe dry weather was triggered mainly by bad agricultural practices and overgrazing.

The research, done at the University of Washington, shows that the drought was at least partially caused by pollution in the Northern Hemisphere.

The researchers said that sulfate-laden aerosols coming from coal-burning factories from the 1960s through the 1980s actually slowed warming in the Northern Hemisphere compared to the Southern Hemisphere. This shifted tropical rain bands south, away from the Sahel region, and led ultimately to the near drying up of Lake Chad, which is used to water crops in surrounding areas.

Africa's Sahel regionAfrica's Sahel region
Africa's Sahel region
Africa's Sahel region
“We think people should know that these particles not only pollute air locally, but they also have these remote climate effects,” said the study’s lead author, Yen-Ting Hwang, a University of Washington doctoral student in atmospheric sciences.

Hwang’s co-author, Dargan Frierson, an associate professor of atmospheric sciences at the University of Washington, said “to some extent, science messed this one up the first time around.”

“People thought that a large part of that drought was due to bad farming practices and desertification,” he said. “But over the last 20 years or so we’ve realized that that was quite wrong, and that large-scale ocean and atmosphere patterns are significantly more powerful in terms of shaping where the rains fall.”

Researchers also studied rainfall in other places on the northern edge of the tropical rain band such as northern India and South America. These areas also experienced less rainfall during the 1970s and 1980s. Meanwhile, areas on the southern edge of the tropical rain band, such as northeast Brazil and the African Great Lakes, saw an increase in rainfall.

The researchers also looked at 26 climate models used by the Intergovernmental Panel on Climate Change, and found that nearly all the models showed some southward shift in rainfall and that slowed warming in the Northern Hemisphere was the “primary cause.”

“One of our research strategies is to zoom out,” said Hwang. “Instead of studying rainfall at a particular place, we try to look for the larger-scale patterns.”

There was a silver lining found in the research.

The study showed that steps taken in the United States and Europe in the 1960s and 1970s to reduce emissions and improve air quality began to improve the situation in the Sahel. While the area still suffers short-term droughts, “the long-term drought began to recover in the 1980s” as the rains began to move north again, according to the research.

“We were able to do something that was good for us, and it also benefited people elsewhere,” Frierson said.

It’s a trend that Hwang says is likely to continue.

As the atmosphere gathers higher levels of greenhouse gases, however, Hwang said the Northern Hemisphere will warm more rapidly than the Southern Hemisphere because there is more land.

“It’s not yet crystal clear what will happen,” she said. “There will be some shift in the tropical rains, and most models predict a northern shift.”

You May Like

Video Russia’s Syrian Escalation Tests Obama’s Crisis Response

Critics once again question whether president has been slow to act on Syrian conflict, thus creating opening for powers like Russia More

Ancient African DNA Shows Mass Migration Back Into Africa

First genetic analysis of ancient human remains in Africa suggests massive migration from north around time of Egyptian empire More

NASA: Pluto Has Blue Sky

New photos also reveal the presence of water ice More

This forum has been closed.
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.
Hungary Criticized for Handling of Refugeesi
Henry Ridgwell
October 08, 2015 8:02 PM
Amnesty International has accused Hungary of breaking multiple international and European human rights laws in its handling of the refugee crisis. As Henry Ridgwell reports, thousands of migrants and refugees continue to travel through the Balkans to Hungary every day.

Video Hungary Criticized for Handling of Refugees

Amnesty International has accused Hungary of breaking multiple international and European human rights laws in its handling of the refugee crisis. As Henry Ridgwell reports, thousands of migrants and refugees continue to travel through the Balkans to Hungary every day.

Video Iraqi-Kurdish Teachers Vow to Continue Protest

Sixteen people were injured when police used tear gas and rubber bullets to disperse teachers and other public employees who took to the streets in Iraq’s Kurdish north, demanding their salaries from the Kurdish Regional Government (KRG). VOA’s Dilshad Anwar, in Sulaimaniya, caught up with protesting teachers who say they have not been paid for three months. Parke Brewer narrates his report.

Video Syrian Village Community Faces Double Displacement in Lebanon

Driven by war from their village in southwestern Syria, a group of families found shelter in Lebanon, resettling en masse in a half-built university to form one of the biggest settlements of its kind in Lebanon. Three years later, however, they now face being kicked out and dispersed in a country where finding shelter as a refugee can be especially tough. John Owens has more for VOA from the city of Saida, also known as Sidon.

Video Bat Colony: Unusual Tourist Attraction in Texas

The action hero Batman might be everyone’s favorite but real bats hardly get that kind of adoration. Put more than a million of these creatures of the night together and it only evokes images of horror. Sarah Zaman visited the largest urban bat colony in North America to see just how well bat and human get along with each other.

Video Device Shows Promise of Stopping Motion Sickness

It’s a sickening feeling — the dizziness, nausea and vomiting that comes with motion sickness. But a device now being developed could stop motion sickness by suppressing certain signals in the brain. VOA’s Deborah Block reports.

Video Making a Mint

While apples, corn, and cranberries top the list of fall produce in the US, it’s also the time to harvest gum, candy, and toothpaste—or at least the oil that makes them minty fresh. Erika Celeste reports from South Bend, Indiana on the mint harvest.

Video Activists Decry Lagos Slum Demolition

Acting on a court order, authorities in Nigeria demolished a slum last month in the commercial capital, Lagos. But human rights activists say the order was illegal, and the community was razed to make way for a government housing project. Chris Stein has more from Lagos.

Video TPP Agreed, But Faces Stiff Opposition

President Barack Obama promoted the Trans-Pacific Partnership on Tuesday, one day after 12 Pacific Rim nations reached the free trade deal in Atlanta. The controversial pact that would involve about 40 percent of global trade still needs approval by lawmakers in respective countries. Zlatica Hoke reports Obama is facing strong opposition to the deal, including from members of his own party.

Video Ukranian Artist Portrays Putin in an Unusual Way

As Russian President Vladimir Putin was addressing the United Nations in New York last month, he was also being featured in an art exhibition in Washington. It’s not a flattering exhibit. It’s done by a Ukrainian artist in a unique medium. And its creator says it’s not only a work of art - it’s a political statement. VOA’s Tetiana Kharchenko has more.

Video Nano-tech Filter Cleans Dirty Water

Access to clean water is a problem for hundreds of millions of people around the world. Now, a scientist and chemical engineer in Tanzania (in East Africa) is working to change that by creating an innovative water filter that makes dirty water safe. VOA’s Deborah Block has the story.

Video Demand Rising for Organic Produce in Cambodia

In Cambodia, where rice has long been the main cash crop, farmers are being encouraged to turn to vegetables to satisfy the growing demand for locally produced organic farm products. Daniel de Carteret has more from Phnom Penh.

Video Botanists Grow Furniture, with Pruning Shears

For something a bit out of the ordinary to furnish your home, why not consider wooden chairs, crafted by nature, with a little help from some British botanists with an eye for design. VOA’s Jessica Berman reports.

VOA Blogs