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
x
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 Falling Gas Prices Impact US Oil Extraction

With the price of oil now less than $80 a barrel, motorists throughout the US are seeing gas prices dip below $3 a gallon More

Afghan Women's Soccer Team Building for the Future

A four-team female league was recently set up in Kabul; It will help identify players for the national team More

Video Tensions Build on Korean Peninsula Amid Military Drills

Pyongyang threatens nuclear test as joint US, S. Korean exercises show forces’ capabilities 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.
New Skateboard Defies Gravityi
X
November 21, 2014 5:07 AM
A futuristic dream only a couple of decades ago, the hoverboard – a skateboard that floats above the ground - has finally been made possible. While still not ready for mass production, it promises to become a cool mode of transport... at least over some surfaces. VOA’s George Putic reports.
Video

Video New Skateboard Defies Gravity

A futuristic dream only a couple of decades ago, the hoverboard – a skateboard that floats above the ground - has finally been made possible. While still not ready for mass production, it promises to become a cool mode of transport... at least over some surfaces. VOA’s George Putic reports.
Video

Video Falling Gas Prices Impact US Oil Extraction

With the price of oil now less than $80 a barrel, motorists throughout the United States are benefiting from gas prices below $3 a gallon. But as VOA’s Kane Farabaugh reports, the decreasing price of petroleum has a downside for the hydraulic fracturing industry in the United States.
Video

Video Tensions Build on Korean Peninsula Amid Military Drills

It has been another tense week on the Korean peninsula as Pyongyang threatened to again test nuclear weapons while the U.S. and South Korean forces held joint military exercises in a show of force. VOA’s Brian Padden reports from the Kunsan Air Base in South Korea.
Video

Video Mama Sarah Obama Honored at UN Women’s Entrepreneurship Day

President Barack Obama's step-grandmother is in the United States to raise money to build a $12 million school and hospital center in Kogelo, Kenya, the birthplace of the president's father, Barack Obama, Sr. She was honored for her decades of work to aid poor Kenyans at a Women's Entrepreneurship Day at the United Nations.
Video

Video Gay Evangelicals Argue That Bible Does Not Condemn Homosexuality

More than 30 U.S. states now recognize same-sex marriages, and an increasing number of mainline American churches are blessing them. But evangelical church members- which account for around 30 percent of the U.S. adult population - believe the Bible unequivocally condemns homosexuality. VOA's Jerome Socolovsky reports that gay, lesbian, bisexual and transgender evangelicals are coming out. Backed by a prominent evangelical scholar, they argue that the traditional reading of the bible is wrong.
Video

Video Ebola Economic Toll Stirs W. Africa Food Security Concerns

The World Bank said Wednesday that it expects the economic impact of the Ebola outbreak on the sub-Saharan economy to cost somewhere betweenf $3 billion to $4 billion - well below a previously-outlined worst-case scenario of $32 billion. Some economists, however, paint a gloomier picture - warning that the disruption to regional markets and trading is considerable. Henry Ridgwell reports from London.
Video

Video Mexico Protests Escalate Over Disappearances

Protests in Mexico over 43 students missing since September continue to escalate, reflecting growing anger among Mexicans about a political system they view as corrupt, and increasingly tainted by the drug trade. Mounting outrage over the disappearances is now focused on the government of President Enrique Pena Nieto, accused of not doing enough to end insecurity in the country. More from VOA's Victoria Macchi.
Video

Video US Senate Votes Down Controversial Oil Pipeline - For Now

The U.S. Senate has rejected construction of a controversial pipeline to transport Canadian oil to American refineries. The $5 billion project still could be approved next year, but it faces a possible veto by President Barack Obama. As VOA’s Michael Bowman reports, the pipeline has exposed deep divisions in Congress about America’s energy future.
Video

Video Can Minsk Cease-fire Agreement Hold?

Growing tensions between government troops and separatists in eastern Ukraine further threaten a cease-fire agreement reached two months ago in the Belarusian capital of Minsk. Critics of U.S. policy in Ukraine say it is time the Obama administration gives up on that much-violated cease-fire and moves toward a new deal with Russia. VOA's Scott Stearns has more.
Video

Video Chaos, Abuse Defy Solution in Libya

The political and security crisis in Libya is deepening, with competing governments and, according to Amnesty International, widespread human rights violations committed with impunity. VOA’s Al Pessin reports from London.
Video

Video US Hosts Record 866,000 Foreign Students

Close to 900,000 international students are studying at American universities and colleges, more than ever before. About half of them come from Asia, mostly China. The United States hosts more foreign students than any other country in the world, and its foreign student population is steadily growing. Zlatica Hoke reports.
Video

Video Ferguson Church Grapples with Race Relations

Many white residents of Ferguson, Missouri, say they chose to live there because of the American Midwest community's diversity. So, they were shocked when a white police officer killed an unarmed black teenager in August – and shaken by the resulting protests and violence. Some local churches are leading conversations on how to go forward. VOA’s Ayesha Tanzeem reports.

All About America

AppleAndroid