News / Science & Technology

Africa Kicks-up A Lot of Dust

NASA satellite captures image of giant dust cloud from Western Sahara on Sept. 14, 2013. Winds carry the dust to the United States, South America and the Caribbean. Credit: NASA
NASA satellite captures image of giant dust cloud from Western Sahara on Sept. 14, 2013. Winds carry the dust to the United States, South America and the Caribbean. Credit: NASA

Multimedia

Audio
Joe DeCapua
Bits and pieces of the African continent are falling on the United States and surrounding regions much of the year. Scientists say large amounts of African dust may be having major effects on the hurricane season, ocean organisms and human health.


African dust particles become airborne during storms and travel anywhere from 7,000 to 10,000 kilometers to reach the U.S.  Scientists can now distinguish between domestic dust particles and those from Africa.

Joseph Prospero studies dust. He’s professor emeritus at the University of Miami Rosenstiel School of Marine and Atmospheric Sciences. Prospero said dust is important for a number of reasons, including its effect on climate.

“The very fact that you can see dust in the atmosphere means that the dust is interacting with solar radiation, scatters and absorbs solar radiation. So, anything that affects the distribution of solar radiation on the Earth’s surface – whether it’s at the surface itself or in the atmosphere – will affect climate,” he said.

Dust will also reduce the amount of sunlight reaching the ocean. That’s a big deal, especially for those who live in the usual paths of hurricanes.

“The surface oceans will be somewhat cooler than they would be in the absence of dust. This is something of considerable interest because this region of the Atlantic is where we see tropical cyclones and hurricanes develop. And the fact that we have so much dust means you have cooler sea surface temperatures and the cooler sear surface temperatures mean less water vapor getting into the atmosphere. And water vapor is an essential component that drives tropical cyclones and hurricanes,” he said.

So, that’s a benefit of African dust for those who fear their houses will be damaged by such storms.

Prospero said, “Until recently – the last few weeks – this year has been unusually dusty and we’ve had remarkably few tropical cyclones and hurricanes.

Dust also affects climate by depositing in the ocean.

“Dust carries with it a lot of elements and one that’s [of] particular interest is iron, which in many regions, ocean regions, is a limiting nutrient. Phytoplankton – marine organisms – need iron in order to photosynthesize. It’s an essential micronutrient. Therefore, if there’s not enough iron, then you have less biological activity, which, of course, affects the carbon cycle. Anything that affects the carbon cycle will affect climate by modulating the amount of CO2 in the atmosphere,” he said.

Now, lest you think that African dust only has benefits, think again. It also ends up in people’s lungs – a problem for those with asthma, for example.

“[In] one of our studies we’ve shown that in the Caribbean region the concentrations of dust are so high that they often exceed the World Health Organization’s 24 hour standard for the concentration of particles,” said Prospero.

Recently, average concentrations of dust particles that could be inhaled more than doubled over Houston, Texas – all due to a major Saharan dust intrusion.

“With satellites we can see that that dust cloud extended from Central America – it was against the mountains of Central America – across all of Texas and up into northern Oklahoma. The satellite images lost the dust in a large area of cloud,” he said.

Prospero said there was a time when scientists did not pay much attention to atmospheric dust. That’s changed.

“When I first started this work in the mid-late 1960s, no one cared about dust and there were very few publications. And now, it’s phenomenal. Every year, there are literally hundreds and hundreds of publications about dust. I mean not only African dust, I mean there’s Asian dust. The other huge area of dust activity is in Asia.  Dust is ubiquitous and there hasn’t been much attention paid to it.”

Prospero -- and colleagues at the University of Houston and the Arizona State University -- published their findings in the journal of Environmental Science and Technology. But there’s much they don’t know because the interaction of dust with the atmosphere is very complex and not well understood.

For example, North Africa is expected to get drier and produce more dust. But computer models don’t agree on what that means in the long-term for climate and human health.

In case you’re wondering, Africa is not expected to blow away. Prospero says it’ll just keep producing more and more dust.

You May Like

Lesotho Faces New Round of Violence, Political Crisis

Brutal killing of military officer has sent former leaders back into S. Africa where they're watching anxiously as regional officials head in to try to restore peace More

Video US Diplomat Expects Adoption of Bosnian Massacre Anniversary Resolution

Samantha Power says there's broad consensus about killings in Bosnia's war, but Russia calls resolution 'divisive,' backs UN countermeasure More

UN Report Exposes Widespread Boko Haram Atrocities

Damning report graphically details pattern of vicious, widespread atrocities committed by Islamist militants More

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Olympics Construction Scars Sacred Korean Mountaini
X
July 02, 2015 4:10 AM
Environmentalists in South Korea are protesting a Winter Olympics construction project to build a ski slope through a 500-year-old protected forest. Brian Padden reports that although there is strong national support for hosting the 2018 Pyeongchang Winter Olympics, there are growing public concerns over the costs and possible ecological damage at the revered mountain.
Video

Video Olympics Construction Scars Sacred Korean Mountain

Environmentalists in South Korea are protesting a Winter Olympics construction project to build a ski slope through a 500-year-old protected forest. Brian Padden reports that although there is strong national support for hosting the 2018 Pyeongchang Winter Olympics, there are growing public concerns over the costs and possible ecological damage at the revered mountain.
Video

Video Xenophobia Victims in South Africa Flee Violence, Then Return

Many Malawians fled South Africa early this year after xenophobic attacks on African immigrants. But many quickly found life was no better at home and have returned to South Africa – often illegally and without jobs, and facing the tough task of having to start over. Lameck Masina and Anita Powell file from Johannesburg.
Video

Video Family of American Marine Calls for Release From Iranian Prison

As the crowd of journalists covering the Iran talks swells, so too do the opportunities for media coverage.  Hoping to catch the attention of high-level diplomats, the family of American-Iranian marine Amir Hekmati is in Vienna, pleading for his release from an Iranian prison after nearly 4 years.  VOA’s Heather Murdock reports from Vienna.
Video

Video UK Holds Terror Drill as MPs Mull Tunisia Response

After pledging a tough response to last Friday’s terror attack in Tunisia, which came just days before the 10th anniversary of the bomb attacks on London’s transport network, British security services are shifting their focus to overseas counter-terror operations. VOA's Henry Ridgwell has more.
Video

Video Obama on Cuba: This is What Change Looks Like

President Barack Obama says the United States will soon reopen its embassy in Cuba for the first time since 1961, ending a half-century of isolation. VOA White House correspondent Luis Ramirez reports.
Video

Video Hate Groups Spread Influence Via Internet

Hate groups of various kinds are using the Internet for propaganda and recruitment, and a Jewish human rights organization that monitors these groups, the Simon Wiesenthal Center, says their influence is growing. The messages are different, but the calls to hatred or violence are similar. VOA's Mike O’Sullivan reports.
Video

Video US Silica Sand Mining Surge Worries Illinois Residents, Businesses

Increased domestic U.S. oil and gas production, thanks to advances known as “fracking,” has created a boom for other industries supporting that extraction. Demand for silica sand, used in fracking, could triple over the next five years. In the Midwest state of Illinois, people living near the mines are worried about how increased silica sand mining will affect their businesses and their health. VOA’s Kane Farabaugh has more in this first of a series of reports.
Video

Video Blind Somali Journalist Defies Odds in Mogadishu

Despite improving security in the last few years, Somalia remains one of the most dangerous countries to be a journalist – even more so for someone who cannot see. Abdulaziz Billow has the story of journalist Abdifatah Hassan Kalgacal, who has been reporting from the Somali capital for the last decade despite being blind.
Video

Video Texas Defies Same-Sex Marriage Ruling

Texas state officials have criticized the US Supreme Court decision giving same-sex couples the right to marry nationwide. The attorney general of Texas says last week's decision did not overrule constitutional "rights of religious liberty," and therefore officials performing wedding services can refuse to perform them for same-sex couples if it is against their religious beliefs. Zlatica Hoke reports on the controversy.
Video

Video Rabbi Hits Road to Heal Jewish-Muslim Relations in France

France is on high alert after last week's terrorist attack near the city Lyon, just six months after deadly Paris shootings. The attack have added new tensions to relations between French Jews and Muslims. France’s Jewish and Muslim communities also share a common heritage, though, and as far as one French rabbi is concerned, they are destined to be friends. From the Paris suburb of La Courneuve, Lisa Bryant reports about Rabbi Michel Serfaty and his friendship bus.
Video

Video Saudi Leaks Expose ‘Checkbook Diplomacy’ In Battle With Iran

Saudi Arabia’s willingness to wield its oil money on the global diplomatic stage appears to have been laid bare, after the website WikiLeaks published tens of thousands of leaked cables from Riyadh’s Ministry of Foreign Affairs. VOA's Henry Ridgwell reports.
Video

Video In Kenya, Police Said to Shoot First, Ask Questions Later

An organization that documents torture and extrajudicial killings says Kenyan police were responsible for 1,252 shooting deaths in five cities, including Nairobi, between 2009 and 2014, representing 67 percent of all gun deaths in the areas reviewed. Gabe Joselow has more from Nairobi.

VOA Blogs