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

Obama: Alaskans Feel Signs of Climate Change

They're seeing bigger storm surges as sea ice melts, more wildfires, erosion of glaciers, shorelines More

1855 Slave Brochure Starkly Details Sale of Black Americans

Document lists entire families that were up for sale in New Orleans, offering graphic insight into the slavery trade More

Katrina Brought Enduring Changes to New Orleans

The city’s recovery is the result of the people and culture the city is famous for, as well as newcomers and start-up industries More

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Colombians Flee Venezuela as Border Crisis Escalatesi
X
August 27, 2015 2:08 AM
Hundreds of Colombians have fled Venezuela since last week, amid an escalating border crisis between the two countries. Last week, Venezuelan President Nicolas Maduro ordered the closure of a key border crossing after smugglers injured three Venezuelan soldiers and a civilian. The president also ordered the deportation of Colombians who are in Venezuela illegally. Zlatica Hoke reports.
Video

Video Colombians Flee Venezuela as Border Crisis Escalates

Hundreds of Colombians have fled Venezuela since last week, amid an escalating border crisis between the two countries. Last week, Venezuelan President Nicolas Maduro ordered the closure of a key border crossing after smugglers injured three Venezuelan soldiers and a civilian. The president also ordered the deportation of Colombians who are in Venezuela illegally. Zlatica Hoke reports.
Video

Video Is China's Economic Data Accurate?

Some investors say China's wild stock market gyrations have been made worse by worries about the reliability of that nation's economic data. And some critics say the reports can mislead investors by painting an unrealistically-strong picture of the economy. A key China scholar says Beijing is not fudging ((manipulating)) the numbers, but that the economy is evolving quickly from smoke-stack industries to services, and the ways of tracking new economic activity are falling behind the change. V
Video

Video Next to Iran, Climate at Forefront of Obama Agenda

President Barack Obama this week announced new initiatives aimed at making it easier for Americans to access renewable energy sources such as solar and wind. Obama is not slowing down when it comes to pushing through climate change measures, an issue he says is the greatest threat to the country’s national security. VOA correspondent Aru Pande has more from the White House.
Video

Video Shipping Containers Provide Experimental Housing

Housing prices around the San Francisco Bay area are out of reach for many people, so some young entrepreneurs, artists and tech industry workers are creating their own houses using converted shipping containers. But as VOA's Mike O’Sullivan reports from Oakland, the effort requires ingenuity and dealing with restrictive local laws.
Video

Video Arctic Draws International Competition for Oil

A new geopolitical “Great Game” is underway in earth’s northernmost region, the Arctic, where Russia has claimed a large area for resource development and President Barack Obama recently approved Shell Oil Company’s test-drilling project in an area under U.S. control. Greg Flakus reports.
Video

Video Philippine Maritime Police: Chinese Fishermen a Threat to Country’s Security

China and the Philippines both claim maritime rights in the South China Sea.  That includes the right to fish in those waters. Jason Strother reports on how the Philippines is catching Chinese nationals it says are illegal poachers. He has the story from Palawan province.
Video

Video Technique May Eliminate Drill-and-Fill Dental Care

Many people dread visiting dentists because they're afraid of drills. Now, however, a technology developed by a British firm promises to eliminate the need for mechanical cleaning of dental cavities by speeding a natural process of tooth repair. VOA’s George Putic reports.
Video

Video China's Spratly Island Building Said to Light Up the Night 'Like A City'

Southeast Asian countries claim China has illegally seized territory in the Spratly islands. It is especially a concern for a Philippine mayor who says Beijing is occupying parts of his municipality. Jason Strother reports from the capital of Palawan province, Puerto Princesa.
Video

Video Ages-old Ice Reveals Secrets of Climate Change

Ice caps don't just exist at the world's poles. There are also tropical ice caps, and the largest sits atop the Peruvian Andes - but it is melting, quickly, and may be gone within the next 20 years. George Putic reports scientists are now rushing to take samples to get at the valuable information about climate change locked in the ice.
Video

Video French Experiment in Integrating Roma Under Threat

Plans to destroy France’s oldest slum have sparked an outcry on the part of its Roma residents. As Lisa Bryant reports from the Paris suburb of La Courneuve, rights groups argue the community is a fledgling experiment on integrating Roma who are often outcasts in many parts of Europe.
Video

Video Kenyans Turn to Agriculture for Business

Each year Kenyan universities continue to churn out graduates for the job market despite the already existing high rate of unemployment among youth in the country. Some of these young men and women have realized that agriculture can be as rewarding as any other business or job, and they are resorting to agribusiness in large numbers as a way of tackling unemployment. Rael Ombuor reports for VOA.
Video

Video First Women Graduate Elite Army Ranger School

Two women are making history for the U.S. Army by proving they are among the toughest of the tough. VOA's Carla Babb reports from Fort Benning, Georgia as 94 men and those two women rise as graduates of the difficult Ranger school.

VOA Blogs