News / Africa

Did Early Man Contribute to Central Africa Climate Change?

The Dzanga-Ndoki National Park and Dzanga-Sangha dense forest special reserve are located in the rainforest in the south-western part of the Central African Republic, Congo Basin. They comprise a total area of more than 4 000 km2 (more than 400 000 hectar
The Dzanga-Ndoki National Park and Dzanga-Sangha dense forest special reserve are located in the rainforest in the south-western part of the Central African Republic, Congo Basin. They comprise a total area of more than 4 000 km2 (more than 400 000 hectar
Joe DeCapua

If humans are responsible for speeding the climate change currently underway, it may not be the first time. Scientists say a long time ago in Central Africa, early farmers may have contributed to the disappearance of rainforests. The question is being raised in the journal Science.

Scientists say about 3,000 years ago some of the rainforests were “abruptly replaced” by savannas – broad grasslands dotted with shrubs and trees. It was thought that climate change was the reason. But now research suggests that climate change alone could not be responsible for the sudden shift -- that perhaps people played a part.

Dr. Germain Bayon, who works for a French research institute, said much less is known about the agricultural history of Africa than either Europe or Asia.

“The onset of agriculture had already an impact on the environment, whereas in Africa, I guess because there have been (a lot fewer ) studies done, the link was not very clear,” he said.

Telltale mud

Bayon and his colleagues have been studying sediment at the mouth of the Congo River.

“Basically, we analyzed the sediment core, which was recovered off the Congo River. Sediments have been accumulating at this site… which provide an integrated record of the particles, which have been discharged by the Congo River through time,” he said.

The sediment tells the story of the Congo Basin climate.

“The climate in Central Africa was much more humid between about 10,000 years ago and 5,000 years ago. And then the climate started to deteriorate. So, it’s only after about 4,000 years ago that the climate started to become dryer and of course the vegetation responded to this climate change,” said Bayon.

That’s when the savannahs started to appear. But Bayon said there may be other major contributing factors, such as erosion and the chemical weathering of soil.

“So, basically, the more it rains in Africa, the more the soils were being eroded. And what we showed is that from 3,000 years ago the weathering erosion signal became completely decoupled from the climatic signal. And this we think is a sign that this event was not only triggered by a change in the climate. And we need to take something else into account,” he said.

Migration of the Bantu

Enter the Bantu people from what is now the border area between Nigeria and Cameroon. Bayon said they brought farming and iron smelting to the Congo Basin. Evidence shows one of the main crops was pearl millet. And that in itself says a lot about the climate.

“Pearl millet to be cultivated actually doesn’t like the warm climate, humid climate. It requires alternating between a dry season and a wet season. It shows that the key factor for introducing agriculture into the rainforest was the establishment of this more pronounced seasonality. This alternates between wet and dry seasons,” he said.

To grow pearl millet and other crops, the Bantu needed open fields. That meant clearing large areas of rainforest. That in turn exposed the land to erosion and resulted in the telltale sediment at the mouth of the Congo River. So, it’s possible, said Bayon, the farmers along with climate change helped the rainforests to disappear.

The period lasted between 1,000 and 1500 years. Then things started to change again. The rainforests began to return. About the same time, the Bantu left for other parts of Africa. The question is: did the Bantu leave because the rainforests started to regrow or did the rainforests regrow because the Bantu left and took their farming with them?

“This, I must admit,” said Bayon, “is something which is a bit puzzling and which is not well known at present, I think.”

Bayon said, however, what the evidence does show is that even 3,000 years ago humans could have a major impact on the environment. It’s now known that agriculture contributes to carbon emissions and that trees help trap that carbon and keep it from the atmosphere. During the Bantu’s stay in Central Africa, there was more agriculture and fewer trees.

You May Like

Lebanese Media Unite to Support Palestinians in Gaza

Joint newscast billed as Arab world’s first unified news bulletin in support of Hamas-controlled Gaza Strip More

Photogallery Australian PM Alleges ‘Coverup’ at MH17 Crash Site

Meanwhile, Russia's ambassador to Malaysia denies plane's black boxes were opened before they were handed over to Malaysian officials More

Despite Advances in AIDS Treatment, Stigma Lingers

Leading immunologist tells VOA that stigma is often what prevents those infected with disease from seeking treatment 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.
IAEA: Iran Turns its Enriched Uranium Into Less Harmful Formi
X
July 22, 2014 10:26 AM
Iran has converted its stockpiles of enriched uranium into a less dangerous form that is more difficult to use for nuclear weapons, according to the United Nations’ Atomic Energy Agency. The move complies with an interim deal reached with Western powers on Iran's nuclear program last year, in exchange for easing of sanctions. Henry Ridgwell reports for VOA from London.
Video

Video IAEA: Iran Turns its Enriched Uranium Into Less Harmful Form

Iran has converted its stockpiles of enriched uranium into a less dangerous form that is more difficult to use for nuclear weapons, according to the United Nations’ Atomic Energy Agency. The move complies with an interim deal reached with Western powers on Iran's nuclear program last year, in exchange for easing of sanctions. Henry Ridgwell reports for VOA from London.
Video

Video Relic of Saint Draws Catholics Worried About Immigration Issue

A Roman Catholic saint who is a figure of devotion for those crossing the border into the United States is attracting believers concerned about the plight of undocumented immigrants. Mike O'Sullivan reports from Los Angeles, where a relic of Saint Toribio has drawn thousands to local churches.
Video

Video Ukraine Rebels Surrender MH17 Black Boxes

After days of negotiations, a senior separatist leader handed over two black boxes from an airliner downed over eastern Ukraine to Malaysian experts early Tuesday. While on Monday, the U.N. Security Council unanimously demanded that armed groups controlling the crash site allow safe and unrestricted access to the wreckage.
Video

Video In Cambodia, HIV Diagnosis Brings Deadly Shame

Although HIV/AIDS is now a treatable condition, a positive diagnosis is still a life altering experience. In Cambodia, people living with HIV are often disowned by friends, family and the community. This humiliation can be unbearable. We bring you one Cambodian woman’s struggle to overcome a life tragedy and her own HIV positive diagnosis.
Video

Video Nature of Space Exploration Enters New Age

Forty-five years ago this month, the first humans walked on the moon. It was during an era of the space race between the United States and the Soviet Union. World politics have changed since then and -- as Elizabeth Lee reports -- so has the nature of space exploration.
Video

Video Chicago’s Argonne Lab Developing Battery of the Future

In 2012, the U.S. Department of Energy’s Office of Science awarded a $120 million grant to a new technology center focused on battery development - headquartered at Argonne National Laboratory in suburban Chicago, Illinois. As VOA’s Kane Farabaugh reports, there scientists are making the next technological breakthroughs in energy storage.
Video

Video In NW Pakistan, Army Offensive Causes Massive Number of Displaced

Pakistan’s army offensive in North Waziristan has resulted in the large-scale displacement of the local population. VOA's Ayaz Gul reports from northwest Pakistan where authorities say around 80 percent of the estimated 1 million internally displaced persons [IDPs] have settled in Bannu district, while much of the remaining 20 percent are scattered in nearby cities.
Video

Video Kurdish Peshmerga Force Secures Kirkuk, Its Oil

The Kurdistan regional government has sent its Peshmerga troops into the adjacent province of Kirkuk to drive out insurgents, and to secure the area's rich oil fields. By doing this, the regional government has added a fourth province to the three it officially controls. The oil also provides revenue that could make an independent Kurdistan economically strong. VOA’s Jeffrey Young went out with the Peshmerga and filed this report.
Video

Video Malaysia Reeling: Second Air Disaster in Four Months

Malaysia is reeling from the second air disaster in four months involving the country’s flag carrier. Flight 340 vanished in March and despite an extensive search, no debris has been found. And on Thursday, Flight 17, likely hit by a surface-to-air missile, came apart over eastern Ukraine. The two incidents together have left more than 500 people dead. VOA Correspondent Steve Herman reports from Kuala Lumpur.

AppleAndroid