[QODLink]
Africa
'Mega-droughts' forecast for Africa
Arizona university scientists say climate change will aggravate droughts.
Last Modified: 18 Apr 2009 16:49 GMT
The study warned that dry periods will be more severe and more difficult for people in Africa [EPA]

Severe droughts could devastate sub-Saharan Africa following a recent decades-long drought that killed 100,000 people in Africa's Sahel region, scientists say.

Sub-Saharan Africa often suffers droughts, but the group of specialists reported on Thursday that global climate change will make these dry periods more severe and more difficult for the people who live there.

The prediction is contained in a study published in the journal of Science by the scientits at the University of Arizona, US.

"Clearly, much of West Africa is already on the edge of sustainability, and the situation could become much more dire in the future with increased global warming," said Jonathan Overpeck, a climatologist and co-author of the study.

Temperatures in the Sahel region are expected to rise by five to 10 degrees this century, the scientists said, despite some curbing of the greenhouse emissions that cause climate change.

"We might actually proceed into the future ... we could cross a threshold driving the [climate] system into one of those big droughts without even knowing it's coming," Overpeck said.

IN VIDEO

Struggle for survival for Kenya's cattle owners

More Videos...

The Sahel is an area between the Sahara desert and the wetter parts of equatorial Africa.

It stretches across the continent from the Atlantic Ocean in the west to the Red Sea in the east.

Overpeck and his colleagues studied sediments beneath Lake Bosumtwi in Ghana that gave an almost year-by-year record of droughts in the area going back 3,000 years.

Until now, the instrumental climate record in this region stretched back only 100 years or so.

The researchers found a pattern of decades-long droughts like the one that began in the Sahel in the 1960s, as well as as centuries-long "megadroughts" throughout this period, with the most recent lasting from 1400 to 1750.

Temperature fluctuations

The scientists also described signs of submerged forests that grew around the lake when it dried up for hundreds of years.

The tops of some of these tropical trees can still be seen poking up from the lake water.

"What's disconcerting about this record is that it suggests that the most recent drought was relatively minor..."

Timothy Shanahan of the University of Texas and co-author of the study

During the Sahel drought, the lake's water level dropped by almost 5m. By contrast, during megadroughts the level fell by as much as 30m.

"What's disconcerting about this record is that it suggests that the most recent drought was relatively minor in the context of the West African drought history," said Timothy Shanahan of the University of Texas, a co-author of the study.

The most recent decades of data culled from Lake Bosumtwi show that droughts there appear to be linked to fluctuations in sea surface temperatures, a pattern known as the Atlantic Multidecadal Oscillation, or AMO, the researchers said.

Overpeck said: "One of the scary aspects of our record is how the Atlantic ... changes the water balance over West Africa on multidecadal time scales."

The cause of centuries-long megadroughts is not known, but Overpeck said the added burden of climate change could make this kind of drought more devastating.

Source:
Agencies
Topics in this article
People
Featured on Al Jazeera
An innovative rehabilitation programme offers Danish fighters in Syria an escape route and help without prosecution.
Street tension between radical Muslims and Holland's hard right rises, as Islamic State anxiety grows.
Take an immersive look at the challenges facing the war-torn country as US troops begin their withdrawal.
Ministers and MPs caught on camera sleeping through important speeches have sparked criticism that they are not working.
Featured
More than 400 gaming dens operate on native lands, but critics say social ills and inequality stack the deck.
The Palestinian president is expected to address the UN with a new proposal for the creation of a Palestinian state.
Nearly 1,200 aboriginal females have been killed or disappeared over 30 years with little justice served, critics say.
Ethnic violence has wracked China's restive Xinjiang region, leading to a tight government clampdown.
Malay artists revitalise the art of puppeteering by fusing tradition with modern characters such as Darth Vader.