The boundaries of the Sahel are shifting. It appears the Sahara desert is expanding southward and infringing on the Sahel, and it's estimated that more than 80 percent of the land is affected by the shift [source: IRIN].
Just south of the Sahel region is the northernmost edge of Africa's tropical rainforests, as well as a rain belt that fluctuates naturally north and south with the seasons. Repositioning the rain belt farther north would bring rains and vegetation into the Sahel and the Sahara desert; move it south and the Sahel becomes a desert.
With the assistance of computer climate modeling, scientists hypothesize a relationship between the position of the rain belt and the change in ocean surface temperatures. They have observed that warmer ocean surface temperatures in the Southern Hemisphere -- and possibly global ocean surface temperatures -- cause a weaker convergence of air in Africa's Intertropical Convergence Zone. This results in fewer clouds and little-to-no-rain in the Sahel. It's still unclear to scientists whether the extreme weather patterns affecting the Sahel are caused by global warming or are rooted in natural climate fluctuations. Scientists hope the climatic history of the region may offer clues.
Previous to the ocean-temperature theory, human behaviors were blamed for the region's drought. Humans aren't off the hook, though. Overgrazing, overfarming, overpopulation and unsustainable uses of natural resources all contribute to the land degradation that, in turn, contributes to the drying of the Sahel. It's a vicious cycle: Vegetation may play a role in rainfall amounts, but without rainfall, there is no vegetation.
Overpopulation in the Sahel continues to be a problem and is estimated to double to 100 million people by 2020 and swell to 200 million by 2050 [source: IRIN]. The humanitarian implications of changes to the Sahel are devastating and include hunger, disease and hostility. The World Health Organization (WHO) predicts that outbreaks of dengue fever and cholera will rise along with the temperatures [source: IRIN]. Workers are migrating from the dried-up countryside into urban areas, overtaxing utilities and worsening crime levels.
The scarcity of food and natural resources such as water, grass for grazing and soil is heightening competition and demand. There is a profusion of small arms and weapons in the region and tensions are growing between ethnic groups, as well as between settled farmers and nomadic herders in Chad, Mali, Niger, Nigeria, Senegal and the Sudan. Niger, for example, is forcing out the Mahamid nomadic peoples. The violence in the Sudan is even more intense than that of Niger and has killed at least 200,000 people and led to more than 2 million refugees [source: National Geographic].
Solutions for inhibiting social, economic and political unrest and strategies for "greening" the Sahel are of great importance in re-establishing the region. Global agencies provide not only food and financial aid to the region, but also assistance for programs supporting education, conflict management and infrastructure projects such as the construction of schools.
Additionally, sustainable agricultural practices and soil and water conservation programs are key for rehabilitating the region's fragile ecosystem. Niger, for example, is lusher with vegetation than it was 20 years ago, yet no one can agree why. Increased rainfall? Maybe. But the rejuvenated vegetation could also be the result of people fleeing the countryside during conflict or even the small, sustainable steps local farmers have taken to safeguard their resources. Rather than clear-cutting fields for planting, farmers are preserving gao trees and saplings by plowing around them. These trees are nitrogen-fixers, meaning they're rich with the nutrient. They also hold soil in place and keep water in the ground, and the nitrogen creates more fertile soil as well.
Progress can grow beyond Niger. Through ongoing climate research, transformative land practices and aid programs, countries in the Sahel may not need to face a future of drought and instability.
Related HowStuffWorks Articles
More Great Links
- "AFRICA - Explore the regions - Sahel." Public Broadcasting Service (PBS). http://www.pbs.org/wnet/africa/explore/sahel/sahel_overview.html
- "Africa Environment Outlook: Past, present and future perspectives." United Nations Environment Programme(UNEP).http://www.unep.org/dewa/Africa/publications/AEO-1/056.htm
- "Conflict in the Africa Region." USAID. 2007. http://www.usaid.gov/our_work/cross-cutting_programs/conflict/support/afr.html
- "Growing deserts 'a global problem'." CNN. 2005. http://www.cnn.com/2005/WORLD/europe/06/17/desertification.report/index.html
- Held, I.M, T.L. Delworth. "Sahel Drought: Past Problems, An Uncertain Future." Geophysical Fluid Dynamics Laboratory, The National Oceanic and Atmospheric Administration. 2007. http://www.gfdl.noaa.gov/research/climate/highlights
- Held, I.M, T.L. Delworth, J. Lu, K.L. Findell, and T.R. Knutson. "Simulation of Sahel drought in the 20th and 21st centuries." Geophysical Fluid Dynamics Laboratory, National Oceanic and Atmospheric Administration, 2005. http://www.gfdl.noaa.gov/~ih/papers/sahel_pnas_pub.pdf
- Murcott, Toby. "Nature caused Sahel drought." BBC News. 1999. http://news.bbc.co.uk/1/hi/sci/tech/527040.stm
- "Oceans linked to Sahel drought." BBC News. 2003. http://news.bbc.co.uk/1/hi/sci/tech/3191174.stm
- Olsson, Lennart. "Greening of the Sahel." Encyclopedia of Earth. 2008. http://www.eoearth.org/article/Greening_of_the_Sahel
- "Pan Sahel Initiative (PSI)." GlobalSecurity.org. http://www.globalsecurity.org/military/ops/pan-sahel.htm
- Pearce, Fred. "A sea change in the Sahel: Climate researchers can now predict African drought in most years, but that doesn't mean they know why it is happening." New Scientist. 1991. http://www.newscientist.com/article/mg12917542.600-a-sea-change-in-the-sahel-climate-researchers-can-nowpredict-african-drought-in-most-years-but-that-doesnt-mean-they-know-whyit-is-happening-.html
- Polgreen, Lydia. "In Niger, Trees and Crops Turn Back the Desert." The New York Times. 2007. http://www.nytimes.com/2007/02/11/world/africa/11niger.html?_r=1&pagewanted=print&oref=slogin
- "SAHEL: Backgrounder on the Sahel, West Africa's poorest region." IRIN. UN Office for the Coordination of Humanitarian Affairs. 2008. http://www.irinnews.org/report.aspx?ReportId=78514
- Salopek, Paul. "Lost in the Sahel." National Geographic Magazine. 2008. http://ngm.nationalgeographic.com/2008/04/sahel/paul-salopek-text
- Spotts, Peter. "Sahel drought: new look at causes." The Christian Science Monitor. 2003. http://www.csmonitor.com/2003/1120/p21s01-sten.html
- "Wet or dry? Sahel's uncertain future." SciDev.net. 2008. http://www.scidev.net/en/features/wet-or-dry-sahels-uncertain-future.html
- Worldwide Guide to Movie Locations. http://www.movie-locations.com/
- Youth, Howard. "Saving the Sahel." Zoogoer. Smithsonian National Zoological Park. 2002. http://nationalzoo.si.edu/Publications/ZooGoer/2002/3/savingsahel.cfm