Africa Heats Up -- climate change threatens future of the continent

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Africa Heats Up -- climate change threatens future of the continent
Tina Butler, mongabay.com
October 11, 2005

Baobabs growing among rice fields in Madagascar.

Global warming has become an increasingly pervasive topic of discussion and concern for the scientific community. From fears over oceanic inundation of low-lying island nations such as the Maldives to glacial melting in the Arctic, higher temperatures around the globe have put experts on edge about the future of the world's health and balance. Nowhere has the phenomenon become more immediate than for the African continent. A series of recent studies have revealed a sobering future for the majority of Africa, a future predicated by undeniable and significant climate change. The threat traverses all levels of the environmental, social, political and economic spheres, from heightened socio-economic disparity to dwindling fish populations, from civil strife to desperate hunger.

One major symptom of climate change is the disruption of regular seasonal patterns over large regions of the continent. Certain areas have long suffered from heady flooding and drought, but these phenomena seem to be on the rise in both severity and duration. In the 1970s, an extended drought in the Sahel was responsible for the deaths of 300,000 people. The Sahel is wide section of land that stretches from the Atlantic Ocean to what is known as the Horn of Africa, encompassing Burkina Faso, Chad, Djibouti, Eritrea, Ethiopia, Mali, Mauritania, Niger, Nigeria, Senegal, Somalia and Sudan. This region is a zone of transition between the aridity of the Sahara Desert in the north and the sub-tropical and tropical south. Previously, the tragedy in the Sahel was attributed to factors such as over-grazing and overpopulation, however recent information is proving otherwise.

A group of researchers presented their findings on the subject at the American Geophysical Union's annual conference in May of this year. Generated from the analysis of 60 separate computer simulations imitating global climate, the results infer that the temperature increase in the Indian Ocean is to blame for the present drought in southern Africa. Further, higher rainfall in the Sahel appears to be linked to temperature changes in the Atlantic. The nature of the change is not as simple as a straightforward increase in temperature however.

Regular droughts have decimated crop yields in various parts of the continent since 1970. The scientists' models reveal consistent and marked warming of the Indian Ocean, implying persistent and increased occurrence of drought in the Horn as well as southern Africa. Results indicate that the droughts in southern Africa can be traced directly to the change in the Indian Ocean, which has warmed by one degree Celsius since 1950. The new models show that the regular monsoon winds that bring seasonal rain to sub-Saharan Africa may be 10-20% drier than in the last 50 year period. With this warming, rainy seasons are becoming markedly shorter.

Rice fields in Madagascar.

In the past, the northern Atlantic has traditionally been cooler than the southern Atlantic, drawing rain-rich winds away from the Sahel. In the last 10 years of this period however, the conditions changed so that the north Atlantic was now warmer, resulting in increased rainfall in the Sahel, ending the drought in the 1990s. In essence a sea-surface temperature reversal has occurred. On dry land, the situation is similar. It has been estimated that the average surface temperature will rise between 1.4 and 5.8 degrees in the next 100 years. The greatest warming is projected to occur in the Sahel and central southern Africa.

Further evidence along this tangent has been published in this month's Geophysical Research Letters, only adding to a growing collection of research on how climate change may impact the continent. A new model suggests that if greenhouse gas emissions are not curbed, higher temperatures over the Sahara will result in an additional 1 to 2 millimeters of rain to fall in the Sahel by 2050 between July and September. This may not sound like much, but compared with the drought figures for the same region in the 1980s, this amount represents a 25 to 50 percent increase in rainfall.

"The greatest and saddest irony of this dark fate projected for the continent is that while Africa has the world's lowest levels of carbon dioxide and other greenhouse gas emissions, contributing the least to global climate change, it has been forced to bear the brunt of the phenomenon."

Another indicator for the effects of climate change is vegetation. Scientists believe that majority of current plant matter in Africa is threatened by the new variance of seasonal patterns, water supply and a general warming trend. Researchers from England's University of York speculate that an effect comparable to the most recent Ice Age and the African forest decline 2500 years ago may occur in light of the changing climatic dynamic. With the creation of climate fluctuation models, scientists have been able to determine the hypothetical impact of predicted climatic change in the responses of over 5000 native plant species. The simulations reveal results similar to other studies, namely a rise in frequency and intensity of drought in the Sahel. Actual plant migrations out of regions like the Congo rainforests were recorded by the models. Additional findings suggest the other areas that will likely feel the impact of climate change are the eastern and southwest coast regions of Africa.

With a paucity of concrete data to work with, scientists used a computer program to effectively study plant response in the face of climate change. Scientists employed a technique called a genetic algorithm to fill in gaps in knowledge. Collaborating with the Nees Institute for Biodiversity of Plants and the South African National Biodiversity Institute, the York team was able to aggregate the world's largest database of Africa-wide plant distribution maps. The Annals of the Missouri Botanical Garden—the premier research institute on African botany, featured the findings in this summer's issue.

Participants in the study drew the shared conclusion that beyond the environment, the predicted climate change would lead to large-scale social impacts in the continent. As resources grow more scarce, tension increases proportionately. Social effects resulting from climate change are inevitably and inextricably tied to politics. The domino effect of increased hunger, subsequent environmental stress and heightened relations between people is simply another symptom of altered climate.

Two pictures from NASA showing Mt. Kilimanjaro. The top image is from February 17, 1993 while the bottom image if from February 21, 2000

Hunger currently affects about half of the continent's people. Presently, various humanitarian organizations contribute six billion dollars annually to help feed the continent. Scientists anticipate even tougher times for Africa with ballooning famines, larger in both severity and duration, stemming from a higher incidence of drought. The majority of the African population relies of rain-fed crops for subsistence, making changes in their environment, especially changes in the water supply, a dire threat. Many farmers operate lacking the most basic of irrigation systems. Close to 40 percent of the GDP of African nations come from agriculture, with 70 percent of workers employed in the industry. When the fields fail to produce, the people struggle for survival and must look elsewhere for sustenance.

Livestock is also affected by the change as animals struggle to find water and vegetation for grazing. Other threatened organisms include fish species that also provide nourishment for people. Fish populations are dropping as the air temperature rises, interfering with the production of algae, the essential link in the aquatic food web. Overfishing is another cause. There has been a 30 percent decline in fish stocks in Lake Tanganyika over the last 80 years. Fish stocks in Ghana are down by 50 percent. Only intensifying the environmental stress, fisherman are beginning to transition into farming, which in turn leads to deforestation and its associated problems, now that the source of their original livelihood is dwindling. Increased pressure has also been placed on wild game, now increasingly hunted for food.

Undernourished Population (2000 - 2002) according to FAO. Courtesy of FAO 2005.

Other related problems emanating from the warming are emerging as serious threats. With the temperature increase, malaria has been on the rise throughout the continent as mosquitoes' ranges have been expanded. The disease is affecting previously safe communities and ravaging populations. One of Africa's most noted landmarks, Mount Killimanjaro, is also showing signs of stress from climate change. Scientists predict that most of the peak's glaciers will melt by 2020. Widespread deforestation on the lower slopes of Killimanjaro is further compounding the effects of global warming.

The greatest and saddest irony of this dark fate projected for the continent is that while Africa has the world's lowest levels of carbon dioxide and other greenhouse gas emissions, contributing the least to global climate change, it has been forced to bear the brunt of the phenomenon. Producing just over one metric ton of carbon dioxide per person a year, Africa is the least-polluting continent on Earth. In contrast, the average American generates close to 16 metric tons over the same period. This works out to a mere four percent for the entire continent, compared with the United States' 23 percent contribution. The mostly poor, developing nations that comprise the continent are the least prepared to adapt to its effects. The impact of the warming will ultimately endanger food availability and security throughout the continent. Climate change is just another problem that compounds the continent's already grave circumstance. Without serious changes, specifically the curbing of emissions in developed nations, scientists believe climate change due to global warming will continue to cripple Africa and destroy chances for progress and the alleviation of poverty and hunger.

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