In Kenya, Sudan, Ethiopia, Somalia, and Chad, people are already seeing the repercussions - including war. The conflict between herders and farmers in Sudan's Darfur region, where farm and grazing lands are being lost to desert, may be a harbinger of the future conflicts.
"You have climate change and reduced rainfall and shrinking areas of arable land; and then you add population growth and you have the elements of an explosion," says Francis Kornegay, a senior analyst at the Center for Policy Studies in Johannesburg.
On Sunday, a new UN report predicted that by 2080, global warming could lead to a 5 percent fall in the production of food crops, such as sorghum in Sudan, Ethiopia, Eritrea, and Zambia; maize in Ghana; millet in Sudan; and groundnuts in Gambia.
Between 25 percent and 40 percent of Africa's natural habitats could be lost by 2085, according to the report produced by the Secretariat of the UN Framework Convention on Climate Change (UNFCCC). It also said that rising sea levels could destroy an estimated 30 percent of Africa's coastal infrastructure. Coastal settlements in the Gulf of Guinea, Senegal, Gambia, and Egypt could be flooded,
Ironically, Africa produces the smallest amount of the greenhouse gases blamed for climate change.
While it's risky to reduce any conflict to a single cause, a growing number of aid workers, government officials, and experts agree that climate change could certainly stretch the tense relations in many regions to the breaking point. Whenever there is less land available, and less water to make that land productive, then competition for that land can turn violent.
"[Climate] changes make the emergence of violent conflict more rather than less likely," said British Home Secretary John Reid last March. "The blunt truth is that the lack of water and agricultural land is a significant contributory factor to the tragic conflict we see unfolding in Darfur. We should see this as a warning sign."
The 1997 Kyoto Protocol - aimed at capping greenhouse gas emissions - expires in six years. Many countries, notably the US, have opted out of the Kyoto accord, which called for higher gas taxes and more regulation to reduce the global consumption of fossil fuels by an average of 5.2 percent from 1990 levels by 2012. Many scientists say the use of fossil fuels has raised the level of carbon dioxide in the atmosphere, which in turn has begun to raise global temperatures.
Some world leaders, such as President Bush, argue that uncertainty over the cause of global warming does not justify the economic costs of switching from fossil fuels to alternatives, such as solar power or fuel cells. But European leaders, including British Prime Minister Tony Blair, call for drastic measures, such as a 60 percent reduction in carbon emission by 2050.
But climate change is already hurting people here in Africa, according to a report issued last month by a coalition of British aid groups. The number of food emergencies encountered each year in Africa have tripled since the mid-1980s, the report says. This year alone, more than 25 million Africans faced a food crisis.
Even though temperatures in Africa have only warmed by an average of 0.5 degree C. over the past 100 years, desert lands are advancing into once arable rain-fed areas, and wetter equatorial parts of Africa are getting wetter, often leading to devastating floods.
According to another British report released last week, by former World Bank economist Nicholas Stern, current weather trends suggest that greenhouse gases will boost overall temperatures by 2-3 degrees C. over the next 40 years.
In the West, conflicts such as the fighting in Sudan's Darfur region are often chalked up to ethnic or religious differences. But equally important is the competition for land, as water sources dry up.
"The fighting in Chad, and the fighting in Darfur are the same," says one North African diplomat, speaking on condition of anonymity. "The problem is resources, especially water. On one side you have herders. On the other side you have farmers. And with the spread of weapons in the region, it becomes very dangerous and hard to control."
Indeed, in Niger, the government halted its planned expulsion late last month of nearly 150,000 refugees from neighboring Chad. The refugees, many of them Arab cattle herders, had fled fighting in Chad, but their encroachment on the farmlands and water resources in Niger has increased tensions and led to sporadic fighting with natives.
Jason Stearns, an analyst with the International Crisis Group in Nairobi, says that the competition for basic resources are behind many African conflicts.
"In Burundi, climate change, together with population growth and shrinking arable land is tightly linked to conflicts," says Mr. Stearns. He says that Burundi will have to work hard to meet the expectations of a population that has doubled since the early 1970s and where there are 400,000 refugees expected to return home after years of civil war.
But as bad as things are in Burundi, Stearns says, "it's even more true in the Horn of Africa, in Kenya, Somalia, as well as Ethiopia and Sudan."
Claudia Ringler, a research fellow at the International Food Policy Research Institute in Washington, says Africa is more vulnerable to climate change because so much of it's agricultural lands rely on rainfall, rather than irrigation.
"All these lobbies say it's bad to build all these dams, but all the dams have been built in Europe, in the US, in Australia, not in Africa," says Ms. Ringler. She has a long list of things that would enable African farmers to better feed their people, including access to paved roads, better weather reports, higher yielding varieties that can survive in times of drought. But above all, Africa needs access to water.
"Water is the most variable input in a changing climate situation," she says. "Strangely enough, on a per capita basis, water availability is not that bad in Africa. In Ethiopia and Somalia, the water's there, but it's not getting to where it needs to be."
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