Previous assessments (Hulme, 1996; IPCC, 1998) concluded that the African continent is particularly vulnerable to the impacts of climate change because of factors such as widespread poverty, recurrent droughts, inequitable land distribution, and overdependence on rainfed agriculture. Timely response actions were considered to be beyond the economic means of some countries. Deterioration in terms of trade, inappropriate policies, high population growth rates, and lack of significant investment—coupled with a highly variable climate—have made it difficult for several countries to develop patterns of livelihood that would reduce pressure on the natural resource base. The reports fell short of assigning relative importance to these different factors in Africa's capacity to adapt to climate change. This still is not possible and presents a new challenge for future assessments.

The main background factors that need to be kept in mind in assessing the vulnerability of the African region to climate change—particularly the capacity of African governments to respond proactively to changes that are largely not of their making or under their control—are as follows:

• Diversity: The term "African region" is a geographical convenience only. There is as much diversity of climate, landform, biota, culture, and economic circumstance within the region as there is between it and, say, South America or Asia. Very few statements are valid for the entire continent. The generalities that follow must be read in that context.
  
• Climate: Africa is predominantly tropical, hot, and dry. There are small regions of temperate (cool) climates in the extreme south and north and at high altitudes in between. Parts of west Africa, as well as the western part of central Africa, are humid throughout the year. A large region north and south of this humid core is subhumid, with substantial rainfall during the wet season (or seasons, in the case of east Africa) but almost no rain during the extended dry season. Poleward from this zone is a large area of semi-arid climates, which permit marginal cropping during the wet season but are characterized by extreme unreliability of rainfall and few permanent surface-water sources. Most of the human population occurs in the subhumid and semi-arid zones. Corresponding to the tropics of Capricorn and Cancer are the vast desert regions of the Kalahari-Namib and the Sahara.
  
• Development Status: Measured by almost any index of human well-being, Africa contains the poorest and least-developed nations of the world. Per capita gross domestic product (GDP), life expectancy, infant mortality, and adult literacy are all in the bottom quartile globally when averaged across Africa, although individual nations may perform somewhat better on one or more of these indices. The general weakness of the science and technology infrastructure—in particular, the relatively small numbers of technically trained professionals—limits the rate at which adaptive research can be performed or implemented.
  
• Food Supply: More than half of the African population is rural and directly dependent on locally grown crops or foods harvested from the immediate environment. Per capita food production in Africa has been declining over the past 2 decades, contrary to the global trend. The result is widespread malnutrition, a recurrent need for emergency food aid, and increasing dependence on food grown outside the region.
  
• Dependence on Natural Resources: The formal and informal economies of most African countries are strongly based on natural resources: Agriculture, pastoralism, logging, ecotourism, and mining are dominant. Climatic variations that alter the viability of these activities, for better or for worse, have very high leverage on the economy.
  
• Biodiversity: About one-fifth of the world's plants, birds, and mammals originate or have major areas of present conservation in Africa. There are major "hot spots" of biodiversity within west, east, central, and southern Africa.
  
• Low Capacity for State-Initiated Interventions: Governance structures typically are underfunded and undercapacity. In many instances they have been undermined by military coups, despotism, tribalism, corruption, maladministration, and economic adjustment programs imposed by the international financial community. Communication from capitals to the remotest provinces—by road, rail, air, or telephone—often is unreliable and slow. State-centered political economies in their postcolonial sense are relatively recent over most of Africa, and their boundaries include wide ethnic diversity within single nations and cut across previous political territories.
  
• Disease Burden: Insect-vector diseases such as malaria and tryanosomiasis; water-borne diseases such as typhoid, cholera, and schistosomiasis; and poverty-related diseases such as tuberculosis are prevalent in Africa. Water and food security are closely linked with health. The HIV/AIDS pandemic is placing great strain on the health infrastructure. Heavy mortalities lead to great loss of productive potential.
  
• Armed Conflict: There has been chronic armed conflict in several regions of Africa almost continuously for the past 3 decades. This weakens the ability of the nations involved to respond to climate change and adds large refugee populations to the local population, which must be supported by the environment.
  
• High External Trade and Aid Dependence: Very little industrial beneficiation takes place in Africa. High volumes of relatively low-value goods dominate export economies. In general, there is no strong internal demand (national or regional) to buffer the economies from changes in global trade. Trade linkages show the pattern established by the former colonial relationships. Many African countries have a negative trade balance, particularly as a result of heavy international debt-servicing burdens, and are chronically dependent on financial aid from the developed world.

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