Africa is highly vulnerable to the various manifestations of climate change. Six
situations that are particularly important are:
- Water resources, especially in international shared basins where there is
a potential for conflict and a need for regional coordination in water management
- Food security at risk from declines in agricultural production and uncertain
- Natural resources productivity at risk and biodiversity that might be irreversibly
- Vector- and water-borne diseases, especially in areas with inadequate health
- Coastal zones vulnerable to sea-level rise, particularly roads, bridges,
buildings, and other infrastructure that is exposed to flooding and other
- Exacerbation of desertification by changes in rainfall and intensified land
The historical climate record for Africa shows warming of approximately 0.7°C
over most of the continent during the 20th century, a decrease in rainfall over
large portions of the Sahel, and an increase in rainfall in east central Africa.
Climate change scenarios for Africa, based on results from several general circulation
models using data collated by the Intergovernmental Panel on Climate Change
(IPCC) Data Distribution Center (DDC), indicate future warming across Africa
ranging from 0.2°C per decade (low scenario) to more than 0.5°C per
decade (high scenario). This warming is greatest over the interior of semi-arid
margins of the Sahara and central southern Africa.
Projected future changes in mean seasonal rainfall in Africa are less well
defined. Under the low-warming scenario, few areas show trends that significantly
exceed natural 30-year variability. Under intermediate warming scenarios, most
models project that by 2050 north Africa and the interior of southern Africa
will experience decreases during the growing season that exceed one standard
deviation of natural variability; in parts of equatorial east Africa, rainfall
is predicted to increase in December-February and decrease in June-August.
With a more rapid global warming scenario, large areas of Africa would experience
changes in December-February or June-August rainfall that significantly
exceed natural variability.
Water: Africa is the continent with the lowest conversion factor of
precipitation to runoff, averaging 15%. Although the equatorial region and coastal
areas of eastern and southern Africa are humid, the rest of the continent is
dry subhumid to arid. The dominant impact of global warming is predicted to
be a reduction in soil moisture in subhumid zones and a reduction in runoff.
Current trends in major river basins indicate a decrease in runoff of about
17% over the past decade. Reservoir storage shows marked sensitivity to variations
in runoff and periods of drought. Lake storage and major dams have reached critically
low levels, threatening industrial activity. Model results indicate that global
warming will increase the frequency of such low storage episodes.
Natural Resources Management and Biodiversity: Land-use changes as a
result of population and development pressures will continue to be the major
driver of land-cover change in Africa, with climate change becoming an increasingly
important contributing factor by mid-century. Resultant changes in ecosystems
will affect the distribution and productivity of plant and animal species, water
supply, fuelwood, and other services. Losses of biodiversity are likely to be
accelerated by climate change, such as in the Afromontane and Cape centers of
plant endemism. Projected climate change is expected to lead to altered frequency,
intensity, and extent of vegetation fires, with potential feedback effects on
Human Health: Human health is predicted to be adversely affected by
projected climate change. Temperature rises will extend the habitats of vectors
of diseases such as malaria. Droughts and flooding, where sanitary infrastucture
is inadequate, will result in increased frequency of epidemics and enteric diseases.
More frequent outbreaks of Rift Valley fever could result from increased rainfall.
Increased temperatures of coastal waters could aggrevate cholera epidemics in
Food Security: There is wide consensus that climate change, through
increased extremes, will worsen food security in Africa. The continent already
experiences a major deficit in food production in many areas, and potential
declines in soil moisture will be an added burden. Food-importing countries
are at greater risk of adverse climate change, and impacts could have as much
to do with changes in world markets as with changes in local and regional resources
and national agricultural economy. As a result of water stress, inland fisheries
will be rendered more vulnerable because of episodic drought and habitat destruction.
Ocean warming also will modify ocean currents, with possible impacts on coastal
Settlements and Infrastructure: The basic infrastructure for developmenttransport,
housing, servicesis inadequate now, yet it represents substantial investment
by governments. An increase in damaging floods, dust storms, and other extremes
would result in damage to settlements and infrastructure and affect human health.
Most of Africa's largest cities are along coasts. A large percentage of
Africa's population is land-locked; thus, coastal facilities are economically
significant. Sea-level rise, coastal erosion, saltwater intrusion, and flooding
will have significant impacts on African communities and economies.
Desertification: Climate change and desertification remain inextricably
linked through feedbacks between land degradation and precipitation. Climate
change might exacerbate desertification through alteration of spatial and temporal
patterns in temperature, rainfall, solar insolation, and winds. Conversely,
desertification aggravates carbon dioxide (CO2)-induced climate change through
the release of CO2 from cleared and dead vegetation and reduction of the carbon
sequestration potential of desertified land. Although the relative importance
of climatic and anthropogenic factors in causing desertification remains unresolved,
evidence shows that certain arid, semi-arid, and dry subhumid areas have experienced
declines in rainfall, resulting in decreases in soil fertility and agricultural,
livestock, forest, and rangeland production. Ultimately, these adverse impacts
lead to socioeconomic and political instability. Potential increases in the
frequency and severity of drought are likely to exacerbate desertification.
Given the range and magnitude of the development constraints and challenges
facing most African nations, the overall capacity for Africa to adapt to climate
change is low. Although there is uncertainty in what the future holds, Africa
must start planning now to adapt to climate change. National environmental action
plans and implementation must incorporate long-term changes and pursue "no
regret" strategies. Current technologies and approachesespecially
in agriculture and waterare unlikely to be adequate to meet projected
demands, and increased climate variability will be an additional stress. Seasonal
forecastingfor example, linking sea-surface temperatures to outbreaks
of major diseasesis a promising adaptive strategy that will help save
lives. It is unlikely that African countries on their own will have sufficient
resources to respond effectively.
Climate change also offers some opportunities. The process of adapting to global
climate change, including technology transfer, offers new development pathways
that could take advantage of Africa's resources and human potential. Examples
would include competitive agricultural products, as a result of research in
new crop varieties and increased international trade, and industrial developments
such as solar energy. Regional cooperation in science, resource management,
and development already are increasing.
This assessment of vulnerability to climate change is marked by uncertainty.
The diversity of African climates, high rainfall variability, and a very sparse
observational network make predictions of future climate change difficult at
the subregional and local levels. Underlying exposure and vulnerability to climatic
changes are well established. Sensitivity to climatic variations is established
but incomplete. However, uncertainty over future conditions means that there
is low confidence in projected costs of climate change.
Improvements in national and regional data and capacity to predict impacts
is essential. Developing African capacity in environmental assessment will increase
the effectiveness of aid. Regional assessments of vulnerability, impacts, and
adaptation should be pursued to fill in the many gaps in information.