Climate Change Impacts on East Africa

Muawya Ahmed Hussein.
Africa contains about one-fifth of all known species of plants, mammals, and birds, as well as one-sixth of amphibians and reptiles. These species compose some of the world’s most diverse and biologically important ecosystems such as savannahs, tropical forests, coral reef marine and freshwater habitats, wetlands and montane ecosystems. These globally important ecosystems provide the economic foundation that many Africa countries rely on by providing water, food, and shelter. However, because of climate change, these ecosystems and the livelihoods that depend on them are threatened. The aim of this paper is to highlight some of the major impacts of climate change on conservation for East Africa countries including Kenya, Tanzania, Uganda and Rwanda. As this paper illustrates, climate change in Africa is not only a conservation problem but is a socio-economic issue that must be dealt with at a global scale.

Climate change is really happening now. The average global surface temperature has warmed 0.8 C in the past century and 0.6C in the past three decades (Hansen et al., 2006), in large part because of human activities (IPCC, 2001). A recent report produced by the U.S. National Academy of Sciences confirms that the last few decades of the 20^th century were in fact the warmest in the past 400 years (National Research Council, 2006). The Intergovernmental Panel on Climate Change (IPCC) has projected that if greenhouse gas emissions, the leading cause of climate change, continue to rise, the mean global temperatures will increase 1.4 – 5.8C by the end of the 21 century (IPCC, 2001).

The effects of climate change such as rising temperature and changes in precipitation are undeniably clear with impacts already affecting ecosystems, biodiversity and people.  In both developed and developing countries, climate impacts are reverberating through the economy, from threatening water availability to sea-level rise and extreme weather impacts to coastal regions and tourism. In some countries, climate impacts affect the ecosystems services that communities are largely dependent upon, threatening development and economic stability. Future impacts are projected to worsen as the temperature continues to rise and as precipitation becomes more unpredictable.

One region of the worked where the effects of climate change are being felt particularly hard in Africa. Because of the lack of economic, development, and institutional capacity, African countries are likely among the most vulnerable to the impacts of climate change (IPCC 2001). Climate change impacts have the potential to undermine and even, undo the progress made in improving the socio-economic well-being of East Africans. The negative impacts associated with climate change are also compounded by many factors, including widespread poverty, human diseases, and high population density, which is estimated to double the demand for food, water, and livestock forage within next 30 years (Davidson et al., 2003).

Observed and Projected Climate Change
Overall Africa has warmed 0.7 Cover the 20^th century and general circulation models project warming across Africa ranging from 0.2C per decade (low scenario) to more than 0.5C per decade (high scenario) (Hulme et al.,2001; IPCC,2001). Hulme et al., 2001, suggest that under intermediate warming scenarios, parts of equatorial East Africa will likely experience 5-20% increased rainfall from December – February and 5-10% decreased rainfall from June-August by 2050 Climatic change of this magnitude will have far-reaching, negative impacts on the availability of water resources, food and agricultural security, human health, tourism, coastal development and biodiversity and are highlighted below.

Water Availability
Arguably one of the most widespread and potentially devastating impacts of climate change in East Africa will be changing in the frequency, intensity, and predictability of precipitation. Changes in regional precipitation will ultimately affect water availability and may lead to decreased agricultural security, human health, tourism, coastal development and biodiversity and are highlighted below.

Projections of climate change suggest that East Africa will experience warmer temperatures and a 5-20% increased rainfall from December –February and 5-10% decreased rainfall from June – August by 2050 (Hulme et al ., 2001; IPCC, 2001). Not only are these changes not uniform throughout the year, but they will also likely occur in sporadic and unpredictable events. It may also be likely that the increased precipitation will come in a few very large rainstorms mostly during the already wet season thereby adding to erosion and water management issues and complicating water management. It is also expected that there will be less precipitation in East Africa during the already dry season, which may cause more frequent and severe droughts and increased desertification in the region.

Recent research also suggests that warming sea surface temperatures, especially in the southwest Indian Ocean, in addition to interannual climate variability (i.e El Nino/Southern Oscillation (ENSO) may play a key role in East African rainfall and may be linked to the change in rainfall across some parts of equatorial-subtropical East Africa (Cane et al. 1986; Pilsnier et al, 2000; Rowe 2001). Warm sea surface temperatures are thought to be responsible for the recent droughts of in equatorial and subtropical Eastern Africa during the 1980s to the 2000s (Funk et al, 2005).  According to the UN Food and Agriculture Organization (FAO, 2004), the number of African food crises per year has water supplies reduce crop productivity and have resulted in widespread famine in East Africa.

In addition to declining moisture needed for pastoral and agricultural activities, the availability of water for human consumption is of paramount concern. Currently, two-thirds of rural Africans and a quarter of urban dwellers in Africa lack access to clean, safe drinking water (Simms, 2005). In Tanzania for example, two of three rivers have reduced flow due to declining regional rainfall, which has had ecological and economic impacts such as water shortages, lowered agricultural production, increased fungal and insect infestations decreased biodiversity and variable hydropower production (Orindi and Murray, 2005). High temperatures and less rainfall during already dry months in the Tanzania river catchments could affect the annual flow to the River Pangani by reductions of 6-9% and to the river Ruvu by 10% (VPO-URT,2003). The Pangani Basin is also fed by the glaciers of Kilimanjaro, which have been melting alarmingly fast and are estimated to disappear completely by 2015-2020 (Thompson et al 2002). The population living around the base of Kilimanjaro uses this meltwater and the fog water from the rainforests that cover the mountain’s flanks for drinking, irrigation and hydropower. The Pangani Basin is one of Tanzania’s most agriculturally productive areas and is an important hydropower production region. Because of this, climate change threatens the productivity and sustainability of this region’s resources, which hosts an estimated 3.7 million people.

Food security
There is a strong link between climate and East African livelihoods and food security highly vulnerable to climate variability such as shifts in growing season conditions (IPCC,2001). Further, agriculture contributes 40% of the region’s gross domestic product (GDP) and provides a living for 80% East Africans (IFPRI,2004). However because the temperature has increased and precipitation in the region has decreased in some areas, many are already being affected. For example, from 1996 to 2003, there has been a decline in rainfall of 50-150 mm per season (March to May ) and a corresponding decline in long-cycle crops (eg, slowly maturing varieties of sorghum and maize) across most of eastern Africa (funk et al; 2005). Long – cycle crops depend upon rain during this typically wet season and progressive moisture deficit results in low crop yields in the fall, thereby impacting the available food supply.

Increased variability (ie deviation from the mean) of crop production is also a major concern of farmers in eastern Africa. Inter-annual climate variability (eg. ENSO) has huge impacts on the region’s climate. Warm ENSO events also referred to as El Nino events produce abnormally high amounts of precipitation in parts of equatorial East Africa and can result in flooding and decreased agricultural yields. Further south, in Zimbabwe, researchers correlated past El Nino events and warm sea surface temperatures in the eastern equatorial pacific with more than 60% of the change between above and below-average agricultural production of maize (Patt et al; 2005).

Climate change may also impact the region’s fisheries. While many tropical fishes have evolved to survive in very warm water, many have a critical thermal maximum and can not survive temperatures that exceed this threshold. For example, spotted tilapia, (Tilapia mariae), native to parts of Africa, prefer temperatures between 25 and 33oC, depending upon acclimation temperature, and have a critical thermal maximum of 37C (Siemien and Stauffer 1989). Though tropical fishes can endure temperatures very near their temperature threshold, a slight (1-2 C) increase in regional temperatures may cause the daily temperature maxima to exceed these limits, particularly for populations that currently exist in thermally marginal habitats (Roessing et al, 2004). However, because there is little data on the ability of this species to adjust their tolerance to water temperature their response to climate change is largely unknown.

An increase in mean temperature may also affect the dissolved oxygen concentrations in the layer of water below the thermocline (hypolimnion) in two ways: increased metabolism of fish and other organisms in a slightly warmer hypolimnion will lead to the faster depletion of the limited oxygen supply, and lake overturn, the primary means of replenishing hypolimnetic dissolved oxygen, will occur less frequently (Fick et al; 2005). The African General Lakes contain deep anoxic hypolimnia of tropical lakes also contain a high concentration of hydrogen sulfide. This chemical compound is a byproduct of anaerobic decomposition of organic matter and is highly toxic to fish. Moderate amounts of mixing allow nutrient influx into the layer of water above the thermocline and benefit fisheries productivity without introducing a high concentration of toxic hydrogen sulfide (Fick et al; 2005) this is demonstrated at the stratified northern end of Lake Tanganyika, Africa, which supports a less productive fishery than the well-mixed southern arm and the main basins (Vuorinen et al; 1999). A comparative study of historical and current levels of primary production in the northern end of Lake Tanganyika indicated that current levels are much lower as a result of strengthened stratification (Verburg et al; 2003). Recent changes in the limnology of lake Victoria have also negatively affected its fishery. In the 1980s decreased turnover in the lake led to low levels and dissolved oxygen and, consequently, fish kills. Stratification in this lake now appears to e permanent (Kaufman et al; 1996).

Human Health
Climate variability has had far-reaching effects to human health, and includes, but is not limited to, the following; heat stress, air pollution, asthma, vector-borne diseases (such as malaria, dengue, schistosomiasis (also referred to as swimmer’s itch or snail fever) and tick-borne diseases), waterborne and foodborne diseases (such as diarrhoea diseases). For this report we concentrate on just two of these effects, malaria and Rift Valley fever; however other health issues are likely to be affected by climate change.

Climate change is expected to exacerbate the occurrence and intensity of future disease outbreaks and perhaps increase the spread of diseases in some areas. It is known that climate variability and extreme weather events such as high temperatures and intense rainfall events, are critical factors in initiating malaria epidemics especially in the highlands of western Kenya, Uganda, Ethiopia, Tanzania, Rwanda and Madagascar (Zhou et al; 2004). While other factors such as topography and health preparedness can influence the spread of malaria, scientists have found a correlation between rainfall and unusually high maximum temperatures and the number of malaria cases (Githiko and Ndegwa, 2001; Zhou et al; 2004). From 1920 to 1950, the highlands of eastern Africa experienced infrequent malaria outbreaks, however, since then the current pattern is characterized by increased outbreak frequencies, expanded geographic range, and increased case-fatality rates (Zhou et al., 2004). The spread of malaria is seasonal and limited to the warm and rainy months; however, changing climate conditions, such as the persistence of warm and rainy days for more of the year can increase the incidence of malaria events (Craing et al., 2004). In addition to longer seasons that are suitable for malaria spread, temperatures have also been warming in formerly cooler, higher elevation East African highlands. Subsequently, these areas are experiencing a spread of malaria in populations that had not previously been frequently exposed to the disease (Patx et al., 2005; Zhou et al., 2004).

Rift Valley Fever epidemics are also correlated to climate variability. Between 1950 and 1988 three quarters of the Rift Valley Fever outbreaks occurred during warm ENSO event periods (i.e., El Nino events). During El Nino, the East African highlands typically receive unusually high rainfall which is correlated with Rift Valley Fever outbreaks (Patx et al 2005).

Extreme Weather Events
Warming temperatures are projected to cause more frequent and more intense extreme weather events, such as heavy rainstorms, flooding, fires, hurricanes, tropical storms and El Nino events (IPCC,2001). Tropical storms can ravage coastal areas and intensive the impacts of sea-level rise by accelerating erosion in coastal areas and by removing protective natural buffer areas that absorb storm energy, such as wetlands and mangroves (Magadza, 2000). Extreme rainfall and subsequent heavy flooding damage will also have serious effects on agriculture including the erosion of topsoil, inundation of previously arid soils, and leaching nutrients from the soil. Regional fluctuations in lake levels are another impact of regional climate variations and are expected to worsen with projected climate change. While land use change can have a dramatic effect on lake levels, climate variability is more unpredictable and difficult to manager for. For example lake levels in Lake Tumba in the Democratic Republic of Congo (Inogwabini et al., 2006) and Lake Victoria in Kenya (Birkett et al., 1999; Latif et al., 1999) have been attributed to climate variations and may become more variable in the future. In 1997, floods and high rainfall, triggered by an El Nino event in eastern Africa, resulted in a surface rise of 1.7 meters in Lake Victoria and disrupted agricultural production and pastoral systems (Lovett et al., 2005).  While climate change is projected to cause more frequent and intense ENSO events (Wara et al., 2005) impact are not uniform across East Africa. In fact, the same year that the waters were rising in Lake Victoria, El Nino triggered a severe drought in another location in Kenya, significantly decreasing hydro-electric power output, limiting the availability of electricity to East Africans ( Locett et al, 2005). Further, a projected increase in precipitation may also have an effect on hurricanes and storms in the Atlantic. Land sea and  Gray (1992) HAVE FOUND THAT RAINFALL IN THE Sahel is positively correlated with the intensity of hurricanes in the Atlantic Ocean.

Climate change-induced, warming land and sea surface temperatures are projected to cause more frequent and intense hurricanes and tropical storms that inundate coastal areas (IPCC, 2001). These same extreme weather events can lead to decreased precipitation in interior regions, causing increased drought and desertification, subsequently threatening food security. Threats to food security can then lead to widespread migration of human settlements in order to seek better agricultural land, more available water resources, and escape increased exposure to malaria and other diseases. The impacts of climate change also have the potential to disrupt and potentially reverse progress made in improving the socio-economic well-being of East Africans such as infrastructure development, sustainable agriculture, and tourism.

Sea-Level Rise
Sea-level rise along coastal areas where high human populations occur is likely to disrupt economic activities there, such as tourism, mining and fisheries. Sea level rise and resulting coastal erosion is of particular concern coastal Kenya and Tanzania. Warm sea surface temperatures, extreme weather events, and sea-level rise can lead to the destruction of coral reefs, which absorb the energy of ocean swells (IPCC,2001). Coral reef loss is a significant cause of coastal erosion and a major coastal management issue in both Kenya and Tanzania (Magadza, 2000)

Productive mangrove ecosystems along coastal areas serve as a buffer against storm surges by providing protection from erosion and rising tides associated with sea-level rise. However, mangroves are at threat from deforestation, coastal erosion and extreme weather and have been identified as the most vulnerable species to sea-level rise and inundation (IPCC, 2001). Sea-level rise is also threatening the availability of freshwater by causing saltwater intrusion into Tanzania’s aquifers and deltas. In the tea-producing regions of Kenya, the world’s second-largest exporter of tea, a small temperature increase (1.2C form now) and the resulting changes in precipitation, soil moisture and water irrigation would cause large areas of land that now support tea cultivation to be largely unusable. Economically, this would have far-reaching impacts because tea exports account for roughly 25% of Kenya’s export earnings and employ about three million Kenyans (10% of its population) (Simms, 2005).

Biodiversity
Despite Africa’s fast-growing human population and the associated impacts on natural resources, it is one of the least studied continents in terms of ecosystem dynamics and climate variability (Hely et al 2006). However, climate change is already having an impact on the dynamics of Africans biomes and its rich biodiversity, although species composition and diversity is expected to change due to individual species response to climate change conditions (Erasmus et al 2002). The projected rapid rise in temperature combined with other stresses, such as the destruction of habitats from land-use change, could easily disrupt the connectedness among species, transforming existing communities, and showing variable movements of species through ecosystems, which could lead to numerous localized extinctions. If some plant species are not able to respond to climate change, the result could be increased vulnerability of ecosystems to natural and anthropogenic disturbance, resulting in species diversity reductions (Malcolm et al, 2002)

Climate change is expected to significantly alter African biodiversity as species struggle to adapt to changing conditions (Lovett et al., 2005).

Historically, climate change has resulted in dramatic shifts in the geographical distributions of species and ecosystems and current rates of migration of species will have to be much higher than rates during post-glacial periods in order for species to adapt (Malcolm et. Al., 2002). Species that have the capability to keep up with climate shifts may survive; other that cannot respond will likely suffer. For example, biome sensitivity assessments in Africa show that deciduous and semi-deciduous closed-canopy forests may be very sensitive to small decreases in the amount of precipitation that plants receive during the growing season, illust5rating that deciduous forests may be more sensitive than grasslands or savannahs to reduced precipitation (Hely et al,.2006). invasive species and other species with high fertility and dispersal capabilities have been shown to be highly adaptive to variable climatic conditions (Malcolm et a.2002). Due to its climate-sensitive native fauna, East Africa may be particularly vulnerable to exotic and invasive species colonization.

Migratory species that use Africa may also be vulnerable to changes in climate. In fact, climate change has the potential to alter migratory routes (and timings) of species that use both seasonal wetlands (e. g., migratory birds) and track seasonal changes in vegetation (e.g., herbivores), which may also increase confects with humans, particularly in areas where rainfall is low (Thirgood et al., 2004). Land-use patterns in Africa can also prevent animals from changing their migratory routes, for example, park boundary fences have been demonstrated to disrupt migratory journeys, leading to a population decline in wildebeest (Whyte and Joubert 1988).

Climate change also threatens some of the large protected areas (including ones that protect migratory species) that have been designated to conserve much of Africa’s that magnificent biodiversity. It is expected that vegetation will migrate or move in order to utilize suitable habitats requirements (i.e., water and nutrient availability); however, this may mean that in some locations the geographical range of suitable habitats will shift outside the protected area boundaries. In some locations, the geographical range of suitable habitats will shift outside the protected area boundaries. In addition, weather extremes can also affect biodiversity in more complex says. For example, in African elephants (Loxodonta Africana), breeding is year-round, but dominant males mate in the wet season and subordinate males breed in the dry season. Subsequently, a change in the intensity or duration of the rainy versus drought seasons could change relative breeding rates and, hence, genetic structures in these populations (Poole, 1989; Rubenstein, 1992).  Strategies for future designations of protected areas in East Africa need to be developed that include projections of future climate change and corresponding changes in the geographic range of plant and animal species to ensure adequate protection.

Large changes in ecosystem composition and function because of regional climate change would have cascading effects on species diversity (Sykes and Prentice, 1996; Solomon and Kirilenko, 1997; Kirilenki and Solomon, 1998).  Vast forest disappearance due to climate change-induced die-back and land-use change would substantially affect species composition and global geochemical cycling, particularly the carbon cycle (Malcolm et al.,2002). In the savannahs of Zambia, research shows that climate change substantially affects growth in certain tree species. Chidumayo (2005) showed that dry tropical trees suffer severe water stress at the beginning of the growing season and that a warmer climate may accelerate the depletion of deep-soil water the species depend on for survival. In sub-Saharan Africa, which includes parts of East Africa, several ecosystems, particularly grass and shrub savannahs, are shown to be highly sensitive to short-term availability of water due to climate variability (Vanacker et al., 2005). Shrub and grassland vegetation types generally have root systems that are shallow and dense; these plants draw their moisture from water that is available in upper soil layers and growth in these species depends highly upon the timing, intensity and duration of rainfall. Climate projections suggest that during already dry months, less precipitation will occur likely reducing the resilience of these plants (Vanacker et al.,2005). Changes in plant composition will also have an impact on ecosystem resilience; less diverse systems can be more sensitive to precipitation fluctuations.  For example, ecosystems that are comprised of a uniform herbaceous cover, such as in savannah plant communities, show the highest sensitivity to precipitation fluctuations when compared with plant communities of a mix of herbaceous, shrub and tree species that support a higher diversity of species (Vanacker et al., 2005).

Climate change may also affect species range, which could have profound impacts on species population size. For example in South Africa, a modelling study found that a reduction in the range of a species I likely to have an increased risk in local extinction climate change 9Erasmus et al.,2002). The authors suggest that this may be due to the positive inter-specific relationship between population size and range size; if range size decreases, there is a likelihood that there will be a rapid decline in population size. Additionally, this relationship could be exacerbated if climate change restricts the range of a species to jus a few key sites and an extreme weather event occurs, thus driving up extinction rates even further(Erasmus et al., 2002). Species ranges will probably not shift in cohesive and intact units and are likely to become more fragmented as they sift in response to changing climate (Channel and Lomolino, 2000). In fact, up to 66% of species may be lost due to predicted range shifts caused by climate change in south Africa’s Krueger National Park (Erasmus et al., 2002). To be able to better conserve biodiversity in the future, it is imperative to understand how species and ecosystems are likely to change under varying climate change scenarios (Erasmus et al.,2002).

Resistance to Climate
Both short and long term adaptation strategies in response to regional climate change are beginning to emerge in a region that is rife with challenges. For every USD$1 spent preparing for disaster, USD$7 is spent recovering from disaster (Simms, 2005). As organizations test and develop new conservation concepts, it is clear that poverty alleviation must be considered with the conservation of nature and biodiversity. As some resources become scarce, conflicts between conservation and other land uses are likely to increase under climate change scenarios. However, human communities across Africa are banding together cooperatively to conserve resources and protect their livelihood.

Along the Tanzania coast, leading conservation groups are working with natural resource mangers and other stakeholders to integrate climate change adaptation strategies into their management philosophies and plans (Hansen et al., 2003). Initial vulnerability assessments and adaptation planning from Tanzania point to the need for mangrove protection, reforestation with “climate-smart species”,  integrated land-use and marine planning, as well as activities to improve resource use technology. Coordinating the testing of adaptation methods in geographically diverse locations within a common habitat type aims to increase the replicability so that the project result can be transferred to other conservation efforts around the globe (Hansen et al.,2003). Conservation of ecosystems and natural resources requires that adaptive management strategies are developed or that we accept that many natural systems will be lost to climate change.

Projects should aim to build the capacity of natural resource managers to assess vulnerability and to adapt management strategies to respond to expected climate change impacts (Hansen et al., 2003).

Climate change impacts to rural farming communities can be reduced by distributing climate data regarding seasonal climate forecasts (based on short-term and long-term forecasts) to small framers so that they can make a more informed farming decision and adapt to the changing climate conditions. Some farmers have already started to use this information and are preparing themselves for dry conditions by planting drought-tolerant crops )Patt et al.,2005).

Food production can be improved dramatically in dry areas when governments and/or organizations use climate forecasts and prepare accordingly by potentially distributing drought-tolerant seeds (Patt et al., 2005). Farmers can also take advantage of climate forecasts by planting less drought-tolerant and higher-yield., long season maize when wetter than usual growing seasons are forecast )Patt et al., 2005). While seasonal forecasts can be useful in some situations, it should be noted that they can not be applied everywhere and that many times they do not consider multiple climate extremes, for example, they may forecast drought but not extreme rainfall. The aforementioned approaches are just a few of the many examples that governments, organizations, and communities need to consider in order to adapt to challenges of subsistence food production and assure future food security (Patt et al., 2005; Ziervogel,2004).

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