Category: Climate risk profile

Climate change threatens the health and sanitation sector through more frequent incidences of heatwaves, floods, droughts and storms, including cyclones. Among the key health challenges in Madagascar are morbidity and mortality through vector-borne diseases such as malaria, waterborne diseases related to extreme weather events (e.g. flooding) such as diarrhoea, respiratory diseases, tuberculosis and HIV [32]. Climate change also impacts food and water supply, thereby increasing the risk of malnutrition, hunger and death by famine. Many of these challenges are expected to become more severe under climate change. According to the World Health Organization, Madagascar recorded an estimated 2.2 million cases of malaria including 5 350 deaths in 2018 [33]. Climate change is likely to have an impact on the geographic range of vector-borne diseases: In Madagascar, malaria usually does not occur above 1 500 m [34]. However, temperature increases could expand occurrence to higher-lying areas. This is already the case in Antananarivo which used to be largely free of malaria but is now observing rising numbers of cases [35]. Malaria is also likely to increase in many parts of Madagascar due to flooding and stagnant waters, which provide a breeding ground for mosquitos [35]. Climate change also poses a threat to food security and malnutrition, particularly for subsistence farmers. Chronic malnutrition is generally high with 42 % and could further increase due to the consequences of the COVID-19 pandemic [36]. Furthermore, access to healthcare is often complicated in Madagascar: 40 % of the population live in areas far away from health centers and have to travel for hours to seek medical treatment [35]. Access is even more difficult in the rainy season when many rural areas are cut off by impassable roads.

Exposure to heatwaves

Rising temperatures will result in more frequent heatwaves in Madagascar, leading to increased heat-related mortality. Under RCP6.0, the population affected by at least one heatwave per year is projected to increase from 0.2 % in 2000 to 4.8 % in 2080 (Figure 18).

Heat-related mortality

Furthermore, under RCP6.0, heat-related mortality will likely increase from 1.3 to 5.4 deaths per 100 000 people per year by 2080. This translates to an increase by a factor of more than four towards the end of the century compared to year 2000 levels, provided that no adaptation to hotter conditions will take place (Figure 19). Under RCP2.6, heat-related mortality is projected to increase to 2.9 deaths per 100 000 people per year in 2080.

References

[32] Ministère de la Santé Publique Madagascar, “Politique nationale de santé,” Antananarivo, Madagascar, 2016.
[33] WHO, “World Malaria Report 2019,” Rome, Italy, 2019.
[34] U.S. President’s Malaria Initiative, “Madagascar: Malaria Operational Plan FY 2017,” Washington, D.C., 2017.
[35] S. Barmania, “Madagascar’s Health Challenges,” Lancet, vol. 386, pp. 729–730, 2015.
[36] WFP, “Madagascar Country Brief August 2020,” Rome, Italy, 2020.

Climate change is expected to have a significant influence on the ecology and distribution of tropical ecosystems, though the magnitude, rate and direction of these changes are uncertain [28]. With rising temperatures and increased frequency and intensity of droughts, wetlands and riverine systems are increasingly at risk of being disrupted and altered, with structural changes in plant and animal populations. Increased temperatures and droughts can also impact succession in forest systems while concurrently increasing the risk of invasive species, all of which affect ecosystems. In addition to these climate drivers, low agricultural productivity and population growth might motivate unsustainable agricultural practices resulting in increased deforestation, fires and soil erosion. In turn, soil erosion, along with heavy precipitation and storms, facilitate the occurrence of landslides, threatening human lives, infrastructure and natural resources [29].

Species richness

Model projections of species richness (including amphibians, birds and mammals) and tree cover for Madagascar are shown in Figure 16 and 17, respectively. The models applied for this analysis show particularly strong agreement on the development of species richness: Under RCP6.0, species richness is expected to decrease almost all over Madagascar, in some parts by up to 50 % (Figure 16). Under RCP2.6, models are far less certain, projecting slight increases in small patches across Madagascar.

Tree cover

With regard to tree cover, model results are very uncertain and only small changes are projected under both RCPs (Figure 17). Hence, no clear tree cover trends can be identified.

It is important to keep in mind that the model projections exclude any impacts on biodiversity loss from human activities such as land use, which have been responsible for significant losses of global biodiversity in the past, and are expected to remain its main driver in the future [30]. In recent years, Madagascar’s vegetation has experienced profound disturbances due to population pressure and increasing demand for firewood as well as agricultural land, leading to high rates of slash-and-burn activities, which are one of the main drivers behind deforestation [17]. The country has lost 3.89 million ha of tree cover between 2001 and 2019, which is equivalent to a 23 % decrease of national forest area [31].

References

[17] J. Busch et al., “Climate Change and the Cost of Conserving Species in Madagascar,” Conserv. Biol., vol. 26, no. 3, pp. 408–419, 2012, doi: 10.1111/j.1523-1739.2012.01838.x.
[29] V. J. Ramasiarinoro, L. Andrianaivo, and E. Rasolomanana, “Landslides and Associated Mass Movements Events in the Eastern Part of Madagascar: Risk Assessment, Land-Use Planning, Mitigation Measures and Further Strategies,” Madamines, vol. 4, pp. 28–41, 2012.
[30] IPBES, “Report of the Plenary of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services on the Work of Its Seventh Session,” n.p., 2019.
[31] Global Forest Watch, “Madagascar,” 2019. Online available: www.globalforestwatch.org [Accessed: Sep. 28, 2020].

Climate change is expected to significantly affect Madagascar’s infrastructure through extreme weather events. High precipitation amounts can lead to the flooding of roads, while high temperatures can cause roads, bridges and coastal infrastructures to develop cracks and degrade more quickly. This will require earlier replacement and lead to higher maintenance and replacement costs. The poorly developed railway network and limited inland waterway transportation increase Madagascar’s reliance on road transportation [24]. Roads, however, are in very poor condition with the majority being unpaved and difficult to access, especially during the rainy season. With an estimated road network of 31 640 km, Madagascar has one of the lowest road densities in the world [24]. Investments will have to be made to build climate-resilient road networks.

Extreme weather events also have devastating effects on human settlements and economic production sites, especially in urban areas with high population densities like Antananarivo, Toamasina or Antsirabe. Informal settlements are particularly vulnerable to extreme weather events: Makeshift homes are often built in unstable geographical locations including steep slopes or riverbanks, where strong winds and flooding can lead to loss of housing, contamination of water, injury or death. Dwellers usually have a low adaptive capacity to respond to such events due to high levels of poverty and lack of risk-reducing infrastructures. For example, the tropical Cyclone Belna made landfall on the north-western coast of Madagascar in December 2019, affecting 128 000 people [8]. The district of Soalala was hit particularly hard, recording damages to roads, electricity posts and wells [25]. Flooding and droughts will also have an impact on hydropower generation: Madagascar draws 29 % of its energy from hydropower, with a total installed capacity of 162 MW in 2014 [26]. However, variability in precipitation and climatic conditions could severely disrupt hydropower generation.

Despite the risk of infrastructure damage being likely to increase due to climate change, precise predictions of the location and the extent of exposure are difficult to make. For example, projections of river flood events are subject to substantial modelling uncertainty, largely due to the uncertainty of future projections of precipitation amounts and their spatial distribution, affecting flood occurrence (see also Figure 4). In the case of Madagascar, median projections show little change in national road exposure to river floods (Figure 13). In the year 2000, 1.6 % of major roads were exposed to river floods at least once a year. By 2080, this value is projected to not change under RCP6.0 and to increase to 2.0 % under RCP2.6. This difference is in line with precipitation trends for Madagascar. The exposure of urban land area to river floods is projected to change only slightly under both RCP (Figure 14).

With the exposure of the GDP to heatwaves projected to increase from around 0.3 % in 2000 to 2.4 % (RCP2.6) and 4.8 % (RCP6.0) by 2080 (Figure 15), it is recommended that policy planners start identifying heat-sensitive economic production sites and activities, and integrating climate adaptation strategies such as improved solar-powered cooling systems, “cool roof” isolation materials or switching the operating hours from day to night [27].

References

[24] Logistics Cluster and WFP, “Madagascar Logistics Infrastructure.” Online available: https://dlca.logcluster.org/display/public/DLCA/2+Madagascar+Logistics+Infrastructure [Accessed: Sep. 30, 2020].
[25] OCHA, “Southern Africa: Cyclone Belna (Flash Update No. 5),” New York, 2019.
[26] World Bank, “Small Hydropower Resource Mapping in Madagascar: Hydropower Atlas,” Washington, D.C., 2017.
[27] M. Dabaieh, O. Wanas, M. A. Hegazy, and E. Johansson, “Reducing Cooling Demands in a Hot Dry Climate: A Simulation Study for Non-Insulated Passive Cool Roof Thermal Performance in Residential Buildings,” Energy Build., vol. 89, pp. 142–152, 2015, doi: 10.1016/j.enbuild.2014.12.034.

Smallholder farmers in Madagascar are increasingly challenged by the uncertainty and variability of weather caused by climate change [21]. Since crops are predominantly rainfed, yields highly depend on water availability from precipitation and are prone to drought. Both the length and the intensity of the rainy season are becoming more and more unpredictable and the availability and use of irrigation facilities remains limited: In 2013, only 60 % of the estimated irrigation potential of 1.5 million ha (42 % of total national crop land) was equipped for irrigation [9]. Constraints to the implementation of adaptation strategies usually include limited access to technical equipment, formal credit and extension services [21]. The main irrigated crop is rice, and while temperature increases could be beneficial where low temperatures are currently a limiting factor to the growth of rice, prolonged periods of high temperatures in combination with strong winds could as well have devastating impacts on rice yields [22], [23]. Drier conditions also facilitate the spread of invasive species including the fall armyworm, which caused a yield loss of 47 % for maize in Madagascar in 2018 [8].

Crop land exposure to drought

Currently, the high uncertainty of projections regarding water availability (Figure 10) translates into high uncertainty of drought projections (Figure 11). According to the median over all models employed for this analysis, the national crop land area exposed to at least one drought per year will increase from 0.4 % in 2000 to 1.4 % and 2.6 % in 2080 under RCP2.6 and RCP6.0, respectively. Under RCP6.0, the likely range of drought exposure of the national crop land area per year widens from 0.04–0.8 % in 2000 to 0.9–6.5 % in 2080. The very likely range widens from 0–1.4 % in 2000 to 0.4–9 % in 2080. This means that some models project a tenfold increase of drought exposure over this time period.

Crop yield projections

In terms of yield projections, model results indicate a negative trend for cassava and maize under both RCPs (Figure 12)⁶. By 2080, compared to the year 2000, yields of cassava and maize are projected to decrease by 3.8 % and 2.7 % under RCP2.6, and by 2.6 % and 2.8 % under RCP6.0. Yields of rice and sugar cane, on the other hand, are projected to increase by 2.7 % and 9.7 % under RCP6.0 and to not change under RCP2.6. A possible explanation for the more positive results under RCP6.0 is that rice, sugar cane and cassava are so-called C3 plants, which follow a different metabolic pathway than, for example, maize (a C4 plant), and benefit more from the CO₂ fertilisation effect under higher concentration pathways. The later drop for cassava can be explained by decreasing levels of precipitation after 2050 under RCP6.0 (see Figure 5). Although some yield changes may appear small at the national level, they will likely increase more strongly in some areas and, conversely, decrease more strongly in other areas as a result of climate change impacts.

Overall, adaptation strategies such as switching to improved varieties in climate change sensitive crops need to be considered, yet should be carefully weighed against adverse outcomes, such as a resulting decline of agro-biodiversity and loss of local crop types.

⁶ Modelling data is available for a selected number of crops only. Hence, the crops listed on page 2 may differ.

References

[8] FEWS NET, “Madagascar Food Security Outlook: February to September 2020,” n.p., 2020.
[9] FAO, “AQUASTAT Main Database: Irrigation and Drainage Development.” Online available: http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en [Accessed: Dec. 07, 2020].
[21] C. A. Harvey et al., “Extreme Vulnerability of Smallholder Farmers to Agricultural Risks and Climate Change in Madagascar,” Philos. Trans. R. Soc. B Biol. Sci., vol. 369, no. 1639, 2014, doi: 10.1098/rstb.2013.0089.
[22] E. Gerardeaux, M. Giner, A. Ramanantsoanirina, and J. Dusserre, “Positive Effects of Climate Change on Rice in Madagascar,” Agron. Sustain. Dev., vol. 32, no. 3, pp. 619–627, 2012, doi: 10.1007/s13593-011-0049-6.
[23] AQUASTAT, Irrigation in Africa in Figures. Rome, Italy: FAO, 2005.

Madagascar is known for its abundant water resources from precipitation. However, these water resources are unevenly distributed across the country. While parts of the eastern coast of Madagascar receive more than 3,300 mm of precipitation annually, the south-west receives as little as 400 mm and is characterised by a semi-arid to arid climate [18]. For instance, in the 2019 / 2020 rainy season, the very south-west of the country, particularly northern Amboasary and parts of Ambovombe, Tsihombe and Bekily, recorded below-average precipitation levels, threatening agricultural crops which were just sown or at the flowering stage [8]. In contrast, northern Madagascar recorded above-average precipitation levels, which resulted in flooding in several regions, including Alaotra Mangoro, Analamanga, Betsiboka, Boeny, Melaky, and Sofia [19]. Increasingly heavy precipitation events and cyclones already have devastating impacts on smallholder farmers. In a study conducted among smallholder farmers in the aftermath of the 2012 cyclone Giovanna, 81 % of farmers reported losing crops and 70 % reported damages to stored grains, resulting in prolonged periods with insufficient food for household consumption [20].

Per capita water availability

Current projections of water availability in Madagascar display high uncertainty under both GHG emissions scenarios. Assuming a constant population level, multi-model median projections suggest a decrease of 13 % (RCP2.6) and 15 % (RCP6.0) in per capita water availability by the end of the century (Figure 9A). Yet, when accounting for population growth according to SSP2 projections⁵, per capita water availability for Madagascar is projected to decline more dramatically, i.e. by 78 % under both RCPs by 2080 relative to the year 2000 (Figure 9B). While this decline is primarily driven by population growth rather than climate change, it highlights the urgency to invest in water saving measures and technologies for future water consumption after 2030.

Spatial distribution of water availability

Projections of future water availability from precipitation vary depending on the region and scenario (Figure 10). In line with precipitation projections, water availability is projected to decrease by up to 25 % in the north and east of Madagascar under RCP6.0. Under RCP2.6, models project decreases of up to 20 % for the north-east with simultaneous increases of up to 40 % in the otherwise very dry south-west of the country. The partial increase in water availability projected under RCP2.6 is based on a constant population level. Hence, water saving measures are likely to become important for Madagascar’s rapidly growing population.

⁵ Shared Socio-economic Pathways (SSPs) outline a narrative of potential global futures, including estimates of broad characteristics such as country level population, GDP or rate of urbanisation. Five different SSPs outline future realities according to a combination of high and low future socio-economic challenges for mitigation and adaptation. SSP2 represents the “middle of the road”-pathway.

References

[18] S. Lange, “EartH2Observe, WFDEI and ERA-Interim Data Merged and Bias-Corrected for ISIMIP (EWEMBI).” GFZ Data Service, Potsdam, Germany, 2016, doi: 10.5880/pik.2016.004.
[19] NASA Earth Observatory, “Flood Waters Overwhelm Northern Madagascar,” 2020. Online available: https://earthobservatory.nasa.gov/images/146225/flood-waters-overwhelm-northern-madagascar [Accessed: Sep. 28, 2020].
[20] Z. L. Rakotobe et al., “Strategies of Smallholder Farmers for Coping with the Impacts of Cyclones: A Case Study from Madagascar,” Int. J. Disaster Risk Reduct., vol. 17, pp. 114–122, 2016, doi: 10.1016/j.ijdrr.2016.04.013.

Temperature

In response to increasing greenhouse gas (GHG) concentrations, air temperature over Madagascar is projected to rise by 1.5 to 3.2 °C (very likely range) by 2080 relative to the year 1876, depending on the future GHG emissions scenario (Figure 2). Compared to pre-industrial levels, median climate model temperature increases over Madagascar amount to approximately 1.6 °C in 2030 and 1.8 °C in both 2050 and 2080 under the low emissions scenario RCP2.6. Under the medium / high emissions scenario RCP6.0, median climate model temperature increases amount to 1.5 °C in 2030, 2.0 °C in 2050 and 2.8 °C in 2080.

Very hot days

In line with rising mean annual temperatures, the annual number of very hot days (days with daily maximum temperature above 35 °C) is projected to rise substantially and with high certainty, in particular over western Madagascar (Figure 3). Under the medium / high emissions scenario RCP6.0, the multi-model median, averaged over the whole country, projects 5 more very hot days per year in 2030 than in 2000, 8 more in 2050 and 24 more in 2080. In some parts, especially on the western coast of Madagascar, this amounts to about 90 days per year by 2080.

Sea level rise

In response to globally increasing temperatures, the sea level off the coast of Madagascar is projected to rise (Figure 4). Until 2050, very similar sea levels are projected under both emissions scenarios. Under RCP6.0 and compared to year 2000 levels, the median climate model projects a sea level rise by 11 cm in 2030, 22 cm in 2050, and 43 cm in 2080. This threatens Madagascar’s coastal communities and may cause saline intrusion in coastal waterways and groundwater reservoirs.

Precipitation

Future projections of precipitation are less certain than projections of temperature change due to high natural year-to-year variability (Figure 5). Out of the four climate models underlying this analysis, two models project a decrease in mean annual precipitation over Madagascar and two models project little change. Median model projections show a precipitation decrease of 114 mm per year by 2080 under RCP6.0, while median model projections for RCP2.6 show a decrease at the beginning of the century, which settles at a decrease of 47 mm by 2080 compared to year 2000. Higher greenhouse gas emissions suggest an overall drier future for Madagascar.

Heavy precipitation events

In response to global warming, heavy precipitation events are expected to become more intense in many parts of the world due to the increased water vapour holding capacity of a warmer atmosphere. At the same time, the number of days with heavy precipitation events is expected to increase. This tendency is also reflected in climate projections for Madagascar (Figure 6), with climate models projecting a slight increase in the number of days with heavy precipitation events, from 7.0 days per year in 2000 to 7.5 and 7.2 days per year in 2080 under RCP2.6 and RCP6.0, respectively.

Soil moisture

Soil moisture is an important indicator for drought conditions. In addition to soil parameters and management, it depends on both precipitation and temperature, as higher temperatures translate to higher potential evapotranspiration. Projections for annual mean soil moisture values for the topsoil (from the surface to a depth of 1 metre) show a slight decrease under RCP2.6 and a stronger decrease of 5 % under RCP6.0 by 2080 compared to the year 2000 (Figure 7). However, looking at the different models underlying this analysis, there is large year-to-year variability and modelling uncertainty, with some models projecting a much stronger decrease in soil moisture.

Potential evapotranspiration

Potential evapotranspiration is the amount of water that would be evaporated and transpired if sufficient water was available at and below land surface. Since warmer air can hold more water vapour, it is expected that global warming will increase potential evapotranspiration in most regions of the world. In line with this expectation, hydrological projections for Madagascar indicate a stronger rise of potential evapotranspiration under RCP6.0 than under RCP2.6 (Figure 8). Under RCP6.0, potential evapotranspiration is projected to increase by 3 % in 2030, 4 % in 2050 and 8 % in 2080 compared to year 2000 levels.

⁴ Changes are expressed relative to year 1876 temperature levels using the multi-model median temperature change from 1876 to 2000 as a proxy for the observed historical warming over that time period.

Climate change threatens the health and sanitation sector through more frequent incidences of heatwaves, floods, droughts and storms. Among the key health challenges in Mauritania are morbidity and mortality through vector-borne diseases such as malaria, waterborne diseases related to extreme weather events (e.g. flooding) such as diarrhoea and cholera, as well as tuberculosis, HIV and respiratory diseases [29]. Climate change is also likely to impact food and water supply, thereby increasing the risk of malnutrition, hunger and death by famine. Many of these challenges are expected to become more severe under climate change. According to the World Health Organization (WHO), Mauritania recorded around 174 000 cases of malaria in 2018 [30]. Climate change is likely to have an impact on malaria transmission periods and the geographic range of vector-borne diseases: In Mauritania, the general malaria risk is projected to fall due to rising temperatures [31]. However, some regions are likely to become more vulnerable to malaria, for instance, due to more frequent incidences of flooding [32]. Climate change also poses a threat to food security and malnutrition, particularly for subsistence farmers. While chronic malnutrition is generally high at 19.6 %, it could further increase due to the consequences of the COVID-19 pandemic [33]. According to the WHO, more than 900 000 people faced food insecurity in June 2020, which is an increase of 48 % within six months [33].

Exposure to heatwaves

Rising temperatures will result in more frequent heatwaves in Mauritania, leading to increased heat-related mortality. Under RCP6.0, the population affected by at least one heatwave per year is projected to increase from 6 % in 2000 to 34 % in 2080 (Figure 18).

Heat-related mortality

Furthermore, under RCP6.0, heat-related mortality will likely increase from about 2 to about 7 deaths per 100 000 people per year by 2080, which translates to an increase by a factor of more than three towards the end of the century compared to year 2000 levels, provided that no adaptation to hotter conditions will take place (Figure 19). Under RCP2.6, heat-related mortality is projected to increase to about 4 deaths per 100 000 people per year in 2080.

References

[29] Republique Islamique de Mauritanie, “Rapport d’analyse de situation du secteur de la santé,” Nouakchott, Mauritania, 2011.
[30] WHO, “World Malaria Report 2019,” Rome, Italy, 2019.
[31] C. Caminade, A. E. Jones, R. Ross, and G. Macdonald, “Malaria in a Warmer West Africa,” Nat. Clim. Chang., vol. 6, no. November, pp. 984–985, 2016.
[32] R. Boyce, R. Reyes, M. Matte, M. Ntaro, E. Mulogo, J. P. Metlay, L. Band, and M. J. Siedner, “Severe Flooding and Malaria Transmission in the Western Ugandan Highlands: Implications for Disease Control in an Era of Global Climate Change,” J. Infect. Dis., vol. 214, pp. 1403–1410, 2016.
[33] WFP, “Mauritania Country Brief: June 2020,” Rome, Italy, 2020.

Climate change is expected to have a significant influence on the ecology and distribution of tropical ecosystems, though the magnitude, rate and direction of these changes are uncertain [27]. With rising temperatures and increased frequency and intensity of droughts, wetlands and riverine systems are increasingly at risk of being converted to other ecosystems, with plant populations being succeeded and animals losing habitats. Increased temperatures and droughts can also impact succession in forest systems while concurrently increasing the risk of invasive species, all of which affect ecosystems. In addition to these climate drivers, low agricultural productivity and population growth might motivate further agricultural expansion resulting in increased deforestation, land degradation and forest fires, all of which will impact animal and plant biodiversity.

Species richness

Model projections of species richness (including amphibians, birds and mammals) and tree cover for Mauritania are shown in Figure 16 and 17, respectively. The models applied for this analysis show particularly strong agreement on the development of species richness: Under RCP2.6, south-western Mauritania is expected to gain up to 30 % of animal species due to climate change. This trend will intensify under RCP6.0, in addition to a decrease of up to 50 % in the south-east of the country (Figure 16).

Tree cover

With regard to tree cover, model results are very uncertain and of low magnitude under both RCPs (Figure 17), which could also relate to the fact that tree cover in Mauritania is generally sparse. Overall, no reliable estimations on the development of tree cover can be made.

It is important to keep in mind that the model projections exclude any impacts on biodiversity loss from human activities such as land use, which have been responsible for significant losses of global biodiversity in the past, and are expected to remain its main driver in the future [28]. In recent years, Mauritania’s vegetation has experienced profound disturbances due to population pressure and increasing demand for pastures, agricultural land and firewood, leading to high rates of deforestation [25]. The country has lost 86 000 ha of forest cover in the period from 2001 to 2016, which is equivalent to a 28 % decrease [2].

References

[2] World Bank, “World Bank Open Data,” 2019. Online available: https://data.worldbank.org [Accessed: 31-Jan-2020].
[25] N. K. Dia, A. A. Bayod-Rújula, N. Mamoudou, M. Diallo, C. S. Ethmane, and B. O. Bilal, “Energy Context in Mauritania,” Energy Sources, Part B Econ. Plan. Policy, vol. 12, no. 2, pp. 182–190, 2017.
[27] T. M. Shanahan, K. A. Hughen, N. P. McKay, J. T. Overpeck, C. A. Scholz, W. D. Gosling, C. S. Miller, J. A. Peck, J. W. King, and C. W. Heil, “CO2 and Fire Influence Tropical Ecosystem Stability in Response to Climate Change,” Nat. Publ. Gr., no. July, pp. 1–8, 2016.
[28] IPBES, “Report of the Plenary of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services on the Work of Its Seventh Session,” n.p., 2019.

Climate change is expected to significantly affect Mauritania’s infrastructure through extreme weather events. High precipitation amounts can lead to the flooding of roads, while high temperatures can cause roads, bridges and protective structures to develop cracks and degrade more quickly. This will require earlier replacement and lead to higher maintenance and replacement costs. The near-total absence of passenger railways and limited airport facilities increase Mauritania’s reliance on road transportation [23]. The country has only 2 743 km of paved roads, which is one of the lowest densities on the continent [23]. While some roads become impassable during the rainy season, cutting off villages and rural communities, others are obscured by drifting sand during the dry season [23]. Investments will have to be made to build climate-resilient and safe road networks.

Extreme weather events will also have devastating effects on human settlements and economic production sites, especially in urban areas with high population densities like Nouakchott or Nouadhibou. Informal settlements are particularly vulnerable to extreme weather events: Makeshift homes are often built in unstable geographical locations including steep slopes or river banks, where flooding can lead to loss of housing, contamination of water, injury or death. Dwellers usually have low adaptive capacity to respond to such events due to high levels of poverty and a lack of risk-reducing infrastructures. For example, heavy precipitation events during the 2019 rainy season caused flooding in the region of Guidimakha in southern Mauritania, affecting 33 600 people [24]. The city of Sélibaby was hit particularly hard, recording damages to houses, markets and infrastructure as well as disruptions to water and energy supplies. Flooding and droughts will also affect hydropower generation: Together with Senegal and Mali, Mauritania shares the Manantali Dam, which has a total installed capacity of 200 MW and which is located on the Bafing River in Mali, a tributary of the Senegal River [25]. However, variability in precipitation and climatic conditions could severely disrupt hydropower generation in the whole region.

Despite the risk of infrastructure damage being likely to increase, precise predictions of the location and the extent of exposure are difficult to make. For example, projections of river flood events are subject to substantial modelling uncertainty, largely due to the uncertainty of future projections of precipitation amounts and their spatial distribution, affecting flood occurrence (see also Figure 4). In the case of Mauritania, median projections show almost no change in national road exposure to river floods (Figure 13). In the year 2000, 0.4 % of major roads were exposed to river floods at least once a year. By 2080, this value is projected to not change under RCP2.6 and to decrease to 0.3 % under RCP6.0. In a similar way, exposure of urban land area to river floods is projected to change only marginally under RCP6.0 from 0.05 % in 2000 to 0.14 % in 2080, with no change under RCP2.6 (Figure 14).

With the exposure of the GDP to heatwaves projected to increase dramatically from around 6 % in 2000 to 25 % (RCP2.6) and 35 % (RCP6.0) by 2080 (Figure 15), it is recommended that policy planners start identifying heat-sensitive economic production sites and activities, and integrating climate adaptation strategies such as improved solar-powered cooling systems, “cool roof” isolation materials or switching the operating hours from day to night [26].

References

[23] Logistics Cluster and WFP, “Mauritanie Infrastructures Logistiques,” 2020. Online available: https://dlca.logcluster.org/display/public/DLCA/2+Mauritania+Infrastructures+Logistiques [Accessed: 14-Jul-2020].
[24] IFRC, “Emergency Plan of Action (EPoA): Mauritania – Floods in Guidimakha,” Geneva, Switzerland, 2019.
[25] N. K. Dia, A. A. Bayod-Rújula, N. Mamoudou, M. Diallo, C. S. Ethmane, and B. O. Bilal, “Energy Context in Mauritania,” Energy Sources, Part B Econ. Plan. Policy, vol. 12, no. 2, pp. 182–190, 2017.

Smallholder farmers in Mauritania are increasingly challenged by the uncertainty and variability of weather caused by climate change [16], [17]. Since crops are predominantly rainfed, yields highly depend on water availability from precipitation and are prone to drought. However, the length and intensity of the rainy season is becoming increasingly unpredictable and the use of irrigation facilities remains limited: In 2004, less than 10 % of the estimated irrigation potential of 250 000 ha (0.6 % of total national crop land) were irrigated [6]. The main irrigated crop is rice, in addition to maize, sorghum and vegetables [22]. Especially in central and northern Mauritania, soils are sandy and poor in nutrients, which complicates irrigation and crop production [22].

Crop land exposure to drought

Currently, the high uncertainty of projections regarding water availability (Figure 10) translates into high uncertainty of drought projections (Figure 11). According to the median over all models employed for this analysis, the national crop land area exposed to at least one drought per year will increase from 6 % in 2000 to 10 % in 2080 under RCP6.0 and decrease to 5 % under RCP2.6. Under RCP6.0, the likely range of drought exposure of the national crop land area per year widens from 0.3–19 % in 2000 to 0.6–36 % in 2080. The very likely range widens from 0–20 % in 2000 to 0.01–44 % in 2080. This means that some models project a doubling of drought exposure over this time period, while others project no change.

Crop yield projections

In terms of yield projections, model results indicate high uncertainty (Figure 12)⁶. Compared to the year 2000, yields of cow peas are projected to decrease by 6 % under RCP2.6 and increase by 4 % under RCP6.0. A possible explanation for the positive results under RCP6.0 is that cow peas are so-called C3 plants, which follow a different metabolic pathway than maize, millet and sorghum (C4 plants), and benefit more from the CO₂ fertilisation effect under higher concentration pathways. For maize, the trend is reversed: Under RCP2.6, yields are projected to slightly increase by 3 % and decrease by 11 % under RCP6.0. Millet and sorghum are projected to gain 8 % under RCP2.6 and 6 % under RCP6.0. The higher increases under RCP2.6 can be explained by higher precipitation projections under RCP2.6 (Figure 5). Finally, yields of rice are projected to not change under either RCP, however, some models project an increase of up to 200 %. Although some yield changes may appear small at the national level, they will likely increase more strongly in some areas and, conversely, decrease more strongly in other areas as a result of climate change impacts.

Overall, adaptation strategies such as switching to improved varieties in climate change-sensitive crops need to be considered, yet should be carefully weighed against adverse outcomes, such as a resulting decline of agro-biodiversity and loss of local crop types.

⁶ Modelling data is available for a selected number of crops only. Hence, the crops listed on page 2 may differ. Maize, millet and sorghum are modelled for all countries, except for Madagascar.

References

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[17] P. Ozer, Y. C. Hountondji, J. Gassani, B. Djaby, and D. L. F, “Évolution récente des extrêmes pluviométriques en Mauritanie (1933–2010),” XXVIIeme Colloq. l’Association Int. Climatol., pp. 394–400, 2014.
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