Climate change risks and adaptation options for Madagascar

Climate change poses an increasing threat to achieving development goals and is often considered in development plans and project designs. However, there have been challenges in the effective implementation of those plans, particularly in the sustained engagement of the communities to undertake adaptive actions, but also due to insufficient scientific information to inform management decisions. Madagascar is a country rich in natural capital and biodiversity but with high levels of poverty, food insecurity, population growth, and exploitation of natural resources. The country faces development and environmental challenges that may be intensified by climate change. The objective of this review is to provide a synthesis of the best-available information regarding climate change impacts on sectoral interests in Madagascar. To do this, we conducted a review of recent literature and conducted formal discussions with development agencies, non-government organizations (NGOs), and other stakeholders. Climate risks in Madagascar include increasing temperatures, reduced and more variable precipitation, more frequent droughts, more intense cyclones, and rising sea levels. We synthesized the observed and projected impacts of climate change on water resources, agriculture, human health, coastal ecosystems, fisheries, and terrestrial ecosystems and ecosystem services, and we discuss ongoing climate adaptation and mitigation activities. Because sectoral challenges and opportunities are linked, coordination among development organizations would be beneficial as they create new climate adaptation and mitigation initiatives. RÉSUMÉ. Le changement climatique présente une menace croissante pour atteindre les objectifs de développement et est souvent pris en considération dans les plans de développement et les conceptions de projet. Toutefois, certains défis sont survenus dans la mise en oeuvre effective de ces plans, en particulier dans l'engagement durable des communautés à adopter des mesures d'adaptation, mais aussi en raison d'un manque d'information scientifique pour étayer les décisions de la direction. Malgré sa richesse en ressources naturelles et en biodiversité, Madagascar est un pays accablé par une grande pauvreté, l'insécurité alimentaire, une forte croissance démographique et l'exploitation de ses ressources naturelles. Le pays fait face à des défis en termes de développement et d'environnement qui pourraient être intensifiés par le changement climatique. Ce document a pour but de présenter une synthèse des meilleures informations disponibles concernant les impacts du changement climatique sur les intérêts sectoriels à Madagascar. Pour ce faire, nous avons réalisé une analyse des articles récemment publiés et organisé des entretiens formels avec des agences de développement, des organisations nongouvernementales (ONG) et d'autres parties prenantes. Les risques climatiques à Madagascar comprennent une hausse des températures, des précipitations plus rares et plus variables, des sécheresses plus fréquentes, des cyclones plus intenses et l'élévation du niveau des océans. Nous avons synthétisé les impacts observés et prévus du changement climatique sur les ressources en eau, l'agriculture, la santé humaine, les écosystèmes côtiers, les pêcheries et les écosystèmes terrestres ainsi que sur les services des écosystèmes, et nous évoquons l'adaptation continue au climat et les mesures d'atténuation. Dans la mesure où les défis et les opportunités sectoriels sont liés, une bonne coordination entre les organismes de développement serait bénéfique, car elle permettrait de nouvelles adaptations au climat et des initiatives d'atténuation.


INTRODUCTION
Climate change impacts on islands globally are severe and exacerbated by their unique geophysical characteristics (Nurse et al. 2014). Across islands, important sectors, including agriculture, water supply, fisheries, transportation, health, biodiversity, and livelihoods, are interconnected and highly vulnerable to the threats of increasing temperatures, sea-level rise, precipitation fluctuations, and changes in severity and frequency of extreme events (Nurse et al. 2014, Veron et al. 2019. Some islands, like Madagascar, have been isolated from the mainland for so long that they contain high numbers of endemic species, making them important contributors to biodiversity locally and globally (Myers et al. 2000, Kier et al. 2009). Habitat fragmentation and deforestation have influenced the natural resilience of island ecosystems to the impacts of climate change (Hannah et al. 2008).
Integration of climate adaptation into development plans is needed to reduce the multiple interacting effects of climate change across sectors (Nurse et al. 2014).
Madagascar is a prime example of the vulnerability of islands to climate change, with climate impacts permeating across multiple diverse sectors. Madagascar is a country particularly rich in natural capital, given its 90% endemic biodiversity (Rakotondravony et al. 2018). The island of Madagascar has lost much of its forested habitat, increasing the vulnerability of communities, biodiversity, and ecosystem services to climate change (Hannah et al. 2008). Chesney and Moran et al. (2016) developed a climate security vulnerability model to map climate change vulnerability and security concerns. Results suggested that Madagascar has moderate to low governance capabilities to In 2010, Madagascar adopted a national policy against climate change that aims to reinforce national resilience to climate change, reduce national vulnerability, and develop approaches for low carbon emissions (Cochrane et al. 2019). A national adaptation plan (NAP) is currently being prepared (CPGU andBNCCC 2017, Cochrane et al. 2019). To support the development and implementation of the NAP, a need exists to base conservation and adaptation decisions on climate change impacts on both human and biodiversity-related sectors (Hannah et al. 2008). A previous working group assessed potential impacts of climate change on Madagascar's ecosystems and human well-being and made recommendations including increased ecological protection and restoration, integrated coastal zone management, and agricultural intensification and diversification (Conservation International and WWF 2008). It is time for an updated assessment of the literature so that adaptation plans can reflect the current state of climate change science. To address this need, the primary objective of this work is to provide an updated synthesis of the best-available information regarding the documented and projected trends and impacts of climate change on specific sectors in Madagascar and to provide potential adaptation options. We focus specifically on adaptation (i.e., managing climate change effects) rather than mitigation (i.e., reducing emissions), although some actions (e.g., reducing deforestation) are important for both adaptation and mitigation. We review the literature and report on in-person and over-thephone discussions with key stakeholders in the Malagasy government, key international development funding agencies, and local and international NGOs. The review and interviews covered country-level climate change impacts as well as effects on six key sectors: water resources, agriculture, human health, coastal ecosystems, fisheries, and terrestrial ecosystems and ecosystem services.

Literature review
A literature review was conducted in January 2020 using Publish or Perish (Harzing 2007) to initiate searches in Google Scholar. Years were set 2014-2020 to capture the most recent literature. The following search strings were entered into the "keywords" field and returned the following number of peer-reviewed papers: . Agriculture: "Madagascar" AND "agriculture" AND ("climate change" OR "global warming") AND ("temperature" OR "precipitation" OR "drought" OR "sea level rise" OR "cyclones" OR "extreme weather events").

results
We conducted a systematic review of the top 100 most relevant and top 50 most cited papers. We first read through article titles and abstracts and excluded papers that were not related to climate change impacts or management strategies in the region. We conducted full text reviews of all papers with relevant titles and abstracts (106 papers).
Our initial literature search was conducted in English, which may have caused us to miss relevant research published in French, Malagasy, or another language. However, in addition to our formal literature search, we also reviewed reports and project overview documents that were opportunistically sent to us by stakeholder groups, including a review in French of recent

Temperature trends
Observed air and coastal water temperatures have been increasing across Madagascar (Niang et al. 2015, Cochrane et al. 2019, Raholijao et al. 2019. Maximum air temperatures increased at a rate of 0.23°C per decade, and sea surface temperatures in the western Indian ocean increased by 0.60°C between 1950 and 2009 (Raholijao et al. 2019). Mean, maximum, and annual temperatures are projected to increase under all greenhouse gas emission scenarios (Rakotondravony et al. 2018). Under a high emissions scenario (representative concentration pathways, i.e., RCP 8.5), mean annual temperature is projected to rise by 4.1°C by 2100 (WHO 2016), which is higher than previous estimates . Under a scenario in which emissions are greatly reduced and even reversed (RCP 2.6), warming could be limited to 1.1°C (WHO 2016).
There has been a warming trend in the ocean since at least 2005 (IPCC 2019). By 2100, the ocean is very likely to warm by two to four times more under RCP 2.6 and five to seven times more under RCP 8.5 compared with the observed changes since 1970 (IPCC 2019).

Precipitation trends
Annual rainfall has decreased across most weather stations in Madagascar, although this trend is weak compared to interannual variability (Raholijao et al. 2019). In the western part of the island, precipitation has become more intense (Rakotondravony et al. 2018), and more extreme precipitation is expected in parts of the island (Chesney and Moran 2016). More dry days are projected as well. Under a high emissions scenario, the longest dry spell is projected to increase by about 20 days on average by 2100 (WHO 2016). Local weather trends can also be impacted by deforestation and land-use change (Ghulam 2014).

Sea-level rise
Sea-level rise (SLR) in Madagascar has been 1.57 mm/year between 1993 and 2017 (Raholijao et al. 2019). Global SLR is projected to be higher by the end of this century under all scenarios, including those compatible with achieving the longterm temperature goal set out in the Paris Agreement (IPCC 2019). There is medium confidence that the global mean sea level (GMSL) will rise between 0.43 m (0.29-0.59 m; RCP 2.6) and 0.84 m (0.61-1.10 m; RCP 8.5) by 2100 relative to 1986-2005. Relative SLR depends on a variety of factors. Differences from the global mean can be greater than ±30% in areas of rapid vertical land movements, including those caused by local anthropogenic factors such as groundwater extraction. Global mean sea level, in combination with tides, storm surge, and extreme waves, have an impact on coastal communities. These extreme events are likely to become more frequent in the future (Oppenheimer et al. 2019).

Cyclones and drought
Madagascar has the highest risk of cyclones in Africa; it currently experiences three to four cyclones per year between November and April (Rakotoarison et al. 2018). The eastern, northeastern, and western regions are most affected by cyclones (Mavume et al. 2010). Similar to earlier findings , cyclone intensity is expected to increase in the future (Delille 2011, CPGU and BNCCC 2017, Rakotoarison et al. 2018, whereas the frequency of tropical cyclones making landfall over Madagascar is projected to decrease in 1°, 2°, and 3°C warmer scenarios (Malherbe et al. 2013, Muthige et al. 2018. There has also been a southerly shift in location of cyclone landfalls, which is expected to continue (Fitchett andGrab 2014, Cattiaux et al. 2020). The projected future of a more violent and unpredictable cyclone season could make adaptation by local communities more difficult and destruction of livelihoods and lives more likely (Shultz et al. 2005, Hsiang andJina 2014).
Droughts are most common in southern Madagascar but can also occur in the central highlands and eastern region (CPGU and BNCCC 2017, Rakotoarison et al. 2018). Droughts have become more common in the southern part of the island (WHO 2016) and have increased slightly in northern Madagascar from 1951-2010 (Spinoni et al. 2014). Evapotranspiration increased significantly at some weather stations between 1980 and 2010 which, combined with reduced rainfall, could lead to increased drought conditions (Djaman et al. 2018). Deforestation and poor land-use practices have exacerbated damage caused by floods (Rakotondravony et al. 2018).

Climate change impacts to development agency focus areas in Madagascar
We provide an overview of climate change effects to water resources, agriculture, human health, coastal ecosystems, fisheries, and terrestrial ecosystems in Madagascar. For each sector, we review the observed and projected climate change effects and discuss ongoing or potential adaptation options. Specific examples from the six sectors are presented in Figure 1.

Water resources
Currently, Madagascar is experiencing one of the worst water crises in the world, with numerous challenges associated with water management infrastructure (Rakotondravony et al. 2018, Serele et al. 2019. Only 27% of households have drinking water on site, and 45% of people use unimproved or surface water for drinking (WHO and UNICEF 2017). About 45% of people practice open defecation (WHO and UNICEF 2017). In 2018, an estimated 66% of rural populations and 49% in urban areas were deprived of drinking water (Serele et al. 2019).
In general, the water and sanitation sectors are characterized by poor water management. Numerous inadequacies exist regarding flood risk reduction, pollution exposure, behavior of the general population, budget allocations, and regulatory enforcement. Sanitation facilities are restricted to the perimeters of city centers; many have exceeded their project life and need repair. Many households do not have the infrastructure needed to dispose of waste, including excrement; tens of thousands of cubic meters of waste are poured into the urban network without treatment. https://www.ecologyandsociety.org/vol26/iss4/art36/ Along with poor water quality, this results in water-based diseases that are the main causes of sickness and death. Other natural and anthropogenic pressures such as deforestation, erosion, and saltwater intrusion exacerbate these problems (García-Ruiz et al. 2017, Rakotondravony et al. 2018. Erosion and resulting excessive sedimentation can damage bridges, irrigation ditches, and reservoirs, leading to enormous infrastructure maintenance costs (García-Ruiz et al. 2017).
Because most of the population relies mainly on surface water, the water supply depends heavily on the rainfall regime and is sensitive to any disturbance of the climate, including projected decreases in annual rainfall and increased evapotranspiration. In addition, SLR might increase saltwater intrusion of the groundwater along parts of the coast. These changes are likely to worsen water availability (Rakotondravony et al. 2018). In the region of Antananarivo, surface water might no longer be able to meet water demands by 2025, let alone 2050 or 2100 (Rakotondravony et al. 2018).
Southern Madagascar generally has erratic rainfall and an arid climate, with very poor access to water for domestic and agricultural consumption, making it among the most waterstressed areas of the country ((Serele et al. 2019; Fig. 1). During the dry season, groundwater (the predominant source of water in southwestern Madagascar) becomes even more limited, resulting in extremely poor hygiene practices and very high pressure on functioning water points. Fifty percent of people living in southern Madagascar, about 1.5 million people, required humanitarian assistance in 2020 (WFP 2020). Groundwater recharge is strongly influenced by rainfall pattern and, in some cases, is highly dependent on rainfall from extreme events (i.e., cyclones and tropical storms; Carrière et al. 2021).
On the ground climate adaptation activities and other opportunities: Possible climate adaptation strategies can include organization and sustainable management of water infrastructure, with improved access to potable water (Rakotondravony et al. 2018). Several organizations are working to improve rainwater collection or investing in local water points to provide access at the community level. Providing water at the local level may be more effective given the current governance challenges associated with managing larger pipelines (ADRA interview). The United States Agency for International Development (USAID) is working to improve water, sanitation, and hygiene (WASH) governance, develop public private partnerships to improve water availability and sanitation, and promote messaging and sensitization on key sanitation and hygiene behaviors (USAID WASH interview). Developing integrated water resources management for watersheds, including water supply, flooding, and drought would also be beneficial, although addressing immediate needs has taken priority (USAID WASH interview).

Agriculture
About 62% of the population in Madagascar is rural and mainly dependent on subsistence farming for food security and household income (CIA 2020). Low land availability and limited investment capacity have led much of this population to maintain traditional slash and burn agricultural practices with low use of agricultural inputs, limited soil conservation practices, and poor use of hydro-agricultural infrastructure (Delille 2011, Harvey et al. 2014, Desbureaux and Damania 2018, Llopis 2018, Rakotondravony et al. 2018. Many farmers have low productivity plots of essential food crops such as rice, cassava, corn, and sweet potato (Rakotondravony et al. 2018), and most do not produce enough rice (a staple food for most Malagasy) to feed their household for the year (Harvey et al. 2014). Anthropogenic pressures from farming such as deforestation and silting have been degrading natural resources, including soil, water, and biodiversity (García-Ruiz et al. 2017, Rakotondravony et al. 2018. Smallholder farmers are particularly vulnerable to climate shocks due to dependence on rainfed agriculture, limited land area for growing crops, high poverty, food insecurity, and lack of information and resources to prepare for and cope with extreme events (Harvey et al. 2014, Rakotobe et al. 2016. Crops may respond positively to elevated CO 2 concentrations, but increasing variability of rainfall, more intense cyclones, and increasing temperatures can reduce agricultural production (Lal et al. 2015). Too much rainfall can lead to crop diseases, whereas too little rainfall can be a disaster for rainfed crops (Amusan and Odimegwu 2015). For example, maize production is projected to decrease over large parts of Madagascar due to reduced precipitation (Shi andTao 2014, Ngwakwe 2019). Reduced precipitation and a longer dry season are projected to decrease the growing season by up to 50 days by 2100, especially in southern and western Madagascar (Chesney andMoran 2016, Rakotondravony et al. 2018). Farmers in some areas have already reported a shortening of the rainy season (Delille 2011). Droughts can also lead to outbreaks of migratory locusts that can extend over large areas and destroy entire fields, although this is also impacted by locust control measures (Gay-des-Combes et al. 2017). Madagascar is projected to become more suitable for cassava pests as well (Niang et al. 2015).
Cyclones can destroy crops; associated flooding, especially in areas with high deforestation, can leave behind a layer of sand that ruins plots for cultivation (Llopis 2018). Heavy rainfall, including rainfall associated with cyclones, intensifies depletion of soil nutrients associated with slash-and-burn agriculture, especially if farmers are not using cover crops (Gay-des-Combes et al. 2017).
After agriculture, livestock production is the second most common livelihood in Madagascar (Rakotondravony et al. 2018). Livestock are used for food and as a source of savings. Although there is only limited evidence to date for climate change impacts on livestock production, projected changes in temperature and rainfall amount and distribution could have direct and indirect impacts on livestock (Thornton et al. 2015). Above 30°C, livestock often reduce their food intake. Changes in rainfall could reduce forage quality and quantity and lower the carrying capacity of rangelands. Interactions with other stressors such as rangeland degradation, variability in water access, and fragmentation of grazing areas could compound climate driven impacts (Niang et al. 2015).
On the ground climate adaptation activities and other opportunities: Diversification of livelihoods and species: To deal with changing conditions, farmers might adapt by diversifying their livelihoods, either through growing secondary crops, livestock farming, or other activities such as fishing, crafts, https://www.ecologyandsociety.org/vol26/iss4/art36/ or labor (Delille 2011). Using crop cultivars and livestock breeds that are resilient to drought, pests, salinity, weeds, and/or flooding might also be an effective approach (Thornton et al. 2015, Zougmoré et al. 2018. For example, recent drought-resistant and short-cycle varieties of rice or maize have allowed some farmers to grow an extra season of crops (Delille 2011). Despite the promise of new crop varieties, unexpected challenges may arise in implementation, such as unintended use of seeds, e.g., eating the seeds directly (United Nations Development Programme (UNDP) interview).
Changing agricultural practices and infrastructure: Altering crop planting calendars can increase yields, and farmers in Madagascar have already reported managing planting schedules to avoid hazard-prone times (Delille 2011, Dawson 2016, Kruger 2016. In some areas, shifting the timing of planting may not be effective because rainfall is more erratic and prone to droughts in the middle of the season (Groupement Semis Direct Madagascar (GSDM) interview). Establishing early-warning systems that provide information on the timing, length, and amount of rainfall would be helpful for farmers in determining planting schedules and crops (Asafu-Adjaye 2014). The German development agency Gesellschaft für Internationale Zusammenarbeit (GIZ) has started a hotline that provides a readout of agricultural calendars for peanuts, onion, rice, corn, and ginger based on the caller's location (GIZ interview).
Improving water infrastructure and promoting small to mediumscale irrigation could help farmers deal with variable rainfall (Asafu-Adjaye 2014). Improving soil and water conservation strategies could also be an effective approach (Dawson 2016, Desbureaux and Damania 2018, Zougmoré et al. 2018. Modernizing production infrastructure, intensifying production, and providing training and technical assistance to promote adoption of new techniques or technologies could also help farmers adapt (Asafu-Adjaye 2014, Rakotondravony et al. 2018).
Using fertilization methods that increase soil organic matter content, protecting against erosion (e.g., through reforestation or cover plants), or use of mulching or composting could help with the reduction of soil nutrients (Delille 2011, Gay-des-Combes et al. 2017. Other adaptation options include the use of agroforestry and implementing agricultural insurance to help manage climaterelated shocks (Zougmoré et al. 2018).
Climate-smart agriculture: Two major potential climate-smart agricultural practices, which may be effective when crops are primarily limited by soil moisture, are conservation agriculture (CA) and the system of rice intensification (SRI;Corbeels et al. 2014, Lima 2014, Penot et al. 2018. Conservation agriculture involves maintaining soil coverage and rotating crops, and in some cases, using no-till agricultural practices; this has improved soil quality and increased resilience to weather events, including erratic rainfall (Kirindy Village interview). Maintaining crop residues using CA may also be an effective adaptation technique for livestock (Thornton et al. 2015). System of rice intensification uses techniques to improve soil, water, and nutrient conditions to increase yields without increasing costs (Lima 2014). System of rice intensification can increase rice yields by 25-100% and decrease water use by 25-50%.
Farmers report that SRI crops are more resilient to water and temperature stress and heavy wind and rain from storms (Andrea Mboyerwa 2018).
Access to markets: One challenge for farmers can be finding buyers for their products, especially because middlemen may pay low prices for crops (Kirindy Village interview). Identifying and removing nonclimate barriers for farmers to enter the market may make it easier for farmers to adapt (GIZ interview). Several organizations (e.g., GIZ, Conservation International (CI), USAID, Prosperer) are promoting crop value chains and market access. For example, the Prosperer program under the Madagascar Ministry of Agriculture, Livestock, and Fisheries is supporting rural microenterprises to create links between rural producers and private sector operators (Prosperer interview).

Human health
Lack of adequate health care and disease prevention, malnutrition, and poverty predisposes many people in Madagascar to climate change effects. Most of the population lacks access to adequate health services; for example, 40% of the rural population is more than five kilometers from a health facility and lacks a means of transportation, and bad weather can make it even more difficult to deliver health care in isolated areas. If roads become impassible after weather events, it can limit medicine supply in health centers (Morondava Centre de Santé de Base (CSB2) interview). Many health facilities also lack sufficient human resources and equipment, in some cases including electricity and running water (Morondava CSB2 interview). Natural disasters can cause significant damage to the health sector each year, and impacts continue long after the event.
In general, the country lacks resources to adequately prepare for, respond to, and recover from damage caused by extreme events (Rakotoarison et al. 2018).
Diseases are the leading cause of morbidity and mortality in Madagascar; many are sensitive to climatic conditions (Rakotoarison et al. 2018). Accessibility of sanitation and water supply is low, as is awareness among rural populations of the risks of communicable, diarrheal, and acute respiratory diseases. Outbreaks of communicable diseases often occur after extreme climatic events, and water-borne diseases are becoming more frequent as waterways are contaminated after more frequent and intense floods (CPGU andBNCCC 2017, Rakotondravony et al. 2018 Temperature, precipitation, and humidity can influence disease spread by altering life cycles and range of disease vectors and by influencing transmission of water and food-borne diseases (WHO 2016). The projected increase in temperature in Madagascar is likely to increase transmission of climate-sensitive vector borne diseases such as malaria, dengue, chikungunya, and yellow fever in many areas (Rakotoarison et al. 2018; Fig. 1). The distribution of the mosquito vectors for West Nile virus and lymphatic filariasis are also projected to increase (Samy et al. 2016. Acute respiratory infections, diarrheal diseases, malnutrition, and malaria (all among the top 10 causes of morbidity in outpatient clinics in Basic Health Centers) are projected to increase in many areas. Malaria: The number of malaria cases and deaths in Madagascar has risen in recent years, due in part to a reduced budget for malaria control and deterioration of overall health after the 2009 coup. Future climate change may facilitate both the expansion of malaria's mosquito vectors to areas in which they do not currently exist and more favorable temperature conditions for transmission in highland areas , Ryan et al. 2015, Rakotoarison et al. 2018. Under a high-emissions warming scenario, 46 million people in Madagascar are estimated to be at risk for malaria by 2070. Although this is driven in part by population growth, a low-emissions scenario reduces the number of people at risk by about 5 million (WHO 2016). Plague: Madagascar has one-third of the reported cases of plague worldwide; it occurs regularly in highland areas above 800 m (Kreppel et al. 2014(Kreppel et al. , 2016. Plague is caused by the bacteria Yersinia pestis, which is transmitted primarily between invasive rodent hosts by fleas. Humans can become infected when they come into contact with the fleas or infected animal tissue (Kreppel et al. 2014). Most plague cases occur during the warm, wet season from September to March. Warmer temperatures can influence the development rate of both the bacteria and the fleas, and warmer temperatures and higher rainfall have been associated with increased plague events in Madagascar (Kreppel et al. 2014). However, because plague is found mostly in cool, highland areas and absent from warm, low lying regions, climate change may decrease plague incidences as these areas become too warm (Kreppel et al. 2016).
On the ground climate adaptation activities and other opportunities: Four regions (Atsimo-Atsinanana, Androy, Anosy, and Analanjirofo) were found to be highly vulnerable to climate change impacts on health (Rakotoarison et al. 2018; Fig. 1). Adaptation measures could include integrating risk management into health system activities (e.g., increasing disaster response capacity) and strengthening community resilience (e.g., by increasing capacity for basic health services). For example, NGOs Impact, Mahefa Miaraka, and Access are working to improve access to basic health services such as malaria treatment, family planning, and mother and child heath in Menabe (Morondava Health Center CSB2 interview). Because some villages are far from health centers, community agents can provide a basic level of care in communities and are trained to treat diarrhea, malaria, respiratory illness, and family planning (Morondava site visit). Reducing vulnerability at the household level, including improving the standard of living, access to health-care infrastructure, and increasing education/literacy, is an important adaptation measure (Rakotoarison et al. 2018). For diseases such as malaria, increasing control efforts and increasing awareness of the disease may be effective (Rakotondravony et al. 2018).

Coastal ecosystems
Madagascar has the highest level of coral biodiversity in the Indian Ocean, contains Africa's fourth largest extent of mangroves, and is home to 8 of the world's 60 seagrass species. Numerous non-climate stressors reduce the resiliency of these systems to climate change. Climate change will also have indirect effects on this ecosystem; for example, populations of migratory marine mammals from the Indian Ocean are likely to be affected by climate change during their feeding season in the polar regions (Rakotondravony et al. 2018). Nematchoua et al. (2018) reported observations of decreased marine species (mollusks, crustaceans) in seasonal activities and migration. These effects, along with other drivers, i.e., insufficient surveillance and maritime and coastal protection; siltation, coastal accretion; urbanization; population growth; poverty; poor governance structures; political instability; and lack of ecologically friendly economic incentives, result in high vulnerability for the coastal and near-shore marine ecosystem (Rakotondravony et al. 2018, Cochrane et al. 2019. Moreover, SLR is likely to have drastic impacts; part of the coastal areas of Morondava and Mahajanga, in the northeast of Madagascar, might be submerged by 2100 because of SLR (Rakotondravony et al. 2018).

Mangroves:
Mangroves provide important ecosystem services such as protection from natural disasters, including wave attenuation during storms and provision of fuelwood and building materials. The heavy reliance on mangrove ecosystems is leading to increasing and wide-spread degradation and deforestation throughout Madagascar, with an estimated net loss of 21% between 1990 and 2010 (Rakotondrazafy et al. 2014, Benson et al. 2017, García-Ruiz et al. 2017, Rakotondravony et al. 2018. Studies indicate that by 2100, climate hazards alone may reduce mangrove coverage by 15%. Intense cyclones can completely https://www.ecologyandsociety.org/vol26/iss4/art36/ destroy mangroves and affect neighboring areas that are no longer able to maintain viable shrimp and crab populations, thus forcing fishermen to sail farther to fish (Rakotondravony et al. 2018). In interviews conducted in fishing villages, Lemahieu et al. (2018) reported an observed decrease in marine and mangrove resources over a 20-year period.
Exposure among Madagascar's mangroves varies depending on the probability of future inundation in that location, and individual species vary in their sensitivity to an increase in salinity, flooding, drying, and siltation. Mangrove regions that have high exposure to SLR and/or silting from upland sources and low regeneration rates are more vulnerable than those with low exposure and moderate to high regeneration rates (Clausen et al. 2010). Healthy mangroves, such as those found in Andranomavo, are less vulnerable because of the availability of potential migration area and the high rate of regeneration. However, degraded mangroves, like those found in Vahilava, have a high vulnerability to climate change and a lower adaptive capacity, with an almost zero regeneration rate ( Fig. 1). About 70% of the mangroves in the Tsiribihina delta have moderate to high vulnerability whereas only about 20% of mangroves in the Manambolo delta have moderate to high vulnerability (Clausen et al. 2010).
Coral reefs: Coral reefs are highly vulnerable because of fishing pressure and population growth, as well as increasing pollution and excessive sedimentation from upland sources (Rakotondrazafy et al. 2014, García-Ruiz et al. 2017, Rakotondravony et al. 2018. In addition to these non-climate stressors, coral reefs are highly vulnerable to climate change due to ocean acidification and ocean warming; a combination of these impacts is causing bleaching around Madagascar (IPCC 2019). Erosion of the coast and destruction of coral reefs due to increased cyclone activity are serious threats to the livelihood activities for many fishing communities (Rakotondravony et al. 2018). According to the IPCC (2019), almost all coral reefs will degrade from their current state, even if global warming remains below 2°C, and the remaining shallow coral reef communities will differ in species composition and diversity from present reefs. Bleaching episodes are likely to multiply, with the possibility of complete disappearance of corals in the Indian Ocean within 20-50 years. Cascading effects of coral reef degradation include the decline of fish populations and eventual erosion of beaches. Beach degradation will affect populations of sea turtles, which are already threatened by rising temperatures due to the influence of temperature on the sex of the turtles during egg incubation (Rakotondravony et al. 2018). Declines in coral reef health will greatly diminish the services they provide to society, such as food provision, coastal protection, and tourism (IPCC 2019).

Seagrasses:
Cyclones can adversely affect seagrass beds (Côté-Laurin et al. 2017). Cyclone Haruna decreased total seagrass coverage by an average of 15.3% to 36.3% through uprooting, breaking, and smothering because of burial and reduced light penetration from suspended sediments. That said, the reduction in seagrass cover that provides food, shelter. and protection for fishes did not appear to significantly affect fish assemblages in the short term.
On the ground climate adaptation activities and other opportunities: Possible adaptation measures to adapt to climate change include coastal land acquisition by local authorities, rehabilitation of sectors degraded by deflation, reprofiling of the coast, and windbreak installation (Rakotondravony et al. 2018). For example, windbreaks such as planting dry-resistant Filaos, can provide biological stabilization of dunes. Education and awareness raising can also increase the success of conservation activities (D'agata et al. 2020). Some adaptation is already occurring. Nosy Hara Marine Protected Area is the first protected area in the country to incorporate climate change into its management, including capacity building, conducting a vulnerability assessment, and prioritizing management actions (Rakotondrazafy et al. 2014).

Mangroves:
Mangrove restoration may be an effective adaptation strategy. For example, Community Centered Conservation (C3) is working on mangrove restoration, including capacity building to support mangrove restoration and management activities. Community Centered Conservation also trains "conservation ambassadors" in the community and environmental education programs in primary and secondary schools (C3 interview). Recently, C3 has moved to using tree nurseries rather than direct planting so that trees are large enough to withstand strong storms when they are planted. However, more information is needed about ideal conditions and timing for restoration activities. Identifying salttolerant mangrove species that are more likely to survive as sea levels rise and water becomes more saline may also be an effective approach (United States Forestry Service (USFS) interview).
Coral reefs: The widespread decline in warm-water corals has led to alternative restoration approaches to enhance climate resilience, such as "coral reef gardening," and research on assisted evolution, colonization, and chimerism for reef restoration (IPCC 2019). Assisted evolution uses gene manipulation to enhance resilience to climate change and other human impacts, whereas assisted colonization involves moving species outside their historical ranges to mitigate loss of biodiversity or in anticipation of climate-induced habitat changes. Coral chimerism occurs when a coral has cells that originate from at least two sexually-born individuals of the same species and is a natural tissue transplantation or fusion (Rinkevich 2019). However, the effectiveness of these approaches to increase resilience to climate stressors is uncertain given the current trend in greenhouse gas emissions (IPCC 2019).  (Rakotondravony et al. 2018). Freshwater fisheries are also important in certain regions in Madagascar. Lake Alaotra contains the largest inland fishery in Madagascar with inland fisheries activities making up one of two main sources of income (Lammers et al. 2015). Additionally, many of the native freshwater fish populations are highly endemic to Madagascar and contribute to a global hotspot of freshwater diversity (Benstead et al. 2003). Freshwater fish in Madagascar include many basal taxa, which are of conservation importance because some provide the only evidence of evolution in related groups (Benstead et al. 2003).

Fisheries
Climate risks for marine and freshwater fisheries include ocean acidification, changes in cyclone events, SLR, increasing temperatures, wind intensification, increased occurrence of extreme weather events, and the facilitated spread of exotic species (Rakotondravony et al. 2018, Cochrane et al. 2019. Fisheries may also face other indirect climate change threats; for example, changes in rainfall could lead to a crop failure, which could lead to an increase in fishing activities and overfishing (World Wide Fund for Nature (WWF) interview). These threats impact fisheries production, marine and freshwater biodiversity, fish growth, reproduction and survival, and endemic species conservation (Bamford et al. 2017, IPCC 2019. Coupled with other anthropogenic stressors (such as exotic species introductions, wetland destruction, marsh clearing, deforestation, overfishing, and siltation from soil erosion), marine and freshwater fisheries and habitats are vulnerable and in need of conservation and management attention (Benstead et al. 2003, Bamford et al. 2017. Climate impacts to coral reefs in Madagascar have cascading effects on marine fisheries populations and the marine fisheries sector production (Cinner et al. 2012). However, some marine fisheries, such as the octopus fishery, may be resilient to the impacts of climate change (Cochrane et al. 2019). Inland fisheries production in wetlands, native freshwater fish endemism, and taxonomic importance are the major management and conservation concerns for the Madagascar freshwater fisheries sector in a changing climate (Benstead et al. 2003, Lammers et al. 2015. Changes in precipitation and forest cover impact freshwater fish habitat and determine whether flow will be available year round or dry up during certain seasons (Benstead et al. 2003). Changes in El Niño patterns, precipitation, and extreme drought and cyclone events from climate change have an impact on streamflow in island regions with impacts to freshwater fisheries.
In marine and coastal fisheries, socioeconomic interactions play an important role in how climate change may impact fishing communities. Extreme or unpredictable weather events reduce fishing activities for shrimp and crab because fishers are less likely to engage in capturing them during dangerous conditions or may switch from shrimp to crab capture, depending on conditions (Cochrane et al. 2019). Some fishers do not have radios and have no way to get warnings about extreme weather events ahead of time, which is a human safety risk (UNDP interview). More intense and persistent prevailing wind patterns could alter fishing capacity and lead to an increase in fishing in coral reefs and mangrove channels, leading to overfishing and habitat destruction (WWF interview). In Ambodivahibe, fishermen have reported that the length of the fishing season has been reduced by three months because of strong wind conditions (CI interview; Fig. 1). Villagers in Lovobe also reported that some species are no longer found, that fishing yields have declined, and that they have to travel farther to catch fish, but it is unclear whether this is due to overfishing, loss of mangroves, or climate change (Lovobe interview).
On the ground climate adaptation activities and other opportunities: Activities described in the coastal section, such as mangrove and coastal reef restoration, are important adaptation strategies for fisheries. Additional strategies include promoting alternative livelihoods and establishing value chains. Access to markets, presence of middlemen in villages, and higher education levels can increase the adaptive capacity of fishing communities (D'agata et al. 2020). In Ambodivahibe, Conservation International is promoting alternative livelihoods such as goat farming and beekeeping. They are also working on restoring mangroves and planting trees near villages to protect them from cyclones (CI interview). In the South, UNDP is working to establish value chains by connecting fishermen with buyers (UNDP interview).

Terrestrial ecosystems and ecosystem services
About 90% of species in Madagascar are endemic, and many are threatened with extinction due to habitat loss and fragmentation, agricultural expansion, invasive species, overharvesting, and climate change (Ganzhorn et al. 2001, Vieites et al. 2009, IUCN 2018. For over a century, deforestation has been a main threat to biodiversity; 44% of natural forest cover was lost between 1953 and 2014 (Rakotondravony et al. 2018, Vieilledent et al. 2018, mostly due to slash-and-burn agriculture for subsistence farming and charcoal production as well as illegal removal of valuable timber such as rosewood ). If these rates continue, habitat loss will threaten the persistence many endemic species (Morelli et al. 2020).
Despite an impressive quadrupling in size of Madagascar's protected area extent since 2003 ), significant problems remain and in some cases are increasing, including lack of effective management, incentives for local communities to participate in management, stable financing, law enforcement, and science-based resource management (Gardner et al. 2018).
Studies have shown over 100 Malagasy species that are vulnerable to climate change (Pacifici et al. 2015). Busch et al. (2012) predicted that many species will shift their ranges south or upslope to follow changing climate conditions or experience range reductions. Eastern humid forests are predicted to contract by 2080, whereas western dry forests may shift to the east (Rakotondravony et al. 2018). On Tsaratanana Massif, the highest mountain in Madagascar, reptiles and amphibians are moving upslope (Niang et al. 2015). A recent study modeled the future distributions of 57 species in Madagascar and projected that 27 species will have future distributions of <50% of their current range; 14 species will have distributions <20% of their range; and Ecology and Society 26(4): 36 https://www.ecologyandsociety.org/vol26/iss4/art36/ 6 species are projected to have distributions <1% of their current range, including 3 species projected to go extinct (Brown and Yoder 2015). Importantly, many of these species lack suitable habitat to connect their current habitat with future suitable habitat (Brown and Yoder 2015).
Changing temperatures and precipitation patterns can also alter phenology; plants inhabiting the gallery and dry forests might be particularly vulnerable to increasing variability in precipitation (Rakotondravony et al. 2018). An additional concern is that phenological mismatches due to species tracking climate change differently will impact ecological communities and function (Morellato et al. 2016). The reproduction of many lemur species has evolved to track availability of food resources; if plants in the dry forest change their phenology in response to water deficits and the ringtailed lemur (Lemur catta) and Verreaux's sifaka (Propithecus verreauxi) do not, these species may experience population declines (Rakotondravony et al. 2018).
An increase in the number, intensity, or duration of extreme events could negatively impact Madagascar's biodiversity. For example, drought can reduce survival of plant species and thus reduce productivity (Rakotondravony et al. 2018). Alternatively, it is possible that plant productivity will increase due to CO 2 fertilization (Lawal et al. 2019). Extreme events can also indirectly impact ecosystems. For instance, people may be able to use new openings in the forest to reach forest areas that were previously inaccessible . Habitat destruction after extreme events can also accelerate the spread of invasive species (Rakotondravony et al. 2018).
Climate change is likely to exacerbate other anthropogenic threats to Madagascar's terrestrial ecosystems. Deforestation is exacerbated by extreme climate events; for example, the Menabe region has lost over 60% of its forest cover over the last 10 years as people have immigrated to avoid the drought in the south (USAID Mikajy/Hay Tao interview, WWF interview). A recent study projected that suitable habitat for two critically endangered ruffed lemurs (Varecia variegata and V. rubra) will decline by 62% in a scenario of no new deforestation in protected areas, and 81% in a scenario in which deforestation in protected areas continues (Morelli et al. 2020). Climate change may also indirectly affect lemur populations; if climate change leads to greater food insecurity, individuals may increase hunting of wildlife such as lemurs (Borgerson et al. 2016) On the ground climate adaptation activities and other opportunities: Ecosystems that are already degraded from non-climate stressors are less resilient to a changing climate. Therefore, increasing enforcement of protected areas, maintaining the integrity of intact forests, promoting restoration of additional habitats, and addressing underlying causes of deforestation are key adaptation strategies for Madagascar (Busch et al. 2012, Morelli et al. 2020. Preventing forest loss and degradation is cheaper and more effective than restoring forests after they have been destroyed, although reforestation will likely still be needed to conserve some species (Busch et al. 2012). Protecting corridors to allow species to shift their distributions as the climate changes will be particularly important , Busch et al. 2012.
Several organizations are working on reforestation. One concern is that many organizations are planting invasive species rather than native trees. Although plants like eucalyptus and pine grow quickly and provide rapid benefits in terms of fuel and soil stabilization, they can have negative ecological effects (Baohanta et al. 2012, Ferreira et al. 2019. Therefore, wherever possible, sustainably harvested seeds from local endemic trees should be used for reforestation efforts. Acacia is an option being used by some reforestation projects, (e.g., UNDP interview, Tany Meva interview). Ny Tanantsika is working with communities to collect and plant seeds from native tree species (Ny Tanantsika interview). Conservation International is planting native species in core protected areas but working with communities on agroforestry in the buffer areas (CI interview). However, changing behavior and species preferences in communities can be challenging and inhibit adoption (Commune Ambalavao visit), therefore more effort is needed to communicate the benefits of native species with local communities.
Many organizations are also working to promote capacity building and sustainable livelihoods, such as more sustainable agricultural practices, agroforestry, and supporting value chains (e.g., Tany Meva, Wildlife Conservation Society (WCS), USAID Mikajy), or family planning (e.g., WCS) to reduce deforestation pressure. Securing land tenure is another strategy that may reduce encroachment into protected areas because it may motivate farmers to invest in their land rather than moving into the forest (USAID Strengthening Entrepreneurship and Enterprise Development (SEED) interview).

DISCUSSION
Climate change will increasingly affect important sectors in Madagascar, including water resources, agriculture, coastal and terrestrial ecosystems, fisheries, and human health. We have documented observed and potential climate change effects and possible adaptation measures (Table 1).
All sectors included in this review are connected; changes are not happening in isolation (Fig. 2). For example, lack of water infrastructure can exacerbate drought impacts. Droughts and associated agricultural declines can increase food insecurity and ultimately result in malnutrition and reduced health (Rakotoarison et al. 2018). Agricultural declines may also lead to increased deforestation as farmers expand areas of cultivation to compensate for reduced crop yields (Desbureaux and Damania 2018). Similarly, reduced agricultural output could lead to increased fishing activities and overfishing (WWF interview). Preliminary analysis suggests a significant increase in healthcenter admissions about one year after a severe drought, illustrating the complexity of the water-food production-human health relationship (Carrière et al. 2021). Increasing frequency of droughts in southern Madagascar is challenging development programs. In the past, organizations have known when food aid would be most needed, but recent changes in drought frequency have made this difficult (CRS interview). Increased foreign disaster assistance may be needed in the future. Continuing to provide humanitarian assistance without reducing underlying causes of vulnerability will not be an effective strategy moving forward (CRS/ADRA interview). Protecting Madagascar's ecosystems continues to be an important strategy to promote adaptation capacity and human well-being (CI and WWF 2008). The biodiversity crisis in Madagascar affects more than just the flora and fauna of the country. Forests provide critical ecosystem services for the nearly 90% of Malagasy who rely on natural products including charcoal, fruit, livestock pasture, and medicinal plants , Dave et al. 2017, Neudert et al. 2017, GIZ 2020. Deforestation can also increase flooding and siltation associated with cyclones, with consequences for agricultural yield and food security (Llopis 2018). For example, Cyclone Giovanna in 2012 caused significant crop loss that increased food insecurity for farmers (Rakotobe et al. 2016). Additionally, loss of Madagascar's ecosystems and biodiversity can reduce tourism and associated economic benefits, although in some cases, the benefits of ecotourism do not compensate for costs of forest protection at local and regional levels (Busch et al. 2012, Neudert et al. 2017. Restoring degraded ecosystems is more costly and less effective than protecting intact ecosystems (Busch et al. 2012). Investing in improved cookstoves or alternative sources of energy could reduce dependence on charcoal, thus reducing deforestation while increasing economic opportunities (GIZ 2020). For example, WWF implemented a renewable energy project in which they trained women from rural areas to install and maintain solar systems in their villages (WWF interview). Installing solar panels in rural areas could also improve health care services in facilities that lack electricity (Marofandilia CSB2 visit; health center).
Although direct work on biodiversity and forest conservation is essential, most organizations that we interviewed have been stepping back from direct conservation activities to implement projects that strengthen local communities (WWF interview, USAID interview). For example, many organizations are working to improve agricultural practices, with the hope that it will reduce encroachment into protected areas. However, adoption and sustained use of new practices is challenging, especially when they involve investing in inputs or agricultural equipment. For example, although benefits of conservation agriculture accumulate over time, initial crop responses may be small or highly variable, and farmers may not see immediate benefits (Corbeels et al. 2014). This is a severe constraint for resource-poor farmers, and even when farmers do adopt these techniques, they may not maintain them after short-term project funding has ceased (Lima, 2014). Therefore, there is a need for more long-term partnerships with farmers (Penot et al. 2018). A recent survey of farmers in the Lake Alaotra region found that even though farmers reported increased and more stable yields while using CA, 39% of farmers stopped using the technique, citing a variety of social, economic, and technical factors (Penot et al. 2018). Groupement Semis Direct Madagascar has found that techniques that have clear results for farmers, such as composting, are more likely to be used after the project ends (GSDM interview).
In the long run, addressing key aspects of vulnerability such as improving education and health and reducing poverty will help people adapt to climate change (Asafu-Adjaye 2014). Education Ecology and Society 26(4): 36 https://www.ecologyandsociety.org/vol26/iss4/art36/

Fig. 2.
Interlinkages among sectors in adapting to climate change. Addressing non-climate stressors (Challenges) will make the system more resilient to climate and allow for increased socioeconomic and ecological sustainability (Opportunities). Efforts across multiple sectors are required to address the challenges that face Madagascar. and awareness raising is a general strategy that is important for promoting adaptive capacity in Madagascar (D'agata et al. 2020). Many organizations are working to increase community knowledge regarding health (e.g., sanitation, vaccines, hygiene), effective farming practices, and the benefits of environmental conservation. Opportunities exist to leverage existing educational infrastructure to support multiple development goals simultaneously. For example, community health agents and health-care centers that are already working with communities to promote healthy behaviors could also provide information on the benefits of environmental sustainability.
One challenge for development organizations is that they can only work with a subset of communities, and the government has limited resources to enforce forest boundaries, making it difficult to control deforestation. Moreover, no organizations that we interviewed have assessed the success of these interventions so far. In fact, there is insufficient evidence that community-based extractive resource management promotes effective biodiversity conservation in the terrestrial developing world context, and success is context specific (Sayer et al. 2017, Gardner et al. 2018. Developing the capacity of government bodies and local authorities to sustainably manage protected areas, and developing Ecology and Society 26(4): 36 https://www.ecologyandsociety.org/vol26/iss4/art36/ a monitoring system to track progress may improve project effectiveness (WWF interview).
Although our understanding of climate change in Madagascar has improved in recent years, there are still uncertainties and knowledge gaps that challenge development organizations trying to incorporate climate resilience into development projects (Appendix 3). In some areas, baseline climate and weather data on a local scale are lacking, which makes developing fine-scale projections of areas at risk of floods, droughts, SLR, and cyclones difficult. Even where these data do exist, greater translation and communication of the information and how it can be used is needed. In addition to basic climate information, there is a lack of climate change impact modeling on a local scale. For example, how will climate change impact agricultural yields of important crops in different locations across the island? On an ecological level, there are still uncertainties regarding how specific species and ecosystems will respond to climate change. One such uncertainty is that while there is a general expectation that species will shift their ranges to maintain their preferred temperature and precipitation niches, it is difficult to predict which species will shift first and by how much. Moreover, species may respond to climate change in different ways and at different rates, which could impact species interactions and other ecosystem functions. Finally, more work is needed regarding how the impacts of climate change are likely to affect human communities. As such, mapping socioeconomic vulnerability to climate change could assist with spatial planning. Information regarding economic impacts and changes in livelihood would also be useful, especially regarding which livelihood activities might be most resilient to climate changes in different locations. Tools like scenario planning (Cobb and Thompson 2012) and structured decision making (Gregory et al. 2012) can help organizations develop project plans that account for uncertainty.
Although linkages between sectors is complex and uncertainties remain, there is an opportunity for the Government of Madagascar, development organizations, NGOs, and the private sector to leverage funds and work across sectors to address challenges (Fig. 2). For example, reducing deforestation would reduce erosion, which could increase agricultural productivity and human health, and would also reduce siltation that is degrading coastal ecosystems. These benefits would provide increased economic opportunities for communities, which in turn would increase community resilience to climate shocks.

CONCLUSIONS
Climate change has and will continue to affect important sectors in Madagascar. Climate and non-climate stressors interact and can exacerbate negative consequences, so addressing underlying vulnerabilities including high-poverty rates, food insecurity, and population growth can help reduce negative impacts. As development organizations design new projects, leveraging expertise, funds, and activities in other sectors would be beneficial as sectoral challenges and opportunities are linked. In addition, increased coordination between the Government of Madagascar, development organizations, NGOs, and the private sector to promote more sustainable and climate-smart adaptation activities will help Madagascar prepare for and respond to this emerging challenge.

Data Availability:
Data/code sharing is not applicable to this article because no data/ code were analyzed in this study.

Appendix #3: Information gaps identified during the literature review and interviews
While there is some information regarding climate change impacts, there is a considerable lack of information specific to Madagascar (Benson et al., 2017;Cochrane et al., 2019;CPGU and BNCCC, 2017;García-Ruiz et al., 2017;IPCC, 2019;Oppenheimer et al., 2019;Rakotondrazafy et al., 2014;Serele et al., 2019). The categories of information needs that emerged from our interviews and literature review include: • Climate information o Some areas do not have accurate climate or weather information at a fine enough scale (e.g. many places have regional weather data rather than local, so it is often inaccurate as there is a lot of variation over the region