Keywords

1 Introduction

The global climate crisis brings significant consequences for Central and South Asian countries. The region is characterized by highly complex geographic and climatic regimes, as well as a low resilience against climate related threats due to each country’s own sociological and political structures. Despite similarities in high exposure to climate impact, the specific consequences on each country and society include various aspects and should be addressed on both regional and transnational scale.

The first part of this chapter addresses the natural geographic patterns and defines climate regimes across the different regions of Central and South Asia. The second part covers the most important climate change impacts, including both known and observed impacts, as well as expected changes in the near and distant future. While there are certainly differences in each region’s specific challenges to a shifting future, which we address separately, intersectoral approaches through the nexus between water, food, and energy have the potential to address transnational challenges and risks for all regions and are covered in the third part.

The necessity to support both societies as well as the natural habitat to balance sustainability despite changing climate regimes will be addressed in the last part of this chapter. As a possible approach to the expected climate changes in both Central and South Asia, we introduce the concept of UNESCO’s biosphere reserves as models for sustainable development which combine different aspects of climate adaptation, whilst serving natural conservation efforts.

2 Natural Spatial Patterns in Central and South Asia

Central Asia with an area of about 4.0 million km2 and South Asia with about 6.9 million km2 cover roughly 7.3% of the Earth's terrestrial surface. Following (Olson et al. 2001), Central Asia belongs to the Palearctic biogeographic realm, whereas South Asia is part of the Indo-Malay region. Central Asia is characterized by four biomes, (1) deserts and xeric shrublands; (2) temperate grasslands, savannas, and shrublands; (3) montane grasslands and shrubs; and (4) boreal forests/taiga (Olson et al. 2001). The region comprises different climate regimes, varying from arid deserts to mountain ranges with high precipitation rates. The strong influence of the Pamir and the Tien Shan mountain ranges is particularly evident by the available water resources in the main rivers of Amu Darya and Syr Darya (Magin 2005). Both rivers are fed by melting glaciers in the high mountains and are of utmost importance for the agriculture and energy sector, especially in Kyrgyzstan and Tajikistan. With the Aral Sea, one of the most prominent examples of man-made environmental disaster lies between the two countries Kazakhstan and Uzbekistan (White 2013).

South Asia comprises mainly (1) tropical and subtropical moist broadleaf forests; (2) tropical and subtropical dry broadleaf forests; (3) tropical and subtropical grasslands, savannas, and shrublands; (4) deserts and xeric shrublands; and (5) mangroves (Olson et al. 2001). Large regional climate differences exist due to a variety of climatic factors such as altitude, proximity to the sea, and the influence of the monsoon. The glaciers of the Himalayas form the basis for the most important river systems in the region, in particular the Ganges, the Indus, and the Brahmaputra (Rasul 2012). The coastal regions have not only a high ecological value, among others due to the mangrove ecosystems, but also a high economic importance. However, these regions are particularly vulnerable to climate change, e.g., due to their low elevation and ongoing degradation of their natural protective mechanisms such as the mangrove ecosystems (Barbier 2015; Giri et al. 2015). Due to the high population density in large parts of South Asia and the increasing pressure on land use, multiple environmental challenges exist, ranging from deforestation and degradation to erosion, pollution, and loss of biodiversity (Barbier 2015). These challenges are addressed i.e., by the growing network of UNESCO Biosphere Reserves, model regions for sustainable development (see Box 6.1).

Box 6.1 The Global Biosphere Reserve Network—Model Regions for Sustainable Development

The Agenda 2030 under the Sustainable Development Goals (SDGs) provide clear targets, while keeping it to the respective national decision-making bodies on how to achieve them. A common approach for breaking new ground in testing and finding answers to ecological challenges under climate change conditions are biosphere reserves. The Dresden Declaration on biosphere reserves and climate change states that “Biosphere reserves are an effective instrument for mitigating climate change and serve as models for adaptation to the impacts of this change” (UNESCO 2011) and call for action on policy level, practical level, and UNESCO level. Biosphere reserves shall also function as climate change observatories and monitoring entities (UNESCO 2016a).

After the initiation of the Man and Biosphere (MAB) Program in 1971, only a few biosphere reserves were established in Central Asia during Soviet times. The perception of biosphere reserves in the Soviet Union was a certification of a high-quality standard of strict nature protected areas (zapovednik, IUCN Category Ia), rather than a complex concept for sustainable development. The modern understanding of biosphere reserves aligns with the Seville Strategy (UNESCO 1995), Madrid Action Plan (UNESCO 2008), and most recently, the Lima Action Plan (UNESCO 2016b). Biosphere reserves, after these conceptions are global model regions for conservation, sustainable use, and environmental research and education.

For testing innovative approaches on sustainable agriculture for example, ecosystem-based adaptation and nature-based solutions communication, education, and networking are important. It belongs to the key principles of the MAB Program that biosphere reserves also function as ambassadors for Education for Sustainable Development (ESD). “The crucial role of MAB reserves is to increase human capacity for climate action. Education and raising awareness are key to strengthen locals’ role as actors in early warning, mitigation, adaptation, and resilience. The more people are aware of climate change issues and about the way they can contribute, the more efficient these processes will be” (Meggle 2015). This concept includes diverse aspects of lifelong learning, testing, and communicating best practices, and linking and connecting with other biosphere reserves under the umbrella of the World Network of Biosphere Reserves (WNBR).

Both Central Asia and South Asia are characterized by large demographic and socio-economic differences. Central Asia is sparsely populated (18.4 person/km2) with primarily small differences between countries, e.g., Kazakhstan (6.8 person/km2) and Uzbekistan (75 person/km2). Contrary to this, with 278.9 person/km2, South Asia is one of the most densely populated regions worldwide, where countries such as India, Bangladesh, and the Maldives face a particularly high population pressure (World Bank, https://data.worldbank.org, data from 2019). In addition, large socio-economic inequalities, not only between countries but also within individual countries, affect the vulnerability and adaptive capacities to projected climate change (Brooks and Adger 2005). For example, outdated and inefficiently operated irrigation infrastructure already became a significant problem in some Central Asian countries (Abdullaev and Rakhmatullaev 2016; Xenarios et al. 2018, p. 131). The biophysical and socio-economic vulnerability is especially high in the coastal areas of South Asia, despite their fast-growing economies (Siddiqui and Hossain 2020).

3 Observed and Projected Climate Change in Central and South Asia

The complex geographical location of Central and South Asia creates diverse climatological and environmental conditions and impose various challenges and threats to the Central and South Asian countries.

Impacts climate change that is already occurring are felt in all facets and regions of Central and South Asia. These changes indicate the magnitude of impact that is expected under progressing climate change.

3.1 Observed Changes

For many regions of Central and South Asia, current climate change is marked by an increase in mean surface air temperature (i.e., 1.1–1.8 °C in South Asia [Aadhar and Mishra 2020] and 0.7 °C in Central Asia [Hong et al. 2017]) and more frequent warm days, while the numbers of cold days have decreased consistently (Hijioka et al. 2014). Precipitation frequency and intensity in South Asia, especially in the tropical countries has changed towards more heavy rainfall events with decreased frequency of light rain events and extension of dry periods (Hijioka et al. 2014). The drying trend in the tropical areas also affects the South Asian summer monsoon in the seasonal mean (June–September) (Neelin et al. 2006; Bollasina et al. 2011; Hijioka et al. 2014) and is associated with the interference of atmospheric and oceanic circulation patterns by rising concentrations of greenhouse gases and aerosols (Ramanathan et al. 2005; Bollasina et al. 2011; Hijioka et al. 2014). Next to the above-mentioned mechanisms, increasing sea surface temperatures are proposed to be causing a spatial shift of monsoonal rainfall, enhancing the regional climate change impact (Annamalai et al. 2013).

Similar to the terrestrial Earth’s surface, climate change has already affected the adjacent ocean basin of the Indian Ocean. The sea surface temperature of the tropical Indian Ocean has increased, on average, about 1 °C from 1951 to 2015 and is significantly higher than the global mean increase of 0.7 °C. In addition to a warming of the ocean, there is a notable increase of the sea level in the North Indian Ocean of around 1.06 to 1.75 mm per year from 1874 to 2004 and an increased rate of 3.3 mm per year, from 1993 to 2017 (Hijioka et al. 2014; Krishnan et al. 2020).

In the Pacific and Indian Ocean, some of the recorded sea level rise is likely due to an intensification of winds (trade winds in the eastern tropical Pacific and enhancements of Hadley and Walker cells in Indian ocean). Thermostatic extension of the warming ocean in the future may add to the sea level change, which has already accounted for around 80% of the sea-level rise in the nearby region of Gulf of Japan between 1993 to 2010 (Hijioka et al. 2014).

Next to the threat of sea level rise, since the 1970s coastal areas have been increasingly endangered by a weak upward trend of tropical cyclones in the western North Pacific. Whereas the Indian Ocean experiences fewer tropical cyclones, it is facing a very recent increase (2000–2018) of severe cyclic storms, usually in the post-monsoon season (Hijioka et al. 2014; Krishnan et al. 2020). A tropical storm describes a rapidly rotating storm system which forms over tropical seas. It is termed a severe cyclonic storm if this happens in the Indian Ocean or South Pacific. Coastal areas are extremely vulnerable to their impacts of heavy rain within a short time, strong winds, waves, and storm surges.

With the lack of a broad recording network, the data for Central Asia is not sufficient to draw specific conclusions on changes in annual precipitation trends over the past century (Hijioka et al. 2014) and regional observations are too scarce for universal descriptions. However, available records show not only mean temperature changes and precipitation values, but also generally, more frequent heat waves and heavy rainfall events since the mid-twentieth century in large parts of Asia (Hijioka et al. 2014). Heatwaves have had significant impacts in India and eastern Pakistan in 2015 and 2010 (Ullah et al. 2020) and have similarly become more frequent in Central Asia since the 1960s (Yu et al. 2020). Other climate extremes, such as floods had devastating effects in Bangladesh in 2018 and 2019 (Rahman and Islam 2019; Ullah et al. 2020). Long lasting heat spells and overdue rainfall have caused droughts over Pakistan and some parts of Afghanistan, India, and Iran (Ullah et al. 2020).

3.2 Projected Climate Change

As heavy weather events have significantly increased in frequency, duration, and strength in the past decades (Mirza and Monirul 2011; Ullah et al. 2020), the need for reliable climate predictions for the near and distant future has increased.

Climate model projections are used to assess future climate change impacts on both regional and transregional scales. For adequate projections of future development, emission and climate scenarios are described which represent possible fossil fuel emissions, their effect on the radiative forcing (cumulative measure of human emissions of greenhouse gases from all sources expressed in watts per square meter), and the subsequent effect on future climate conditions (Nakicenovic and Swart 2000; Moss et al. 2010). A low emission scenario is, for instance, the RCP 2.6 (RCP—Representative Concentration Pathway), which assumes the peak of radiative forcing at around 3 W/m2 before 2100 and a decline afterwards. An extreme example of high emission scenario is the RCP 8.5, which assumes rising radiative forcing up to 8.5 W/m2 in the same period.

Model capacity has significantly improved on all scales and simulations of recent years offer decreasing uncertainties about future climate projections. However, the reliability about regional results decreases with progressing time and increasing uncertainty about future emission trends, which requires deliberate interpretations of the projections. Despite uncertainties in the models themselves, knowledge about future climate trends on a regional scale can help to integrate measures for climate change adaptation specialized on regional needs and impacts (Dessai et al. 2009).

Model simulation of the IPCC AR5 Chapter 24—Asia (Hijioka et al. 2014) suggests a future increase of temperature relative to the late twentieth century, over all Asian land areas until the end of the twenty-first century. For low emission scenarios, this ranges around 2–3 °C and 3–6 °C in a high emission scenario, depending on the latitude. Under high emission scenarios, temperature increased significantly well into the future.

Robust temperature increase is also projected for the ocean surface in all emission-scenario cases, which indicates a strong vulnerability of the ocean. This implies significant issues for coastal countries in South Asia, where regional sea level rise is likely to exceed the global mean, as projected for the northern Indian Ocean under the higher emission scenarios (Krishnan et al. 2020). The frequency of tropical cyclones is difficult to determine and even if there is some confidence in a shift of North Pacific storm tracks, there is low certainty about the projection of impacts from tropical cyclones (IPCC AR5). However, there are some indications for an increase of tropical cyclones in the northern Indian Ocean under a warming climate (Krishnan et al. 2020).

Predictions are also difficult for consistent future precipitation changes especially on regional levels. While directions for change are robust (Hijioka et al. 2014; Zhang et al. 2019), precise values are hard to forecast. This includes the impact of precipitation changes on parameters like runoff, water availability, and impact of water availability on the stability of the ecosystem under changing temperatures (Zhang et al. 2019).

Overall, precipitation is likely to increase in high latitudes, while at low latitudes, there is high uncertainty about precipitation changes. This is especially true for the low-CO2 emission scenario RCP 2.5. In this scenario, changes in the monsoon system will increase precipitation in South Asia, with both mean and extreme precipitation increasing during the Indian summer monsoon (Mirza and Monirul 2011; Hijioka et al. 2014), whereas observations and predictions agree with a decreasing trend of mean precipitation during the summer monsoon (Ashfaq et al. 2009).

3.3 Regional Climate Change in South Asia

The current global warming trend and the geographical location with its topography and various climatological conditions make South Asia very vulnerable to climate change and one of the hotspots of future climate change (i.e., Byers et al. 2018; Mirza and Monirul 2011; Ullah et al. 2020).

Regional modelling studies for South Asia indicate increasing warming under all proposed scenarios; however, concrete effects vary with region and scenario, indicating additional effects coming from, for example, population density and/or land use. Stronger warming effects are expected in higher latitude areas than in mid to low latitudes, as well as in highly climate sensitive mountain areas (Pepin et al. 2015; Ullah et al. 2020).

Early season melting of snow and glaciers in high mountain areas of Asia affects the potential of the large rivers of South and Southeast Asia, such as Brahmaputra, Yellow, Yangtze, Indus, and Mekong, in particular to buffer water resources for drier seasons (Zhao et al. 2014). The development of glaciers of this area is not only affected by rising atmospheric temperatures. A regional study on glaciers of the northern Karakorum region illustrates how a smaller group of glaciers of the Karakorum seem to be preserved by a combination of enhanced cloudiness from monsoon moisture and an increase in debris cover over the glaciers (Zhao et al. 2014; Zafar et al. 2016). This development seems to be unique for the Karakorum, while the majority (~75%) of Asia’s high mountain glaciers will significantly lose in extent (Zhao et al. 2014). However, unregulated discharge may cause flooding in melting seasons and endanger deltaic regions of Indus and Ganga–Brahmaputra Rivers (Ullah et al. 2020). For particularly vulnerable population groups with low adaptive capacities to climate change, this means additional burdens (Aadhar and Mishra 2020).

Results of future precipitation modelling for South Asia are quite variable and range from increasing amounts (Maldives, Sri Lanka, India, and Bangladesh) to decreasing amounts (Nepal), or very small changes (Bhutan), but in most cases with very low confidence or poor agreement across model simulations (Bhutan, Nepal, Sri Lanka) (Ahmed and Suphachol 2014).

Regional simulations for changes in the monsoon system in the near and distant future still lack certainty and model agreement on small scale changes. Turner and Annamalai (2012) review model weaknesses and difficulties when simulating the key processes of the monsoon system and discover large discrepancies in reconstructions of present and future interannual variability across models. They summarize arguments for an increase of aerosol forcing over South Asia, leading to reduced monsoonal rainfall from observations of the twentieth century. This might hinder a climate change induced increase of monsoon intensity over South Asia in the future that would be expected from rising atmospheric temperatures alone (Turner and Annamalai 2012). The key to lighten the expected changes to the monsoon system will be an improvement of the monsoonal processes in the general circulation models (GCMs) used to simulate future climate change in Asia.

Coastal areas are especially affected by climate change related sea-level rise. Observations already indicate a yearly sea level rise of about 1.0 mm (Vivekanandan and O’Brien 2016) in the Bay of Bengal. While regional differences exist, sea level will rise at all coasts across South Asia and pose threats for human life especially in densely populated areas. For instance, calculations show that 1 m sea level rise would displace 7.1 million people in India (Vivekanandan and O’Brien 2016). Another study simulated that around 18% of the land area in Bangladesh would be lost by an increase of only 1 m, threatening the life of millions of people and the economy of an entire nation with more than 160 million inhabitants (Minar et al. 2013).

The main cause of sea level to rise is thermal expansion of the warming ocean and this trend follows global observations and future simulations (Unnikrishnan and Shankar 2007; Vivekanandan and O’Brien 2016). Additional difficulties and threats are those in those coastal areas, formed by large river deltas. Here, reduced sediment delivery by drying rivers hinders deltas to keep up with the sea level rise and maintain a certain elevation. These coasts are highly vulnerable to erosion hazards and salt-water intrusion in fresh-water ground water sources (Oppenheimer et al. 2019).

3.4 Regional Climate Change in Central Asia

Temperatures in Central Asia likewise depend on the global emission scenario. These scenarios show with considerable certainty an increase in temperature by 2071 to 2099 of about 2.5 °C in the low-emission scenario and as much as 6.5 °C higher in the high emission scenario, relative to 1951 to 1980 (Reyer et al. 2017). Warming is especially pronounced in the southern part of Central Asia, indicating a potential to shift the climate regime towards a new one by the end of the century under the assumption of high emission scenario (Hijioka et al. 2014; Reyer et al. 2017). This comprises heat extremes, such as hot days and nights and warm spells, which will notably appear more frequently in Central Asia, with the length of warm spells being prolonged.

For northern regions of Central Asia, warming and specifically summer warming will be less intense. Most studies conclude that climatic change in high altitudes is less pronounced than in lower elevation plains (Unger-Shayesteh et al. 2013; Reyer et al. 2017), whereas there are indications for strong warming in winter in higher elevations in Tien Shan mountains (Kriegel et al. 2013; Reyer et al. 2017).

Atmospheric warming significantly contributes to melting of the regions’ most valuable fresh-water source—high mountain glaciers of Tien Shan (Kyrgyzstan) and Pamir (Tajikistan) and smaller glaciers in Kazakhstan and Uzbekistan (Reyer et al. 2017), which feed, among others, the large rivers of Amu Darya and Syr Darya. These freshwater resources provide the livelihood for communities in arid and semiarid regions of Central Asia. These communities strongly depend on the water supply coming from these rivers for agriculture and hydropower. The largest freshwater source of the arid Central Asia area, the Aral Sea, is likely to continue to shrink under decreasing inflow of tributary rivers, already endangered by increased water evaporation and precipitation changes (Cretaux and Bergé-Nguyen 2013; Reyer et al. 2017). Increased runoff from glacier and snow during warming spring seasons may time the spring flood earlier in the year, while shrinking glaciers imply water scarcity the Syr Darya and Amu Darya rivers in the future (Reyer et al. 2017 and references therein).

Both developments of temporal change and runoff rates are strongly dependent to climate change projections, as well as water usage upstream (Bernauer and Siegfried 2012; Reyer et al. 2017). The glacier area loss is projected to be anywhere from 50 to 80% (2 °C and 4 °C global temperature increase, respectively) by 2100. The exact future development of changes in meltwater fluxes and glacier area loss are difficult to assess, owing to the lack of consistent observational data. While attempts are made to improve glacier models and understanding of glacier processes, inconsistent measurements in High Mountain Asia imply gaps in datasets needed for explicit spatial glacier models (Reyer et al. 2017; Miles et al. 2021).

While the results for regional warming are relatively robust and higher relative to the global mean, future development of precipitation lacks certainty and agreement throughout the model ensembles, largely due to incomplete data coverage as a basis for reliable future simulations (Hijioka et al. 2014; Reyer et al. 2017).

Precipitation projections show a drier Southwest and wetter Northeast, with changes more pronounced in the winter than during summer, depending on the intensity on the scenario. In a 2 °C world, models disagree about direction, but indicate changes. In a 4 °C world, there would be less rain in Turkmenistan, parts of Tajikistan, and Uzbekistan, with a stronger decrease in summer. However, accuracy of seasonal changes with present reconstruction of precipitation is still difficult (Bhend and Whetton 2013; Hijioka et al. 2014; Reyer et al. 2017).

Water stress will not only be amplified by decreasing precipitation, but also enhanced evaporation under warming temperature. In a 2 °C world, hyper arid or arid land area would increase by about 6% in a 4 °C world, it would be 20% more, relative to the reference period.

Increase melt of glacier ice and snow may counteract the loss of precipitation, as projected in some studies; however, a shift in the spring peak flow will limit water availability in dry summers (Hagg et al. 2013; Reyer et al. 2017).

4 Impact of Climate Change on the Water, Food, and Energy Sectors

With water and food resources being directly shaped by temperature and freshwater availability, climatic changes will heavily affect these sectors under the observed and simulated climate changes. Economic and social sectors dependent on natural resources will experience increasing stress, risking wealth and economic standards of the countries and communities.

4.1 Water

Central Asia is one of the driest areas in the world and water scarcity is going to become more frequent under a changing climate. Observed and proposed changes in water availability due to changes in meltwater discharge will not only directly affect freshwater availability from large rivers, but also food availability, due to the strong dependency of agriculture on irrigation (Schlüter et al. 2010).

On one hand, increasing runoff from glaciers and snowfields feeding the two largest rivers (Amu Darya and the Syr Darya) can occasionally substitute the lack of rainwater, and are already in use for irrigational agriculture (Xenarios et al. 2019). On the other hand, increasing water flow in those meltwater-fed rivers in warm months may pose threats to the environment and people if river flow is not regulated.

A contrast to this is South Asia, whose countries receive significant amounts of rain through monsoon seasons (Mishra et al. 2012). Some simulations suggest that in the future, there will be higher intensity and higher frequency of heavy rain events. However, this will pose high risk from heavy rain fall, runoff, and flooding events, especially dangerous in densely populated coastal areas. Rising damage and higher frequency of flood events has already been documented (Mirza and Monirul 2011).

Although climatically different developments will dominate the future of Central and South Asia, associated risks and inevitable impacts to the water, food, and energy sectors pose considerable threats to urban and rural communities and areas.

Regional impacts of climate change might even hold similar implications for both regions. Increasing heavy rain fall and glacier/snow field melt may improve freshwater supply in rivers for arid and semi-arid areas of the Amu Darya and Syr Darya as transboundary rivers of Central Asia. The same effect appears at the large delta areas of Indus and Ganges–Brahmaputra in South Asia. Though, if the glaciers of Tien Shan, Pamir-Alay, and Himalaya lose their water storage capability, flooding in melting seasons can negatively impact deltaic regions downstream (Mirza and Monirul 2011; Reyer et al. 2017; Aadhar and Mishra 2020; Ullah et al. 2020).

Securing water resources and ensuring equal management of river water resourced among all riparian countries requires transnational efforts. While five different countries, Kyrgyzstan, Tajikistan Uzbekistan, Turkmenistan, and Kazakhstan depend on the water resources of Syr Darya (Siegfried et al. 2010), four countries are involved in water management of the Indus and Ganges–Brahmaputra-Meghna basins: Bangladesh, India, Nepal, and Pakistan (Uprety and Salman 2011). Integrated management across borders can allow communities to use river discharge for irrigation or energy production and preserve water resources in a drier and warmer future. Current efforts in Central Asia to manage demands over water resources of the Syr Darya still reveal disputes between Kyrgyzstan and Uzbekistan and will become more complicated with decreasing water resources under climate change (Bernauer and Siegfried 2012).

For those areas in Central and South Asia, where modelling studies predict decreasing precipitation, increased glacier melt might counteract seasonal water deficits in the medium-term. However, increasing runoff in the melt season might be thwarted by an increasing demand for water for agriculture in dry and hot seasons and associated evapotranspiration (Reyer et al. 2017; Zhang et al. 2017, 2019).

4.2 Agriculture

Climate change impacts on agriculture, and as a result food availability, are closely tied to water availability. Difficulties for adequate risk assessment arise from uncertainties in model simulations for exact regional temperature and precipitation development, as well as the link between water availability and excessive water use for irrigation methods in agriculture.

Some regions in Central Asia currently experiencing year-round cool weather might benefit from climate change, with increased crop yields under lengthening growing seasons. However, droughts might hinder the growth if not compensated by irrigation methods. But to preserve water resources, changes in agriculture methods need to be employed under the consideration of sustainable development (see Box 6.3).

For large parts of South Asia, the monsoonal seasonal precipitation from June to September is the most important freshwater resource (Mishra et al. 2012), for which significant changes are forthcoming. While heavy and unpredictable rainfall events endanger crop yield by water excesses, the frequency of longer dry spells and monsoon break periods increase water stress on plants and crops. This results in losses in yield, hardly compensated by the growth increase during a lengthened growing season. While higher CO2 and temperature might force plants to grow faster, studies showed decreased biomass production in fast growing plants, reducing the total yield in the end (Aryal et al. 2020).

Additional threats in coastal areas are salt-water intrusions into the rivers and river-flooding areas under rising sea levels (Sivakumar and Stefanski 2010), which can only be overcome in the longterm by either abandoning these areas for agricultural use or coastal protection measures to prevent increased salinity (Aryal et al. 2020). However, in countries with huge pressure on land use such as Bangladesh, it is questionable whether the highly valuable resource of land and its use will be abandoned especially by poor households with a lack of alternative income sources.

In many regions reduced crop yield can exacerbate problems of communities purely relying on agriculture for their living. While heat (excess) and water (lack, or excess of) pose the largest stress on crops of all kinds, heavy rain events and salinity intrusions in coastal and low-lying areas call for agriculture plans that provide more stability to these various threats.

4.3 Energy

Both Central and South Asia are widely applying hydropower for energy production and regulation of river flow. Changes in Central Asia’s river flow throughout the year and water in pulses poses difficulties for solving conflicts about water use in agriculture and hydropower, as well as increase risk of floods and destruction of hydropower plants (Reyer et al. 2017). In South Asia, additional danger is posed by flooding of power plants on islands, low lying countries, or coasts, and hydropower, as well as heavy heatwaves or droughts (Ahmed and Suphachol 2014).

The various impacts of climate change on the energy and food sectors illustrate the nexus between water, food, and energy in Central and South Asia and the threats to life and wealth in poor or vulnerable communities.

Access and security of resources of energy, water, and food are closely connected and strongly depend on the wealth of each sector. Securing these resources is the overall aim at the political and social level to guarantee access for all communities. Collaborative efforts and projects need to be designed to adjust to new climatic conditions and guarantee sustainable use of resources, especially under increasing climate change and reduced resource capacity.

5 Future Perspective: Climate Change Adaptation Between International Strategies and Local Projects

To reduce the future impact of climate change on resources and social structures in Central and South Asian countries, collective efforts for climate change mitigation are undoubtedly the most urgent actions to be undertaken globally. However, global greenhouse gas emissions have risen since industrialization, and we are now experiencing irreversible changes in climate and long-term impacts because system feedbacks and thresholds are expected to accelerate this change climate.

While uncertainty about small scale climate change impacts hamper regional predictions, measures can be undertaken to attenuate the impact of heavy weather events, droughts, and heat spells and to protect disaster prone regions.

Climate change adaptation can reduce vulnerability to climate change induced threats, support local communities, and secure their resilience against climate change. It may also yield opportunities to create nationwide projects or collaborate across countries and borders, increase economic conditions, for example, by assuring food or energy independence (Sovacool et al. 2012), and help to implement Sustainable Development Goals (SDGs) in respective countries (see Box 6.2).

Box 6.2 Impact on Implementation of the Sustainable Development Goals (SDGs)

The legally binding Paris Agreement, adopted in December 2015, as an international response to global warming, is already far behind its targets. As part of the 2030 Agenda, the global community has set up 17 Sustainable Development Goals (SDGs) for a sustainable development. The implementation of these targets is deficient in both regions. According to the Sustainable Development Report, Kyrgyzstan performed best, ranking 52nd out of 166 countries rated. According to Sachs et al. (2020), Central Asian countries implemented the SDGs better than South Asian countries (average country rank 75 compared to 102) (Sachs et al. 2020). However, focusing on SDG 13—Climate Actions individually, several countries are already on track to achieve specified targets, ranging from strengthening resilience and adaptive capacity up to policies, planning, and capacity development measures. On the other hand, the climate change vulnerability monitor shows that countries such as Bangladesh, India, Iran, and Tajikistan are particularly exposed to potential impacts of global warming (Lafortune et al. 2018).

According to United Nations Development Program (UNDP), most of the countries of Central and South Asia have established, or are in development of a National Adaptation Plan (NAP) with partly massive support by the UNDP and the Green Climate Fund (GCF) as part of the historic Paris Agreement (Ahmed et al. 2019).

Various reports summarize current implementation of national adaptation plans and projects in South Asian countries (e.g., in Sterrett 2011; Sumit Vij et al. 2017; Ahmed et al. 2019). They provide a review of political strategies and outline the existing difficulties prohibiting nationwide efforts for adaptation plans often in close relation to disaster risk management. This includes prohibiting factors such as the lack of widespread financial support and lack of integration of adaptation into climate change policies (in addition to mitigation) or the lack of clear institutional structures to initiate and supervise adaptation projects.

Several reports on adaptation projects in Central Asian countries reveal similar fundamental difficulties when it comes to implementing adaptation in policies and institutions (Schlüter and Herrfahrdt-Pähle 2007; Pollner et al. 2008; Sutton et al. 2009; Novikov et al. 2009; UNDP 2018; GIZ 2020a, b).

To meet country specific requirements and vulnerability, a combination of different approaches can meet climate change related need for adaptation.

The Adaptation Committee (AC) of the United Nations Framework Convention on Climate Change (UNFCCC) describes different approaches to meet adaptation to climate change in the longterm, whilst integrating SDGs of various sectors (Adaptation Committee 2019). Among the suggested methods, two approaches stand out to support integration of sustainable development as part of climate adaptation: (1) community-based adaptation, an approach which focuses on strengthening the community by integrating them into the adaptation process, and (2) ecosystem-based adaptation, where nature-based solutions for adaptation are integrated to reduce vulnerability of the ecosystem and the local community to climate risks (Colls et al. 2009; Adaptation Committee 2019; GIZ 2020b).

In order to implement and evaluate the above-mentioned and other approaches (find more in Sterrett 2011; UNDP 2018), the network of UNESCO biosphere reserves can serve as examples and model regions for sustainable development. Biosphere reserves in Central and South Asia can facilitate changes towards sustainability and adaptation, serve nature conservation efforts, as well as support local communities in their desire for socio-economic development (see Box 6.3). In nearly all research and development projects education strategies about climate change adaptation and the implementation of natural conservation are integrated. These innovative and tested ideas are of utmost importance when facing climate change.

Box 6.3 Examples of Biosphere Reserves from Central Asia

There are three biosphere reserves whose location and ecological interconnectedness makes them representative for the major ecosystem types along the inner Asian watershed of Amu Darya and Syr Darya.

The Tian Shan mountains are represented by the Biosphere Reserve Issyk-Kul (Kyrgyzstan), established in 2001. Here, glacier meltdown and a changed water regime of the high mountain glaciers have been observed for decades (Narama et al. 2010; Hagg et al. 2013; Kriegel et al. 2013; Unger-Shayesteh et al. 2013). The surplus meltdown, but also the hydropower stations and dams that have been built affect water availability in the lowlands and have caused a shift in the annual water cycle pattern, with considerable implications for livelihoods (Lioubimtseva 2015).

This can exemplarily be shown in the Lower Amu Darya State Biosphere Reserve (Uzbekistan), established in 2011. The biosphere reserve is located in the lowlands adjacent to the estuary system of wetlands of the southern Aral Sea region. Agriculture in the region is mainly crop and cotton oriented and depends on timely and sufficient water supply (Conrad et al. 2010; Dubovyk et al. 2013). A change in agricultural practices is necessary to adapt to the changing water regime and to ensure food security and energy supply in this densely populated region of Central Asia. Correspondingly, the ecosystem is severely hit by sinking water table, and insufficient or absent flooding events (Kuz’mina and Treshkin 2012). The results are lacking natural rejuvenation and descending riparian forests including the complete species composition. Alternatives are sufficiently investigated and available for upscaling in the transition zone of the biosphere reserve and beyond (Khamzina et al. 2006, 2012; Lamers and Khamzina 2008; Gupta et al. 2009).

Another pearl of this necklace of biosphere reserves along the hydrologic lifelines of Central Asia is the Barsakelmes Biosphere Reserve (Kazakhstan), established in 2016. Barsakelmes is a true witness of man-made ecosystem change within less than half a century. An island in the formerly 4th biggest lake worldwide, the Aral Sea, is nowadays a tiny hilly ridge with steep cliffs within the most recent desert in the world—the Aralkum. It is among the worst ecological disasters of mankind. The biosphere reserve status may leverage the necessary national and international attention and resources to implement the changes needed for the adaptation to climate change.

To tackle the various targets of the SDGs, inter- and transdisciplinary efforts are vital. All kinds of approaches, which are designed, developed, and implemented according to the needs of the specific region and local communities can support local structures and increase resilience against climate change impacts in a sustainable way. Nevertheless, the fight against climate change remains a global task and support from other regions of the world, whether through research and development, support for the network of biosphere reserves and the establishment of global learning networks, efficient use of resources and emission reductions, or through financial contributions, is absolutely necessary to limit the most harmful consequences.