Keywords

1 Introduction

The mountain biomes are considered sensitive to climate change (Nogués-Bravo et al. 2008). The climate change affects directly or indirectly different key features (ecosystems, agriculture, biodiversity, snow cover, glaciers, run-off processes, and water availability) of the mountains (Bharali and Khan 2011; Tiwari and Joshi 2012; Joshi et al. 2012; Bhagawati et al. 2017; Lamsal et al. 2017a; Tewari et al. 2017; Bajracharya et al. 2018). There are growing evidences that the rate of warming is amplified with elevation (Shrestha et al. 1999; Sun et al. 2017). As a result, the high-mountain environment is witnessing more rapid changes in temperature than at lower elevations (Pepin et al. 2015). As a result of higher warming and visible changes in cryosphere and ecosystems, the mountains are considered as an early indicators of climate change (Singh et al. 2010) and such elevation-dependent warming can accelerate the rate of change in mountain ecosystems, cryosphere, hydrological regimes and biodiversity (Beniston 2003; Pauchard et al. 2009; Brandt et al. 2013; Pepin et al. 2015). Mountains have been considered as the last bastion for biodiversity with fragile ecosystems and recognized as major sources of ecosystem services contributing for human wellbeing (Messerli and Ives 1997; Viviroli et al. 2011). Climate change is likely impacting food production and security, sustained water supply, biodiversity and other natural ecosystems, human health limiting sustainable development (Xu et al. 2009; Ravindranath et al. 2011, Iizumi et al. 2013; Palomo 2017).

The maintenance of mountain ecosystem resilience is vital for human well-being as 85% of the people living in the mountains depends directly on ecosystem services, yet despite increase in conservation activities, the vulnerability of mountain ecosystems has been a major challenge (Nogués-Bravo et al. 2008; Rodríguez-Rodríguez and Bomhard 2012; Palomo 2017). Although habitat degradation, fragmentation, and destruction, overexploitation, and invasive species have driven recent biodiversity loss, climate change is projected to be a major driver of extinction throughout the twenty-first century, impacting ecosystems directly or indirectly or via synergies with other stressors (Parmesan 2006; Aukema et al. 2017). Climate change impacts over ecosystem degradation have put the Hindu Kush Himalayas (HKH) at the centre of regional and global attention (Brooks et al. 2006; Shrestha et al. 2012; Xu and Grumbine 2014). There is paucity of systematic research and long term analysis in the HKH due to differences on research priorities, accessibility to the remote areas, availability of financial and human resources and political will. However, the anecdotal information and scatted case studies have realized the vulnerability of diverse ecosystems in the context of changing climate in the HKH (Pandey and Jha 2012; Negi et al. 2017). Evidences showed that climate change have major implications on the poor and marginalized communities who exclusively depend on the ecosystem services for their livelihoods (Chettri et al. 2010). Broadly, the interaction between climate change and healthy ecosystems is twofold, on one hand healthy ecosystems is threatened by climate change, and on the other hand, proper management of ecosystems provides significant opportunities to mitigate the impacts of climate change (Lo 2016).

The HKH play a key role on supporting economy of the countries within the region and downstream of ten major river basins, which depend largely on hydropower, water supply, agriculture, and tourism. For example, Bhutan’s export revenue from hydropower contributed up to 16.3% to the nominal gross domestic product (GDP) or 39% in terms of total exports in 2009/2010 (RMA 2011). Addressing vulnerability is a key issue in the HKH and analyses of existing knowledge, and gaps on how mountain ecosystems could be impacted under climate change is essential. The fragile landscapes of the HKH are highly susceptible to natural hazards, leading to ongoing concern about current and future climate change impacts in the region (Xu and Grumbine 2014). Climate change concerns in the Himalayas are multifaceted encompassing floods, droughts, landslides (Barnett et al. 2005), human health, biodiversity, endangered species, agriculture livelihood, and food security (Xu et al. 2009). While there are some reviews of existing literature on climate change observations and physical impacts on some of these aspects, a comprehensive review covering the HKH from all dimensions of impacts is still missing. Thus, this study has two specific objectives: (i) to synthesize the current state of knowledge on climate change impacts on the biophysical system (e.g., temperature, precipitation, snow coverage, streamflow, glacier melt, and ecosystem changes) in the Himalayan region and (ii) to review existing literature on resilience building practices to address impacts of climate change in the region. This study will help identify critical research gaps on the impacts of climate change in the Himalayas and strengthen understanding on social-ecological interlinkages necessary to understand the resilience contributing to evolutionary adaptation.

2 Hindu Kush Himalaya – The Vulnerable Mountain Ecosystem

The HKH mountain ecosystems is one of the most fragile ecosystems in the world (Ren and Shrestha 2017). Stretched over more than 4.3 million km2 area includes areas of Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal, and Pakistan, the HKH is characterized by some of the most complex terrain, and has a substantial influence on the East Asian monsoon, and even on global atmospheric circulation (Chettri and Sharma 2016). The region provide key livelihood resources such as food, timber, fibre, medicine and a wide range of services such as drinking water, water for irrigation, climate regulation, carbon storage, and the maintenance of aesthetic, cultural, and spiritual values (Sharma et al. 2015; Sandhu and Sandhu 2014; Chaudhary et al. 2017). The natural and semi-natural vegetation cover on mountains helps to stabilize headwaters, prevent flooding, landslide and maintain steady year-round flows of water by facilitating the seepage of rainwater into aquifers, vital for maintaining human life in the densely populated areas downstream. As a result, mountains have often been referred to as ‘water towers’ (Molden et al. 2014; Mukherji et al. 2015). Recognizing the importance of mountains for biodiversity and sustaining ecosystem services, the Convention on Biological Diversity (CBD) in Chapter 13 of Agenda 21 (1992) has recognized the significance of the mountains that supports all forms of living organisms, animals (including humans), and plants (UN 1992).

Driven by plate tectonics, the mountains of the HKH have unique ecosystems with altitudinal variation giving rise to numerous micro climates and diverse ecological gradients. It is the youngest and one of the most diverse ecosystems among the global mountain biomes, with extreme variations in vegetation, climate, and ecosystems resulting from altitudinal, latitudinal, and soil gradients (Xu et al. 2009; Sharma et al. 2010). This diverse biophysical habitat sets the stage for a rich biodiversity and species evolution (Miehe et al. 2014; Hudson et al. 2016). The region is the source of 10 major river systems with productive landscapes and strong upstream downstream linkages (Xu et al. 2009), and includes all or part of four global biodiversity hotspots — Himalaya, Indo-Burma, mountains of Southwest China, and mountains of Central Asia (Mittermeier et al. 2004; Chettri et al. 2010) — which contain a rich variety of gene pools and species with high endemism and novel ecosystem types with one of the highest rate of deforestation and habitat degradation. In addition, the region supports more than 60 different ecoregions, many of them are part of the Global 200 ecoregions (Olson and Dinerstein 2002). The ecosystem services from the HKH sustain 240 million people in the region and benefit some 1.6 billion people in the downstream river basin areas and have been well recognized by many scholars (Quyang 2009; Xu et al. 2009; Molden et al. 2014; Sharma et al. 2015).

However, the HKH region, has been witnessing various direct and indirect pressure through wide range of drivers such as habitat degradation, pollution, invasive species and climate change to name a few (Chettri and Sharma 2016). Climate change trigger higher rate of erosion manifested by change in precipitation pattern (Burbank et al. 2003; Pandit et al. 2007) increasing the frequency of disasters leading to vulnerability of these fragile ecosystems. Forest fragmentation has been identified as one of major drivers leading to vulnerability in both western (Uddin et al. 2015) and eastern Himalayas (Ravindranath et al. 2011). Sensitive ecosystems such as wetlands and high altitude rangelands are more vulnerable to combined effects of various drivers such as climate change, land use change, overexploitations etc. (Chettri et al. 2010; Chaudhary et al. 2017). As a result, the soil retention capacity has been reduced with increased erosions and frequency of floods (Burbank et al. 2003; Joshi and Kumar 2006; Cánovas et al. 2017).

3 Climate Change Trend in the Hindu Kush Himalayas

3.1 Weather and Climate of Hindu Kush Himalayas

The Himalayas are sensitive to climate change and variability (Eriksson et al. 2009; Shrestha and Aryal 2011). The climate of this region is found to be related to several large scale global climatic phenomena. The climate in this region has experienced large scale change in the historical and paleoclimatic time scales owing to natural changes and variability such as solar variability, orbital changes, tectonics and volcanism (Chettri and Sharma 2016). Moreover, topography, seasonality, and variability of weather patterns strongly determine the spatial and temporal pattern of temperatures and precipitation across different geographic regions of the HKH. The average summer and winter temperatures are about 30 °C and 18 °C respectively in the southern foothills. In the middle Himalayan valleys mean summer temperatures range between 15 °C and 25 °C and very cold winters (Shrestha and Aryal 2011). Areas having elevations above 4800 m experience winter temperatures below freezing point and receive precipitation largely in the form of snow. Topography also plays important role in the form of precipitation with a major part of precipitation from the southwest Indian summer monsoon, fall as frozen precipitation at higher elevations and liquid precipitation at lower elevations and adjacent plains of the Himalaya. As revealed by the sparse rain gauge network, the southern slopes of the Himalaya typically experience large annual precipitation totals as high as 400 cm per year during the period of 1998–2007 (Bookhagen and Burbank 2010). Since the influence of summer and winter monsoon circulation is not evenly distributed over the Himalayas, the summer (winter) rainfall is typically the greatest over the southeast (northwest) part of the HKH. Monsoon precipitation is found to be the highest over the Siwalik and Pir Panjal ranges of the lower Himalaya, while it reduces northwards into the Great Himalaya, Zanskar, Ladakh, and Karakoram ranges. However, most of the warming observed during the last few decades of the twentieth century is attributed to the increase in anthropogenic greenhouse gas concentration (IPCC 2007; You et al. 2017).

3.2 Past Climate Changes

3.2.1 Temperature

Several studies have been conducted on surface air temperature change for a different areas of the HKH, including the Tibetan Plateau (Liu and Chen 2000; Wang et al. 2008; Liu et al. 2009; Yao et al. 2012; Duan and Xiao 2015; Wang et al. 2016; Fan et al. 2015; Ren et al. 2017; You et al. 2017). These studies show significant warming in recent decades and the last century, in spite of the fact that the warming varies in different part of the HKH. Among them Ren et al. (2017) covered the whole HKH domain. According to this study, during the period 1901–2014, annual mean surface air temperature significantly increased in the HKH at a rate of about 0.11 °C per decade. For the full period of record (1901–2014), annual temperature trends show significant upward trends (p < 0.05), and the increase rates of Tmean, Tmax and Tmin are 0.10 °C per decade, 0.08 °C per decade, and 0.18 °C per decade, respectively (Fig. 25.1; Ren et al. 2017). Diurnal Temperature Range (DTR), the difference between the daily maximum and minimum temperature, shows a significant negative trend of −0.10 °C per decade, due to the much larger rise of minimum temperature than of maximum temperature in the region. Locally, deviations from the general pattern described above have been found in the Karakoram region, where in decreasing (most notably) summer temperature have been measured (Forsythe et al. 2017). These trends are comparable with or greater than the global land- surface temperature trends.

Fig. 25.1
figure 1

Annual mean temperature anomaly series (°C) relative to 1961–1990 mean values for Tmean (a), Tmax, Tmin, and DTR (b) for the HKH between 1901 and 2014 (data source: CMA GLSAT; Ren et al. 2017)

Full size image

3.2.2 Precipitation

Analysis of past 114 years’ (1901–2013) trends of annual precipitation in the entire HKH using Global Land Monthly Precipitation (GLMP) and Global Land Daily (GLDP) data sets recently developed by the China Meteorological Administration (CMA) did not show significant trends (Ren et al. 2017). It is typical to the region and could be due to due to the sensitivity to topography. The regional average annual precipitation standardized anomaly (PSA) and annual precipitation percent anomaly (PPA; Fig. 25.2; Zhan et al. 2017) show fluctuations from one year to another, but the fluctuation became relatively larger from 1930 to 1960 (Fig. 25.2). While the overall trend was negative for the HKH the trends were small and not significant at the 0.05 confidence level (Ren et al. 2017).

Fig. 25.2
figure 2

The regional average annual PSA (a) and PPA (b) over 113 years (1901–2013) in the HKH. Time series, with the green line denoting the 5-year moving average, and the black line the linear trend

Full size image

3.3 Past Changes in Extremes

3.3.1 Temperature

Changes in extremes are important as adapting to extremes, both by humans and ecosystem is more challenging. Our studies have suggested that most parts of the HKH underwent significant long-term changes in extreme temperature events over the past decades. Temperature extreme indices have shown changing trends, with extreme cold events significantly decreasing and extreme warm events significantly increasing over the HKH during the past six decades (Sun et al. 2017). The trends of the extreme events related to minimum temperature were greater in magnitude than those related to maximum temperature. Similar results were found in the Koshi Basin by Rajbhandari et al. (2016). Further, extreme values of the highest Tmax (TXx) and the lowest Tmin (TNn) showed increasing trends in the HKH, with the rising rate of TNn double that of TXx (Sun et al. 2017). In addition, summer day (SU) frequency also show increasing trend, while annual frost day (FD) frequency decreased (Sun et al. 2017). The minimum temperature is rising more rapidly than maximum temperature and as a result the daily temperature range (DTR) is decreasing. Like in the HKH almost all the extreme temperature indices in the Tibetan Plateau region showed statistically significant trends over the past half century (You et al. 2008; Zhou and Ren 2011; Sun et al. 2017).

3.3.2 Precipitation

Like temperature the extremes in the precipitation are also changing in the HKH, although changes in temperature are more homogeneous at than the patterns in precipitation due to the sensitivity to topography, for example The regional average annual amount, and day and annual intensity anomalies for the percentile based light (below the 50th percentile), moderate (between the 50th and 90th percentiles), and intense (beyond the 90th percentile) precipitation over the period 1961–2013 in the HKH (Zhan et al. 2017). The intense precipitation show most significant increasing trend (p ≥ 0.95). The increase in in annual intense precipitation amount, days and intensity are 5.28 mm per decade, 0.14 day per decade and 0.39 mm/day per decade respectively. The light precipitation indices also show increasing trend but not of the similar significance as intense precipitation, while moderate precipitation do not show any trend.

3.4 Elevation Dependent Warming

The elevation-dependent warming (EDW) phenomenon is reported globally (Wang et al. 2014; Fan et al. 2015; Pepin et al. 2015). Similar phenomenon is also reported in the HKH as a whole and different parts of HKH (Shrestha et al. 1999; Liu and Chen 2000; Yan and Liu 2014; Wang et al. 2014, 2016; Duan and Xiao 2015; Guo et al. 2016; Yan et al. 2016; Sun et al. 2017). The exact physical mechanism driving EDW is not understood properly and needs further investigation. Study by Yan et al. (2016) on EDW over the Tibetan Plateau, and suggested that the increase in surface net radiation is driving the EDW phenomenon. One hypothesis suggests that the positive feedback associated with a diminishing cryosphere, particularly the snow cover is the cause of EDW (You et al. 2010). As the HKH has the largest extent of cryosphere (glaciers and ice caps, snow, river and lake ice, and frozen ground) outside the Polar Regions EDW is likely to have strong impact, which could further impact various ecosystem services of this region.

3.5 Future Climate Change

3.5.1 Temperature

The climate projections are unequivocal in suggesting continued warming in the future (Kumar et al. 2011; Kulkarni et al. 2013; Rajbhandari et al. 2015, 2016). A recent modelling work done under the Coordinated Regional Climate Downscaling Experiment (CORDEX) initiative suggested continued warming into the future (Sanjay et al. 2017). Sanjay et al. (2017) conducted analysis for the HKH domain based on CORDEX data. Present review is based on their results The magnitude of the projected seasonal warming is found to different for different part of the region, and dependent on season, averaging period, and scenario. Higher warming is projected during winter and the projected warming differs by more than 1 °C between the eastern and western HKH, with relatively higher values during winter (Sanjay et al. 2017). The highest warming is projected to be over the central Himalaya for the far-future period with the RCP8.5 scenario.

The projections made by the study for the near-future and far-future periods for HKH are relatively higher than the seasonal global means based on the same subset of CMIP5 GCMs (Table 25.1). The summer season global mean projected change for the far-future period is 1.9 °C (RCP4.5) and 3.3 °C (RCP8.5), while for the winter season global mean projected changes are 2.0 °C (RCP4.5) and 3.5 °C (RCP8.5; Table 25.1 Sanjay et al. 2017). Analysis of an ensemble of five General Circulation Model runs projecting a global temperature increase of 1.5 °C by the end of the twenty-first century reveals would mean a temperature increase of 1.8 ± 0.4 °C averaged over the region (Fig. 25.3). Moreover this enhanced warming is even more pronounced for the mountain regions, for example for the Karakoram, Central Himalayas, and Southeast Himalayas, a 1.5 °C global temperature increase would imply regional temperature increases of 2.2 ± 0.4 °C, 2.0 ± 0.5 °C, and 2.0 ± 0.5 °C, respectively (Fig. 25.3).

Table 25.1 Seasonal ensemble mean projected changes in near-surface air temperature (°C) relative to 1976–2005 in three HKH sub-regions defined by grid cells within each sub-region above 2500 m a.s.l.: northwest Himalayas and Karakoram (HKH1); central Himalayas (HKH2); southeast Himalayas and Tibetan Plateau (HKH3). The ranges for the 10 GCMs and 13 RCMs analysed are given in brackets
Full size table
Fig. 25.3
figure 3

Comparison of results of models projecting 1.5 °C increase in near-surface air temperature (°C) globally and for the HKH and the three sub-domains: northwest Himalayas and Karakoram (HKH1); central Himalayas (HKH2); southeast Himalayas and Tibetan Plateau (HKH3). The temperature changes are for the end-of-century from the pre-industrial period (2071–2100 vs 1851–1880)

Full size image

3.5.2 Precipitation

CORDEX projections for the HKH suggest summer season increase in precipitation over the hilly regions in the central Himalayas and southeast Himalayas and Tibetan Plateau for both RCP4.5 and RCP8.5 scenarios in the near-future and far-future periods. The largest projected seasonal ensemble mean total precipitation increase during the summer monsoon season is about 10% over HKH2 with RCP4.5 scenario and about 22% over HKH3 with RCP8.5 scenario. During winter season the largest projected increase in precipitation is over HKH1 of about 14% and 13% with RCP4.5 and RCP8.5 scenarios respectively. However, it has to be noted that the spread among the models is large for the high resolution CORDEX RCMs, as well as for their driving CMIP5 GCMs resulting in higher uncertainty in precipitation projection compared to temperature (Sanjay et al. 2017). The observed and projected future climate change can have profound impact in the ecosystem of this region directly and indirectly through changes in water availability, extreme events, cryospheric changes, etc. Adapting to long- and short-term climate-related problems requires a thorough understanding of climate changes in the past and possible changes in the future (You et al. 2017).

4 Implication of Climate Change in Ecosystem Resilience

Climate change affects human wellbeing in two ways, directly through altering local weather conditions inviting extreme weather events and hazards, and indirectly through its effects on ecosystems and ecosystem services that people need for their sustenance (Xu et al. 2009). The Earth’s atmosphere has a natural greenhouse effect, without which the global mean surface temperature would be about 33 °C lower and life would not be possible. Human activities have increased atmospheric concentrations of carbon dioxide, methane, and other gases which has enhanced the greenhouse effect, resulting in surface warming (Serreze 2010). There are numerous implications from impact of climate change on ecosystems and biodiversity at different levels and scales. An anecdotal list of climate change impacts have been reviewed and included in Table 25.2. Here, we bring some examples where both social and ecological facets of resilience are being challenged with the past trends and projected future climate change:-.

Table 25.2 Impact of climate change on ecosystem and biodiversity at various systems, levels and range
Full size table

4.1 Ecosystem Resilience

In the HKH, and elsewhere, ecosystems influence human societies, leading people to manage ecosystems for human benefit and poor environmental management can lead to reduced ecological resilience and social–ecological collapse (Cumming and Peterson 2017). One of the central questions in resilience science is how ecological function related to human wellbeing. This question has become increasingly relevant in the HKH as climatic and anthropogenic transformation of the region has intensified (Miehe et al. 2009). The distribution and abundance of species have been radically transformed due to climate change and massive land-use changes which have eliminated numerous endemic species (Chettri et al. 2010), and the expansion of developmental activities has added challenges in management of the natural ecosystem (Pandit et al. 2007). The variations on climatic variables such as temperature and precipitation have directly or indirectly affected the natural ecosystems (Table 25.2). This biotic reorganization is co-occurring with a variety of other changes, including climate change, alteration of nutrient cycles, and chemical contamination of the ecosystems (Xu et al. 2009; Chettri and Sharma 2016). Maintaining the ecosystem services that support humanity, and other lifeforms, during this extensive and rapid ecological reorganization requires understanding how ecology interacts with human society (Wangchuk 2007; Cumming and Peterson 2017). Here, we bring some empirical evidence of changes interpreted as a result of climate change.

4.1.1 Vegetation Shift

Mountains ecosystems are both fragile and sensitive. But is also provide opportunity for adaptation for many species sensitive to climate change with the provision to change the range shift to higher elevation. A number of studies have evolved indicating northward and high altitude movements of species due to climate change (Beckage et al. 2008; Pauchard et al. 2016; Lamsal et al. 2017b; Pecl et al. 2017). Evidences showed that a wide number of species have been reported to change their reported altitudinal range and moving northwards and higher altitude (Telwala et al. 2013). One of the recent study on sub-alpine species from Nepal, namely (i) Himalayan Fir (Abies spectabilis), (ii) Maple (Acer campbellii), (iii) Birch (Betula utilis), (iv) Black Juniper (Juniperus indica, (v) Brown oak (Quercus semecarpifolia), (vi) Himalayan hemlock (Tsuga dumosa), (vii) Bell rhododendron (Rhododendron campanulatum), (viii) Gerard jointfir (Ephedra gerardiana), and (ix) Himalayan heather (Cassiope fastigiata) have shown potential northward movements with projected climate change till 2100 (see Fig. 25.4; Lamsal et al. 2017b). Such upward or northward movement have major implications to alpine ecosystem, which accounts about 60% of the HKH (Chettri et al. 2008) and the cryosphere which are taken over by tree line advancement (Baker and Moseley 2007; Gaire et al. 2017). Alpine ecosystems are particularly vulnerable to warming, as species occurring near the mountain tops will have no space for their upward march and available areas are encroached from the south of low elevation (Pauchard et al. 2009; Singh et al. 2011). Such movements even change the land cover, bioclimatic zones and ecoregions (Sharma et al. 2009; Fig. 25.5) as also predicted by Zomer et al. (2014) and enabling invasive species to make inroad to such fragile areas (Lamsal et al. 2017b) making the ecosystems more vulnerable.

Fig. 25.4
figure 4

Spatial extent of current climatic suitability (a) and changes for 2050 (b) and 2100 (c) for the nine species (Source Lamsal et al. 2017b)

Full size image
Fig. 25.5
figure 5

Decadal land cover change in the Eastern Himalayas during 1998 (a) and 2002 (b). (Source Chettri et al. 2010)

Full size image

4.1.2 Degradation of Fragile Ecosystems

Approximately 39% of the HKH is comprised of grassland, 20% forest, 15% shrub land, and 5% agricultural land. The remaining 21% is other types of land cover such as barren land, rock outcrops, built-up areas, snow cover, and water bodies (Chettri et al. 2008). Among these, rangeland constitute to major part of the HKH with combined shared of grassland and shrub land. The Tibetan Plateau and Greater Himalayas is mostly dominated by rangeland where pastoralists’ communities are dependent (Chettri et al. 2012). Intensification of water stress because of higher warming temperatures and changing precipitations are adversely affecting phenology, regeneration and productivity of many of these ecosystems, specially the high altitude rangeland (Singh et al. 2011; Yu et al. 2010; Wang et al. 2017). As a result, the entire mosaic of ecosystems found in the HKH have been witnessing changes manifested by climate change and other anthropogenic drivers.

Forest ecosystem, which covers about 20% of the total areas of HKH is one of the most important ecosystems for the region. It is sources of a wide range of provisioning ecosystem services and regulatory services including carbon sequestration (Lamsal et al. 2017c; Chaudhary et al. 2018). However, the forest degradation, fragmentation and loss have been widely reported with varied scenarios (Pandit et al. 2007; Hansen et al. 2013). Increasing fragmentation trend has been reported from the region such as India (Reddy et al. 2013), Nepal (Uddin et al. 2015; Reddy et al. 2018) and Bhutan (Reddy et al. 2016; Sharma et al. 2017). The rate of deforestation along the HKH has been reported to be 0.5% in Bhutan to 1.7% in Myanmar (Fig. 25.6).

Fig. 25.6
figure 6

The Himalayan temperate forest zone and deforestation rates (in parentheses) from 2000 to 2014 in forests that are not officially protected. (Source Brandt et al. 2017)

Full size image

Wetlands, an important ecosystem for the millions people living on the valley floors and plateau areas of the HKH, wetlands are central to their livelihoods (Trisal 2009). Lakes, floodplains, and peat lands support wide range of ecosystem services including tourism to the region’s poorest communities (Sharma et al. 2015; Chaudhary et al. 2017). The wetlands maintain water quality, regulate water flow (floods and droughts), and in the case of high-altitude peat lands, regulate the global climate (storage of carbon in peat) and also support both regional and global biodiversity (Chettri et al. 2013).

However, the wetland ecosystem in the region is rapidly degrading: in some areas as many as 30% of the lakes and marshes have disappeared because of overexploitation of wetland resources and climate change during the past few decades (Trisal 2009). Climate change, along with land use change, anthropogenic pressure for ecosystem services and natural hazards are collectively changing the wetland ecosystems in many parts of the HKH (Rashid and Romshoo 2013; Chettri et al. 2013; Lamsal et al. 2017c; Chaudhary et al. 2017).

Likewise, the agro-ecosystem, which is merely 5% of the total HKH area has also witnessed changes either due to agricultural intensification in some areas or by leaving it fallow due to social restructuring of the communities in the remote villages. However, the impact of climate change is yet to be studied and ascertain. At the global level it is estimated that the major crops such as rice, wheat and maize could see 26–36% decrease based on the trend of past climate change (Iizumi et al. 2013). The brunt of climate change has been witnessed in many parts of the HKH evident as reported on studies from people’s perceptions (Chaudhary et al. 2011; Negi et al. 2017; Suberi et al. 2018), reported low productivity (Vedwan 2006) and loss of traditional varieties such as finger millets, buckwheat’s etc. (Aryal et al. 2017). Owing to the higher than average warming, the HKH region is facing adverse challenges for vulnerability from climate change and other drivers of change impacting in a wide spectrum of fragile ecosystems.

4.2 Social-Ecological Interdependency

In the recent years, the significance of mountain ecosystems for its ecosystem services for human wellbeing has been realized (Grêt-Regamey et al. 2008, 2012; Palomo 2017). The inhabitant of the HKH is extensively dependent on the natural ecosystems for ecosystem services contributing to wellbeing. This is evident from a recent series of documentation on people’s dependency on ecosystems across the HKH (Gosain et al. 2015; Paudyal et al. 2015; Chaudhary et al. 2016, 2017; Murali et al. 2017). Following standard frameworks (De Groot et al. 2010; Muller et al. 2010), some of the recent studies have shown strong interdependency between the local communities and surrounding ecosystems and also being impacted due to change of such dependent ecosystems (see Chaudhary et al. 2016, 2017; Kandel et al. 2018). It was observed that about 85% of the provision services are contributed by the Koshi Tappu wetland ecosystem where 7.5% is from cultural services alone (Sharma et al. 2015).

There was significant change observed in the surrounding ecosystems of Koshi Tappu which has threatened the flow of these ecosystems services. These is evident as the forest ecosystem has reduced by almost 85% over the past 30 years making people dependent on forest for services more vulnerable (ICIMOD and MoFSC 2014). Similar results were also documented from other wetlands (ICIMOD and RSPN 2014; ICIMOD and MoNREC 2017) and forest and agro-ecosystems (ICIMOD and BCN 2017; ICIMOD and RSPN 2017). These studies categorically indicates that there is a strong social-ecological interdependency and the strategies for addressing climate change including others drovers of change need new innovations.

5 Discussion and Conclusion

Climate change has been identified as one of the major drivers of global change and reported to be more pronounced in the HKH with higher warming rate (Krusic et al. 2015; Sanjay et al. 2017). These changes have already made cascading effects to the fragile ecosystems of the HKH with increasing temperature trend and projections, with variable precipitation patterns across the region (Srivastava et al. 2017; Zhan et al. 2017). It is also evident that the changing climate has influenced directly or indirectly the ecosystems health, functions and productivity which are directly linked to human wellbeing through its ecosystem services flow (Xu et al. 2009; Chettri and Sharma 2016). The diverse ecosystems of the HKH, the source of wide range of ecosystems services including water and habitat for numerous globally significant species, are witnessing increasing vulnerability (Chettri et al. 2010; Pandey and Bardsley 2015; Forrest et al. 2012). The study from Eastern Himalayas have already indicated that some ecosystems such as freshwater, forest, savannas grassland are categorized as vulnerable (see Chettri et al. 2010). The roots causes of driver of change – the anthropogenic activities have no sign of improvement, at least in immediate near future (Ceballos et al. 2017). However, there is little debate in scientific circles about the importance of human influence on ecosystems. To improve overall resilience, an understanding of contributing factors such as economic, social and environmental resource is necessary (Gardner and Dekens 2007; Norman et al. 2012).

High mountain areas are arguably the region most affected by climate change (Shrestha et al. 1999; Beniston 2003; Keller et al. 2005; Xu et al. 2009). Assessments of climate change impacts in these regions have been mostly single-disciplined. Biophysical studies have focused on temperature changes, glacier retreat, hazards, and biodiversity (Dullinger et al. 2012; Pepin et al. 2015). Social research has focused on impacts associated with water availability and livelihoods, and these impacts have been described more for downstream communities (Xu et al. 2009; Immerzeel et al. 2015) than upstream inhabitants (Beniston et al. 1997; Kohler et al. 2010). Integrative approaches that focus on climate change impacts on multiple ecosystem services in high mountain areas are still limited (Chettri and Sharma 2016; Chakraborty et al. 2018).

Climate change effects varied across the HKH but mostly they are devastating for mountain communities, accentuating their vulnerability to disasters, conflicts, migration and poverty (Gerlitz et al. 2015; Hoy et al. 2016; Sharma et al. 2017). As the HKH ecosystems are contiguous and the impacts are not limited to one national border, to address climate change, it is crucial to develop innovative joint research programmes at landscapes or river basins considering transboundary approach combined with efficient communication platforms to raise public awareness about its impacts in the mountains (Molden et al. 2017).

It is well known that the rate of temperature change with increased levels of greenhouse gases in the atmosphere is amplified at high latitudes, but there is growing evidence that the rate of warming is also amplified with elevation, such as in mountain environments (Shrestha et al. 1999; Pepin et al. 2015). However, because of sparse high-elevation observations, there is a danger that we may not be monitoring some regions of the globe that are warming the most (Wijngaard et al. 2017). In response to the prevailing threat from climate change, new regional and innovative efforts on climate change adaptation in terms of policy and practices have begun to emerge (Gerlitz et al. 2015; Hoy et al. 2016; Rasul and Sharma 2016). However, many of the current wave of contributions are observational and correlational, and few are experimental in nature, and too often at conceptual levels in which convincing results are lacking. We conclude with recommending a future strategy for multidisciplinary research at landscape or basin levels to reduce current uncertainties and to ensure that the changes taking place in remote high-elevation regions of the HKH are adequately observed and accounted for. The use of contemporary geospatial science and modelling tools may add value for informed decision making.