The Global Energy and Water Exchanges (GEWEX) Project in Central Asia: The Case for a Regional Hydroclimate Project

Central Asia is a region that is very vulnerable to climate change. The majority of its water resources are from summer melting of the regions’ mountain glaciers and annual snowpack. In a warming world, glacial extent and volume, as well as the snowpack, are declining. Agriculture is an important basis of the region’s economies and is highly dependent upon irrigation but also vulnerable to rising growing-season temperatures. For the region to efficiently and effectively adapt to these changes, it needs significantly improved observational networks and modeling that can provide more useful information for policymakers to invest in climate adaptation.

Central Asia is generally considered to include the five countries that were the former five Republics in the Soviet Union—Kazakhstan, Kyrgyz Republic, Tajikistan, Turkmenistan, and Uzbekistan. The total area is nearly 4 000 000 km². These five countries border Afghanistan and Iran in the south, China in the east, with Russia in the west and north, and India and Pakistan in the southeast (Fig. 1). As defined, Central Asia has a total combined population (2022) of about 78.5 million and a combined 2022 GDP (Turkmenistan data from 2020) of approximately $368 billion US (World Bank, 2023). The climate in the region is continental, mostly arid, or semi-arid. The average precipitation (concentrated in the winter and spring) is about 270 mm, varying from 600–800 mm in mountains zones and 80–150 mm in desert regions (ICWC, 2023).

Figure 1.  Map of the study area comprising the five main Central Asian countries as well as their neighboring countries, the main rivers, lakes, and mountain ranges (Global Mountain Explorer; Karagulle et al., 2017; BGR, 2004, Made with Natural Earth—naturalearthdata.com).

Agriculture is a major source of income in the region. In 2019, the most recent year available for all five countries, the added value (% of GDP) of agriculture, forestry, and fishing was 4.5% for Kazakhstan, 11.7% for the Kyrgyz Republic, 11% for Turkmenistan, 20.9% for Tajikistan, and 24.4% for Uzbekistan (World Bank, 2023). By its nature of intensive water use, agriculture is extremely vulnerable to climate change [for example, in Uzbekistan, see UzHydroMet (2016)] and water limitations for ecosystems. Central Asia is one of the biggest irrigation regions in the world [with about 9.1 million hectares of irrigated crops (ICWC, 2023)].

Population growth and irrigated croplands have significantly increased the demand for water in the region, especially during the past 40 years. Actual consumptive water withdrawal in Central Asian countries varies from 20% of available water resources (Kazakhstan, Kyrgyzstan, Tajikistan) to 80%–90% (Uzbekistan, Turkmenistan) with about 9.1 million hectares of irrigated crops (ICWC, 2023). The largest rivers over the region are mostly transboundary, including the Syr Darya and Amu Darya (Afghanistan, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, Uzbekistan), Chu and Talas (Kyrgyzstan and Kazakhstan), Tarim (Kyrgyzstan, Tajikistan, China), Ili (China, Kazakhstan), Irtysh (China, Kazakhstan, Russia), and Ural, Ishim, and Tobol (Kazakhstan, Russia) (ICWC, 2023).

Major climate change issues include melting glaciers and a shrinking snowpack, which are the foundation of the region’s water resources, and a changing precipitation regime (type/ occurrence/ quantity/ uncertainty). The glaciers are primarily located in Kyrgyzstan and Tajikistan, leading to more transboundary water resource issues. The already extremely high summer temperatures are increasing. Thus, the region’s irrigation-dependent agricultural systems are highly vulnerable, especially in Uzbekistan and Kazakhstan. These are downstream countries in terms of river flows with very large areas of croplands. There are climate-vulnerable habitats and ecosystems that are important to traditional pastoral lifestyles and riparian ecosystems, as well as for conservation of habitats for snow leopards (van Oevelen and Brody, 2022).

There are analyses that show that, as a region, Central Asia has been significantly warming and precipitation might be increasing (Haag et al., 2019). Like all regions of the world, Central Asia is expected to continue to warm, but by how much, and its spatial and temporal distribution, is highly uncertain (e.g., IPCC, 2014, 2022). Projections of future precipitation quantity, type, and distribution—whether country-specific (Climate Risk Country Profile: Uzbekistan, World Bank Group, and Asian Development Bank, 2021a; Climate Risk Country Profile: Kyrgyz Republic, World Bank Group, and Asian Development Bank, 2021b) or for the region as a whole (Jiang et al., 2020)—show significant variabilities and uncertainties both within and between modeled scenarios.

GEWEX is the Global Energy and Water Exchanges project of the World Climate Research Program (WCRP) and has as one of its priority areas the improved understanding of the impacts of climate variability and change on water availability and food security across mountain ranges and river basins. GEWEX was founded over 30 years ago with the objective of addressing significant gaps in the understanding of Earth’s energy and water cycles given a lack of information about basic fluxes and reservoirs of these cycles. In the late 1970s, understanding of the global and regional aspects of water and energy budgets was relatively poor, and even less was known about the processes that connect these two major components of the Earth system (Stephens et al., 2023).

Because it continues to investigate critical aspects of Earth system science and particularly those processes that establish the Earth’s climate, GEWEX has remained relevant. GEWEX also continues to advance the use of well-established scientific methods based on theory and models with observations. GEWEX has also shown the importance of engaging diverse communities and the necessity of international collaboration for the monitoring of the changes in the energy and water cycles and for an improved understanding of these cycles under ever increasing human pressures (Stephens et al., 2023).

To support research activities in a specific region, GEWEX has developed so-called Regional Hydroclimate Projects (RHPs) that are led by, and bring together, scientists and stakeholders at every level from within a certain region (Fig. 2).

Figure 2.  Map showing the locations of RHPs. Regions rendered with blue stripes are the current RHPs (Baltic Earth, GWF, USRHP, ANDEX, AsiaPEX and TPE-WS) and initiating/prospective (Central Asia, FutureMed) RHPs. (Not shown are newly planned initiatives in Africa and New Zealand) (Stephens et al., 2023).

RHPs have evolved from the successful “continental scale experiments” (Lawford and Unninavar, 2017) in the early 1990s and 2000s to these highly successful RHPs, such as Global Water Futures (https://gwf.usask.ca/index.php), formerly the Changing Cold Regions Network (CCRN) (DeBeer et al., 2015), the Hydrological Cycle in the Mediterranean Experiment (HYMEX) (www.hymex.org; Drobinski et al., 2014), and Baltic Earth (Meier et al., 2014). One aspect that is becoming increasingly important is “enhancing the actionability” (see Morrison, 2023). Along with that comes responsibility of regional research that is accessible, comprehensible, and useful for environmental policy and management. A clear example here would be the implications and limitations of downscaling climate projections from global climate models [such as from CMIP (Eyring et al., 2016)] to local projections for local policy.

For the Central Asian region, international wildlife conservation issues, such as the snow leopard, pose an additional challenge that we would like to address in the context of global environmental change (Snow Leopard Trust, 2023). Furthermore, there are still local inhabitants who live somewhat traditional pastoral lifestyles in very rural and climate-vulnerable mountainous areas. The Central Asian countries face severe challenges related to water quality, water scarcity, management, and availability, which calls for joint efforts among these countries (Bernauer and Siegfried, 2012; Siegfried et al., 2012). Developing sustainable solutions for future water resources is a critical task for the region. Scientific and technological cooperation will be required to solve these problems. Cooperation and innovative solutions that use reliable evidence and promote broader regional approaches are needed (van Oevelen and Brody, 2022).

GEWEX has projects on every continent, although its network of scientists and institutions in Central Asia is limited (van Oevelen and Brody, 2022). Central Asia is unique in terms of its water resources, conservation issues, and vulnerability to climate change (Lioubimtseva and Henebry, 2009), as well as weather and climate extremes, and encompasses some of the highest mountain ranges in the world along with the largest endorheic lake in the world (the Caspian Sea). As was highlighted in October 2019 at the WMO’s High Mountain Summit (https://highmountainsummit.wmo.int/en; Call to Action), the high mountains are a new focal point for both the WMO and GEWEX. With the presence of high mountain regions and the Caspian Sea being the largest inland waterbody, Central Asia is a unique environment to study the effects of changing land–atmosphere interactions and how climate, weather, and water availability will be affected (van Oevelen and Brody, 2022).

The overarching goal is to establish an RHP in Central Asia led by regional scientists and stakeholders that can better observe and predict climate change and its effects at the regional and local levels. This will be critical to support mitigation and adaptation measures (van Oevelen and Brody, 2022). Successful RHPs all have strong and cohesive scientific and stakeholder networks. The first task is to build a community of scientists and stakeholders with mutual interests. This can be done through workshops, summer and winter schools, newsletters, and any other platform or media to exchange data, information, and interests (van Oevelen and Brody, 2022). It is also necessary to build capacity and capabilities (e.g., through collaboration with START: www.start.org).

For any scientific community to successfully collaborate, sufficient and accessible data are needed. Thus, we need to bring together observational networks/observational data and promote open access and data/knowledge sharing (Open Science). Although not data networks, there are already-existing initiatives and efforts (e.g., Central Asia Regional Information Network, CARIN, https://www.centralasiarin.net; and the Mountain Research Initiative, https://www.mountainresearchinitiative.org/) to build upon and collaborate with. The future is in the hands of our younger generation and hence it is important to contribute to the development of a network of young Central Asian climate researchers that can support a longer-term vision and execution of much needed research in climate and sustainability fields in the region. This can be done in the context of existing early-career networks (e.g., www.yess-community.org, www.younghs.com) or through development of new networks if there is no sufficient overlap with existing ones.

The first step to build a community is to get to know the community, its interests, priorities, and current capabilities and capacities. To achieve that, GEWEX and START developed an online survey called “An Exploration of Climate Science in Central Asia – Moving Towards Frontiers of Knowledge and Action”, which was widely circulated and followed up with a workshop to further explore the outcomes of the survey. The three-day virtual workshop on climate science in Central Asia was conducted on 4–6 October 2021 and was carried out in partnership between GEWEX, START, and the American University of Central Asia (AUCA) in Bishkek (GEWEX, 2022). This workshop was in part based on the results from the online survey on climate science needs and priorities in Central Asia that the three partner organizations conducted earlier in 2021. The series of objectives of the virtual workshop included collaboratively identifying key priorities for research and capacity development related to linking climate science into hydrologic research and application, glacier retreat, agriculture, land-use and land-cover change, and other critical challenges. Plus, initial ideas were put forward for identifying and mobilizing resources that can build towards a GEWEX RHP, and that serve to inform the emerging WCRP Regional Information for Society (RIFS) core project and develop a regionally based group of experts and networks that are committed to work with the partners to advance this effort.

There were six key recommendations that emerged from the workshop. They emphasized more regional collaboration on water and climate is needed, including bridging the policy–science gap. Inclusivity (culturally and across stakeholders) needs more attention. There is a need for more complete and better-quality data and observations that go beyond just open data and resource sharing. Capacity development is needed at all levels, and should include strategies for adaptation and mitigation, from research to applications with appropriate implementation. Global and regional hydrologic projects should be coordinated and linked to the relevant communities, and this includes indigenous knowledge. Finally, there is a strong need to prevent brain drain and attract and retain young talent.

As a follow up to the virtual workshop, an in-person workshop, Climate Change, Water Resources and Agriculture in Central Asia (https://www.gewexevents.org/meetings/water-resources-central-asia/), was held from 18–20 May 2023 at the National Research University Tashkent Institute of Irrigation and Agricultural Mechanization Engineers of Uzbekistan (NRU TIIAME) (Brody and van Oevelen, 2023). The main goal of the workshop was to facilitate collaborative discussions for study led by Central Asian researchers. This core group would then work to establish a regional project in Central Asia on hydroclimate, water resources, food security, conservation, and land use. A crucial aspect for successful regional project development is the existence of a strong and cohesive scientific and stakeholder network—an established community with relevant interests. Such a community can better observe and predict climate change and its effects. This will support adaptation and mitigation measures for improved water resource management, land-use planning, and food supply sustainability.

The workshop was organized through a collaboration between GEWEX/George Mason University (USA), Wageningen Metropolitan Food Clusters/Wageningen University and Research (The Netherlands), the Central Asia and South Caucasus consortium of Agricultural universities for Development (CASCADE), the EcoGIS center of TIIAME (Uzbekistan), and the Research Institute of Environment and Nature Conservation Technologies at the Ministry of Nature Resources of the Republic of Uzbekistan (Uzbekistan).

Highlights from the technical presentations included the GEWEX need for assessments of datasets related to (global) water and energy fluxes and their consistency (difficult to fund, but essential), along with their uncertainty and error characterization and to develop support of in situ observational networks in the long-term, complemented by mutually supportive modeling and process studies. An overview of cooperation among Uzbek universities on Earth observation and remote sensing studies has been broadly designed to support land management, including the classification of farm fields, assessment of soil salinity, and landslide susceptibility assessment. Major areas of research also include evapotranspiration assessment, precision agriculture, smart water management, and finally, forest resources assessment in Uzbekistan. In Tajikistan, there is applied remote sensing, GIS technologies, and permanently operating satellite base stations for monitoring land and water. Applications were developed to identify emerging issues such as gully formation, pasture exposure and overuse, erosion, land degradation, salinization, and landslides. Observations will be used to detect the deterioration of the state of land from climate change on the production of agricultural goods over the last 20 years.

Interdisciplinary studies (Kulenbekov et al., 2019; Azarov et al., 2022; Caiserman et al., 2022; Isaev et al., 2022a, b; Kulikov et al., 2023; Sidle et al., 2023) in Kyrgyzstan and Tajikistan have been designed to improve mountain livelihoods through sustainable management of natural resources, mitigating the effects of natural hazards and climate change and building community resilience. Research areas include innovation in snow avalanche monitoring in the remote high mountains of Central Asia, impacts of climate change on food security and health, high-resolution forest mapping, and agrarian change and labor migration in rural Kyrgyzstan. Additional studies (Kulikov et al., 2020, Kulenbekov et al., 2021, Orunbaev et al., 2021) in Kyrgyzstan focus on the development of river systems, water reservoirs, ecosystems, and risks, as well as the impact of climate change on water resources, reflecting the importance of understanding and managing water-related challenges in the region. The effects of excessive water use and agricultural intensification on the ongoing decline of the Aral Sea, include looking at the socioeconomic systems within the Syr Darya river basin. This included studies of the interdependent changes of food, energy, and water fluxes to develop mechanistic understandings of coupled changes between climate and land use. Greenhouse gas emissions from fertilizers and tillage types are also being analyzed.

Discussions after the presentations provided a basis for future collaborations. Major conclusions included the need for meteorological stations, regional data, and data sharing. Since the region has significant transboundary rivers, stream monitoring needs to be regional, rather than country-based; thus, monitoring data and trends should be analyzed regionally. Open access and data sharing are hence crucial in making progress. The amount of water used in agriculture needs to be better quantified along with its effects on regional hydrologic systems. Meteorological stations across the region should transect elevation, not just on glaciers, but covering a wider range of elevations. Biomass and carbon stock assessments are needed for carbon fluxes. Models are needed to help understand which parameters are most important for understanding the future of regional climate and water systems and for the design of observational networks. Details about the conference and presentations at the conference are available at https://www.gewexevents.org/meetings/water-resources-central-asia/agenda/.

Priorities for GEWEX for the region include both observations and modeling, such as supporting the development of better precipitation observations/networks/measurements (covering the region and elevations). This would include trying to use our models to develop such a network. Thus, there is a need to better define the observations/models to better understand regional atmospheric circulation changes (as perturbed by large-scale circulation changes) and regional hydrological responses. These efforts should lead to reductions in critical climate uncertainties in policy-relevant timeframes that can influence decisions on investments in adaptation, especially in expensive new water infrastructure. Neighboring countries, as shown in Fig. 1, do have connections to the region. For example, Afghanistan will begin water withdrawals from the Amu Darya (Busch, 2023), the river that defines the border with Uzbekistan, complicating water conservation efforts there. And the Caspian Sea, as well as the Tibetan Plateau, will also have influences on Central Asian climate and hydrological systems. However, although there is a real need to start with an RHP that is concrete and manageable, other researchers can nonetheless contribute with relevant research in these neighboring countries, as this is not a closed scientific system.

GEWEX is currently planning its next in-person workshop for the spring of 2024 in Kyrgyzstan. The main objectives of the workshop will be to develop quantitative modeling approaches and design data collection systems to reduce the very large uncertainties in future water resources in Central Asia. These uncertainties include the rates of glacial and snowpack decline, and future precipitation. Future precipitation uncertainties include both the type (increasing rainfall), timing, overall quantity, and variability. In addition to these physical science topics, the workshop goals will also include to begin development of quantitative economic methods to support more efficient and effective investments in updating water infrastructure. New dams, reservoirs and irrigation canals and canal upgrades have potentially huge costs and neither of these might be the best possible solution.

In addition to planning for this workshop, GEWEX is in the process of forming a small leadership circle, starting with several key participants from the May Tashkent workshop. We may explore collaboration with CARIN. There may be potential for deployment of, for example, state-of-the-art instrumentation, such as the US Department of Energy’s Atmospheric Radiation Measurement Climate Research Facility. And finally, we will continue to search for funding opportunities, especially to increase the size and geographic extent of monitoring networks.

The concept of an RHP embraces several goals, among which the stimulation of international research collaboration on climate and water in a local/regional context, driven by local researchers, is key. GEWEX as well as WCRP have relatively small interactions in the region, and hence the development of an RHP in the region is an approach that can remedy that. Each region has its own challenges, and for Central Asia that is no different. For example, compared to the Third Pole Environment – Water Sustainability RHP effort, there is much overlap when it comes to water in a changing climate. However, some distinct differences include the type of agricultural economy (high-value crops such as cotton are a main economic driver), different social/cultural background (former Soviet Republics), and a more limited in situ observational network. The development of an RHP in the region should not be in competition with other endeavors, but a contribution to those endeavors, and built upon existing and planned activities. As such, collaboration is welcomed with, for example, the Mountain Research Initiative, as well as the activities of the various UN agencies and Development Banks.

Acknowledgements. The American University of Central Asia provided internet logistics for both the 2021 online survey and the virtual workshop. The National Research University Tashkent Institute of Irrigation and Agricultural Mechanization Engineers of Uzbekistan hosted and provided financial support for the in-person workshop in May of 2023.