Workshop A1: Integrated Nexus Modelling at Global Scale
Chaired by Joseph Alcamo
Presenting speakers :
We present three conceivable future pathways of Asian water resources, determined by feasible combinations of two RCPs and three SSPs. Such a scenario approach provides valuable insights towards identifying appropriate strategies as gaps between a “scenario world” and reality. In addition, for the assessment of future water resources a multi-criteria analysis is applied. A classification system for countries and watershed that consists of two broad dimensions: (i) economic and institutional adaptive capacity, (ii) hydrological complexity. The latter is composed of several sub-indexes including total renewable water resources per capita, the ratio of water demand to renewable water resource, variability of runoff and dependency ratio to external. Furthermore, this analysis uses a multi-model approach to estimate runoff and discharge using 5 GCMs and 5 global hydrological models (GHMs). Three of these GHMs calculate water use based on a consistent set of scenarios in addition to water availability.
As a result, we have projected hot spots of water scarcity in Asia and their spatial and temporal change. For example, in a scenario based on SSP2 and RCP6.0, by 2050, in total 2.1 billion people (46% of Asian population) are going to live in countries classified as high hydrological complexity. In particular, in Afghanistan, Azerbaijan and Pakistan, then home to 370 million people, hydrological complexity will be high while adaptation capacity is still low. On the other hand, a part of people however who live in countries with higher expected adaptive capacities may have better futures depending on policies and investment. Besides country scale, grid scale analyses clearly highlighted that a large part of population living under strong water stress in highly populated areas of Asia, such as east and coastal areas in China and large parts of India.
Our preliminary results show that a significant impact of socioeconomic scenarios on each of the indexes which is comparable to that of climate scenarios. For instance, the least timing, trend and spatial distribution of water resource per capita are highly affected by projected population. This study shows that features of time series change in each indexes are also informative particularly for decision makers because they support in optimal timing of investment for countermeasures.
The nexus approach has become central to discussions regarding the development and subsequent monitoring of the SDGs. Acknowledge nexus approach, a number of theoretical frameworks have recently been used. However, very few of these studies provide quantitative assessment of synergies and trade-offs. For achieving sustainability, integrated assessment of synergies and tradeoffs among global challenges is required at different scales – global, national and local scales. In order to fill this gap, the objective of this study is to describe quantitative assessment of nexus approach at different scales. Among the available literature on nexus, this study will review three key studies which have been applied at global, national and local scale for assessing synergies and tradeoffs of global sustainability challenges.
At global scale, Giupponi and Gain (2016, in review, Reginal Environmental Change) present a comprehensive indicator-based approach for the assessment of water, energy and food securities with the ambition to highlight synergies and tradeoffs among the three dimension of WEF nexus. The WEF nexus index is developed through spatial multi-criteria analysis for current periods using available data sources. Results of this study is limited only to the indicators related to water, energy and food securities. However, the analysis can be extended taking into account all SDG indicators. The performance for each country can also be carried out to achieve SDG targets by 2030. With further improvement of the study by Giupponi and Gain (2016), the outcome of the global analysis can support in monitoring the SDGs targets. Similarly, Daher and Mohtar (2015) have recently developed a comprehensive nexus tool for resource planning and decision making in the national context of Qatar. This study offers a common platform for scientists and policy-makers to evaluate scenarios for identifying sustainable national resource allocation strategies. Improving the current limitation of the tool, the study can be applied to other national context.
At sub-national or local scale, Bartos and Chester (2014) provided a comprehensive assessment on water-energy interdependencies in Arizona. However, this study focused on interdependence of only two sectors, i.e., water and energy. For a better outcome to the society, more integration is needed incorporating food production and agricultural practices, manufacturing processes and transportation systems, and interactions with surrounding ecosystems.
The pros and cons of these studies are critically reviewed. With further improvement, these studies have high potential for wider applicability.
This presentation will highlight the multidimensional global trade-offs between large-scale biomass potentials and future development, also in relation to a “safe operating space” as defined by “planetary boundaries”. Similar to the UN’s Sustainable Development Goals, this framework is well suited for the analysis of multidimensional trade-offs in environmental and social spheres.
Scenarios of land availability for biomass plantations were developed with a multi-criterial optimization framework, taking into consideration the precautionary need to stay within several planetary boundaries (for climate change, freshwater use, land-system change, biosphere integrity and biogeochemical flows) vis-à-vis the need to sustain agricultural production.
A range of scenarios based on different constraints of planetary boundaries are simulated with a comprehensive global dynamic vegetation of the terrestrial biosphere, LPJmL. Results indicate considerable biomass potentials. However, if sustainability considerations such as as limiting freshwater use or forest and biodiversity conservation come into play, global biomass potentials are reduced significantly, which highlights important trade-offs between water, bioenergy and food production.
Simulation models are useful tools to provide a better understanding of the linkages between water, food, energy and ecosystems and may guide planning and investment as they can project combined scenarios. We used an existing global modelling framework (IMAGE-GLOBIO) to analyse a Trend scenario as well as some global scenarios designed to achieve the SDGs and at the same time contribute to the 2050 Biodiversity Vision. Input data are derived from several global databases. Aquatic systems such as lakes and inland wetlands were included into this model by a hydrological, water quality and aquatic ecosystem module, and important ecosystem services like water retention, water quality and algal blooms were analysed as a function of land-use, hydrology and climate. Three investment pathways were developed to simulate different combinations of technological and land use measures and behavioural changes that reach the envisaged objectives, which include eradicating hunger, providing universal access to modern energy, preventing dangerous climate change, conserving biodiversity and controlling air pollution. The results show in which world regions and in what ecosystem types ecosystem services and biodiversity are under stress or will be threatened in future decades.
The Trend scenario identified key water challenges (water shortage, flood risks, pollution and degradation of aquatic ecosystems), which can be elaborated for specific sub-sectors, such as water for food, urban water supply and sanitation, flood management, and energy. The analysis of the three investment pathways demonstrated that minor interventions in the sub-sectors separately are insufficient and that substantial transformations in our water, energy and food systems are required, that go far beyond historic progress and currently formulated policies. Only an integrated approach to the water systems in their nexus of interdependencies provides a basis to underpin restoration schemes and manage trade-offs and synergies between different ecosystem services from terrestrial, aquatic and wetland systems.
We use an integrated modelling framework of the water-energy-food-climate system to assess how changes in electricity and land use systems, induced by climate change mitigation, impact on water demand under alternative socio-economic (Shared Socio-economic Pathways; O’Neill et al. 2014) and water policy assumptions (irrigation of bioenergy crops, cooling technologies for electricity generation). The analysis is based on the LPJmL-MAgPIE-REMIND modelling framework, which is based on three coupled models representing different aspects of the water-energy-food-climate nexus (Popp et al. 2011). LPJmL (Bondeau et al. 2007; Rost et al. 2008) is a dynamic vegetation and hydrology model. MAgPIE (Lotze-Campen et al. 2008, 2010; Popp et al. 2010) is a spatially explicit agro-economic land and water use model representing costs of agricultural production, food and bioenergy production, and land and water constraints. The REMIND model (Luderer et al. 2012; Bauer et al. 2012; Leimbach et al. 2010) is a multi-regional model incorporating the economy, the climate system and a detailed representation of the energy sector. It features an elaborate representation of water demand for electricity production, taking into account key elements for cooling water requirements, such as power plant thermal efficiencies and vintage structures.
Our results indicate that the impacts of climate change mitigation on cumulated water demand across the century are highly uncertain, and depending on socio-economic and water policy conditions, they range from a reduction of 15,000 km3 to an increase of more than 160,000 km3. The impact of irrigation of bioenergy crops is the most prominent factor, leading to significantly higher water requirements under climate change mitigation if bioenergy crops are irrigated. Differences in socioeconomic drivers and fossil fuel availability result in significant differences in electricity and bioenergy demands, and in the associated changes in electricity and primary energy mixes. Economic affluence and abundance of fossil fuels aggravate pressures on water resources due to higher energy demand and greater deployment of more water intensive technologies such as bioenergy and nuclear power. The evolution of future cooling systems was also identified as an important determinant of electricity water demand. Climate policy can result in a reduction of water demand if combined with policies on irrigation of bioenergy, and the deployment of non-water-intensive electricity sources and cooling types.
Target audience: We invite interested participants from all disciplines and at all career stages specially early stage PhD student and postdocs.
Date and time: Jun 15th, 13:30 – 15:15
Location: ZUK, Osnabrück, Room 3
- Joseph Alcamo