Integrated Solutions for the Water-Energy-Land Nexus: Are Global Models Rising to the Challenge?

Abstract

Increasing human demands for water, energy, food and materials, are expected to accentuate resource supply challenges over the coming decades. Experience suggests that long-term strategies for a single sector could yield both trade-offs and synergies for other sectors. Thus, long-term transition pathways for linked resource systems should be informed using nexus approaches. Global integrated assessment models can represent the synergies and trade-offs inherent in the exploitation of water, energy and land (WEL) resources, including the impacts of international trade and climate policies. In this study, we review the current state-of-the-science in global integrated assessment modeling with an emphasis on how models have incorporated integrated WEL solutions. A large-scale assessment of the relevant literature was performed using online databases and structured keyword search queries. The results point to the following main opportunities for future research and model development: (1) improving the temporal and spatial resolution of economic models for the energy and water sectors;(2) balancing energy and land requirements across sectors; (3) integrated representation of the role of distribution infrastructure in alleviating resource challenges; (4) modeling of solution impacts on downstream environmental quality; (5) improved representation of the implementation challenges stemming from regional financial and institutional capacity; (6) enabling dynamic multi-sectoral vulnerability and adaptation needs assessment; and (7) the development of fully-coupled assessment frameworks based on consistent, scalable, and regionally-transferable platforms. Improved database management and computational power are needed to address many of these modeling challenges at a global-scale. IntroductionWater, energy and land (WEL) represent fundamental resources needed for human survival and are critical for supporting economic development and ecosystem services, such as flood control, carbon sequestration and biodiversity. Socioeconomic and climate trends are rapidly increasing global demands for WEL resources. Based on the "middle-of-the-road" Shared Socioeconomic Pathway (SSP2) scenario in which population reaches about 9 billion in 2050, food demand is projected to increase on average 74% (59-98%) from 2005 to 2050 [1], primary energy supply will increase on average 92% (81-113%) [2], agricultural land is projected to increase on average 5% (3-7%) [3], and global water demand is projected to increase about 50% [4,5]. Meanwhile, WEL resources are regionally constrained for physical or economic reasons and several global "mega-trends", such as climate change, urbanization, and globalization, are expected to have regional impacts that may either exacerbate or alleviate resource constraints and the associated supply challenges [6]. There is an urgent need to better understand the impacts and vulnerability of human populations and ecosystems to future socioeconomic and climatic change as well as to identify sustainable strategies for m...

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