title: The world's road to water scarcity: shortage and stress in the 20th century and pathways towards sustainability.
abstract: Water scarcity is a rapidly growing concern around the globe, but little is known about how it has developed over time. This study provides a first assessment of continuous sub-national trajectories of blue water consumption, renewable freshwater availability, and water scarcity for the entire 20thcentury. Water scarcity is analysed using the fundamental concepts of shortage (impacts due to low availability per capita) and stress (impacts due to high consumption relative to availability) which indicate difficulties in satisfying the needs of a population and overuse of resources respectively. While water consumption increased fourfold within the study period, the population under water scarcity increased from 0.24 billion (14% of global population) in the 1900s to 3.8 billion (58%) in the 2000s. Nearly all sub-national trajectories show an increasing trend in water scarcity. The concept of scarcity trajectory archetypes and shapes is introduced to characterize the historical development of water scarcity and suggest measures for alleviating water scarcity and increasing sustainability. Linking the scarcity trajectories to other datasets may help further deepen understanding of how trajectories relate to historical and future drivers, and hence help tackle these evolving challenges.
authors.affiliation: Water &Development Research Group (WDRG), Aalto University, Espoo, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Kummu
authors.affiliation: Water &Development Research Group (WDRG), Aalto University, Espoo, Finland.|National Centre for Groundwater Research and Training &Integrated Catchment Assessment and Management Centre, The Fenner School of Environment and Society, The Australian National University, Australia.
authors.forename: J H A
authors.initials: JH
authors.lastname: Guillaume
authors.affiliation: Institute for Environmental Studies (IVM), Vrije Universiteit Amsterdam, Amsterdam, Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: de Moel
authors.affiliation: Center for Environmental Systems Research (CESR), University of Kassel, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Eisner
authors.affiliation: Center for Environmental Systems Research (CESR), University of Kassel, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Flörke
authors.affiliation: Water &Development Research Group (WDRG), Aalto University, Espoo, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Porkka
authors.affiliation: Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Siebert
authors.affiliation: Institute for Environmental Studies (IVM), Vrije Universiteit Amsterdam, Amsterdam, Netherlands.
authors.forename: T I E
authors.initials: TI
authors.lastname: Veldkamp
authors.affiliation: Institute for Environmental Studies (IVM), Vrije Universiteit Amsterdam, Amsterdam, Netherlands.
authors.forename: P J
authors.initials: PJ
authors.lastname: Ward