Suchergebnisse

| openaire: EC/H2020/819202/EU//SOS.aquaterra Funding Information: M.K. received financial support from the Academy of Finland projects WASCO (grant 305471), WATVUL (grant 317320), and TREFORM (grant 339834); the Academy of Finland SRC project ?Winland?; the Emil Aaltonen Foundation project ?eat-less-water?; and the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme (grant agreement 819202). M.H. and M.T. received financial support from Maa- ja Vesitekniikan Tuki Ry. M.H. was also supported by the Aalto University Engineering doctoral program. We appreciate the help of Johannes Piipponen with livestock production data. M.K. D.V. and M.H. designed the research with support from all co-authors. M.K. and D.V. compiled the Holdridge life zone mapping. M.H. and M.K. performed the spatial analyses with support from D.V. M.K. led the writing of the manuscript with contributions from all co-authors. We declare no competing financial interests. Funding Information: M.K. received financial support from the Academy of Finland projects WASCO (grant 305471 ), WATVUL (grant 317320 ), and TREFORM (grant 339834 ); the Academy of Finland SRC project "Winland"; the Emil Aaltonen Foundation project "eat-less-water"; and the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme (grant agreement 819202 ). M.H. and M.T. received financial support from Maa- ja Vesitekniikan Tuki Ry . M.H. was also supported by the Aalto University Engineering doctoral program. We appreciate the help of Johannes Piipponen with livestock production data. Publisher Copyright: © 2021 The Authors ; Food production on our planet is dominantly based on agricultural practices developed during stable Holocene climatic conditions. Although it is widely accepted that climate change perturbs these conditions, no systematic understanding exists on where and how the major risks for entering unprecedented conditions may occur. Here, we address this gap by introducing the concept of safe climatic space (SCS), which incorporates the decisive climatic factors of agricultural production: precipitation, temperature, and aridity. We show that a rapid and unhalted growth of greenhouse gas emissions (SSP5–8.5) could force 31% of the global food crop and 34% of livestock production beyond the SCS by 2081–2100. The most vulnerable areas are South and Southeast Asia and Africa's Sudano-Sahelian Zone, which have low resilience to cope with these changes. Our results underpin the importance of committing to a low-emissions scenario (SSP1–2.6), whereupon the extent of food production facing unprecedented conditions would be a fraction. ; Peer reviewed

Abstract. Estimates for rare to very rare floods are limited by the relatively short streamflow records available. Often, pragmatic conversion factors are used to quantify such events based on extrapolated observations, or simplifying assumptions are made about extreme precipitation and resulting flood peaks. Continuous simulation (CS) is an alternative approach that better links flood estimation with physical processes and avoids assumptions about antecedent conditions. However, long-term CS has hardly been implemented to estimate rare floods (i.e. return periods considerably larger than 100 years) at multiple sites in a large river basin to date. Here we explore the feasibility and reliability of the CS approach for 19 sites in the Aare River basin in Switzerland (area: 17 700 km2) with exceedingly long simulations in a hydrometeorological model chain. The chain starts with a multi-site stochastic weather generator used to generate 30 realizations of hourly precipitation and temperature scenarios of 10 000 years each. These realizations were then run through a bucket-type hydrological model for 80 sub-catchments and finally routed downstream with a simplified representation of main river channels, major lakes and relevant floodplains in a hydrologic routing system. Comprehensive evaluation over different temporal and spatial scales showed that the main features of the meteorological and hydrological observations are well represented and that meaningful information on low-probability floods can be inferred. Although uncertainties are still considerable, the explicit consideration of important processes of flood generation and routing (snow accumulation, snowmelt, soil moisture storage, bank overflow, lake and floodplain retention) is a substantial advantage. The approach allows for comprehensively exploring possible but unobserved spatial and temporal patterns of hydrometeorological behaviour. This is of particular value in a large river basin where the complex interaction of flows from individual tributaries and lake regulations are typically not well represented in the streamflow observations. The framework is also suitable for estimating more frequent floods, as often required in engineering and hazard mapping.