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Consistent assessment of global green, blue and virtual water fluxes in the context of food production: regional stresses and worldwide teleconnections GREENWATER

Description: Das Projekt "Consistent assessment of global green, blue and virtual water fluxes in the context of food production: regional stresses and worldwide teleconnections GREENWATER" wird vom Umweltbundesamt gefördert und von Potsdam-Institut für Klimafolgenforschung e.V. durchgeführt. This project provided comprehensive and spatially explicit analyses of the past, present and potential future water flows in global irrigated and rainfed agriculture, the results of which have been published in, or are under review for, almost a dozen peer-reviewed scientific journals. As a precondition for these studies, two macro-hydrological models - the Lund- Potsdam-Jena managed Land model (LPJmL) and ihe Global Crop Water Model (GCWM) - were developed from eariier model versions toward state-of-the-art global agro-hydrological models with unique features. In addition, a new landmart^ dataset of crop areas at 5' resolution (MIRCA 2000) was created, which for the first time consistently combines inigated and rainfed areas at an unprecedented (monthly) temporal resolution. Both models were used to assess the total water consumption (evapotranspiration) and the water consumption per unit of yield (virtual water content) of the worid's major crops in a novel way, in that the contributions of blue water (stemming from rivers, surface water bodies and groundwater) and green water (precipitation stored in the soil) were thoroughly differentiated. A key result is that the majority of global agricultural water use, about 90%, is constituted by green water, which quantitatively underpins the need to consider the green water resource in any freshwater assessments. The specific impact of irrigation on global crop production was quantified for the first time, and a key finding was that present irrigation an increase in global cereal production by about 20% is achieved. Given the outstanding importance of green water and the demonstrated fact that food production is presently water-limited over many areas, the project also investigated the potential to increase global food production of optimised green-blue water management ('vapour shift' from unproductive soil evaporation to productive plant transpiration, and 'harvesting' of runoff from cropland used for supplemental irrigation in dry periods). It was found that such management could substantially increase crop production in many regions and globally by up to about 20% or even more. Adverse effects of climate change are suggested to be partially offset by the fertilisation effects of rising atmospheric CO2 concentration, but we found that irrespective of the actual degree of the (rather uncertain) CO2 effect there will be not enough water on present cropland, even if effectively used, to produce the food for a higher world population of 9-10 billion by the mid of this century. The project also made a significant contribution to the scientific debate about what drivers have caused the variations and trends in global discharge (blue water flows) over the past century. (abridged text)

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SupportProgram

Origin: /Bund/UBA/UFORDAT

Tags: Atmosphärische CO2-Konzentration ? Baumstamm ? Fluss ? Brüden ? Evapotranspiration ? Befruchtung ? Transpiration ? Virtueller Wasserverbrauch ? Bodenwasser ? Grundwassermodell ? Nahrungsproduktion ? Pflanzenbestand ? Pflanzenproduktion ? Stress ? Süßwasser ? Dürre ? Verdunstung ? Wasserverbrauch ? Virtuelles Wasser ? Getreideproduktion ? Studie ? Wasserströmung ? Wassernutzung ? Wasseranalyse ? Stand der Technik ? Lebensmittelsicherheit ? Wasser ? Klimafolgen ? Literaturauswertung ? Weltbevölkerung ? Oberflächengewässer ? Bewässerung ? Klimafolgenforschung ? Regenfeldbau ? Klimawandel ? Wasserressourcen ? Wasserwirtschaft ? Globale Aspekte ? Niederschlag ?

Region: Brandenburg

Bounding box: 13.01582° .. 13.01582° x 52.45905° .. 52.45905°

License: cc-by-nc-nd/4.0

Language: Deutsch

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Time ranges: 2005-07-01 - 2010-12-31

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