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- Title
Quantifying the "Energy-Return-on-Investment" of desert greening in the Sahara/Sahel using a Global Climate Model.
- Authors
Bowring, S. P. K.; Miller, L. M.; Ganzeveld, L.; Kleidon, A.
- Abstract
"Greening" the world's deserts has been proposed as a way to produce additional food, sequester carbon, and alter the climate of desert regions. Here, we quantify the potential benefits in terms of energetic quantities and compare these to the energetic costs. We then compare these using the metric of Energy-Return-On-Investment (EROI). We apply EROI to a series of global climate model simulations where the arid Sahara/Sahel region is irrigated with various rates of desalinated water to produce biomass. The energy content of this biomass is greater than the energy input rate for a minimum irrigation rate of about 200mmyr-1 in the winter and 500mmyr-1 in the summer, thereby yielding an EROI ratio >1 : 1, expressing energetic sustainability. Quantified annually, the EROI was >1 : 1 for irrigation rates more than 500mmyr-1, progressively increasing to a maximum of 1.8 : 1 with 900mmyr-1, and then decreasing with further increases in the irrigation rate. Including the precipitation feedback arising from changes in moisture-recycling within the study region approximately doubles these EROI ratios. This overall result varies spatially and temporally, so while the entire Sahara/Sahel region is irrigated equally, the western coastal region from June to August had the highest EROI. Other factors would complicate such a large-scale modification of the Earth System, but this sensitivity study concludes that with a required energy input, desert greening may be energetically sustainable. Furthermore, we suggest that this type of EROI-analysis could be applied as a metric to assess a diverse range of human alterations to, and interventions within, the Earth System.
- Subjects
SAHARA; SAHEL; DESERT ecology; CLIMATE change mathematical models; BIOMASS production; SUSTAINABILITY; SIMULATION methods &; models
- Publication
Earth System Dynamics Discussions, 2013, Vol 4, Issue 2, p717
- ISSN
2190-4995
- Publication type
Article
- DOI
10.5194/esdd-4-717-2013