scholarly journals Integrated assessment of global water scarcity over the 21st century – Part 2: Climate change mitigation policies

2013 ◽  
Vol 10 (3) ◽  
pp. 3383-3425 ◽  
Author(s):  
M. I. Hejazi ◽  
J. Edmonds ◽  
L. Clarke ◽  
P. Kyle ◽  
E. Davies ◽  
...  

Abstract. We investigate the effects of emission mitigation policies on water scarcity both globally and regionally using the Global Change Assessment Model (GCAM), a leading community integrated assessment model of energy, agriculture, climate, and water. Three climate policy scenarios with increasing mitigation stringency of 7.7, 5.5, and 4.2 W m−2 in year 2095 (equivalent to the SRES A2, B2, and B1 emission scenarios, respectively), under two carbon tax regimes (a universal carbon tax (UCT) which includes land use change emissions, and a fossil fuel and industrial emissions carbon tax (FFICT) which excludes land use change emissions) are analyzed. The results are compared to a baseline scenario (i.e. no climate change mitigation policy) with radiative forcing reaching 8.8 W m−2 (equivalent to the SRES A1Fi emission scenario) by 2095. When compared to the baseline scenario and maintaining the same baseline socioeconomic assumptions, water scarcity declines under a UCT mitigation policy but increases with a FFICT mitigation scenario by the year 2095 particularly with more stringent climate mitigation targets. The decreasing trend with UCT policy stringency is due to substitution from more water-intensive to less water-intensive choices in food and energy production, and in land use. Under the FFICT scenario, water scarcity is projected to increase driven by higher water demands for bio-energy crops. This study implies an increasingly prominent role for water availability in future human decisions, and highlights the importance of including water in integrated assessment of global change. Future research will be directed at incorporating water shortage feedbacks in GCAM to better understand how such stresses will propagate across the various human and natural systems in GCAM.

2014 ◽  
Vol 18 (8) ◽  
pp. 2859-2883 ◽  
Author(s):  
M. I. Hejazi ◽  
J. Edmonds ◽  
L. Clarke ◽  
P. Kyle ◽  
E. Davies ◽  
...  

Abstract. Water scarcity conditions over the 21st century both globally and regionally are assessed in the context of climate change and climate mitigation policies, by estimating both water availability and water demand within the Global Change Assessment Model (GCAM), a leading community-integrated assessment model of energy, agriculture, climate, and water. To quantify changes in future water availability, a new gridded water-balance global hydrologic model – namely, the Global Water Availability Model (GWAM) – is developed and evaluated. Global water demands for six major demand sectors (irrigation, livestock, domestic, electricity generation, primary energy production, and manufacturing) are modeled in GCAM at the regional scale (14 geopolitical regions, 151 sub-regions) and then spatially downscaled to 0.5° × 0.5° resolution to match the scale of GWAM. Using a baseline scenario (i.e., no climate change mitigation policy) with radiative forcing reaching 8.8 W m−2 (equivalent to the SRES A1Fi emission scenario) and three climate policy scenarios with increasing mitigation stringency of 7.7, 5.5, and 4.2 W m−2 (equivalent to the SRES A2, B2, and B1 emission scenarios, respectively), we investigate the effects of emission mitigation policies on water scarcity. Two carbon tax regimes (a universal carbon tax (UCT) which includes land use change emissions, and a fossil fuel and industrial emissions carbon tax (FFICT) which excludes land use change emissions) are analyzed. The baseline scenario results in more than half of the world population living under extreme water scarcity by the end of the 21st century. Additionally, in years 2050 and 2095, 36% (28%) and 44% (39%) of the global population, respectively, is projected to live in grid cells (in basins) that will experience greater water demands than the amount of available water in a year (i.e., the water scarcity index (WSI) > 1.0). When comparing the climate policy scenarios to the baseline scenario while maintaining the same baseline socioeconomic assumptions, water scarcity declines under a UCT mitigation policy but increases with a FFICT mitigation scenario by the year 2095, particularly with more stringent climate mitigation targets. Under the FFICT scenario, water scarcity is projected to increase, driven by higher water demands for bio-energy crops.


Author(s):  
Basanta K. Pradhan ◽  
Joydeep Ghosh

This paper compares the effects of a global carbon tax and a global emissions trading regime on India using a dynamic CGE framework. The sensitivity of the results to the value of a crucial elasticity parameter is also analysed. The results suggest that the choice of the mitigation policy is relatively unimportant from an efficiency perspective. However, the choice of the mitigation policy and the value of the substitution elasticity between value added and energy were found to be important determinants of welfare effects. Global climate change mitigation policies have the potential for promoting low carbon and inclusive growth in India.


Author(s):  
Basanta K. Pradhan ◽  
Joydeep Ghosh

This paper compares the effects of a global carbon tax and a global emissions trading regime on India using a dynamic CGE framework. The sensitivity of the results to the value of a crucial elasticity parameter is also analysed. The results suggest that the choice of the mitigation policy is relatively unimportant from an efficiency perspective. However, the choice of the mitigation policy and the value of the substitution elasticity between value added and energy were found to be important determinants of welfare effects. Global climate change mitigation policies have the potential for promoting low carbon and inclusive growth in India.


2021 ◽  
Vol 166 (1-2) ◽  
Author(s):  
Charlie Wilson ◽  
Céline Guivarch ◽  
Elmar Kriegler ◽  
Bas van Ruijven ◽  
Detlef P. van Vuuren ◽  
...  

AbstractProcess-based integrated assessment models (IAMs) project long-term transformation pathways in energy and land-use systems under what-if assumptions. IAM evaluation is necessary to improve the models’ usefulness as scientific tools applicable in the complex and contested domain of climate change mitigation. We contribute the first comprehensive synthesis of process-based IAM evaluation research, drawing on a wide range of examples across six different evaluation methods including historical simulations, stylised facts, and model diagnostics. For each evaluation method, we identify progress and milestones to date, and draw out lessons learnt as well as challenges remaining. We find that each evaluation method has distinctive strengths, as well as constraints on its application. We use these insights to propose a systematic evaluation framework combining multiple methods to establish the appropriateness, interpretability, credibility, and relevance of process-based IAMs as useful scientific tools for informing climate policy. We also set out a programme of evaluation research to be mainstreamed both within and outside the IAM community.


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