| The Paris Agreement has strengthened the goals of containing the rise in global mean temperature to no more than 2 °C above the pre-industrial level and attempting to limit the temperature increase even further to 1.5 °C.Transition of the energy system is at the heart of greenhouse gas mitigation to achieve the goals.The structural transformation of power sector which depends on the global massive expansion of new energy technology is the key of energy transformation.However,in addition to being central y relevant for carbon emissions,the power sector is also an important water consumer.The global transition of power sector will inevitably bring complex and regionally differentiated cross-system impacts on water resources.The impacts of power sector transition will also influence the virtual flow embodied in export through industrial chains.Because international trade has profoundly driven the virtual transfers of carbon emission and water consumption,it further strengthens the complexity of the cross-system impacts from climate policy.This study aims to investigate the impacts on water resource of power sector transition under climate policies and its influences on virtual flow transfers.Based on the idea of life cycle,this study constructs an input-output based hybrid model to study the direct and indirect impacts on carbon emission and water consumption from only the power mix adjustment in the world's seven largest emitting economies,under near-term Intended National Determined Contribution(INDC)targets and long-term 2 °C pathways,while ignoring the relevant technical development.The study indicates that structural transformation of power sector has differentiated influences in regional distribution,direct and indirect terms and other dimension.(1)Fulfilling the INDCs could decouple increases in carbon emission and electricity output among all the emitters.However,the INDCs may result in larger increases of power sector life cycle water consumption in China and Japan.The INDC of China can bring a decrease of 29% in its life cycle carbon emission intensity,ranking the third among the seven emitters,while it results in a highest growth in life cycle water consumption intensity of 10%,mainly attributed to the increase of indirect water consumption from upstream input.(2)Under the long-term mitigation scenario pathways,the total emissions of the seven emitters can peak around 10 Gt at the first half of the current century,which brings a significant carbon reduction effect compared to the no-climate-policy pathways.In terms of water consumption,China(448-2419 Gt)and India(93-1197 Gt)will obtain the highest cumulative additional water consumption within the century caused by structural effects in the mitigation scenario compared with the no-climate-policy one,where the increases of indirect water consumption contribute significantly.The highest additional water consumption indicates that China and India are more likely to be chal enged by their higher domestic water stress.On the other hand,the USA(-364-171 Gt)can potentially achieve water conservation and relieve its water scarcity.(3)In respect of genera tion technologies,a transition toward less coal-fired power production will not only avert carbon emissions but also conserve water resources.Further implementation of nuclear and hydro power will promote growth in the power sector's direct water consumption and the deployment of renewable energy such as wind power,solar power and biomass power will lead to the growth of indirect water consumption.(4)Power sector transition is conductive to the decarbonisation of export,and has stronger effects on virtual water export.China and Japan will even obtain increases in water embodied in export.The study suggests that by evaluating the efforts of INDCs in light of water stress,China is undertaking great risks to pursue its INDC targets,which affirms the difficulty and ambition of China's deep carbon reduction. |
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