Ensemble Projections Of Future Air-Conditioning Energy Consumption In The Context Of Global Warming

Global climate change has become one of the most pressing issues around the world as it can result in many significant impacts on human society.Particularly,the warming temperature in many tropical or subtropical cities is very likely to cause increasing electricity consumption for cooling in summer.This effect can also vary significantly due to the regional variations of global climate change.Quantifying such an effect can provide a scientific basis for the management and planning of urban electric power systems in order to adapt to global warming from a long-term perspective,yet it is not well understood due to the uncertainties in future climate change projections.In this study,we propose an ensemble modeling approach for assessing the potential effects of global warming on air-conditioning energy consumption at regional scales,with consideration of different global climate models(GFDL-ESM2M,HadGEM2-ES,and CanESM2),regional climate models(PRECIS and RegCM),and greenhouse gases(GHGs)emissions scenarios(RCP4.5 and RCP8.5).In detail,we first use the ensemble modeling approach to develop high-resolution regional climate change projections under different GHGs emissions scenarios,which are then used to calculate cooling degree days(CDD)at grid scales.The relationship between per capita electricity consumption and temperature is quantified through regression analysis for the recent records of per capita air-conditioning energy consumption and CDD.Future projections of CDD from the ensemble modeling approach are used as inputs to the regression equations to estimate future changes in per capita air-conditioning energy consumption caused by global warming.Combined with the population prediction model of each city in the future,the total air-conditioning power consumption of the city can be obtained.The proposed approach has been applied to 21 major cities in the Province of Guangdong.China in order to assess the plausible increases in electricity consumption for air conditioning throughout the 21st century in the context of global warming.Our results show that under RCP4.5 the electricity consumption for air-conditioning in the Province of Guangdong is very likely to increase by 86.77%in 2020(with an uncertain range of 28.83%to 200.24%),by 92.70%in 2025(with an uncertain range of 11.70%to 215.26%),by 110.21%in 2030(with an uncertain range of 22.61%to 257.45%).by 119.24%in 2035(with an uncertain range of 41.12%to 257.37%):by contrast,its electricity consumption for air conditioning under RCP8.5 is projected to increase by 78.36%in 2020(ranging from 16.16%to 188.21%).by 100.75%in 2025(varying from 20.51%to 224.21%).by 116.89%in 2030(ranging from 21.32%to 239.44%)and by 144.66%in 2035(ranging from 25.66%to 295.30%).The results from this study can provide an insight into the possible effects of global warming on the regional and local energy systems in the Province of Guangdong,meanwhile,the proposed ensemble modeling approach can also be applied to other regions around the world to help investigate the potential increases in air-conditioning electricity consumption due to global warming.