基于共享社会经济路径的“一带一路”沿线国家城市化水平与经济预测研究

Projection of urbanization and economy in the 'Belt and Road' countries based on the shared socioeconomic pathways

城市和经济发展对气候变化的贡献不容忽视。政府间气候变化专门委员会(IPCC)提出的共享社会经济路径(SSPs),描述了气候变化与社会经济要素之间的相互关系,以及不同的社会经济发展道路所面临的气候变化适应与减缓挑战。本文设计5种共享社会经济路径下城市化和经济发展情景,包括可持续路径(SSP1)、中间路径(SSP2)、区域竞争路径(SSP3)、不均衡路径(SSP4)和化石燃料为主的发展路径(SSP5),开展2020—2100年"一带一路"沿线国家城市化和经济预测。研究表明:(1)"一带一路"沿线国家城市化水平和经济总量将呈增加趋势,城市人口比重由2016年的48%增长至2100年的77. 9%(55%～92%),GDP总量由57万亿美元增长至371万亿(210万亿～611万亿)美元。(2)未来城市化及经济水平在5种发展路径下将呈现不同的发展趋势,SSP1、SSP4和SSP5路径下"一带一路"沿线城市发展迅速,未来几乎所有国家都能达到极高城市化水平,SSP2和SSP3路径发展相对缓慢,绝大部分国家能够达到中度城市化水平以上。经济水平在SSP5路径下发展较快,大部分国家能达到当前水平的5倍以上,SSP3和SSP4路径下发展缓慢,多数国家增幅1～4倍。(3)在低、中度城市化水平国家,发展道路的选择对未来城市化和经济影响显著,到21世纪末期各路径间城市化差距达40%以上,经济水平相差3倍左右;具有较高城市化水平的国家,未来城市和经济发展均较为稳定,各路径间城市化差异少于20%,经济发展相差约1. 5倍。

Contribution from urbanization and economic development to climate warming cannot be ignored.The Intergovernmental Panel on Climate Change (IPCC) proposed the Shared Socioeconomic Pathways (SSPs),describing the relationship between climate change and socio-economic elements,and the adaptation and mitigation challenges of climate change in different socioeconomic development.In this paper,urbanization and economic scenarios under five shared socioeconomic pathways were designed,including Sustainability (SSP1),Middle of the Road (SSP2),Regional Rivalry (SSP3),Inequality (SSP4) and Fossil-fueled Development (SSP5).Then,urbanization and economy in the ‘Belt and Road’ countries between 2020 and 2100 were projected.Our findings show that:① Urbanization and economy in the ‘Belt and Road’ countries will increase.The proportion of urban population will increase from 48% in 2016 to 77.9%(55%~92%) in 2100 and GDP will increase from 57 trillion to 371 trillion (210 trillion^611 trillion) US dollars.②The future urbanization and economic level will show different trends under the five development pathways.Urbanization in the ‘Belt and Road’ countries will develop rapidly under SSP1,SSP4 and SSP5,and almost all countries will reach a very high level of urbanization.Under SSP2 and SSP3,The development of urbanization will relatively slow,and most of the countries can reach the medium level.Meanwhile,economy will grow more than five folds under SSP5 for most countries,but growth of GDP under SSP3 and SSP4 will be 2~5 times.③ For countries currently at the low and medium level of urbanization,gap of urbanization level and GDP will grow to more than 40% and 3 folds in the end 21 st century,respectively,between different SSPs.On the contrary,future urbanization process and economic development will be quite steady for countries already in comparative high levels of urbanization.In the end 21 st century,gap of urbanization level and GDP can be less than 20% and 1.5 times,respectively,between different SSPs.