Municipal solid waste (MSW) under the population shrinking and aging: Spatio-temporal patterns, driving forces, and the impact of smart city development

The phenomenon of shrinking and aging populations has profound implications for socioeconomic sustainability and presents unique challenges for managing municipal solid waste (MSW). These challenges have yet to be comprehensively understood thus far. In this study, we focus on the Circum-Bohai-Sea area in China (CBS) to investigate the spatiotemporal patterns of MSW generation under the population shrinking and aging. Results showed that the MSW growth rate reduced from 3.2% (2011–2015) to 1.6% (2016–2020) with population shrinking and aging. Geographical and temporal weighted regression (GTWR) revealed that disposable personal income and total population are the predominant drivers of MSW growth. In contrast, the population change rate and the proportion of elderly were the key factors for MSW reduction. Urban MSW reduction exhibited higher sensitivity to population shrinking, resulting in a 141.6% greater reduction compared to rural MSW for every 1% population shrinking. Conversely, rural MSW reduction displayed a greater response to population aging, with a 19.7% reduction more than urban MSW for every 1% increase in the proportion of the elderly. Based on scenario analysis, the smart city development will curb population shrinking (7.6%), while increasing the well-being, life expectancy, and population share of the elderly (3.4%). Future population shrinking and aging is expected to contribute to the growth of MSW, and this trend is further amplified by the development of smart city. However, smart city development led to MSW reduction overall with an MSW amount of 76.8 Mt (7.5% lower than in the business-as-usual scenario) by 2040, mainly attributed to smart sanitation technology. This study offers valuable insights for decision-makers in MSW management, not only in China but also for other countries grappling with population regression challenges.