Analysis of carbon emissions from social water cycle in the Pearl River Delta of COVID-19: Perspectives from water-energy-carbon nexus

Carbon emissions from various sectors during COVID-19 pandemic have become a hot research topic. However, the impact of COVID-19 on carbon emissions from social water cycle (SWC) processes is unclear. This study uses the Pearl River Delta (PRD) urban agglomeration as the research object and considers the water system carbon emissions in the study region pre- (2018, 2019) and post-COVID-19 (2020, 2021). First, the findings indicate that carbon emissions from SWC systems in PRD cities increased during the COVID-19 pandemic. Guangzhou had the most significant growth of 2.868 Mt, and Zhongshan had the highest annual growth rate of approximately 9%. Second, carbon emission intensity of each subsystem in 2021 is higher than that in other years, with the water use system emitting much more carbon than the other systems. Finally, the amount of water in the SWC showed a significant positive relationship with carbon emissions and average carbon emission intensity. Guangzhou and Shenzhen released more carbon emissions than other cities, and Zhaoqing and Huizhou had a lower average carbon intensity. This study's conclusion differs from other research findings that, indicate a declining carbon emission trend during the COVID-19 pandemic. This study is the first to analyze the changing patterns of carbon emissions from SWC systems during the COVID-19 pandemic. The results can provide carbon recommendations for SWC system development in response to major public health emergencies.