Study reveals inter-city collaboration on emission reduction boosts sustainability performance

A recent international investigation conducted by The Hong Kong University of Science and Technology (HKUST) has demonstrated that collaboration between cities in emission reduction can significantly enhance overall sustainability performance by over 10%. The comprehensive study, led by Prof. Lu Mengqian, analyzed data from 4,116 cities across 11 years, revealing the interconnected nature of urban emission challenges on both regional and global scales.

Traditionally, urban emission reduction has been perceived as a local issue, with cities focusing on measures like industrial upgrading, energy transitions, and environmental policies. However, this research highlights the broader impact of atmospheric pollutants and greenhouse gas emissions, which transcend national borders. The team employed a novel spatial econometric model to account for the complex spatiotemporal interactions between emission-related Sustainable Development Goal (SDG) indicators among the selected cities.

The findings underscore that the vast majority (93.51%) of cities are influenced by the emission-related SDG indicators of others. A 10% improvement in particulate matter pollution (PM2.5 and PM10), gaseous pollutants (SO2 and NOX), and greenhouse gases (CO2 and CH4) in neighboring cities can result in an average 0.2% to 0.45% improvement in the focal city's corresponding SDG performance.

However, these intercity interactions can be either synergistic, leading to positive outcomes, or trade-off, resulting in negative impacts.

For example, Hong Kong experienced positive synergistic effects on SDG 13.2 (CO2 emissions) due to industrial upgrading by neighboring cities in the Greater Bay Area. Conversely, Beijing saw negative trade-off effects on SDG 11.6 (PM2.5 and PM10) due to the relocation of pollution-intensive activities. The research also found that less-developed cities, particularly in Africa and Asia, are more vulnerable to cross-city influences, exhibiting greater dependence on resource flows and industrial collaboration.

Furthermore, the study observed a declining trend in the intensity of intercity influences over time, with 75.66% of influences decreasing and only 21.31% increasing. The team also explored various interaction scenarios, demonstrating that intercity collaborations can improve overall SDG performance by 10.81%, surpassing independent city actions.

The researchers emphasize that emission governance is now a global issue requiring coordinated action across regions and cities. They hope their findings will encourage governments and international organizations to develop more coordinated and evidence-based strategies for emission reduction and sustainable urban development.