Digital infrastructure construction, diversified environmental regulation, and dual control of urban carbon emissions—quasi-natural experiment from “broadband China” strategy

This study used three batches of “broadband China” strategies (BCS) implemented from 2014 to 2016 as quasi-natural experiments (QE) to distinguish the level of urban digital infrastructure construction (DIC). Using 231 prefecture-level cities in China from 2011 to 2019 as research samples, a progressive differences-in-differences (DID) model was used to empirically test the relationship characteristics between DIC and urban carbon emission (CE) total and intensity. The results show that (1) DIC has a significant negative correlation with total carbon emissions (TCE) and carbon emission intensity (CI), which is conducive to the “dual control” of urban CE, which is still valid after the five robustness tests. (2) The mechanism test shows that the DIC is conducive to improving the level of formal environmental regulation (FER) and informal environmental regulation (IER) and strengthening the synergy between formal and informal environmental regulation (ER), so as to achieve “dual control” of carbon emissions, of which the synergy is the most significant, followed by FER. (3) In heterogeneity research findings, only the third batch of pilot projects can achieve “dual control” of CE, which has the advantage of latecomers. The “dual control” effect of carbon emissions in DIC is more significant in cities with higher levels of marketization and eastern cities. Therefore, DIC plays the role of “icing on the cake,” not “providing charcoal in the snow.”