Environmental regulation and the widening inequality in urban green innovation: Evidence from China.

Green innovation is crucial in sustainable development, yet its progression is uneven across cities. This research employs a Difference in Difference (DID) model and Changes in Changes (CIC) model to investigate both the average and distributional effect of environmental regulations (ER) on green innovation (GI) quantity and quality. The conclusions indicate that ER significantly improves urban GI quantity and quality, benefiting both the urban economy and the environment. However, the beneficial impacts of ER on GI are stronger in cities with higher quantiles of innovation quantity and quality. That is to say, although environmental regulation promotes green innovation, it further widens inequality in urban green innovation. Consequently, such inequality in urban green innovation growth may further lead to inequality in urban economic development and environmental quality, potentially exacerbating environmental injustice.