Can geographically proximate activism induce real changes in corporate environmental performance? We exploit geocoded data on the September 2019 Global Climate Strikes and US corporate headquarters locations in a difference-in-differences design. Firms headquartered within a 5 km radius of a strike reduce Scope 1 emissions by approximately 12% and Scope 2 emissions by 7% in subsequent years, corresponding to roughly 5.3 million tons of CO2 across treated firms. Scope 3 emissions also decline sharply, although these effects partly reflect reporting adjustments. These reductions occur under the absence of pre-trends and without measurable ex-post declines in profitability or market valuation, suggesting that firms adjust along efficiency-enhancing margins. Effects are concentrated in low emission industries and firms with more gender-diverse boards, increase with crowd size and favorable protest settings (dry weather, walkability, and large metropolitan cities), and attenuate with increasing treatment radius size, consistent with a localized stakeholder pressure mechanism. Our findings provide causal evidence that, despite lacking formal governance rights, spatially proximate social movements can function as an informal external governance mechanism that shapes real corporate environmental outcomes.
