The authors hypothesize that unionization's contribution to lower carbon emissions comes from a variety of factors, including weakening the grip of industry on government thus generally improving the quality of regulation, agitating for better workplace health and safety conditions, and political alliances with left-wing causes, including environmentalism.
These effects are tempered by unions' sometime commitment to "growth" at any cost, including environmental costs, and capital's tendency to neutralize unions by relocating their production to low-regulation, poor, corrupt states where they can pollute freely.
In this article, we assess whether unionization of national workforces influences growth in national carbon dioxide (CO2) emissions per capita. Political-economic theories in environmental sociology propose that labor unions have the potential to affect environmental conditions. Yet, few studies have quantitatively assessed the influence of unionization on environmental outcomes using cross-national data. We estimate multilevel regression models using data on OECD member nations from 1970 to 2014. Results from our analysis indicate that unionization, measured as the percentage of workers who are union members, is negatively associated with CO2 emissions per capita, even when controlling for labor conditions. This finding suggests that unionization may promote environmental protection at the national level.
(Thanks, Michael Pulsford!)