Typically, debates about jobs and environmental protection are often framed in a zero-sum fashion such that what is good for jobs is bad for the environment and vice versa. As a result, labor unions are often depicted as being protective of their workers' jobs at all costs, including the risk of environmental degradation. Given the rise of alliances between labor and environmental activists on the Left and the burgeoning union platform of a "just transition," they wanted to explore if the old "jobs vs. environment" framework holds true for labor unions on average in affluent countries. 

They found that, net of controls, labor union density is associated with less GHG emissions, net of a robust set of controls, and that this relationship becomes stronger (more negative) when unions have a seat at the table in policy making along with corporate and government leaders in corporatist systems of governance.

Overall, this article contributes to our understanding of the role of labor unions in addressing climate change. https://www.tandfonline.com/doi/abs/10.1080/23251042.2018.1544107