Abstract We hinge on a panel data of 4660 firms across 79 countries and over 15 years to explore how country, industry, and firm effects influence firms' CO2 emissions. Our results show that firm effects are the main factor influencing firms' CO2 emissions (32.8% of the total variance), ahead of industry (30.6%), country (29.3%), or country‐industry effects (4.0%). These results highlight the need to overhaul current public policy baselines that mainly focus on environmental regulation and technological development, for the dissemination of proactive environmental practices within the firm also appears to be—at least—as important to ground a low‐carbon future. Our findings should also permeate the rhetoric of the agents setting business collective beliefs and influencing management training, as well as that of international organizations at the forefront of the crusade for decarbonization. By contrast, if the misleading idea of marginal firm effects entrenches in our set of beliefs, it could become a self‐fulfilling prophecy in the normative system under which policymaking and organizational behavior unfold.