Climate change is one of the greatest collective action problems we face as a society. Yet, the costs associated with reducing carbon emissions to address the changing climate continues to constrain the degree to which governments and voters make necessary changes. In this paper, we study the conditions that induce voters to accept higher costs for collective climate action in international organizations. Specifically, we are interested in how benchmarking the relative vulnerability to climate change and the relative costs associated with climate change policies vis-a-vis other nations influence support for costly collective climate action in international organizations. Using a pre-registered visual survey experiment fielded across all 27 European Union nations following the 2024 European Parliament elections with over 25,000 respondents, we examine the degree to which relative vulnerability to the negative impacts of climate change and relative contribution to related costs shape voters’ support for costly climate change policies. Our findings show that when people are informed that their country is a net contributor to the cost of climate action, they become less supportive of the European Green Deal, whereas higher country vulnerability to the effects of climate change has less of an effect. These insights are important to inform scholarly and policy debates on how to garner popular support for international initiatives on climate action.