Agree to disagree? Making sense of vagueness in International Environmental Agreements

The prevailing literature on International Environmental Agreements (IEAs) commonly posits the existence of a Depth-Participation Dilemma (DPD), suggesting that while precise agreements with well-defined obligations promote deeper cooperation, their specificity often deters participation. This paper revisits this assumption and introduces the differing institutional capacities of the negotiating countries. It thus provides a theoretical framework for understanding the interplay between vagueness, institutional capacities, and, most importantly, the dynamics of the DPD. Our analysis suggests that the DPD is only relevant when institutional capacities are highly uneven across negotiating states, or when a significant number of participants have limited capacities. In contrast, we find that greater precision enhances participation when most negotiating countries possess moderate to high institutional capacities. To test these predictions, we analyze ratification behavior for five climate-related IEAs from 1995 to 2018, constructing a precision index. Our empirical findings reveal (i) a bandwagon effect, where countries are more likely to ratify agreements when others do, (ii) that greater institutional differences weaken this bandwagon effect, thereby reducing ratification rates, (iii) that vagueness in agreements generally undermines incentives to ratify, and (iv) that vague agreements, once ratified, are less binding and correlate with higher CO2 emissions. This framework and evidence provide new insights into how agreement design influences participation and effectiveness in IEAs.