National polarization and international agreements

Abstract

The network of international environmental agreements (IEAs) has been characterized as a complex adaptive system (CAS) in which the uncoordinated responses of nation states to changes in the conditions addressed by particular agreements may generate seemingly coordinated patterns of behavior at the level of the system. Unfortunately, since the rules governing national responses are ill understood, it is not currently possible to implement a CAS approach. Polarization of both political parties and the electorate has been implicated in a secular decline in national commitment to some IEAs, but the causal mechanisms are not clear. In this paper, we explore the impact of polarization on the rules underpinning national responses. We identify the degree to which responsibility for national decisions is shared across political parties and calculate the electoral cost of party positions as national obligations under an agreement change. We find that polarization typically affects the degree but not the direction of national responses. Whether national commitment to IEAs strengthens or weakens as national obligations increase depends more on the change in national obligations than on polarization per se. Where the rules governing national responses are conditioned by the current political environment, so are the dynamic consequences both for the agreement itself and for the network to which it belongs. Any CAS analysis requires an understanding of such conditioning effects on the rules governing national responses.

Keywords: international environmental agreements; polarization; spatial competition.

Fig. 1.

The distance between positions taken by parties on an agreement at the Nash equilibrium as a function of the electoral costs of both the distance between party and stakeholder positions and the similarity between party positions. The Left panel reports results for a uniform distribution of stakeholders in opinion space. The Right panel reports results for a bimodal distribution.

Fig. 2.

Party polarization and willingness to commit to international agreements at the Nash equilibrium as a function of the electoral cost of distance from stakeholders. The Left two panels report results for a uniform distribution of stakeholders in opinion space and for two levels of the electoral cost of party similarity, $c=0.1,c=0.5$. The Right two panels report results for a bimodal distribution and for the same levels of $c$. In all cases, $a=10,b_1=1,b_2=0.75$.

Fig. 3.

Party polarization and willingness to commit to an international agreement at the Nash equilibrium as a function of the electoral cost of noncompliance. The Left two panels report results for a uniform distribution of stakeholders in opinion space and for two levels of national obligation, $q_r=10,q_r=15$. The Right two panels report results for a bimodal distribution and for the same levels of $q_r$. In all cases, $a=10,b_1=1,b_2=0.75$.

Fig. 4.

National commitment, national obligation, and the electoral cost of noncompliance at the Nash equilibrium. The Left reports results for a uniform distribution of stakeholders in opinion space. The Right reports results for a bimodal distribution. National commitment is measured by $q_1+q_2$.