Decades of research demonstrate that a variety of overlapping policies at city, subnational, national, and international levels is more likely to succeed than are single, overarching binding agreements. Such an evolutionary approach to policy provides essential safety nets should one or more policies fail.
The good news is that evolutionary policymaking is already happening organically. In the absence of effective national and international legislation to curb greenhouse gases, a growing number of city leaders are acting to protect their citizens and economies.
Fundamentally, this is the right approach for managing systemic risk and change in complex interconnected systems, and for successfully managing common resources – though it has yet to dent the inexorable rise in global greenhouse-gas emissions.