After more than two decades of inadequate international efforts to address climate change resulting from rising greenhouse gas emissions, the 2015 Paris Climate Change Agreement shifted gears. That agreement advances a “bottom-up” model of global cooperation that requires action commitments from all national governments and acknowledges the important role that cities, states, provinces, and businesses must play in delivering deep decarbonization. Given the limited control that presidents and prime ministers have over many of the policies and choices that determine their countries’ carbon footprints, the Paris Agreement missed an opportunity to formally recognize the climate change action commitments of mayors, governors, and premiers. These subnational officials often have authorities complementary to national governments, particularly in federal systems (including the United States, China, Canada, and Australia). They therefore possess significant independent capacities to reduce greenhouse gas emissions through their economic development strategies, building codes, zoning rules and practices, public transportation investments, and other policies. Likewise, the world community missed an opportunity to formally recognize the commitments of companies to successful implementation of the Paris Agreement and thereby to highlight the wide range of decisions that business leaders make that significantly affect greenhouse gas emissions.
Changing International Law for a Changing Climate
