Chapter 4 – Climate Change: An “Existential Threat” Not Yet Addressed


Because greenhouse gas (GHG) emissions blanket the Earth, climate change poses a particularly difficult policy challenge requiring international collaboration to manage the atmosphere as a global commons. Although the global community adopted the 1992 UN Framework Convention on Climate Change (UNFCCC), supplemented in 1997 by the Kyoto Protocol, these accords did little to lower the world’s GHG emissions trajectory as they imposed obligations only on developed nations. In 2015, with the Intergovernmental Panel on Climate Change (IPCC) pressing for deep decarbonization with ever greater urgency, 195 nations concluded the Paris Agreement, establishing a broader global emissions control framework, which asks every country to develop its own nationally determined contribution (NDC) to climate action. With a divided Congress, the U.S. government has been unable to establish a coherent federal climate change strategy, but cities, states, and companies have advanced climate change mitigation and adaption agendas.