In 4°C, Ruhl and Craig effectively argue that governance measures, particularly adaptation planning, will fall short if institutions fail to embrace the real possibility that the planet will blow well past 2° Celsius (°C) above pre-industrial temperatures. Further, they argue that 4°C is a better target for adaptation planning because this metric better captures the future risk the nation faces. Ruhl and Craig are keenly aware that serious talk of a possible 4°C future will almost certainly trigger accusations of “doomism” from various critics.

In 4°C, Ruhl and Craig acknowledge that the Earth’s climate is changing at an increasingly rapid rate, outside the range to which society has adapted in the past. Realistically, achieving the goal set in the 2015 Paris Agreement of limiting global warming to 1.5°C will be almost unattainable without drastic actions to reduce greenhouse gas emissions.

Accelerating ice loss and expanding wildfire zones are potential markers of what are known as tipping points—thresholds along a nonlinear pattern of system change that accelerate the pace of change. Scientists are concerned that our global climate system is dangerously close to passing these points. This trend has significant implications for governance and law. Climate change disruptions will extend beyond biophysical systems to social systems, including systems of governance.