Figure 1. The enhanced burning embers diagram, providing a global perspective on climate-related risks. (Source: “IPCC reasons for concern regarding climate change risks,” Nature Climate Change, January 2017)
More troubling, even the damages we know a good deal about, and can expect at these higher temperatures, do not tell the whole story. There are risks, still poorly understood, of so-called tipping points, suggested by the right-most column in the figure, in which case the Earth might undergo a radical environmental shift. Examples include an unstoppable melting of Greenland and the Antarctic ice sheets that will yield many meters of sea-level rise, or an acceleration in the outgassing of CO2 and methane (an especially potent greenhouse gas) from tundra ecosystems that would rapidly increase the pace of warming.
Needed soon – ‘tenacious, long-term effort’ to control greenhouse gas emissions
Continued greenhouse emissions will push these risks higher and higher, and managing them demands a prompt, vigorous emissions control effort. In framing a response there is no simple temperature goal or emissions target that will determine success or failure of the effort. A focus on such a mistaken, do-or-die, achievement, if some particular target appears unlikely to be met, would risk causing despair, and a shift elsewhere, of public energies. Managing the climate threat will require a tenacious, long-term effort to limit greenhouse emissions whatever the level of achievement at any time along the way.
Of course, as economists are wont to say, there is no free lunch. There will be costs to the economy in the transition away from fossil fuels and in the cutting of other greenhouse emissions. Fortunately, studies of long-term climate policy routinely find that, with effective international cooperation, deep reductions in global emissions could be achieved over time with only a few percent loss in economic activity. And these estimates don’t account for the costs avoided by the lowering of future climate change.
Moreover, there is continuing improvement in technology and policy design. For example, the costs of low-carbon technologies like wind and solar power continue to fall, and economically efficient emissions pricing initiatives are being ever more widely applied to wean economies off fossil fuels. One indication of growing confidence that costs are manageable is that the European Union and China talk of reducing their emissions to zero by around mid-century.
Whatever the overall economic costs of cutting warming emissions may turn out to be, the greatest burdens will fall on a narrow set of businesses, fuel producing regions, and employment groups. In a number of U.S. states and regions, the prerequisites for aggressive emissions reduction likely include programs to ameliorate these short-term impacts, perhaps including extended unemployment support and training for workers whose jobs disappear permanently,
As the second largest emitter of greenhouse gases and world power, the U.S. and its response to the climate challenge are crucial. Evaluation of U.S. performance to date depends on where you look. On the one hand, many individuals, non-profit organizations and business firms are actively pursuing emissions-reducing investments and changes in operating practices. Also, states and cities have adopted aggressive emission targets and are implementing policies and programs to meet them.
On the other hand, the achievements of these earnest efforts are limited by a lack of supportive, coordinated emissions policies from the U.S. federal government. Still more troubling, one side-effect of this domestic inaction is a failure of national leadership within the global climate effort, a topic for our next essay.
Our message, then, is clear. With intelligent actions, strenuous emissions control policies will impose manageable costs on the overall economy, though the energy transition will be more painful for some business sectors and regions. Not taking prompt action would, however, be very expensive. Further delay raises the risk of ever-increasing, perhaps catastrophic, environmental and economic damages.