The international community acknowledged for the first time in the 2015 Paris Accord that halting climate change at an acceptable level would require net human emissions of greenhouse gases to approach zero in the second half of this century. Many national governments, international organizations, businesses, cities, philanthropies, and nongovernmental organizations are pursuing activities aimed at deep decarbonization. But study after study is clear: With the current scale and scope of decarbonization efforts, net emissions are likely to fall short of the level needed to cap the dangerous risks of climate change.
A Way Forward: Acknowledging Uncertainty
The path to deep decarbonization is both difficult and deeply uncertain. At present, over 80 percent of humanity's economic activity depends on processes that emit greenhouse gases. Reducing net emissions to zero requires change in the global energy, transportation, and building sectors at an unprecedented rate and scale. Early indicators of such a transformation are easy to find, but no one can predict if and how such a transformation would unfold.
Those pursuing decarbonization often shy away from uncertainty, concerned that acknowledging it will delay action or show a lack of leadership. But uncertainty is at the heart of the issue. And achieving deep and rapid decarbonization will require technical, political, and social breakthroughs that result in even more unpredictability—forcing decisionmakers to assess risky and seemingly implausible tradeoffs.
Amid this uncertainty, the asymmetry of irreversible risk is a clear challenge. While many impacts of climate change will be irreversible, society may still be able to identify and correct mistakes along the path to deep decarbonization. In other words, lessons learned during the process will allow for some risk to be reversed.
Understanding the asymmetry of irreversible risk is important, but it provides little guidance on how to pursue decarbonization in a way that enhances human well-being while avoiding adverse consequences. Two concepts can help navigate this terrain: risk governance, and robust and flexible responses to deep uncertainty.
Risk governance applies the principles of good governance (i.e., an appropriate arrangement of actions, processes, traditions, and institutions) to the identification, assessment, communication, and management of risks. Robust strategies address deep uncertainty by performing well over a wide range of plausible scenarios, while flexible strategies can evolve over time in response to new information. Together, these concepts can create a locus of certainty in an otherwise unpredictable and fast-changing world.
The Need for Shared Understanding
As the work of scholars such as Elinor Ostrom make clear, societies have addressed other collective-action challenges (though not of the same scale as decarbonization) through the interactions of independent actors. The actors are guided by a mix of formal institutions (property rights and regulations), norms of behavior, and trust.
Fortunately, many actors are already aggressively pursuing decarbonization. But this is a particularly difficult challenge of collective action. When pathways for addressing collective problems are complex and unknown—two hallmarks of decarbonization—it becomes harder to coordinate actions, develop norms, establish appropriate rules, and ultimately, collaborate effectively.
Decarbonization is complex because it requires many types of interventions, including technical solutions, regulatory changes, financial innovations, and shifts in consumer behavior. No one action will suffice. No silver bullet exists. Some progress creates positive feedback, such as when increased renewable energy production reduces costs. Other progress generates negative feedback, such as when increased use of carbon neutral biofuels leads to increases in food prices.
Decarbonization is also highly unknown. There are many potential pathways, each of which is dependent on numerous contingencies. For example, is decarbonization best driven by changes in technology or in human behavior? Should rich nations be leading the way? Or should developing nations take the lead because they are unencumbered by large stocks of carbon-emitting infrastructure?
Effective collective action in this landscape of complexity and deep uncertainty requires a shared understanding of potential decarbonization pathways and how various actors can affect their course. To avoid being brittle and non-inclusive, this shared understanding should
- engage multiple worldviews
- recognize tangled feedbacks
- acknowledge potential surprises along the way to a carbon-neutral future
- acknowledge that the best mix of interventions will likely differ among paths
- reflect contrasting tradeoffs among objectives and risks
- make clear the implications of various bets—the risks of choosing one path over another.
In any collective-action solution, bottom-up tactics—through markets, entrepreneurial innovation, and initiatives at the local and city scale—will prove vital. Such efforts must also be embedded in a context of still emerging national and global policy, institutions, and norms to guide competition and cooperation.
Deep decarbonization can reduce the risk of climate change, and it offers opportunities to reimagine energy, transportation, and infrastructure. But deep decarbonization could also fail in many ways. A shared understanding reflective of the endeavor's complexity and deep uncertainty is essential to helping diverse, independent actors design a solution to this daunting, necessary, and opportunity-laden challenge.
Robert Lempert is a principal researcher at the nonprofit, nonpartisan RAND Corporation, director of the Frederick S. Pardee Center for Longer Range Global Policy and the Future Human Condition, and a professor at the Pardee RAND Graduate School. Horacio Trujillo is an adviser to the Metanoia Fund, a philanthropy.
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