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Vol. 52-1 Recent Publications

October 4, 2022




J.B. Ruhl* and Robin Kundis Craig


May 2021



The impacts of climate change are upon us. Recent climate change policy discussion emphasizes adaptation, rather than mitigation. This shift reflects a sober recognition that avoiding 2 degrees (Celsius) of warming, a central goal of climate mitigation efforts, is highly unlikely given the amount of greenhouse gases already emitted and the continued growth of global emissions. Illustrating this point, the Intergovernmental Panel on Climate Change’s most recent (Sixth) Assessment concluded that under any scenario, whether or not global greenhouse gas emissions reach net negative, the global surface temperature will continue to increase until at least mid-century.  Global surface temperature will increase by at least 2 degrees Celsius during the 21st century unless deep reductions in greenhouse gas emissions occur within the next few decades.

While reducing greenhouse gases remains critical to staving off the worst effects of climate change, awareness that a changing climate is our present and future has given rise to more discussion and study of how to best adapt to the impacts of climate change and build climate resilience. Growing evidence, including the recently published IPCC report, show the range of disruptive impacts that varying levels of global temperature rise will bring.  IPCC data indicates that changes in the climate system become larger in direct relation to increasing global warming, including “increases in the frequency and intensity of hot extremes, marine heatwaves, heavy precipitation, agricultural and ecological droughts in some regions, and proportion of intense tropical cyclones, as well as reductions in Arctic sea ice, snow cover and permafrost.”


The key issue of adaptation policy is how to best adapt to a changing climate. The answer to this question depends on determining the baseline assumptions of the scale and severity of climate impacts. This is why meta discussion of the proper adaptation response largely centers on the expected global temperature increase and the local or regional impacts that this temperature increase will bring. Obviously, the climate adaptation measures for 2 degrees of warming will be inadequate if the planet warms by 4 degrees. This concern for basing adaptation measures on inaccurate future temperature rises informs the recently published article, 4°C , written by J.B. Ruhl and Robin Kundis Craig.  Ruhl and Craig caution that adaptation measures based on the goal of limiting warming to 2 degrees are unworkable given that most peer-reviewed climate models now show that 2 degrees of warming will likely be exceeded this century.  While Ruhl and Craig still advocate for a mitigation strategy focused on limiting warming to 2 degrees, they urge policymakers to separately shape their adaptation policy plans based on 4 degrees of warming, at a minimum.  They call this  “dual-minded approach to climate change . . . necessary to simultaneously give the planet the best future possible (mitigation governance) while preparing humanity for the worst of the probable realities (adaptation governance).”

Ruhl and Craig pull together scientific studies to examine what a world of 4 degrees warming may look like. First, Ruhl and Craig note that the impacts of climate change with rising temperatures are nonlinear. By this, they mean that each increment of warming brings multiplying and accelerating impacts, and at some threshold, changes these changes become transformative—“fundamentally altering social-ecological systems into new states of being.”  To illustrate the nonlinearity of climate impacts as the planet warms, the authors cite a 2019 study that looked at 30 different climate change impacts and concluded, among other things, that “the global average chance of a major heat wave increases from 5% in 1981–2010 to 28% at 1.5 °C and 92% at 4°C[.]”

Drawing from studies of climate impacts, Ruhl and Craig suggest that the overlapping and interrelated changes to social-ecological systems at 4 degrees Celsius will result in an utterly new world. Water scarcity, food supply disruptions, increased flooding, loss of land mass to sea level rise, and longer and more intense wildfires are predictable impacts, but the uncertain severity and cascading effects raise added adaptation planning concerns. Increases in forest fires and even drought in low-lying coastal areas will result in the virtually assured mass-migration of human populations. Beyond this, water scarcity could lead to social conflict, meanwhile increased precipitation in areas would result in greater runoff that could overwhelm stormwater infrastructure and wastewater treatment facilities.

While severe impacts of climate change are assured with rising average temperatures, the scale and severity of these impacts and the corresponding human reaction to such effects makes climate adaptation inherently difficult. However, as Ruhl and Craig argue, this makes the need for more robust adaptation measures all the more imperative. In short, the policy goals of adaptation must meet the needs of what would be a significant shift of human populations and their support systems “northward and inward, while simultaneously preserving (or opening up) lands for agriculture, species habitat, and migration corridors.”


The main thrust of Ruhl and Craig’s argument is that a shift in adaptation policy assumptions, commensurate with an expected 4 degrees of warming, will necessitate a shift in conventional climate adaptation policies.  Standard adaptation policy centers on a combination of the “Three Rs” — resistance, resilience, and retreat.  Ruhl and Craig note that this adaptation strategy, which primarily emphasizes resistance and resilience, is incremental and place-based adaptation.

Resistance—also known as protecting, defending, or fortifying—emphasizes building infrastructure to protect human communities.  Sea walls, which physicall resist stormwater surges amid rising sea levels, are a prominent resistance measure,. Resilience includes “social-ecological systems” that build resilience to climate change impacts like heat waves, like improving urban populations’ capacity to withstand heat waves.

Resilience policies, focused on adjustment and management of climate impacts, are designed to increase community capacity to cope with climate impacts where the impacts cannot be resisted or adequately mitigated.  Resilience measures can be wide-ranging. For example, resilience could include subsidizing greater air conditioning installation in older urban housing or, in rural, agrarian context, planting diverse, drought-resistant, crops.

Finally, where resistance or resilience efforts are not adequate, retreat involves leaving areas where the impacts cannot be combatted—think coastal communities leaving areas where sea level rise is unavoidable despite sea walls.  Or even where sea walls stop storm surge, the saltwater may intrude groundwater, impairing the drinking water supply of the community.

After surveying the science of the potential impacts of climate change in a world of 4-degree temperature increase, the authors state that the scope and intensity of these impacts will render the “Three Rs” insufficient to achieve adaptation.  Ruhl and Craig identify the relatively adjunct, secondary focus on adaptation to the primary concern of mitigation facilitated by the emphasis placed on incremental, “in situ” (in place) adaptation strategies like resilience and resistance. This climate policy of the past made sense when the political community hoped that limiting warming to 2 degrees, or even 1.5 degrees, seemed a workable mitigation goal. In light of an increased likelihood that warming will not be limited to 2 degrees, “future proofing” policies will likely be insufficient in many areas of high climate vulnerability.


Ruhl and Craig posit that the associated climate impacts of temperature rise beyond 2 degrees Celsius requires a fourth climate change adaptation policy strategy that focuses on “redesign.”  In short, the “redesign” approach emphasizes radical and sweeping measures to “reconfigure and relocate our nation’s population distribution, land uses, infrastructure, economic and production networks, natural resource management, and other social, ecological, and technological systems.”

This is a radical shift in adaptation policy, and the authors further define what a “redesign” policy is. First, they say it encompasses letting go of intact, in situ adaptation. This is a recognition that 4 degrees of warming will fundamentally alter climate systems and will often require populations to move. For example, while resistance and resilience strategies allow for keeping agriculture in situ but adapting drought-resistant crops or water-conserving irrigation techniques, redesign would likely mean relocating agricultural crop and livestock lands to areas more suitable for these activities in a transformed climate of 4 degree warming. The authors say that “redesign is about designing and facilitating–perhaps even requiring–the relocations and reconfigurations necessary for these adaptations to succeed.”

Second, and, as the authors suggest, more importantly, redesign requires a shift from the “inward-looking” state and local planning of the Three Rs to more “outward-looking,” inter-regional or national planning. This is because 4 degrees of warming will have differential regional impacts that will lead to population migration and require broad-scale planning to manage the acute regional risks that will undoubtedly impact other areas. This “outward-looking” planning allows for a more integrated response rather than disjointed, locally-dependent measures that are often characteristic of resistance and resilience policies.

    Recognizing the incredible challenge of actualizing an adaptation plan of this magnitude, Ruhl and Craig focus the last section of their article on how to conceptualize, plan, and implement redesign adaptation. In summary, the main discussion centers on implementation of redesign adaptation by looking at the high-level tools available to effectuate this broad-scale adaptation policy.


In the last section of their article, Ruhl and Craig pay special attention to how an adaptation strategy centering redesign policies can be planned and implemented. While recognizing the “gross simplification” of “reducing adaptation governance to three top-level modes,” Ruhl and Craig discuss and analyze Laissez Faire, Planning and Prompting, and Preemption and Mandates as the high-level tools for implementing a redesign adaptation policy. The authors note that all of these tools have their pros and cons and should be harnessed together to varying degrees to effectuate redesign adaptation policies that meet the challenges of 4 degrees of warming.

In fact, the authors suggest that the greatest challenge to governance of adaptation redesign is the disruptive and simultaneous changes that temperature increase will involve.  They specifically mention that some impacts, such as sea level rise, will be gradual and linear. These changes are easier to plan for in an adaptation context. But nonlinear changes, such as increased storm intensity, and cascading changes, such as human migration from triggering events, will assuredly be less predictable and difficult to respond to without prior anticipatory planning.  Therefore, all of the tools for implementing a comprehensive adaptation strategy must be harnessed.

Regarding laissez faire tools, the author’s note that “the normal forces of supply and demand may in fact work surprisingly well to push and pull adaptation to a 4°C United States in the right directions.”  They exemplify this by noting that the private insurance industry has been a good indicator of weighing the financial costs and benefits of in situ climate adaptation.  Planning and prodding involve using incentives and disincentives, such as tax subsidies, to motivate redesign adaptation.  Preemption and mandates are the most heavy-handed approach whereby government mandates would intervene to force redesign adaptation.

In looking at the tools, laissez faire is helpful in responding to linear change, but limited when responding to nonlinear changes that tend to be unpredictable. The private market relies on information and predictability, something that 4-degrees of warming will not foster. The article highlights the way that private insurance companies stopped insuring homes in areas vulnerable to Hurricanes and storm surges in the Gulf or wildfires in the West. Similarly, private insurance companies have given up insuring areas of high flood risk. Meanwhile, planning/prodding and preemption/mandates are necessary and effective when used in tandem to ensure that redesign adaptation policies are being adequately implemented in the areas most vulnerable to severe climate impacts. These are the tools most critical to planning for nonlinear and cascading change.

In essence, the article does not delve into overly specific or prescriptive laws to effectuate a redesign adaptation policy. Instead, the authors categorize the modes of change (linear, nonlinear, and cascade change) that 4 degrees of warming will bring on and the governance tools available to implement a redesign adaptation plan. In doing so, Ruhl and Craig provide a high-level conceptual framework for how to utilize these tools to implement redesign-focused adaptation plans that prepare for the massively complex and urgent changes that a world of 4-degrees of warming will likely bring.


Liam Veazey is a 3L from Dallas, Texas, who received his undergraduate degree from St. Francis College Brooklyn. He plans to practice as a public interest attorney in the substantive areas of environmental justice, housing, and community development. Immediately after law school, he will begin a public interest law fellowship at Legal Assistance of Western New York.

Josh Katz is a partner at Bickerstaff Heath Delgado Acosta LLP and represents public and private entities before agencies and in state and federal court in the areas of environmental law, municipal law, water rights, and utilities.