How to Worry about Climate Change

Winter 2017

"No challenge — no challenge — poses a greater threat to future generations than climate change," said President Barack Obama in his 2015 State of the Union address. Yet his own administration's best estimate for the economic cost of that challenge, if left unaddressed, totaled only 1% to 4% of annual global GDP by 2100. For comparison, while promoting the Affordable Care Act in 2009, the president's Council of Economic Advisers estimated that "genuine health care reform" could increase U.S. GDP by 8% by 2030. A 2015 report by the McKinsey Global Institute estimated that improvements in gender equality worldwide could increase global GDP by 11% by 2025. In what way, then, is the challenge of climate change "greater"?

To be sure, GDP offers a notoriously incomplete measure of human flourishing. But the real problem with assessing Obama's assertion is more fundamental: Climate change is a different kind of problem from health-care reform, gender equality, or almost any traditional subject of political attention and action. Its relevant effects are still decades or centuries away. Scenarios with the most extreme effects, rather than the most likely ones, provide the sense of urgency and the rationale for policy responses. Those extreme outcomes are often distant ripples from the initial effect of a warmer climate, transmitted outward through multiple steps of causation and combined with other factors to produce or amplify the damage. By the time actual impacts arrive, the time for action may have long passed. But if climate change is not a typical policy problem, how should policymakers approach it?

This is not an abstract question. As a new administration takes office, it must recalibrate from the extraordinary attention its predecessor lavished on the issue. Where does climate change fit in the constellation of challenges facing the nation and the world? For the administration's opponents, how much energy should go toward lamenting a shift in climate policy versus highlighting other areas of concern?

Much of the political rhetoric and policy analysis surrounding climate change starts from a premise that the challenge is truly unique, demanding unparalleled levels of focus and action. A climate-change conference could attract the United Nations' largest ever gathering of world leaders in 2015 because, as French president Francois Hollande declared at its opening, "never — truly never — have the stakes of an international meeting been so high. For the future of the planet, and the future of life, are at stake." Comparisons to World War II have become commonplace, and proponents of strong climate action deride their opponents as "deniers" — a term previously associated with refusal to acknowledge the occurrence of the Holocaust. Left-wing politicians from former vice president Al Gore to Senator Bernie Sanders to New York City mayor Bill de Blasio warn that human civilization hangs in the balance.

This framing influences policy directly. During the 2016 Democratic primaries, for instance, Senator Sanders suggested the nation's mobilization for World War II in 1941 was "exactly the kind of approach we need right now," while former senator and Secretary of State Hillary Clinton offered her plan to create a dedicated "climate map room" in the White House, akin to President Franklin Roosevelt's own map room during that same war. The mindset is reflected in the Democrats' official platform, which "commit[s] to a national mobilization, and to leading a global effort to mobilize nations to address this threat on a scale not seen since World War II." Lest the claims be taken as less than literal, the New Republic clarified in its headline of an article by activist Bill McKibben: "We Need to Literally Declare War on Climate Change."

Based on such dire outlooks, advocates of aggressive climate action justify their proposals under the "precautionary principle" or as "insurance," even where the measurable costs appear to far outweigh measurable benefits. They dismiss skepticism about that approach as an irrational failure to understand the scope of the problem or an excessive discounting of future damage. "If global warming took out an eye every now and then," scoffed Dan Gilbert, professor of psychology at Harvard University, "OSHA would regulate it into nonexistence."

But the unmooring of climate change from any conventional policy framework has been rhetorical rather than reasoned. It requires justification — otherwise, the obsessive and apocalyptic politics built atop it cannot be supported. Yes, climate change is a problem. But what kind of problem?

CALIBRATING OUR WORRIES

Climate change stands apart from typical challenges in three important respects. First, whereas most challenges are immediate, climate change is forecasted. The political process usually engages with problems as they present themselves or based on expected consequences of current events. The claim that high corporate-tax rates drive businesses overseas, or that high college tuition burdens graduates with overwhelming debt, can be tested against experience and quantified in terms of ongoing costs. Claims about climate change cannot. Scientists do strive to identify contemporary costs, but the scale of the challenge and the case for action depend on calamities yet to come — indeed, assertions that climate change will be far outside of existing experience often play a central role in the case for its significance. Yet this absence of reference points creates a double-edged uncertainty: Compared to most policy issues, the level of risk seems high but the level of confidence in predictions is low.

Second, whereas most challenges are static, climate change is irreversible. Medical errors kill more than 250,000 Americans each year, according to researchers at Johns Hopkins University. Those deaths each represent an individual tragedy and, applying the EPA's preferred estimate of $10 million per life, cost a staggering 15% of national GDP. But deaths one year have little effect on society's capacity to make future progress on the issue. Even most forecasted problems share this characteristic: If demographic trends suggest an impending shortage of nursing-home beds and politicians ignore the warnings, more capacity can still be built after the crisis hits. With climate change, by contrast, scientists warn the planet will reach a point of no return. Carbon dioxide, once emitted into the atmosphere, remains there for centuries. If temperatures rise and predicted meteorological dominos begin to fall, subsequent efforts to reduce emissions will not offer relief.

Third, whereas most challenges are confined, climate change is pervasive. The typical forecasted problem, even if irreversible, has limited reach. Population growth in the American Southwest may drive some species to extinction in the coming decades. But there, or near there, that particular causal chain likely ends. It is constrained geographically, thematically, and in the extent of damage. Not so with climate change. Its global scope and linkages to many critical environmental and economic systems invite the conjuring of disruptions in every cranny of modern civilization.

Climate change — forecasted, irreversible, and pervasive — might therefore be called a "worrying problem." Here, "worrying" does not mean "concerning" (though it is that as well), but rather something tailor-made for worry. Its effects exist primarily in the imagination and have poorly defined bounds that encourage speculation; a point of no return looms. Yet the contours of those bounds and that point may become clear only after it is too late to correct course.

Other worrying problems exist. They tend to emerge where clear long-term trends in technological or social change produce concerning side effects. The obvious trajectory of growing fossil-fuel consumption, prerequisite (with current technology) to continued global industrialization, produces the climate challenge. Similarly, ever-denser urbanization coupled with ever-more-frequent travel from ever-more-remote locations produces an ever-greater risk of a global pandemic. Such a pandemic is widely forecast to occur though the timing is unknowable; it will be too late to prevent once underway, and it has the potential to cause catastrophic damage throughout society. Increasing urbanization also exposes society to both higher levels of social unrest and disruption by increasingly powerful and well-coordinated non-state actors.

Overuse of antibiotics around the world could render them useless in the face of rapidly evolving bacteria, possibly setting back medical progress against disease and infection by decades. The rising sophistication, ubiquity, and interconnectivity of financial systems threaten a global economic meltdown of the type only narrowly averted in 2008. The democratization of communications technologies has already provided fertile ground for terrorist networks to recruit, coordinate, and promote themselves. Nuclear weapons represent in some respects a quintessential worrying problem, though an oddly binary one: Their likely effects are all too well understood; their risk remains roughly as present this year as last year as next. The issue typically attains salience only when conditions suggest risk is trending upward — as early in the Cold War, during periods of proliferation, or when leaders appear potentially willing to countenance their use.

Just as technology can provide a vector to heighten some risk, it can also pose the risk itself. For instance, many experts fear the prospect of faster computing hardware and more sophisticated software ultimately yielding superhuman and potentially hostile artificial intelligence. Computer viruses, meanwhile, might someday allow their creators to commandeer the basic infrastructure of modern society. Continued advancements in nanotechnology — especially if weaponized — raise comparable fears of tools either inadvertently escaping the control of their creators or being deployed maliciously.

All these are worrying problems. All present a potential scope of damage that is at this point only hypothetical but could be almost unlimited — in part because it is only hypothetical. Each is plausibly foreseeable given present trends, and each would defy prevention once underway, yet for each the moment or probability of reckoning is impossible to know.

Worrying problems can also be sociological, rather than technological. Declining fertility rates coupled with extending lifespans, for instance, pose precisely a forecasted, irreversible, and pervasive challenge to modern civilization. So too do economic and social transitions with the potential to make large swathes of the working-age male population effectively unemployable. Insofar as two-parent families are a crucial contributor to successful child-rearing, the collapse of that social norm and its compounding across generations likewise exhibits the characteristics of a worrying problem.

Those may not seem intuitively like problems similar to climate change. But imagine President Obama describing riots in Baltimore as he might describe a major hurricane strike: "While sociologists say no individual riot can be linked conclusively to the absence of two-parent families, this social unrest is exactly the type they say will become more prevalent and severe as the trend worsens." The problems may not seem as catastrophic. But that is a question of degree, not kind, and therefore one that permits relevant comparison. If one of these worrying phenomena were only to slow annual productivity growth by one-tenth of one percentage point for only one-tenth of the population, the economic impact three generations hence would be of the same magnitude which is forecast in climate-change models.

Even the sustainability of the Western welfare state itself is a worrying problem. In the United States, the federal government has tens of trillions of dollars in unfunded entitlement liabilities and a debt poised to spiral out of control if interest payments begin to swallow the national budget; most other developed economies face situations at least as dire. A collapse would have immeasurable economic and geopolitical implications yet may give almost no advance warning.

There is, in short, much to worry about. But while these problems all look fundamentally different from other policy challenges — and by their forecasted, irreversible, and pervasive nature defy traditional tools of policy analysis — they stack next to each other quite cleanly. Perhaps climate change and deferred bridge maintenance require different risk-tolerance assumptions. But the thinking applied to climate change and pandemics should be similar. Perhaps it makes no sense to compare the long-term threat from water-supply disruptions with the present cost of medical errors. But water stability and family stability have much more in common.

Worrying problems demand greater focus than day-to-day political pressure might otherwise prompt, but long-term risks cannot be allowed to sap all attention away from the more routine but also more painful realities of the moment (consistent progress on the latter is every bit as important to society's long-term health). In isolation, each worrying problem can seem overwhelming. But they cannot all be the greatest challenge of future generations, or grounds for mobilization on a scale not seen since the global fight against fascism.

Each reader will likely have his own reaction to the worrying problems listed here — which genuinely qualify and which others have been overlooked; which among them is truly forecasted, irreversible, and pervasive; whether those are even the correct dimensions. But at least those are concrete and constructive discussions. The classification of problems into hierarchies, the establishment of shared assumptions built with a common vocabulary, and reasoning by analogy are all critical to determining appropriate tools of government power, the allocation of resources, and the tolerance for risk.

We should heed the well-known warning: "What worries you masters you." We need to choose and calibrate our worries with care. If, at least, climate change is a worrying problem but not the only one, what makes it most worrying of all?

EXPECTATIONS IN PERSPECTIVE

Environmental activists have an immediate and predictable response: "because we know climate change is going to happen." But that conflates two very different conceptions of climate change: expected change and extreme change.

The scientific consensus holds that the climate is warming and human activity plays a substantial role. But there is no consensus about how much warming human activity has caused or will cause. According to the Fifth Assessment Report of the United Nations' Intergovernmental Panel on Climate Change (IPCC) in 2013, the best estimates of warming for a given increase in the atmospheric concentration of carbon dioxide range by a factor of three, a range that has grown wider in recent years. A doubling of carbon dioxide could produce a temperature increase of 1.5 degrees Celsius, or 4.5 degrees Celsius, or more likely something in between. Expected climate change, averaging the widely varying projections and assuming no aggressive efforts to reduce greenhouse-gas emissions, entails warming of 3 to 4 degrees Celsius by 2100.

Even focusing within that range, estimates for the expected environmental impacts of warming vary widely. The IPCC represents the gold standard for synthesizing scientific estimates, and, crucially, its best guesses bear little resemblance to the apocalyptic predictions often repeated by activists and politicians. For instance, the IPCC estimates that sea levels have risen by half a foot over the past century and will rise by another two feet over the current century. At the high end of the 3-to-4-degree range, it reports the impact on ecosystems will be no worse than that of the land-use changes to which human civilization already subjects the natural world.

The responsibility for translating these and other disruptions into economic costs falls to Integrated Assessment Models (IAMs). To create its "Social Cost of Carbon," the Obama administration surveyed this economic literature and focused specifically on three models whose forecasts themselves vary widely, even starting from a common level of warming. For warming of 3 to 4 degrees Celsius by 2100, the middle of the three models estimates an annual cost of 1% to 3% of GDP. The low case estimates 0 to 1%. The high case estimates 2% to 4%. While 4% is a large dollar amount, arriving at that impact over nearly 100 years implies almost imperceptibly small changes in economic growth.

The specifics of this high-case model are informative: The Dynamic Integrated model of Climate and the Economy (known as the DICE model) developed by William Nordhaus at Yale University estimates 3.8 degrees Celsius of warming by 2100 costing an associated 3.9% of GDP in that year. But over time, this cost is the equivalent of slowing economic growth by less than one-tenth of one percentage point annually. By 2100, regardless of climate change, the world is more than six times wealthier than in 2015 under this model; global GDP is $500 trillion. The effect of climate change is to reduce that gain from a multiple of 6.7 to a multiple of 6.5. The economy also continues to grow, so that the climate-change-afflicted world of 2105 is already much wealthier than a world of 2100 facing no climate change at all.

Such estimates might seem counterintuitively low, especially given the rhetoric often employed. Part of the explanation lies in the almost incomprehensible economic progress that human civilization is capable of making over the course of a century. The annual cost identified by Nordhaus in 2100 is $20 trillion — massive by the standards of 2015, manageable by the standards of 2100. Further, that cost repeats every year even as the impacts are spread over many years. Thus, over the 2090 to 2110 time period, Nordhaus envisions the world spending a stunning $350 trillion to cope with climate change. One might despair over what else such resources might accomplish over that time period. But one must also recognize that the economy of 2100 will likely be able to allocate those resources toward climate change while also allocating to every other facet of society far more resources than are available today.

Corroborating these models, the IPCC concludes that "for most economic sectors, the impacts of drivers such as changes in population, age structure, income, technology, relative prices, lifestyle, regulation, and governance are projected to be large relative to the impacts of climate change." In other words, other worrying problems have a far greater capacity to influence progress.

None of this means the dislocations from climate change would be painless or the disruptions cheap. It is merely to observe that the impacts expected from climate change over the next hundred years look similar to those through which both civilization and our planet have successfully muddled over the past hundred and continue to struggle with today. Other worrying problems have their own anticipated but less-severe analogs, too. Whether a global pandemic strikes, epidemics will inevitably occur like the 2014 Ebola outbreak in West Africa that claimed more than 10,000 lives and cost the three countries at its center more than a tenth of their GDP. Whether artificial intelligence makes humans superfluous, self-driving vehicles could throw millions out of work in the years to come. Some countries will default on their debt; some business cycles will spawn deep global recessions.

These challenges are not existential threats or even ones that require analysis outside the standard policy process — that is, they are not really worrying problems at all.

EXTREME CASES

If expected climate change represents the most likely outcome, extreme climate change represents the worst case: Models could be underestimating the warming that emissions will cause; feedback loops could send a 3-degree increase suddenly careening higher; or even at the expected level the climate could hit a tripwire that collapses global ecosystems or ocean currents or ice sheets or some other prerequisite of modern civilization.

Any of these things may be true — as is the nature of genuinely forecasted challenges, they are mostly non-falsifiable. But while extreme climate change is a quintessentially worrying problem, it is also one that has no guarantee or even likelihood of occurring. Certainly, the "scientific consensus" or even the "scientific mainstream" on climate change does not extend to confidence in such scenarios.

To compare extreme climate change with other worrying problems, it is helpful to consider the dimensions that make a problem "worrying": that it is forecasted, irreversible, and pervasive. On all three, climate change appears less worrying than most.

Consider, first, the magnitude of the forecasted impact. Many worrying problems feature the credible prospect of killing a significant share of the human population or erasing modern civilization. Not extreme climate change. For instance, even considering higher temperature increases, the IPCC concludes that:

Global climate change risks are high to very high with global mean temperature increase of 4°C or more above preindustrial levels in all reasons for concern, and include severe and widespread impacts on unique and threatened systems, substantial species extinction, large risks to global and regional food security, and the combination of high temperature and humidity compromising normal human activities, including growing food or working outdoors in some areas for parts of the year.

Obviously, each of those effects would entail enormous economic costs, carry severe consequences for entire nations, and wreak havoc with the natural environment. But as a worst case, it nevertheless pales in comparison to catastrophes that might kill a significant share of the human population or erase the basic physical and economic infrastructure of modern civilization.

Serious efforts to quantify existential threats concur. A 2016 report by the Global Priorities Project at Oxford offered as its example of a worst case that climate change could "render most of the tropics substantially less habitable than at present," as compared to hundreds of millions or billions of deaths associated with other challenges. Another Oxford study from 2008 asked conference participants to estimate the probability of various global catastrophes leading to human extinction in the coming century, and did not even see fit to include climate change as an option, while respondents gave molecular nanotechnology, super-intelligent artificial intelligence, and an engineered pandemic each at least a 2% chance of erasing humanity by 2100.

Some analysts nonetheless place climate change among humanity's genuinely existential threats on the basis of its "fat tail," arguing that some unknowable but non-zero chance exists at the far-right end of the probability distribution for an outcome with essentially infinite cost. But this is true of all worrying problems — indeed, the characteristics of worrying problems might be viewed as those that generate such unknowable non-zero probabilities. Climate change cannot be distinguished from other worrying problems on that basis. Rather, the argument begs the question: What characteristics of climate change make its tail relatively fatter or thinner?

The weight accorded to a worrying problem's forecasted effects depends greatly on the number of causal steps between the underlying phenomena and worst-case outcomes. Where fewer steps are necessary, or where steps are relatively more likely to occur, the probability of the worst case arising should increase. For instance, whether an engineered pandemic devastates humanity depends on development of the necessary technology (highly likely), its use by a malicious actor (indeterminate), and its spread defying efforts at containment (indeterminate). Generally speaking, technological threats will have the shortest chains while sociological threats will have the longest ones.

Climate change would appear to sit somewhere in between. It has a very short chain to some impact — indeed, higher atmospheric concentrations of carbon dioxide are already having effects. But the connection from warmer temperatures to civilizational catastrophe is highly attenuated. The initial warming must cross thresholds that produce feedback loops. The ensuing warmth must produce environmental effects that cause unprecedented crises across societies. Those crises must in turn overwhelm the coping capacity of the entire global community, which must in turn produce wide-scale breakdowns in social order or trigger military conflict, which must in turn metastasize into...what? Certainly, one can invent a scenario. But the specifics quickly become hazy, and a worst case entirely outside of human experience difficult to articulate.

The intent of this analysis is not to dismiss the severity of worst-case climate scenarios or to suggest that "wide-scale breakdowns in social order" are acceptable. But all worrying problems have worst-case forecasts that look this way, all with indeterminate probabilities of occurring, which leaves only a few options: We could become overwhelmed with despair, emphasize whichever problems are most politically useful, or seek out qualitative and quantitative bases for analysis. Too much discussion of climate change adopts the first or second approach. Efforts at the third approach will inevitably be imprecise and imperfect, but the burden of proof should lie on those declaring that climate change stands apart from other worrying problems to explain why that is so. The suggestion here is not that the forecasted threat of climate change does not belong alongside other worrying problems, only that the nature of its forecast cannot be what separates it as uniquely worrying.

WORRYING IN SLOW MOTION

In the other ways climate change is a worrying problem, meanwhile, it is less worrying than most. This is especially true with respect to irreversibility. While President Obama has lamented that climate change is a "comparatively slow-moving emergency," the one thing worse is a fast-moving one. Most worrying problems have worst-case scenarios that sweep the globe in a matter of months, days, or even minutes. For climate change, the damage unfolds over decades or centuries. This has several implications.

First, while climate change is irreversible compared to the typical policy problem, it does allow for some potential interventions even once well underway. For instance, natural processes already exist for extracting carbon dioxide from the atmosphere, and new technologies could be developed that accelerate those processes or create artificial ones. Alternatively, humans could use so-called "geoengineering" to effect other changes in the climate system that might counteract an intensifying greenhouse effect. These approaches offer no guarantee or even likelihood of success; turning to geoengineering might be seen as a disaster in its own right. But they offer more cause for optimism than exists with many other worrying problems.

Second, time permits adaptation. While the prospect of losing 50% of existing agricultural capacity is daunting, over a 50-year period only 1% of capacity needs to shift annually. By comparison, over the past 50 years, total agricultural output has tripled. Similarly, the need for hundreds of millions of people to migrate over a century amounts to little out of the ordinary on an annual basis. There are, for instance, more than 200 million migrant workers within China, as well as another 200 million international migrants and at least 60 million refugees around the world right now. The United Nations estimates 2.5 billion people will migrate to cities in just the next 35 years. Further migration, or perhaps the gradual abandonment of some cities or even entire regions, would obviously be extraordinarily costly and disruptive in human, economic, and environmental terms. But the reason such adaptations are rarely mentioned in the context of other worrying problems is not that they would be unnecessary, but rather that, in those other cases, they would be either impossible or else futile.

Purveyors of creatively catastrophic climate cases also face a Catch-22: Developing ever-more extreme scenarios typically requires ever-longer timescales. Even higher temperatures and risks of further dominos falling are threatened — by 2300, or after "centuries." Confident forecasts of multi-meter sea-level rises are issued, to occur over multiple millennia. Harvard University's Martin Weitzman, the leading proponent of the case that climate change presents a uniquely "fat tail," falls into precisely this trap: The worst case he offers relies on continued temperature increases over multiple centuries. But if heightening the threat requires extending the timeframe further, it becomes diluted threefold: More time becomes available for adaptation, for economic progress and technological innovation that render the threat irrelevant, or for the model to fail. Any impact forecasted for 200, let alone 2,000, years into the future becomes almost inherently less cognizable than those already under study for 2100.

Finally, consider the pervasiveness of extreme climate change. By influencing the literal atmosphere in which all other human activity takes place, climate change perhaps exceeds any other challenge in the breadth of its causal connections and potential effects. But this same dynamic also leaves its connections to ultimate damage more dependent on interaction with other contributing factors. As a result, more alternative approaches exist for mitigation.

If one wants to prevent a financial collapse from sending the world into economic depression, one needs to prevent the collapse. By contrast, consider a favorite present-day causal chain used to illustrate the full specter of the climate threat: the asserted connection between climate change, drought in the Middle East, social upheaval in Syria, the country's gruesome civil war, the rise of ISIS, and the flood of refugees into Europe. Perhaps the catastrophe might have been averted or lessened had there been no drought. But better weather would seem an odd prescription for stability and prosperity in the Middle East — plainly neither necessary nor sufficient. Democratic governance, social progress, more effective Western intervention by either regional or global powers, or even just better water-usage practices are all superior approaches.

Another country, bordering Syria, has suffered the same drought. But a report in Scientific American explains, "Water is driving the entire [Middle East] to desperate acts. Except Israel. Amazingly, Israel has more water than it needs." While Syria's oppressed society was crumbling, Israel launched a new era of desalination technology. The writer concludes: "The contrasts couldn't be starker. A few miles from [Israel], water disappeared and civilization crumbled. Here, a galvanized civilization created water from nothingness. As Bar-Zeev and I drink deep, and the climate sizzles, I wonder which of these stories will be the exception, and which the rule."

This is compelling storytelling. At first glance it seems a cautionary tale of climate change. But read the concluding sentence again. Climate change is not the independent variable, it is the constant. The question is whether civilization will equip itself to thrive anyway. What separates a world of 2100 dominated by drought-plagued failed states and one filled with prospering democracies that export water from blooming desert plains is not climate change. It is the world's ability to supplant radical ideology with modernity. This same pattern repeats itself in equipping societies to withstand natural disasters, feed themselves, eradicate disease, or thrive in the face of any other challenge climate change might pose.

Perhaps sociological challenges like declining fertility, workforce participation, or family stability seemed out of place in the initial list of worrying problems. Yet it is these, not genuinely existential threats to humanity, with which climate change has the most in common. They all impose real costs but rely on lengthy causal chains to reach from basic phenomenon to true catastrophe. They all unfold slowly and leave opportunity for intervention. Their pervasiveness in each case depends on interaction with other sociological conditions that all invite policy interventions themselves. These worrying problems deserve attention, but not out of proportion to the genuine nature of the threat they pose.

WORRYING PROPERLY

"ISIS is not an existential threat to the United States," President Obama told the Atlantic's Jeffrey Goldberg. "Climate change is a potential existential threat to the entire world if we don't do something about it." The claim is nonsensical because it compares a worrying problem to the traditional national-security challenge of a specific terrorist group. Obviously, the former will appear more like an "existential threat." Conversely, one might choose a measure that would shift the calculus: ISIS and ISIS-inspired actors killed more Americans in 2016 than did climate change.

The discussion would be more constructive, and dramatically different, if "ISIS" were converted into the worrying problem of which it represents an early manifestation: As an existential threat, how does climate change compare to increasingly potent religious extremism that leverages technological advances to increase coordination, propaganda, and force? Which links more credibly to greater catastrophe given a 100-year timeframe? Which will prove more difficult to reverse or adapt to? In October, President Obama observed:

There's already some really interesting work — not definitive, but powerful — showing that the droughts that happened in Syria contributed to the unrest and the Syrian civil war. Well, if you start magnifying that across a lot of states, a lot of nation states that already contain a lot of poor people who are just right at the margins of survival, this becomes a national security issue.

Surely that remains at least as true if the word "droughts" is replaced with "rise of radical Islam."

The president's insistence on treating ISIS only on its current terms rather than considering a long-term, worst-case scenario is precisely the purported error in logic for which he chides anyone who refuses to feel the burning urgency of climate change because its effects today are not large. Or conversely, the over-politicization of radical Islam he insists on rising above bears striking resemblance to the over-politicization of climate change he purveys.

According to the Associated Press, only 17% of Americans "are alarmed by climate change and want action now." At the other extreme, 10% "are dismissive, rejecting the concept of warming and the science." The silent majority is either "concerned, thinking it's a man-made threat, but somewhat distant in time and place" (28%) or "cautious, still on the fence" (27%). That "alarmed" 17% tends to believe it has a monopoly on rational assessment of the situation and resorts to psychological explanations for the failure of others to join. But if climate change is just one worrying problem among many, the silent majority may have it right. In which case some of that psychological analysis might best be turned inward.

For instance, Harvard geology professor Daniel Schrag observed in a recent lecture, questioning reluctance to take decisive climate action: "People scratch their heads and say: Why don't people do what's right? Well, maybe they're rational. It's hard to accept. But in fact, maybe they actually don't value the future as much as some of us do." Schrag correctly identifies that the divide in perspectives on climate change reflects in part two different views on the future. But he simply assumes it is he and his audience who have it right. Yes, humans may irrationally discount future harms. But they also routinely fail to account for the way technological and societal change will render forecasts of the distant future useless. This latter error is especially prevalent in the environmental realm, where predictions of impending resource scarcity and civilizational collapse have been made frequently and proven wrong with equal frequency.

"Alarmed" analysts also complain that climate change is difficult to communicate because it is too abstract or too far removed from everyday concerns. But at least compared to most worrying problems, climate change is highly accessible. At the conceptual level, environmental calamity — especially one purportedly caused by malfeasance — has been a subject of fascination for the human psyche since the beginning of recorded history. More tactically, every natural disaster, extreme temperature reading, and even geopolitical event has become an excuse to talk about climate change — either by claiming a potential link, or else by asserting that it represents the kind of incident that will become more common. People who understand these events to be an endless rush of "signals" would understandably but irrationally elevate climate change above other worrying problems, even as the majority correctly tunes out most of the speculation as mere noise.

Perhaps most important, motivated reasoning might play a role. The typical claim holds that, because people do not like the proposed solutions to climate change, they prefer to minimize the extent of the problem. But it also seems to be the people most enamored of those policies who consider climate change uniquely demanding of the world's attention. If they are wrong, it might be in part their enthusiasm for a government-led green agenda that has led them astray. Notably, their emphasis on addressing climate change has fallen by the wayside when faced with policy options — nuclear power, fracking in China, carbon taxes offset by tax cuts, renewable facilities in environmentally sensitive areas — that demand tradeoffs with their other priorities. In 2016, for instance, activists in Washington state opposed a statewide carbon tax partly because its revenue would not be set aside for "necessary investments in our communities" and because tax supporters were not "listening to communities of color."

"Global warming," they wrote, "does not just represent an intersection of some of the most pressing challenges of our times — it also represents our opportunity to address these core issues."

A more dispassionate placement of climate change alongside a range of worrying problems does not mean there is nothing to worry about. But it points away from sui generis mitigation at all costs and toward an existing model for addressing problems through research, preparation, and adaptation. It suggests that analytical exercises that would never be applied to other worrying problems, like assigning a "social cost" to each marginal unit of carbon-dioxide emissions, are as inappropriate as estimating a "social cost of computing power" as it brings humanity closer to a possible singularity, or a "social cost of international travel" as it elevates the risk of a global pandemic. Taxes on any of them are closer to political statements than efficient corrections of genuine externalities, and each would be more likely to stall meaningful economic and technological progress than to achieve a meaningful reduction of risk.

Lessons might run in the other direction as well: We are not focusing as much on other challenges as we should. And perhaps, if climate change were consigned to its rightful place in the crowd, some additional attention might be available to concentrate elsewhere. If the level of research support, policy focus, and international coordination targeted toward climate change over the past eight years had gone instead toward preventing and managing pandemics, imagine the progress that could have been made. For a fraction of the cost of de-carbonizing an industrial economy, it could be hardened against cyber attacks; with a fraction of the attention corporations pay to their own purported climate vulnerability, they could make real strides in their own technological security.

A little bit of worry provides healthy motivation. Too much is a recipe for paralysis, distraction, and overreaction.