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The Oxford Handbook of International Climate Change Law edited by Carlarne, Cinnamon P; Gray, Kevin R; Tarasofsky, Richard (24th March 2016)

Part III Climate Change—Principles and Emerging Norms Concepts in International Law, Ch.8 Precaution and Climate Change

Jonathan B. Wiener

From: The Oxford Handbook of International Climate Change Law

Edited By: Cinnamon P. Carlarne, Kevin R. Gray, Richard Tarasofsky

Natural resources — Climate change — Environmental disputes — Pollution — Precautionary principle — Arbitration

(p. 163) Chapter 8  Precaution and Climate Change

(p. 164) 1.  Introduction

precaution’ is surely a central topic of climate change law and policy. The flagship international climate treaty, the 1992 United Nations Framework Convention on Climate Change (FCCC), expressly called for ‘precautionary measures’ in Article 3. Because climate change poses uncertain but serious and even catastrophic risks, and because greenhouse gas emissions have latent and long-lasting effects (over decades or centuries), precautionary action is widely urged as essential to preventing future climate change—rather than waiting to act after the damage is done and it is too late to address the cause. The ‘Precautionary Principle’ is sharply controversial, but if there is any sensible form of precaution to apply to any problem, then climate change seems an especially apt and urgent case. So far, though, precautionary measures on climate change have been elusive. For another global atmospheric problem, stratospheric ozone depletion, the 1987 Montreal Protocol (and related national policies) took early action and have achieved substantial success (WMO 2014). Has there been comparable early action to prevent climate change? Not so much. What accounts for this, and what can be done?

This chapter examines the role of precaution as applied to climate change. Section 2 identifies the key features of precaution, reviewing differing formal versions of ‘The Precautionary Principle’ and attempting to distill the core elements of a ‘precautionary posture’ for policy-making.

Section 3 assesses the normative pros and cons of applying precaution to the problem of climate change. Then it compares that normative case to the positive record of the application of precaution to climate change in actual practice—a record of only partial precaution in action.

Section 4 explores options beyond exhortations to precaution against climate change. First, it addresses the problem that espousing precaution is not enough to motivate policy action. It considers what could be done to make precautionary policy more successful in the future—such as reducing its costs and countervailing risks, enhancing the incentives for participation in global cooperation, and using the ‘provisional’ character of precaution as a call for continuous learning and policy updating. Second, it addresses the possibility that, with growing global emissions and rising greenhouse gas concentrations (now passing 400 parts per million (ppm)), climate change may already have passed beyond the time for precaution. It therefore explores ‘post-cautionary’ policy options that remain to address climate change—such as adaptation, liability for loss and damage, and geoengineering.

(p. 165) 2.  Precautionary Principles

It is common to refer to the ‘Precautionary Principle’ (PP) as a formal doctrine. But there is no one authoritative statement of the PP. Instead there are several different Precautionary Principles (for reviews, see Bodansky 2004; Wiener 2007). To understand the meaning of the PP and its role in climate change law, it is useful to review several versions of the PP, and then attempt to distill from them the core elements of what might be called a precautionary posture for climate change policy-making.

Versions of the PP have now been adopted in more than fifty international agreements (Trouwborst 2002: 63). Early versions of the PP emerged by the early 1970s, notably the German Vorsorgeprinzip, and related concepts in Swiss and Swedish law. In the United States, the federal Court of Appeals held in Ethyl Corp. v EPA, 541 F.2d 1 (D.C. Cir. 1976) that the US Clean Air Act is a ‘precautionary’ law, authorizing US EPA to take regulatory decisions to prevent anticipated but uncertain future harms.

Some versions of the PP appear not just to authorize regulation despite uncertainty, but to require regulation or even to forbid risky activities. According to the 1998 Wingspread Statement on the PP (drafted by non-governmental organizations): ‘When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established.’ Going even further, the UN World Charter on Nature (UNGA Resolution 37/7 (1982)) declared that ‘where potential adverse effects are not fully understood, the activities should not proceed’—but as risks are never ‘fully understood,’ this would amount to forbidding those activities. The Intergovernmental Panel on Climate Change (IPCC) (2014b) has recently commented that ‘[t]‌he PP allows policymakers to ban products or substances in situations where there is the possibility of their causing harm and/or where extensive scientific knowledge on their risks is lacking. These actions can be relaxed only if further scientific findings emerge that provide sound evidence that no harm will result’. But because providing evidence that ‘no harm will result’ is effectively impossible (everything poses some risk, particularly energy systems whether fossil or renewable), this formulation is tantamount to a prohibition.

By the late 1980s, the PP began to gain adherence in global atmospheric and climate change law. The Montreal Protocol on Substances that Deplete the Stratospheric Ozone Layer (1987) (by now universally adopted) spoke of ‘precautionary measures’ in its Preamble, stating that it was ‘[d]‌etermined to protect the ozone layer by taking precautionary measures to control equitably total global emissions of substances that deplete it, with the ultimate objective of their elimination on the basis of developments in scientific knowledge, taking into account technical and (p. 166) economic considerations and bearing in mind the developmental needs of developing countries,’ and also ‘[n]oting the precautionary measures for controlling emissions of certain chlorofluorocarbons that have already been taken at national and regional levels’.

As climate change became the subject of international negotiations, the Bergen Declaration (1990) provided:

In order to achieve sustainable development, policies must be based on the precautionary principle. Environmental measures must anticipate, prevent and attack the causes of environmental degradation. Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing measures to prevent environmental degradation.

A widely cited formulation is the version in the 1992 Rio Declaration, paragraph 15, which provides:

In order to protect the environment, the precautionary approach shall be widely applied by States according to their capabilities. Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.

The Rio Declaration was adopted by country governments at the 1992 Earth Summit (UN Conference on Environment and Development). Compared to the earlier Bergen Declaration, the Rio Declaration maintained the core message that where there are ‘threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing … measures to prevent’ harm, while also introducing several modifications, including the term ‘approach’ in place of ‘principle,’ the qualifier ‘by States according to their capabilities’, and the qualifier ‘cost-effective’.

Similarly, the FCCC, signed and ratified by virtually all countries, provides in its Article 3(3):

The Parties should take precautionary measures to anticipate, prevent or minimize the causes of climate change and mitigate its adverse effects. Where there are threats of serious or irreversible damage, lack of full scientific certainty should not be used as a reason for postponing such measures, taking into account that policies and measures to deal with climate change should be cost-effective so as to ensure global benefits at the lowest possible cost. To achieve this, such policies and measures should take into account different socio-economic contexts, be comprehensive, cover all relevant sources, sinks and reservoirs of greenhouse gases and adaptation, and comprise all economic sectors. Efforts to address climate change may be carried out cooperatively by interested Parties.1

(p. 167) Also in 1992, the European Union adopted the Maastricht Treaty, which provided in Article 130r (now Lisbon TFEU (2009), Article 191) that EU policy on the environment ‘shall be based on the precautionary principle’—though without defining what that meant. Eight years later, the European Commission (2000) issued its explanation of the PP in an important statement, providing that precaution must be based on risk assessment, must consider costs and benefits, ‘must not aim at zero risk,’ and must be ‘provisional’ to be revised over time as understanding improves.

Several national and local governments have also formally adopted versions of the PP. In 1999, Canada incorporated the precautionary principle in its revised Canadian Environmental Protection Act. In 2005, France adopted the PP as part of its Constitution (including the qualification that precautionary measures must be ‘provisoires et proportionnées’—provisional and proportionate). The City of San Francisco’s version of the PP emphasizes thorough evaluation of alternative policy options, which of course is general advice on good decision-making, rather than distinctive of precaution. Some observers imbue the PP with a role in fostering public participation or stakeholder input in the regulatory process, but the texts of the PP (such as those quoted above) do not seem to address this issue (and there can also be public participation in non-precautionary regulatory processes, such as public comment on policies adopted after a problem has arisen, as well as public protests and government hearings held after a disaster).

This brief review illustrates the advance of the PP across the terrain of national and international law, and also the variation among its proliferating versions (for more details, see Bodansky 2004; Wiener 2007). The result is that there is no one formulation of the PP. Each of these versions was negotiated by a different set of parties for a different time and topic. Several of the official versions quoted above refer not to a ‘Precautionary Principle’ but rather to the desirability of taking ‘precautionary measures’ subject to several qualifications. Sandin (1999) found 19 versions, with significant differences regarding threat, uncertainty, action, and command. VanderZwaag (1999) identified 14 formulations. Stone (2001) found no coherent statement, and only ‘disarray’. Wiener and Rogers (2002) and Wiener (2007) grouped the many versions into three basic approaches: (i) authorization to take policy measures despite uncertain risk, (ii) obligation to take policy measures to address uncertain risk, and (iii) shifting the burden of proof (of safety or of acceptable risk) to the proponent of the activity. Bodansky (2004) found that versions of the PP differ on multiple dimensions, including the permission to act versus duty to act, the trigger of application, and what action should be taken; he concluded that the PP has ‘not moved … towards consensus’ and ‘the only point of overlap is a truism’. In addition to the sources cited above, further details on the PP’s many versions are offered in Wiener (2007) and Wiener et al. (2011).

Among these numerous differing versions of the PP, there is still much left unspecified. These versions of the PP typically do not say what level of risk triggers its invocation (beyond vague terms like ‘serious’), nor which risks deserve priority (p. 168) for precautionary measures among the vast array of the multiple serious and uncertain risks a society may face. They do not say how early or how anticipatorily measures must be taken. They sometimes say that action need not wait for ‘proof’, but as there is never conclusive proof of risks—the essence of risk is that there is always uncertainty about the future—any version calling for action before proof is actually addressing all decision-making about risks in the face of uncertainty, which is to say all decision-making about risks. And they often do not say which measure(s) should be taken to anticipate or prevent the risk. Words like ‘prevent or minimize’ lean toward more stringent measures, and some of the burden-shifting versions go further toward prohibiting risky activities. Some versions of the PP, notably Rio 15 and FCCC 3(3), qualify the choice of measures by calling for ‘cost-effective’ measures (achieving climate protection benefits at least cost); the European Commission version calls for assessing costs and benefits, and the French version calls for proportionality. But many other versions of the PP do not speak to cost, proportion, reasonableness, optimization, or other criteria for choosing which measures to take.

In some cases, these gaps in official formulations of the PP may be intentional. Specifying risk priorities, or regulatory stringency, or cost–benefit balancing, would oblige the drafter to confront the difficult tradeoffs in policy-making and might dilute enthusiasts’ support for precaution. Two advocates of the PP have remarked:

Paradoxically, we conclude that the application of precaution will remain politically potent so long as it continues to be tantalizingly ill-defined and imperfectly translatable into codes of conduct, while capturing the emotions of misgiving and guilt … [I]‌t is neither a well-defined nor a stable concept. Rather, it is has become the repository for a jumble of adventurous beliefs that challenge the status quo of political power, ideology, and environmental rights (Jordan and O’Riordan 1999: 15).

In order to evaluate the application of precaution to climate change policy, it may be useful to try to characterize precaution as a general posture for policy-making, rather than as a legal principle, and to distill its main features from the several versions noted above (especially from the 1992 FCCC Article 3(3), which speaks most directly to climate change, as well as from the European Commission (2000) and the French charter (2005), cited above). The core elements of such a precautionary posture appear to include: (i) a threat of serious or irreversible or catastrophic risk or damage; (ii) a stance on knowledge, providing that scientific uncertainty about such risks does not preclude policy measures; (iii) a stance on timing, favoring earlier measures to anticipate and prevent the risk; (iv) a stance on stringency, favoring greater protection (on a spectrum from preventive measures to burden-shifting that prohibits risky activities at least until they are shown to be safe or acceptable); and (v) a qualifying stance on the impacts of the precautionary measures themselves, calling for assessment of their cost-effectiveness or costs and benefits, their coverage of multiple countries and gases and sectors, and their provisional character and hence their need for reassessment and improvement over time as knowledge (p. 169) is gained. In short: such a precautionary posture favors earlier measures to prevent important risks, despite uncertainty, rather than waiting, while also recognizing that such early actions should be well designed to avoid their own drawbacks, and are provisional and should be updated over time in light of learning. Framing the general precautionary posture in this way enables precaution to be translated into a spectrum or continuous variable (rather than a binary classification of precautionary-or-not), which measures the degree of precaution (e.g. in terms of (iii) timing and (iv) stringency), so that different policies can be scored and compared for their relative precaution (Hammitt et al. 2005; Wiener et al. 2011). And rather than rigidly dictating precaution irrespective of other considerations, this posture leans in favor of precaution, while taking at least some account of costs, complexities, and continued learning over time.

3.  Precaution and Climate Change

3.1  Pros and Cons

The Precautionary Principle remains controversial. One appraisal summed up the debate: ‘The precautionary principle may well be the most innovative, pervasive, and significant new concept in environmental policy over the past quarter century. It may also be the most reckless, arbitrary, and ill-advised’ (Marchant and Mossman 2004: 1).

Some of this debate is about the specific language in strong versions of the PP. More generally, seeing precaution as a posture, or as a spectrum of the degree of precaution, illustrates its pros and cons as applied to climate change.

Precautionary measures (early and anticipatory) can be essential to address risks of latent impacts—impacts that do not occur until long after their causes. In these cases, waiting for proof of the causal relationship or the magnitude of harms can mean waiting until it is too late to address the cause. Greenhouse gases (GHGs) accumulate in the atmosphere and affect the climate with time lags of months to years to decades or more. It has long been understood that in the case of GHGs and climate change, ‘a wait-and-see policy may mean waiting until it is too late’ (National Research Council 1979: viii). The latent impacts of GHGs on climate may last a long time and be very hard to reverse. Once emitted, GHGs have long-term latent impacts on the order of 1,000 years (Solomon et al. 2009).

Further, the possibility of catastrophic climate risks favors precaution (Posner 2004; Weitzman 2009; Nordhaus 2011). Consider the possibility of a ‘tipping (p. 170) point’, where the damages from rising GHG concentrations suddenly turn sharply disastrous (e.g. due to rapid melting of land-based ice sheets in Greenland and Antarctica, or positive feedbacks such as release of frozen methane which then accelerates warming). If we are uncertain about just where the tipping point lies, we may need to take added precautions to avoid getting too close to it. A recent report by White House economists summarized the literature on this issue: ‘the prospect of a potential tipping point with unknown location enhances the precautionary motive for climate policy. … [T]‌he uncertainty about the tipping point generally leads to a policy that is more stringent today than it would be absent uncertainty. To the extent that delayed implementation means higher long-run CO2 concentrations, then the risks of hitting a tipping point increase with delay’ (CEA 2014: 24–5).2 Thus, whereas some argue that uncertainty about the cause or magnitude of climate change warrants waiting longer to study the problem before adopting policies, here uncertainty about a catastrophic threshold warrants greater precaution (IPCC 2001, section TS—noting, however, that ‘the question of timing and extent of mitigation and/or adaptation policies remains unquantified by the precautionary principle’).

On the other hand, precaution may pose problems. First, precautionary measures may be costly. Critics of precaution worry that anticipatory measures to restrict new technologies may inhibit innovation. Debates over precaution versus innovation often involve new technologies with nascent risks, such as genetic modification or nanotechnology. But in the case of climate policy, precaution would largely be applied to restrict old technologies, such as fossil fuels and deforestation. Still, strong versions of the PP could be very costly: applying the PP version under which risky activities may not proceed until their proponents demonstrate that they are ‘safe’ or pose ‘no risk of harm’ would seem to prohibit not just all burning of coal or oil, but all energy sources of any kind, including natural gas, nuclear, hydro, wind, and solar, because there is no energy system that does not pose some risk of some kind of environmental harm. More moderate versions of the PP would consider cost, such as the FCCC 3(3) qualification to be ‘cost-effective’, the European Commission’s attention to assessing costs and benefits, and perhaps the French use of ‘proportionate’.

Second, precautionary measures do not affect just one risk at a time. We live in a multi-risk world (Wiener 2002). Precautionary measures must select which risks to make top priority, and must confront their potential to affect multiple risks at the same time. Precautionary measures to prevent one risk may induce ‘side-effects’ (p. 171) or ‘risk–risk tradeoffs,’ including increases in other countervailing risks (ancillary harms), and decreases in other accompanying risks (ancillary co-benefits) (Graham and Wiener 1995; Wiener 2002; Revesz and Livermore 2008). Yet many versions, or applications in practice, of the PP in regulatory policy tend to focus on only one salient risk at a time (Graham and Wiener 1995; Heyvaert 2011). Sound policy-making has to assess the full portfolio of policy impacts, including these ancillary impacts (both harms and benefits), rather than focusing narrowly on just a single target risk. Indeed, if precautionary measures themselves increase some risks, then very stringent versions of the PP (forbidding risky activities) would ironically block the PP itself (Wiener 2002; Wiener 2007). Sunstein (2005) argues that in a world of risks on all sides, the PP points nowhere. Graham and Wiener (1995) and Wiener (2002) argue that the solution is to take a broader, more holistic approach that confronts the multi-risk reality, assesses the full portfolio of multiple impacts, and seeks ‘risk-superior moves’ that reduce multiple risks in concert.

Examples of such risk–risk complexities are rife in climate change policy. Consider shifting energy sources from coal to natural gas, which would reduce CO2 emissions but could increase methane (CH4) emissions, potentially with even larger climate impacts. Or shifting from fossil fuels to some types of biofuels, which could again reduce CO2 emissions from vehicles, but could also increase emissions of N2O (a more potent GHG) if nitrogen fertilizers are heavily used to grow corn ethanol; and demand for land to grow crops for biofuels might also increase deforestation (thus reducing a key sink for CO2), as well as raise food prices. Or, shifting from fossil fuels to nuclear energy would reduce climate risks but could add risks from nuclear waste, reactor accidents, and weapons proliferation. Or shifting from fossil fuels to wind and solar energy might pose risks to migratory birds. One further example: the highly successful precautionary measures to phase out chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) to protect the stratospheric ozone layer, under the Montreal Protocol and national laws, have also had the unintended consequence of potentially adding to climate change risk by increasing the use of non-ozone-depleting substitutes that are potent GHGs, such as HFCs (WMO 2014; this tradeoff was foreseen in Graham and Wiener 1995: 198–202). In all of these examples, the PP typically offers little guidance, but a full portfolio multi-risk approach counsels confronting and weighing the tradeoff to reduce overall risk, and seeking new risk-superior options that reduce multiple risks in concert (Graham and Wiener 1995; Wiener 2002).

At the same time, there may be important co-benefits in climate policy. For example, reducing methane and black carbon may both reduce climate change risks and protect public health from the heavy toll of conventional air pollution (Shindell et al. 2012; Shindell 2015). These opportunities for ancillary benefits further illustrate the key point that every climate or energy policy choice affects multiple risks, and we must confront the full portfolio of impacts while searching for multi-risk-superior moves.

(p. 172) Advocates of precaution often invoke commonsense adages such as ‘better safe than sorry’. Yet because in reality we face multiple interconnected risks, simple adages are insufficient. Of course one prefers ‘safe’ to ‘sorry’—almost by definition. The real questions are ‘better safe against this, or against that?’, and ‘how safe—what are the pros and cons of seeking this much safety or in this way?’ In a world of multiple risks, which risks should we address more than others, and which actions will reduce overall risk rather than create new risks? ‘Better safe than sorry’ is an old adage, but ‘the cure may be worse than the disease’ has at least as old a pedigree.

Precaution need not be opposed to full portfolio analysis of multiple policy impacts. First, in formal law, although some versions of the PP appear insensitive to costs and risk–risk tradeoffs, other versions expressly combine them. As noted above, both FCCC Article 3(3) and the European Commission (2000) included cost-effectiveness or cost–benefit in precaution. In fact, the EU’s 1992 Maastricht Treaty adopted not only the PP, but also cost–benefit analysis, in the very same Article 130r (now Lisbon TFEU Article 191). And the FCCC called for regulatory impact assessment (RIA) addressing both cost–benefit and risk–risk analyses, in its Article 4(1)(f) which required parties to ‘employ appropriate methods, for example impact assessments, formulated and determined nationally, with a view to minimizing adverse effects on the economy, on public health and on the quality of the environment, of projects or measures undertaken by them to mitigate or adapt to climate change’.

Second, the general idea of precaution as a posture for policy-making is not at odds with cost–benefit analysis or risk–risk tradeoff analysis. As noted above, quantitative economic analyses of optimal climate change policy that incorporate tipping points and uncertainty can favor greater precaution. There is a growing literature showing how precaution and cost–benefit or decision analysis can be combined to favor optimal or robust policies that account for uncertainty, catastrophe, option value, and related precautionary factors (Graham 2001; DeKay et al. 2002; Stewart 2002; Wiener 2002; Gollier and Treich 2003; Lempert and Collins 2007; Weitzman 2009; Nordhaus 2011; Driesen 2013).

3.2  Positive Politics in Practice

Given the case in favor of precautionary measures to address the latent, uncertain and potentially catastrophic risks of climate change, what have governments actually done?

To combat stratospheric ozone depletion, national laws and the Montreal Protocol took early action and succeeded in phasing out CFCs and related substances (WMO 2014). To combat climate change: not so much.

In the case of stratospheric ozone depletion, the uncertainty of the risk, and the earliness and stringency of the policy measures taken, were greater than for climate change. (For a comparison of the relative precaution on these two issues, see (p. 173) Hammitt 2011). Chlorofluorocarbons (CFCs) were invented in the 1920s; the theory that they could break apart and deplete stratospheric ozone was published fifty years later by Molina and Rowland (1974). Just four years after the publication of that theory, before observational evidence of such depletion occurring had been collected, the United States banned CFCs in aerosol spray cans in 1978—about a decade before Europe took comparable measures. After discovery of the Antarctic ozone hole in 1985–86, countries agreed to the Montreal Protocol in 1987, which eventually phased out CFCs and HCFCs, and the ozone level has begun to recover (WMO 2014).

By contrast, the risks of climate change were less uncertain, and yet policy measures were adopted later and less stringently. The burning of fossil fuels began in the 1800s, and the theory of greenhouse warming was well known by 1896 (when Svante Arrhenius began his famous article ‘A great deal has been written on the influence of the absorption of the atmosphere upon the climate’ (Arrhenius 1896: 237)). By the 1980s, observational evidence of rising CO2 concentrations was being collected, and computer models were forecasting damages to come. Policy measures to limit GHG emissions came mainly after the 1992 FCCC and its 1997 Kyoto Protocol (KP), including the European Union climate package and emissions trading system (EU ETS) since 2001, and several US regional programs (chiefly the Regional Greenhouse Gas Initiative (RGGI), and California’s AB32). Major US federal policies were adopted after a key US Supreme Court decision in 2007 (Massachusetts v EPA), including EPA’s GHG Reporting Rule in 2008, its vehicle emissions rule in 2010, and its ‘Clean Power Plan’ final rule for electric power sources in 2015.

Thus, both the United States and EU were faster to act to phase out CFCs despite less evidentiary basis on stratospheric ozone depletion, and slower to act to limit GHG emissions despite greater evidence on climate change. And while the United States was more precautionary than Europe on CFCs and stratospheric ozone, Europe was more precautionary than the United States on GHGs and climate change (Hammitt 2011).3

Several hypotheses may explain why both American and European policy on CFCs has been more precautionary than on GHGs (see Sunstein 2007; Wiener and Richman 2010). Both problems pose short-term costs and long-term global benefits, discouraging action by politicians focused on short-term local re-election. But the two problems also differ in other ways. The perceived threat from CFCs may have been higher, especially after the discovery of the ozone hole, whereas climate change may have been seen as more gradual and lacking a focusing crisis event (so far, notwithstanding heatwaves in Europe and hurricanes Katrina and (p. 174) Sandy in the United States). The perceived cost of abatement for CFCs was much lower (than for GHGs); CFCs were a far smaller share of the economy and substitutes were more readily available than for GHG-emitting activities. Fewer countries were major sources of CFCs (than of GHGs), facilitating international cooperation. Moreover, when climate did arrive on the policy agenda in the 1990s, the EU initially resisted US proposals for cost-effective flexibility mechanisms such as emissions trading (which the United States was then enacting for acid rain domestically, and was advocating for GHGs internationally) (Wiener 2001), and the EU also resisted inclusion of any quantitative targets for China and other major developing country emitters, both of which raised the perceived cost to the United States (Stewart and Wiener 2003). The EU later changed course and adopted its ETS after 2001. But by then the United States was withdrawing from Kyoto because of the rise of China (marked by the United States Senate’s Byrd–Hagel Resolution in 1997; President Clinton then declined to submit the Kyoto Protocol to the Senate for ratification; and President Bush-43 withdrew the United States from the Kyoto Protocol in 2001). Later, Canada and Australia also withdrew from Kyoto, and Russia, Japan, and New Zealand withdrew from the second commitment period (2013–2020). (For further analyses of the political economy of CFCs and GHGs in the United States and EU, see Sunstein 2007; Wiener and Richman 2010; and Hammitt 2011.)

A tension between precaution and distributional equity persists in climate policy. Major developing countries such as China, India, Brazil, and Indonesia were not bound by quantitative commitments in the Kyoto Protocol. In 1990, China emitted only about half as much GHGs each year as the United States. But by 2006, China had rapidly surpassed the United States, and by 2014, China emitted almost twice as much GHGs each year as the United States. Moreover, cumulative global greenhouse gas emissions since 1850 from the developing countries have matched, and will soon exceed, the cumulative emissions of industrialized countries over that period. (On these emissions trends, see IPCC 2014d: section, at 60–1.)

At the same time, climate initiatives have proliferated beyond the FCCC and KP, growing into a multifaceted and fragmented ‘regime complex’ (Keohane and Victor 2011; IPCC 2014d: 13.2, 13.13). ‘A major challenge is assessing whether highly decentralized policy action is consistent with and can lead to global mitigation efforts that are effective, equitable, and efficient.’ (IPCC 2014a: TS 4.4, p. 92.) The fragmentation of legal regimes addressing stratospheric ozone, climate change, long-range transboundary air pollution, and other atmospheric issues, poses problems of omissions, disregard, and risk–risk tradeoffs, but efforts to integrate these issues into a more coherent approach—or even to study such a coherent approach under the auspices of the International Law Commission—face persistent obstacles (Sand and Wiener 2015).

So far, the most successful precaution on climate change has not been the FCCC or other climate treaties, nor national climate policies in the EU or United States, but, it turns out, has been a co-benefit of the Montreal Protocol to protect the stratospheric ozone layer. The Montreal Protocol’s phase out of CFCs and HCFCs—which (p. 175) happen to be potent GHGs as well as ozone-depleting gases—has (so far) delivered five times more GHG abatement than the Kyoto Protocol (see WMO 2014—which notes, however, that the increasing use of HFCs as a substitute poses a countervailing climate risk). The Conference of the Parties (COP 21) meeting Paris in December 2015 aims to mobilize greater action by all countries to reduce GHG emissions, but faces challenges in motivating sufficient collective action and in linking national policies for cost-effective abatement and financing.

4.  Beyond Precaution: Politics, Provisionality, and Post-Cautionary Policies

If some sensible precautionary measures would be warranted to address the latent, uncertain and potentially catastrophic risks of climate change, but governments have not done enough, what can still be done? This section offers three kinds of answers: politics, provisionality, and post-cautionary policies.

First, the politics: as should by now be evident even to earnest advocates of strong versions of the Precautionary Principle, simply espousing the PP is not enough to move actual policy-making (and extreme versions of the PP could be too strong, only hindering political acceptance). Political governments tend not to follow aspirational principles when the costs are high and short term and local, while the benefits are uncertain and long term and distant (i.e. to people in the future and elsewhere, who do not vote for the government policy-makers being asked to adopt precaution) (Sunstein 2007; Wiener and Richman 2010). The flip-side of this reality is the inequity that the impacts of climate change may be hardest on people in countries and future generations who were not the major sources of GHGs. Still, motivating action by political leaders of major GHG emitters requires more than exhortations to precaution as a principle.

Climate and precaution present a cognitive puzzle. Precaution is predicated on acting in the face of uncertainty—so it confronts uncertain benefits, which may be less persuasive to politicians (even if uncertainty and tipping points favor precaution in economic models, as noted above). ‘[T]‌he precautionary principle as applied to climate change … inadvertently played into the hands of critics of swift and aggressive action on climate change, feeding the industry-funded view that the science of climate change was too uncertain to justify such action’ (Heinzerling 2008: 458). The PP may be intended to solve cognitive biases that neglect future risks (Dana 2009), but the PP itself may succumb to heuristics that distort its application to focus on recent events that grab public attention (Sunstein 2005). Unlike (p. 176) many other risks in debates over the PP, climate change does not seem to exhibit the heuristics and biases that spur public outcry and demand for greater precaution than experts would recommend; rather, climate change exhibits experts (including sober economists) recommending greater precaution than the public, or at least than politicians in some places, seem willing to adopt.

In this sense, fully optimal precautionary policies need to account not only for their risks, costs, and benefits once adopted (as discussed above), but also for their ability to get adopted. Put another way, if a problem warrants precaution—early anticipatory measures—then its timing of adoption matters, and delay in adoption is costly. Drawing on positive political economy, psychology, and policy instrument design, researchers can and should assess the probability and timing of adoption in evaluations of optimal climate change policy design (Wiener 1999a; Wiener 1999b; Gilligan and Vandenbergh 2014). This is especially true at the international level, where adoption depends on consent rather than majority rule or fiat (Wiener 1999a).4

Precaution in climate policy may therefore be more successful in actual politics if it is designed to attract adoption and implementation. Key strategies include: increasing its climate benefits; increasing its co-benefits in public health or other areas; decreasing its costs, through more cost-effective policy design; decreasing its ancillary harms (countervailing risks) through risk-superior policy design; and better informing the public and political leaders about all of these improvements in net benefits. Opposition to precautionary climate policies appears to derive in part from implicit fears of the cost of mitigation measures (Campbell and Kay 2014). It is also important to appeal to citizens’ public and prospective aspirations, and to their core values as well as their scientific literacy (Kahan et al. 2012).5

Thus, to achieve sensible precaution, one must solve the governance challenge: overcoming the obstacles to collective action by designing climate law to attract the participation of key actors (e.g. the United States, the EU, China, India, Brazil, Japan, Canada, Australia, Korea, Russia, Indonesia, South Africa, and others). Designing climate policy to be cost-effective, to promote co-benefits, and to avoid adverse side-effects, can both improve outcomes and help attract participation, which explains why the climate treaty already calls for these features as part of or alongside precaution in FCCC 3(3) and 4(1)(f), as noted above.6

(p. 177) Second, as to provisionality: Some versions of the PP provide that precautionary measures are ‘provisional,’ adopted under uncertainty and to be revised in light of new information and learning (e.g. European Commission 2000). The rounds of negotiations on the FCCC, KP, and subsequent commitments also exhibit a rough sequence of learning and updating. The choice is not between acting now, versus waiting to learn; the choice is between acting and learning versus waiting and learning. That is, there can be learning while acting—so long as the actions are monitored to evaluate their impacts, and they avoid ‘lock-in’ so that they can be revised over time (McCray et al. 2010; IPCC 2014b: section 2.8 at 56).7

Provisionality offers a bridge from precaution to adaptive learning and policy revision. In a section immediately following its discussion of precaution, the IPCC offers: ‘adaptive management represents structured processes for improving decision-making and policy over time, by incorporating lessons learned’ IPCC 2014b: section 2.5.6 at 31–2). The IPCC distinguishes ‘passive adaptive management’ which ‘involves carefully designing monitoring systems, at the relevant spatial scales, so as to be able to track the performance of policy interventions and improve them over time in response to what has been learned’, from ‘active adaptive management’ which ‘design[s]‌ the interventions themselves as controlled experiments, so as to generate new knowledge’ (id.). In the former, observations can track the diffusion of varying policy approaches and compare results. In the latter, experiments can be conducted in the ‘lab’, that is with volunteers in a university research setting (Ludwig et al. 2011), or in the ‘field’, that is with real policies applied by accountable governments (Greenstone 2009; McCray et al. 2010; van Gestel and van Dijck 2011). In both passive and active adaptive regulation, well-designed monitoring and performance evaluation are essential (Wiener 2015).

Indeed, because precaution is predicated on uncertainty, that premise implies that there are opportunities for learning, by testing different policy approaches—subject to the costs of errors and of revising those policies over time (Greenstone 2009; Listokin 2008). For climate change, there are many different policy designs that could serve as precautionary measures to limit emissions, with different costs (p. 178) and ancillary impacts in different settings, so there could be value in careful experiment designs. Governments conduct such variation and policy experiments all the time—but they often do so haphazardly or unintentionally, and they neglect to structure the experiment carefully to compare treatment options, monitor performance, and evaluate outcomes. Successful provisionality and adaptive management require careful data monitoring and analysis, in order to evaluate policy performance over time, both compared to alternative policy designs and compared to the counterfactual scenario of what would have occurred without the policy (McCray et al. 2010; Wiener 2015).

In addition to precaution informing climate change policy, climate change policy can also inform precaution. The complexities of climate change offer lessons for improving the broader regime of risk regulation (of all types of risks), favoring greater comprehensiveness in scope (to address systems more holistically and thereby avoid risk–risk tradeoffs), and greater adaptability over time (through learning and updating) (Wiener 2008a; Heyvaert 2011; Sand and Wiener 2015).

Third, as to post-cautionary policies: The difficulty in adopting sensible precautions against future climate change may have shifted the timing for climate policy. If some observers are correct, we may now be (part way) past the time for precaution. We may have moved from ex ante regulation toward ex post remedies, or at least to somewhere in the middle along this spectrum.

Some climate modelers have forecast that, given accumulating GHG concentrations now passing 400 parts per million (ppm), it is already (or almost, and with varying levels of confidence) too late to limit future temperature increases to the political long-term goal of 2°C. (Even if that is true, further temperature increases might still be prevented.) Some observers infer that the window of opportunity for precaution to prevent ‘dangerous anthropogenic interference with the climate system’ has closed (e.g. Harvey 2007; Shaw 2009). Heinzerling (2008: 452) argues:

We should cease discussing responses to climate change in terms of the ‘precautionary principle’ and should begin to think instead in terms of a ‘post-cautionary’ approach. For a long time, climate change has been the exemplar for application of the precautionary principle. This principle has taken many forms over the years, but in its simplest and perhaps most common formulation, it stands for the idea that we should not wait for scientific certainty before acting on a threat. The underlying principle is that we are better off being safe than being sorry. At this moment in history, discussing climate change in terms of the precautionary principle is a serious mistake. … [w]‌e probably blew past our precautionary opportunity sometime in the 1980s. We are now, and have been for some time, in a post-cautionary world.

This point of view is not necessarily saying that nothing can be done now, just that we are no longer taking precautions early in anticipation of the risk. Nor is it to say that countries violated their international agreements on GHG emissions. The IPCC reports that Annex I countries, as a group, actually met their aggregate targets in both the FCCC (reducing their aggregate emissions below 1990 levels by (p. 179) 2000—partly due to the economic downturn in former Soviet countries), and in the Kyoto Protocol (reducing their aggregate emissions more than 5.2 percent below 1990 levels by 2012) (IPCC 2014d: section, at 59–60).

But these emissions reductions by Annex I countries under the FCCC and KP, plus their additional pledges of new policy measures, are apparently not sufficient to achieve the long-term goal of limiting temperature rise to 2°C, largely because rapid increases in emissions from non-Annex I countries (i.e. major developing countries) are driving overall growth in global emissions and thus in global GHG concentrations (IPCC 2014d: Executive Summary, at 6–7; IPCC 2014d: section, at 60). A forecast of plausible pledges to be made at the 21st Conference of the Parties (COP 21) in Paris in 2015 shows that they could significantly bend down future emissions, but that the likely agreement will still not produce global emissions within the window of paths to 2050 that are consistent with frequently proposed climate goals (such as 2°C) (Jacoby and Chen 2014). New studies suggest that major melting of Antarctic ice may already be underway (Joughin et al. 2014; Rignot et al. 2014).

If so, policy will shift toward an array of in-progress or ex post or ‘post-cautionary’ policies. In several areas, this is already occurring. For example, there has been an important shift in attention in the international climate negotiations from mitigation (prevention, emissions abatement) to adaptation. For many years, adaptation was downplayed or treated as taboo by climate activists, lest it invite moral hazard—a sense that precaution was not so urgently needed because adaptation would be available as a backup or insurance strategy. That seems to be changing, and adaptation is now widely discussed and sometimes mobilized. Adaptation assistance is sought by vulnerable countries, for whom it offers defenses against ongoing weather extremes and sea level rise (due to climate change or other causes). Bangladesh, for example, has developed improved strategies to cope with periodic flooding displacing millions of people. It remains unclear if adaptation can succeed for small island states, whose entire territory may be submerged. After hurricanes Katrina and Sandy, the United States (or some key cities) have tried to adopt adaptation plans, though reform of the national flood insurance system has been halting. Heinzerling (2008: 459) advocates adaptation, arguing that the moral hazard problem is now moot because climate change is occurring. Hartzell-Nichols (2014) suggests that adaptation can still be considered precautionary, in the sense that it reduces expected damages.

Another type of post-cautionary policy is ‘loss and damage’, a form of ex post civil liability. Advocates seek not funding for prospective adaptation projects, but compensation for retrospective losses. The issue of loss and damage was raised at the Durban COP in 2011 and debated at the Warsaw COP in 2013. So far, there is no functioning legal mechanism for litigation over transboundary liability for climate harms, though a variety of international and national law tort claims have been attempted—not yet successfully, though conceivably that could change. (p. 180) Plaintiffs face major challenges, including in establishing the jurisdiction of a tribunal over the case and the defendant(s), avoiding preemption by regulatory law (as in Connecticut v AEP, US S.Ct. 2011), proving causation, assessing damages, and enforcing any judgment (IPCC 2014c: section 3.3.6, at 16–17). Thus loss and damage remains a political negotiation, in which major emitting countries are not offering compensation (Myers and Kulish 2013). As major developing countries’ share of cumulative emissions rises to exceed the cumulative share of industrialized countries, the set of possible defendants may be expanding, but the political opposition to compensation is likely to remain high.

If precautionary emissions limits and adaptation do not limit climate damages, a different post-cautionary strategy may be geoengineering. Countries may attempt to manage the Earth’s temperature directly through Solar Radiation Management (SRM)—methods of changing the Earth’s albedo, screening out some of the sun’s incoming energy—such as by adding sulfate aerosol particles to the upper atmosphere. SRM could be deployed very quickly, and some methods are extremely inexpensive (Barrett 2008), so if a climate emergency seems imminent, SRM might be the last resort to cool the planet (Moreno-Cruz and Keith 2013). In a match of odd bedfellows, SRM appeals both to those who see climate change as so imminent and catastrophic that it is too late for emissions limits, and to those who see climate change as not so serious, hence emissions limits are too costly, and SRM is attractive for its very low cost. SRM poses its own serious countervailing risks, such as cooling the planet too much, or adversely affecting stratospheric ozone, or causing adverse regional impacts, or changing the color of the sky, or unexpectedly failing and allowing a rapid temperature rebound (see IPCC 2014c: section 3.3.7 at 17–18). Some experts advocate greater research now to learn and clarify those impacts (thus enabling well-designed SRM if needed, and avoiding hasty resort to poorly designed or dangerous SRM) (see NRC 2015); others fear that research will encourage premature deployment.

The very low cost of SRM and its ancillary impacts raise the opportunity—and concern—that it might be deployed by a single country or even a wealthy individual. The governance challenge of SRM is thus, in part, to restrain ‘rogue’ unwise deployment. The IPCC comments: ‘Whereas emissions abatement poses challenges of engaging multilateral action to cooperate, SRM may pose challenges of coordinating research and restraining unilateral deployment of measures with potentially adverse side-effects’ (IPCC 2014d: Executive Summary at 7). If precaution is understood not as a formal binary classification, but as a general posture—a continuum of degrees of precaution in terms of earliness and stringency—then the lack of early precautionary measures to combat climate change does not mean that precaution is irrevocably unavailable. There may still be opportunities to take mid-course precautionary measures that reduce future damages. And, in the meantime, we may have learned better ways to design climate policies, to yield more benefits at lower costs. Still, we can learn more while we undertake provisional (adaptive regulation) climate policies now and study their performance (p. 181) over time. And the prospect of post-cautionary geoengineering (SRM) poses an appropriate coda for precaution and climate change: if we have not been sufficiently precautionary against emissions, then we may need to be precautionary regarding the measures that could be taken to remedy those emissions.


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*  I am grateful to Cinnamon Carlarne for her invitation and graciousness, and to Christa Owens for helpful research assistance.

1  Disclosure: while serving in the US Government in 1989–93, I helped negotiate the 1992 FCCC, including Article 3(3) on precaution. I also contributed to the IPCC First Assessment Report (1990) in Working Group (WG) III on Response Strategies. I joined the faculty at Duke in 1994. I was also a co-author of the IPCC Fifth Assessment Report (AR5) (2014), WG III, chapter 13 on ‘International Cooperation: Agreements and Institutions,’ which critically assessed the climate treaties and their performance.

2  Cf. the IPCC’s 2014 report, observing in Chapter 13 that ‘the principle of precaution emphasizes anticipation and prevention of future risks, even in the absence of full scientific certainty about the impacts of climate change … [a]‌ key ongoing debate concerns whether or not this principle implies the need for stringent climate change policies as an insurance against potentially catastrophic outcomes, even if they may have very low probability’ (IPCC 2014d, section, p. 10) (citations omitted).

3  It is not the case, though, that Europe has become generally more precautionary than the United States across the board—despite conventional wisdom to this effect, the reality is more complex. The United States and EU are both highly precautionary, but sometimes diverge on specific risks, with each more precautionary than the other in selected cases. See Sand (2000) on variation in precaution among member states within Europe, and Wiener et al. (2011) and Wiener et al. (2013) on variation in precaution across numerous risks in both the United States and EU.

4  Gilligan and Vandenbergh (2014) argue that ‘comprehensive’ policies may take too long to be adopted, while ‘incremental’ policies are faster. But comprehensive policies may offer lower abatement costs and deliver more benefits (e.g. avoiding leakage due to the partial coverage of incremental policies), thus fostering faster and wider adoption. See Stewart and Wiener (2003).

5  Exhortations to a moral obligation to prevent climate change, see e.g. Heinzerling (2008), may be counterproductive if the relevant public (such as in the United States, Europe, China, India, or elsewhere) views such exhortations as in conflict with their deeply held views, such as on the right to develop or the right to be free of government overreaching or foreign eco-imperialism; in many cases, economic incentives in policy design may be more effective than such exhortations, see Wiener (2008b).

6  Still, governments evidently find these issues so contentious that they could not agree on the text of the Summary for Policymakers (SPM) section summarizing the IPCC chapter on ‘International Cooperation’ (IPCC 2014d), so they deleted most of that SPM section (Stavins 2014).

7  Lazarus (2009: 1157–8) worries that interest groups will seek to unravel and relax climate policies because these policies impose short-term costs and redistributive impacts for long-term benefits, so he advocates that climate policies be ‘simultaneously … flexible in certain respects and steadfast in others. Flexibility is necessary to allow for the modification of legal requirements over time in light of new information. Steadfastness or “stickiness” is important to maintain the stability of a law’s requirements over time.’ He proposes entrenching ‘precommitment strategies that deliberately make it hard (but never impossible) to change the law in response to some kinds of concerns [i.e., relaxing emissions limits]. At the same time, the legislation should also include contrasting precommitment strategies that deliberately make it easier to change the law in response to other longer-term concerns that are in harmony with the law’s central purpose, which is to achieve and maintain greenhouse gas emissions reductions over time.’ Yet initial policies—not only in their stringency, but in their instrument choice—may be more ‘sticky’ than intended, as implementation efforts and vested interests grow up around them (as the history of environmental law often shows). They may be worth revising over time as we learn more about effectiveness, costs, and ancillary side-effects.