1 Introduction
Short-lived climate pollutants (slcps) encompass a vast range of substances with highly diverse properties – so how did they all come to be included under this one label? As the previous chapter shows, there is more that divides than unites them scientifically speaking, so their grouping under one category has political reasons as well, rendering slcps a policy concept rather than a purely scientific term. This chapter traces the history of this concept by analysing how these pollutants have been framed over time, first individually and later as one category, and tracing the scientific and political drivers behind this process.
Such a conceptual history of slcps had not been written before, but offers crucial insights to those aiming to promote their governance – in particular as it is a tale of ups and downs that reveal the concept’s strengths and weaknesses in terms of political effect. After all, like the following chapters show, the politico-legal response to slcps has much room for improvement – so it is worthwhile investigating the concept’s merits. This chapter thus delves into the connection between the alarming scientific inputs, reviewed before, and political outputs that fail to live up to them, discussed thereafter, all with the aim of drawing lessons for the future.
In particular, such a history sheds light on the political dimension of conceptual innovations like slcps. Concepts exist to simplify the world, which is necessary to render it governable, but also imposes a framing on it and thereby introduces an element of politics. They always have a normative content and are never purely descriptive.1 slcps are a perfect example of this: The short acronym contains a plethora of pollutants with highly diverse properties, but only highlights those aspects that matter most to policy-makers – that they are all short-lived, pollute the air, and also impact the climate. Such simplifications help decision-makers, in this case by suggesting that substances which contribute to several environmental problems deserve special attention. However,
In short, this chapter thus analyses the history of how and why various strands of science were combined under the label of slcps, what political implications this has, and uses this to draw lessons on where we should go next.
1.1 Theoretical Background
The history of slcps is approached here through a global environmental governance lens, which posits that how we govern the environment is not just shaped by lawmakers, but rests on a wider societal debate among numerous stakeholders, including many private actors.2 In this particular case, scientists play an especially important role, since the concept in focus derives from scientific research and assessments.
A key concept for this chapter is therefore the science-policy interface, meaning the processes of interaction between scientists and policy-makers, through which information may be exchanged and jointly constructed in order to enrich decision-making with scientific expertise.3 Such arrangements are common in environmental policy due to the complexity of this field requiring expert-involvement – and as the previous chapter shows, slcps are particularly complex. Hence, theory on science-policy interfaces informed the focus of this research: At the international level, scientists and policy-makers frequently interact through the medium of scientific assessment reports requested by governments, but written by experts.4 The concept of slcps has its origins in such documents, so they play a key role in this history.
Furthermore, it has frequently been shown that scientific information is particularly effective at crossing the science-policy interface if so-called epistemic communities are promoting it.5 These are transnational networks of experts who share both causal beliefs about a particular problem and a policy
Given that slcps were formulated as a concept by scientists in reports requested by policy-makers, it responds to both scientific and political demands. This renders it a boundary object, meaning it has to fulfil the expectations of scientists and decision-makers alike – requiring an often precarious balance between scientific credibility and political relevance.10 These concepts and the theories behind them informed this chapter.
1.2 Methodology
In line with the theoretical framework, the main sources for this historiography were both the scientific reports that have shaped the slcp agenda and political proclamations on the subject by states. This covers each side of the science-policy interface and allows to trace how the epistemic community’s arguments and framings developed, how they were received by governments, and how the concept as we know it today ultimately resulted from interactions and co-production between these realms. These documents were furthermore supplemented with seven key informant interviews and existing literature on the subject.
Primary documents were first subjected to a framing analysis, meaning a qualitative content analysis of how slcps were portrayed over time in scientific assessments and ccac statements. Following Entman’s14 definition of “framing” as highlighting certain problems under the status quo at the expense of others and suggesting solutions to them, as well as causal and normative reasons to support this view, guiding questions for this analysis were: What problems are slcps perceived to cause (if any)? What solutions are suggested to this? And why do (or don’t) these substances deserve special attention in the first place? Passages that answer these were coded over an iterative reading process and, where several codes tend to occur together, that was considered a
To identify the root causes behind identified changes in framing, the description yielded by this analysis was finally subjected to process tracing.16 For this, it was considered in the context of secondary literature and interviews and, using all sources in conjunction with one another, a timeline of events was created. Process tracing then involved going backwards through this chain of events to identify the original impulses that led to observed changes in the framing, whether they be political, scientific, or both. Causality was only considered as established where multiple sources suggested the same root cause and this both sufficiently and necessarily explains observed outcomes. Where sources are insufficient or inconsistent, this is explicitly noted in the text.
2 Linking Climate Change and Air Pollution: 1990s–2000s
To start this history, it is helpful to compare where we are now in terms of the framing of slcps to where we have come from. The concept is still fairly young, with its first formulation only dating back around 15 years, but it represents a fundamental challenge to how the problems of climate change and air pollution are traditionally framed.
While we now know that slcps contribute significantly to global warming and are among the main health risks of our age, they were all perceived to be fairly unimportant to both these challenges up until the 1990s: Black carbon was then considered a problem of the industrial past, already dealt with at least in Western countries, and its climate impacts were underestimated.17 Methane was known to be a climate forcer and ozone precursor, but also considered fairly benign due to its low atmospheric concentration and reactivity – and as those concentrations were hardly rising at the time, it was also seen
Firstly, scientific assessments and political statements on slcps today naturally highlight two problems: Climate change and the health risks of air pollution. They vary in the extent to which they focus on one or the other, but nearly always thematise them together. Causally, they support this holistic focus by showing that slcps are important to both issues (hence their label as climate pollutants) and, increasingly, quantifying their effects on them. Suggested solutions involve the targeted mitigation of these pollutants, generally by using different technologies or techniques. For instance, these include filters or newer motors for black carbon, certain best practices in fossil fuel production and agriculture against methane, and replacing hfcs with alternative substances.
Normatively, such policies are promoted as they often deliver co-benefits for both human health and the climate – but also for economic reasons, as they rely on proven techniques and technologies that can generally be implemented at low or even negative cost. Furthermore, due to the short-lived nature of slcps, they yield results much faster than the mitigation of CO2 emissions. Later assessments and statements even go as far as to say that they are necessary to reach our collective climate goal of limiting global warming to 1.5°C above pre-industrial levels, as this requires precisely such immediate changes.
Scientific assessments acknowledge there is some uncertainty about all this but still argue that we know enough to act now, precisely due to the low costs of slcp-mitigating actions and high potential for co-benefits. A further caveat, present repeatedly in all main assessments, is that these policies must be additional to continuing CO2-reductions and not replace them. Despite the caveats, all this clearly represents a significant reframing of the pollutants we now call slcps compared to their earlier perception. This was only possible through a string of discoveries around the turn of the millennium, which are the subject of this section.
2.1
The most significant early discoveries connecting climate change and air pollution were made in the unep-sponsored “Indian Ocean Experiment” (indoex), the first comprehensive study of air pollution over South and East Asia.21 Rapidly growing populations in the region – and an associated rise in the use of fossil fuels, traditional cookstoves, and agricultural burning – had led to visibly increased air pollution there, sparking concerns about local health and climate effects.22 Soot particles, i.e. black carbon, which accounted for much of this phenomenon, have long been known to be a health risk and it was also posited that they may distort temperatures and rainfall by dimming the sunlight as it passes through the atmosphere.23 However, their effects had been vastly underestimated as it was also believed that they rapidly rain back to the ground soon after emission, leaving no longer-term, wider impacts.24 Through large-scale, concerted measurements from ships, planes, and satellites, indoex showed this to be a flawed and incomplete picture.
The experiment revealed that particles can stay airborne longer than previously thought and thus spread much further, seasonally leading to aggregations of soot and other pollutants that can cover much of South and East Asia, dubbed “brown clouds” by researchers.25 The previously unforeseen scale and density of these clouds, it was now argued, could not only dim the surface, but even distort regional weather patterns to such an extent as to divert the entire monsoon, which sustains agriculture in the region, increasing the risk of droughts and harvest failures.26 The new data also showed that – even while cooling the surface below – soot particles measurably heat the atmosphere above by absorbing solar radiation otherwise reflected back into space, thus contributing to global warming, too.27 The implications were clear: Air pollution is not merely a local health concern, but can also change the climate on a regional and even global scale.
2.2 Taking a Closer Look at Trace Gases: Methane and hfcs Re-examined
Around the same time, scientists were also gaining a greater understanding of the outsize impacts certain trace gases can have.33 In particular, methane was rising considerably on both the climate and air pollution agendas since analyses of ancient air trapped in the ice of Greenland showed that its concentration over time correlated with historic changes in the climate much stronger than had previously been realised.34 Even though it still only makes up a miniscule fraction of the atmosphere, a better understanding of methane thus became crucial to the modelling of future warming and it attracted increasing scientific attention.35
Beyond this, atmospheric concentrations of hfcs also started rising faster than had been expected around the mid-2000s, as developing countries were transitioning to the new chemicals.38 Prospects for their future contribution to climate change thus shot up and added to the generally dawning conclusion that even trace gases can play a major role in changing the climate. Together, all the above observations supported indoex’s claims that global warming and air pollution are linked, opening possibilities for co-benefits between the policies addressing them.
2.3 Reframing Climate Change for the 21st Century
The first to pull together these and other strings of research into a policy-relevant argument was the influential climate scientist James Hansen. He had built his public profile as one of the first experts to draw political attention to the warming impacts of CO2, but was now shifting his focus to other climate forcers.39 In an article boldly entitled “Global Warming in the 21st Century”, he even went as far as to argue that policy-makers should prioritise these other forcers – in particular black carbon, methane, and chlorofluorocarbons, a list that is very close to what we now call slcps – as CO2 emissions would inevitably rise over the next half century anyways.40 Without actually coining the concept, this article anticipated key arguments later attached to slcps, in particular that their mitigation can deliver immediate results and buy time for
However, this proved highly controversial because Hansen’s argument lacked important nuances and was released into an already charged political atmosphere: In his native US, the article became embroiled in concurrent presidential elections, alluded to by George W. Bush to counter his opponent Al Gore’s demands for more ambitious cuts in CO2, and was consequentially shunned by environmentalists as well as many fellow scientists.42 Meanwhile internationally, some developing countries led by India denounced the research it was based on, particularly indoex, as essentially a ploy by Western governments to divert from their responsibility for climate change through historic CO2-emissions and shifting blame onto subsistence farmers in the global South.43
In the context of already tense domestic and North-South debates over the US’s refusal to ratify the Kyoto Protocol as it entailed no substantial obligations for developing nations, this argument gained enough traction to temporarily block further studies into the brown cloud phenomenon unep had envisioned – setting back international slcp science for the next several years.44 Nonetheless, the nucleus of a future epistemic community had already been formed: unep would go on to become a key node for international investigations into slcps – a decision that can be directly traced back to its early involvement in indoex and other science cited above.45 However, this was ten years after the initial controversy and, until then, most research into the issue was funded by the US and European governments on a regional, not global scale.46
3 The Concept’s Arctic Origins: 2007–9
The first articles to unite the above science under one cohesive concept were two technical reports published in 2008 by amap,47 an advisory scientific working group of the Arctic Council, followed by a summary report for
Given previous controversies, it only made sense for the concept to emerge in the global North, where virtually all funding was coming from: amap’s 2008 reports have been gestated at a workshop organised by National Aeronautics and Space Administration (Nasa) and were thus sponsored directly by the US government.51 Indeed, even some within amap still questioned the virtue of such research, perceiving it as a potential distraction from CO2 as previous critics had, and it was only upon the continued urging of the US – which also provided initial funding – that these reports came to be.52
However, it was also science, not just politics, that determined the concept would specifically be born in an Arctic context: The high North warms faster than more southerly latitudes, and there were indications that slcps contributed to this – particularly black carbon, which not only heats the atmosphere there (as was the case over the Indian Ocean), but also the surface, as it significantly darkens the ice-sheets it eventually lands on.53 Hence, the concept of slcps clearly emerged at the science-policy interface, from scientific reports responding to political priorities – particularly those of the US at this early stage.
3.1 amap’s Contributions to the slcp Debate
Like Hansen, amap focused on the potential for slcp cuts to immediately slow down climate change, particularly in the Arctic, while also protecting human health.54 However, having learned from earlier controversies, its reports also
Indeed, a former amap official argues these were some of the most influential reports in the organisation’s history because they inspired the Council’s ongoing involvement in slcp governance:56 At the 2009 Arctic ministerial meeting in Tromsø, its member states for the first time noted that cutting the emissions of “shorter-lived climate forcers such as black carbon, methane and tropospheric ozone precursors” may “slow the rate of Arctic snow, sea ice and sheet ice melting”, even while CO2 remains the most important issue – in large parts copying amap’s argumentation.57 As further credit to the impact of amap’s early work, this framing analysis shows that all aspects it focused on – co-benefits, immediate rewards, and the continuing importance of CO2 – remain central pillars of the concept even now.
Nevertheless, several important features of slcps as they are currently portrayed are still missing in these first reports. Most notably, they did not yet include hfcs and lacked some crucial details in their assessment of the other pollutants – in particular their health impacts, which are mentioned, but not elaborated on, as most of amap’s experts were climate scientists.58 Furthermore, even the more detailed assessment of the pollutants’ climate impacts at this stage lacked solid numbers: While writing that slcfs “may have a combined effect comparable to that of CO2”,59 scientists did not hazard to quantify this, instead noting repeatedly that there is “considerable uncertainty” around it.60 Everything that was included, meanwhile, was limited to a regional scope only, given amap’s Arctic focus.
As a result of these many knowledge gaps, there was also hardly any practical policy advice in these reports apart from a call for further research, so their findings were not yet politically actionable.61 At least this limited advice was followed when the Arctic Council set up a Task Force on slcfs to further study the issue and provide concrete policy advice by 2011.62 amap’s early
3.2 Wider Political Impact of Arctic Research
Despite its limitations, amap’s work did start a larger conversation as it happened at a politically opportune moment: Global climate negotiations hit a low-point at the Copenhagen climate summit mere months later, prompting a search for new approaches to complement these stalling efforts.64 Promises of a new global climate agreement by 2009 had not been met, leaving many in the policy-sphere frustrated with the unfccc process and making the idea of slowing warming to buy more time for decarbonisation, a central pillar of amap’s reports and current arguments around slcps, seem very appealing.65 Earlier controversies were thus put aside in this moment, allowing unep – which had never lost interest in the climate-pollution nexus since indoex but had been politically blocked from pursuing it – to re-engage.66
The result are two ambitious new assessments on the impacts of black carbon, methane, and tropospheric ozone published by unep in 2011.67 Their results and framings dominated the slcp agenda for years to come and still echo strongly today – even though they also still called them slcfs. These reports frequently reference amap’s assessments and cite the Arctic Council’s calls for action as part of their underlying rationale,68 but also went beyond what amap had been able to achieve with its organisational limitations and the limited data available at the time. While amap started an intergovernmental debate on the substances we now call slcps, it was only unep’s reports that ultimately made this an actionable concept and launched it into the global policy sphere.69
4
Much like amap, unep still emphasised the potential to slow warming and achieve health co-benefits by mitigating slcf emissions – which it still understands to not include hfcs. Also like previously, its assessments stress that this should be additional to ongoing CO2 reductions. However, as this section shows, they offer much more detail and context on each of these aspects and managed to quantify the impacts of mitigating slcf pollution, providing a stronger impetus for action.70
4.1 Conceptual Development in unep’s Assessments
unep’s reports build on amap’s work in four crucial ways. Firstly, while still emphasising the pollutants’ impacts on the Arctic and often referencing amap in doing so, they complement this with data on their effect in other regions, particularly the Himalayas – another glaciated region and consequently impacted in similar ways – building on the organisation’s previous work with indoex.71 unep thus constructed a new, global framing of slcfs, without losing sight of their well-established regional dimensions. Secondly, its reports also place much greater emphasis on non-climate co-benefits than amap did, which was presumably possible as unep drew on a broader range of experts not limited to climate scientists. Hence, the reports include significantly more detail on which slcps have what health effects, as well as where people are most affected by this.72
Further setting itself apart from earlier studies, unep thirdly suggests a concrete list of policies – 16 in total – targeting most important sources of slcps, focused especially on fossil fuel production, agriculture, waste management, as well as residential heating and transport.73 Fourthly and finally, the reports’ authors managed to quantify what impacts these measures would have, with the two headline facts being that full implementation of proposed policies could prevent 2.4 million premature deaths each year as well as around 0.5°C of global warming by 2050 – the first time concrete numbers entered the slcp debate, making a powerful case for action.74
Beyond just building on amap’s work, unep also constructed two new arguments that have frequently been repeated since and become further pillars of
With this, following ten years of increasing interest in non-CO2 climate forcers, unep was the first organisation to articulate all the main elements of the slcp concept as it is framed today: That mitigating these pollutants slows climate change and protects lives, that it can be done relatively easily and cost-effectively, and that it must be additional to ongoing decarbonisation efforts. By combining this with a concrete list of actions to be considered by governments, the reports launched this concept into the global policy sphere, where it remains in a very similar form to this day.
4.2 Emergence of an Epistemic Community for slcps and the ccac
As a side-effect of unep’s reports, from 2011 onwards it also makes sense to speak of an epistemic community promoting the governance of what we now call slcps: Previously largely disconnected research and independently operating researchers, e.g. from the Arctic and South Asia, were brought together in the unep assessments and given a shared policy agenda through the 16 concrete actions they recommend. These scientists may not directly cooperate like this very often, given the complexity and diversity of slcps, but they are aware of one another’s work and share a desire to bring more prominence to these pollutants – so all conditions for an epistemic community are fulfilled.78
Less than a year after unep’s assessments, this group of experts was also given a political outlet for their work through the launch of the ccac – a public-private partnership specifically dedicated to promoting slcp governance. The Coalition is discussed further in Chapter 6, but for this conceptual history of
Up to this point, hfcs had been addressed by separate assessments and framed in a distinct way from other slcps.79 For example, early ipcc publications explicitly referred to them as “long-lived gases” alongside CO2,80 and major pre-2011 reports about hfcs lack some of the main arguments made for the mitigation of other slcps, such as the potential for immediate benefits. This was partly for historical reasons, as hfcs were generally studied by scientists specialised in ozone depletion – a separate group from the climate and pollution scholarships – but also based in the science itself: Unlike other slcps, hfcs cause no widespread, direct health effects (though they indirectly cause ill-health through global warming) and some of them can indeed be quite long-lived, longer even than methane.81
The reason for hfcs’ inclusion in the concept – and for its relabelling as slcps, not slcfs – was political: This was around the time that negotiations about these substances started under the Montreal Protocol and the ccac was used as a vehicle to push these forwards.82 As is often the case in the history of slcps, the political impetus for this came mostly from Washington, DC: While the ccac has six co-founders – including also Bangladesh, Canada, Ghana, Mexico, and Sweden – the US was the instigator and driving force behind its launch.83 Initially, the US turned to Canada and Mexico for support, with whom they already closely cooperate on environmental matters through the North American Commission on Environmental Cooperation, whereas the other founding members were invited later to ensure geographical balance.84
US domestic politics may also be why the new label of slcps became attached to the concept: According to multiple sources, the Obama administration was actively trying to link global warming and air pollution because
Interestingly, the concept appealed to the ccac’s middle-and low-income members for exactly the opposite reason: Very broadly speaking, they were more concerned with air pollution and perceived richer countries to be overly focused on the climate – so for them, the climate pollutants label became a way of refocusing global environmental debates more towards human health.86 Therein lies a key strength of the slcp concept: By combining two issues in one term, it also unites these different political coalitions behind a shared agenda. This delicate balance was only possible since amap and unep made clear that both slcps and long-lived greenhouse gases must be mitigated and, as the following section shows, it enabled the concept’s widespread diffusion in global environmental policy circles.
5 Reception and Diffusion in the Policy Sphere since 2012
unep’s framing of slcps was taken up by governments nearly unchanged and persists in large parts to this day: Not only was the ccac founded in direct response to its assessments, but state partners of the Coalition also generally repeat its arguments and conclusions in their communiqués.87 For example, the first such statement explicitly cites unep’s reports to call for “urgent action” against slcps to “address near-term climate change, improve air quality and public health”, as well as attain some economic benefits – though also
Indeed, these arguments appear to have been very popular among governments: Just within its first year of existence, the ccac grew to include over 50 state partners (a number that has since risen to 80, as of 2023).90 Around the same time, the first international legal regimes also took note of slcps, with negotiations on hfcs beginning under the Montreal Protocol and black carbon being included in the Gothenburg Protocol.91 The Arctic Council meanwhile intensified its slcp action through the “Framework for Action on Enhanced Black Carbon and Methane Reductions”, which establishes an iterative process of expert review of member states’ policies on these pollutants and thereby formalised and strengthened its previous Task Force.92 All these initiatives are discussed in further detail elsewhere in this volume.
Nonetheless, there are important differences in emphasis between scientific assessments and official government positions on slcps. Firstly, it should be noted that not all states stick to the same framing and there is a general pattern that developed countries focus overwhelmingly on slcps’ climate impacts, while developing ones pay more attention to their consequences for human health.93 This is not reflected in their joint communiqués, which combine both viewpoints, but even those emphasise different aspects of the concept than initial scientific reports had: Most notably, there is less focus on concrete action in these official communiqués than there had been in the unep reports: While the 2011 assessments recommended a list of 16 policies to tackle slcps, early ccac statements stop short of promoting any particular
5.1 The “Paris Effect” on the slcp Debate and Scientific Progress
From 2016 onwards, governments’ communications on slcps through the ccac suddenly become significantly more urgent and action oriented – a change largely owed to the 2015 Paris Agreement, but also significant scientific progress.96 The Paris Agreement’s key contribution towards this was the introduction of a global collective goal of limiting warming to well below 2°C and ideally 1.5°C above pre-industrial temperatures: These numbers require rapid and ambitious action and have since been taken up in many national laws and even private company policies, creating significant momentum behind climate mitigation that has been dubbed the “Paris Effect”.97 As we are on track to overshoot 1.5°C, every decimal degree that can be spared matters – particularly so in the near-term – which is why the argument that slcp governance can slow warming by half a degree by 2050 became highly appealing once again.98
This new urgency manifests both in ccac statements’ language and their substantive contents: From 2016, they become much more concrete about mitigating slcps, no longer just identifying the problem and vaguely calling for action, but actively promoting specific policies to tackle it: For example, the Marrakech Communiqué focuses on policies to reduce black carbon emissions from transport through fuel and technological standards, while the Bonn Communiqué highlights options to reduce methane from agriculture and waste management.99 Furthermore, their tone is increasingly pressing: Where, in 2015, the Coalition still referred to slcp governance as merely an “effective and pragmatic complement to aggressive mitigation of CO2” that “could help reduce near-term warming”,100 they start acknowledging it as a
The new urgency was further intensified by scientific progress, as certainty around slcps’ impacts rose and estimates quantifying them were revised upwards: The number of degrees of warming projected to be prevented by fully implementing recommended policies rose from 0.5°C to 0.6°C,102 while estimates of avoided deaths through this was revised to at least 3.5 million per year, up from previously 2.4 million.103 Scientific progress is also evident in amap’s continuing work on slcps, whose conclusions are presented in increasingly more certain language than its highly tentative early reports.104 By 2015, they even put forth a first quantification for black carbon’s climate effect specifically in the Arctic, estimating this at 0.25°C of warming already by 2025.105 This kind of modelling, focusing on a particular forcer in a particular region, had previously eluded scientists due to the sheer complexities involved, so the field has progressed significantly – though some uncertainty remains around this number.106
Even the ipcc, which had previously been sceptical of aerosols’ warming potential, acknowledged in its fifth assessment report that it had significantly under-estimated the effect of black carbon in this regard.107 Indeed, in 2018 it went on to write one of the assessments most cited by those promoting slcp governance today: Its Special Report on Global Warming of 1.5°C found no realistic scenarios that reach the Paris Agreement’s goals without “deep reductions
Notwithstanding its now more ambitious rhetoric, it is also important to point out that the ccac is still a fractious coalition – which has become particularly evident in its post-Paris communiqués: Unlike previously, there is an “à la carte” quality to these statements, where rather than all endorsing the same message, different groupings of states undersign different parts of it. For example, the afore-mentioned section on mitigating black carbon from transport comes with its own list of signatures that differs from that of the document as a whole.112
5.2 Recent Developments: Shifting the Focus from Black Carbon to Methane
While the concept’s overall framing has remained relatively stable, the political priority attached to different slcps has fluctuated over time. According to people involved in the ccac, states initially focused largely on black carbon since it lay at the centre of some of the most shocking early discoveries on the climate-pollution nexus.113 This was followed by a period of intense international interest in hfcs, starting when negotiations under the Montreal Protocol became more serious and lasting until 2016, when an agreement on the Kigali Amendment114 was reached.115 Recently, however, both black carbon and hfcs faded into the background, while methane gained ever greater
Despite the clear advantages of mitigating methane, this new focus may become politically contentious for several reasons. Firstly, it must be noted that reducing methane is easier in some sectors than others: While there are easy fixes for the fossil fuel industry, such as better leak detection in pipelines, techniques to mitigate its emissions in agriculture are still at an earlier stage of development.120 Consequently, the shift to methane may be perceived as politically motivated: The instigator of the Pledge were the US, who have a large natural gas industry that makes it easy to meet this commitment, while the initiative has garnered relatively little support in Asia, where agricultural emissions play a more important role.121 Furthermore, methane’s connection to human health – generally the main concern of the ccac’s medium- and low-income members – is less direct than that of other slcps since its main impact in this regard stems from secondary ozone pollution, not methane itself. Hence, this new focus may also disrupt the delicate balance between developed countries (who care mostly about climate change) and developing countries (more concerned with pollution) that lies at the heart of the concept’s acceptability.122 This once again illustrates that even scientifically-informed concepts always have political contents and raises the prospect for conflict about the future direction of the slcp agenda.
6
In conclusion, this history shows that the concept of slcps emerged at the science-policy interface and was co-produced by both scientific and political actors. To be more precise, tracing the concept’s framing over time has revealed that the scientific input to it largely comes from a growing epistemic community that emerged and communicated gradually through the medium of international assessment reports, ultimately finding its home in the ccac, while the political priorities they responded to were often those of the US.
This Western bias sparked intense controversy in the concept’s early and pre-history, when research into the climate-pollution nexus was obstructed at the global level by some developing countries’ objections. Ultimately, the concept was therefore developed in an Arctic context and only became popularised globally through later assessments by unep, at a moment when traditional climate policy was in doubt following the 2009 Copenhagen climate summit. unep’s framings proved highly convincing and slcps were quickly put at the centre of a new, rapidly growing climate club – the ccac. Despite this Coalition’s reach, however, states continue emphasising different aspects of the concept based on their own national priorities. Lately, for example, the US has been using the Coalition in particular to promote cuts to methane emissions, which are much easier to mitigate there than in many developing countries – so even now that a global coalition has formed around the concept, the potential for controversy persists. This history of ups and downs can teach those promoting the governance of slcps three important lessons.
Firstly, it should be noted that uncertainty is an inescapable fact of the slcp agenda. This is due to its high complexity – encompassing numerous pollutants of diverging properties, each with their own uncertainties attached – and because scientific interest in untangling these complexities only arose relatively recently. Such uncertainty was particularly problematic in the concept’s early history, when there was even outright disagreement about whether to conduct further studies into it. While this opposition subsided with scientific progress and we can now be certain that slcps need to be mitigated to prevent dangerous warming and health effects, reasonable debates still remain around which specific slcp contributes how much to these issues and what are the best policies for tackling them. Those promoting the governance of slcps should be keenly aware of this.
Secondly, precisely because of these complexities, the concept cannot be seen as a purely scientific category, but is steeped in politics. Like all such conceptual innovations, it highlights some issues over others and therefore has a normative content: Using slcps as a policy-concept rests on the implicit value
Thirdly and lastly, all this goes to show that having roots in both science and politics has been a strength and a weakness for the slcp agenda: As the scientific assessments that framed the concept responded to political demands, they were automatically policy relevant, explaining their successful transition into the policy realm. However, this close link to politics is also what has made slcps controversial at times, particularly early on in this history. In order maintain a stable balance between scientific credibility and political relevance, those promoting the concept should thus pay equal attention to its scientific and political dimensions.
Overall, this means the central challenge for those promoting the governance of slcps is to contextualise the science for decision-makers and turn it into policy-relevant advice without being perceived as overly politicising it. This, in turn, requires a greater focus on global equity and inclusiveness when discussing these pollutants and how they should be tackled. In the past, such nuances were sometimes lacking and the concept’s history was plagued by allegations of a Western bias. To prevent this controversy from recurring in the future, acknowledging this history and learning its lessons is an important first step.
James Meadowcroft and Daniel Fiorino, ‘Conceptual Innovation in Environmental Policy’ in J Meadowcroft and D Fiorino (eds.), Conceptual Innovation in Environmental Policy (mit Press 2017) 31f.
Frank Biermann and Philipp Pattberg, ‘Global Environmental Governance: Taking Stock, Moving Forward’ (2008) 33 Annual Review of Environment and Resources 277.
Sybille van den Hove, ‘A Rationale for Science-policy Interfaces’ (2007) 39 Futures 7, 815.
Henrik Selin and Noelle Eckley, ‘Science, Politics, and Persistent Organic Pollutants: The Role of Scientific Assessments in International Environmental Co-operation’ (2003) 3 International Environmental Agreements 17; Ronald Mitchell and others, ‘Global Environmental Assessments: Information and Influence (mit Press 2006).
Emanuel Adler and Peter Haas, ‘Conclusion: Epistemic Communities, World Order, and the Creation of a Reflective Research Program’ (1992) 46 International Organization 367; Mai’a Davis Cross, ‘Rethinking Epistemic Communities Twenty Years Later’ (2012) 39 Review of International Studies 137.
Peter Haas, ‘Introduction: Epistemic Communities and International Policy Coordination’ (1992) 46 International Organization 1.
Mai’a Davis Cross, ‘The Limits of Epistemic Communities: EU Security Agencies’ (2015) 3 Politics and Governance 90, 92.
Davis Cross (n5) 139.
Niklas Löther, ‘The Long Debate around Short-lived Climate Pollutants: History of a Policy Concept and its Impact on Global Environmental Governance’ (MSocSci thesis, University of Eastern Finland 2022).
David Guston, ‘Boundary Organisations in Environmental Policy and Science: An Introduction’ (2001) 26 Science, Technology, and Human Values 399; Simo Sarkki and others, ‘Balancing Credibility, Relevance and Legitimacy: A Critical Assessment of Trade-offs in Science–policy Interfaces’ (2014) 41 Science and Public Policy 194.
Löther (n9) 28, 88.
ccac, ‘About’ (2022) <
Löther (n9) 51f.
Robert Entman, ‘Framing: Toward Clarification of a Fractured Paradigm’ (1993) 43 Journal of Communication 51.
Sandra Halperin and Oliver Heath, Political Research: Methods and Practical Skills (oup 2012) 318–327.
David Collier, ‘Understanding Process Tracing’ (2011) 44 Political Science and Politics 4, 823–830.
Tica Novakov and Hal Rosen, ‘The Black Carbon Story: Early History and New Perspectives’ (2013) 42 Ambio 840; Spencer Weart, ‘Aerosols: Volcanoes, Dust, Clouds and Climate’ (2021) <
Spencer Weart, ‘Other Greenhouse Gases’ (2022) <
ipcc, Second Assessment – Climate Change 1995: Synthesis Report (cup 1995) 21.
Entman (n14).
Novakov and Rosen (n17) 10; Weart, ‘Aerosols’ (n17); Interview 5.
John Fialka, ‘Discovery of “Asian Brown Cloud” Sets off Fight’ The Wall Street Journal (New York, 6 May 2003) <
Novakov and Rosen (n17) 10.
ibid; Fialka (n22).
Fialka (n22); The Economist, ‘Pollution and Global Warming: Climate Change in Black & White’ (London, 17 February 2011) <
Weart, ‘Aerosols’ (n17).
Fialka (n22); Novakov and Rosen (n17) 10.
ipcc, First Assessment Report Overview and Policymaker Summaries and 1992 ipcc Supplement (cup 1992) 78; ipcc, Second Assessment (n19) 21f.
ibid; Weart, ‘Aerosols’ (n17).
Spencer Weart and James Hansen, ‘James Hansen: Session ii’ (2000) <
ibid; Weart, ‘Aerosols’ (n17).
ibid.
Weart, ‘Other Greenhouse Gases’ (n18).
ibid; Gavin Schmidt, ‘La Fulgurante Ascension du Méthane’ (2004) 378 La Recherche 48, 50–53.
Schmidt (n34) 53.
Jason West and Arlene Fiore, ‘Management of Tropospheric Ozone by Reducing Methane Emissions’ (2005) 39 Environmental Science & Technology 4685, 4685.
ibid.
unep, hfcs: A Critical Link in Protecting Climate and the Ozone Layer (unep 2011) 9f; Weart, ‘Aerosols’ (n17).
Jonathan Mingle, Fire and Ice: Soot, Solidarity, and Survival on the Roof of the World (St. Martin’s Press 2015) 356.
James Hansen and others, ‘Global Warming in the Twenty-First Century: An Alternative Scenario’ (2000) 97 pnas 9875.
ibid.
Mingle (n39) 356f.
ibid 360–362; Fialka (n22).
ibid; Interview 5.
The Economist (n25).
ibid; Interviews 1 and 5.
amap, ‘The Impact of Short-Lived Pollutants on Arctic Climate’ (2008) <
amap, ‘Update on Selected Climate Issues of Concern: Observations, Short-lived Climate Forcers, Arctic Carbon Cycle, and Predictive Capability’ (2009) <
amap, ‘Update’ (n48).
ipcc, Global Warming of 1.5°C (cup 2018) 118.
amap, ‘The Impact of slcps’ (n47).
Interviews 3 and 1.
David Stone, The Changing Arctic Environment: The Arctic Messenger (cup 2015) 240f.
Hansen and others (n40); amap, ‘Update’ (n48).
Interview 3.
Stone (n53) 240f.
Arctic Council, ‘Tromsø Declaration’ (2009) <
Interview 3.
amap, ‘Update’ (n48) 14.
amap, ‘Update’ (n48) v, 7, 14.
ibid; Interview 3.
Arctic Council, ‘Tromsø Declaration’ (n57) 3.
Interviews 1 and 3.
Charlotte Unger, Kathleen Mar, and Konrad Gürtler, ‘A Club’s Contribution to Global Climate Governance: The Case of the Climate and Clean Air Coalition’ (2020) 6 Palgrave Communications 99, 2; Interview 5.
ibid.
The Economist (n25).
unep, Near-term Climate Protection and Clean Air Benefits: Actions for Controlling Short-Lived Climate Forcers (unep 2011); unep and wmo, Integrated Assessment of Black Carbon and Tropospheric Ozone: Summary for Decision Makers (unep and wmo 2011).
unep and wmo (n67) 5.
Interviews 5 and 6.
unep and wmo (n67); unep, Near-term Climate Protection (n67).
See for example unep, Near-term Climate Protection (n67) xvi; unep and wmo (n67) 2.
unep, Near-term Climate Protection (n67) xii–xv.
ibid, 9f.
ibid, xii–xiii.
See for example unep and wmo (n67) 2.
ibid, 3; unep, Near-term Climate Protection (n67) x.
unep, Near-term Climate Protection (n67) xvi.
Interviews 3 and 4.
ipcc and teap, Safeguarding the Ozone Layer and the Global Climate System (cup 2005); teap, ‘2010 Report of the Technology and Economic Assessment Panel’ (2010) <
ipcc, Second Assessment (n19) 21.
Interview 4; ipcc and teap (n79) 7.
ccac, ‘Vienna Communiqué’ (2016) <
Interviews 5, 6, and 7.
Interview 7.
Mingle (n39) 356f; Interviews 6 and 7.
Interviews 6 and 7.
ccac ‘Oslo Communiqué’ (2013) <
ccac, ‘Oslo Communiqué’ (n87) 1.
ibid, 1f.
ccac, ‘About’ (n12).
unece Executive Body Decision 2012/2 (4 May 2012) UN Doc ece/eb.air/111/Add.1.
Arctic Council, ‘Enhanced Black Carbon and Methane Reductions: An Arctic Council Framework for Action’ (2015) <
Interviews 5, 6, and 7.
ccac, ‘Oslo Communiqué’ (n87); ccac, ‘Paris Communiqué’ (n87); ccac, ‘Five-Year Strategic Plan’ (n87).
ibid.
Interviews 3, 5, and 6.
Julia Turner, Mark Meldrum, and Jeremy Oppenheim, ‘The Paris Effect: How the Climate Agreement is Reshaping the Global Economy’ (2020) <
Interviews 3, 5, and 6.
ccac, ‘Marrakech Communiqué’ (n87) 2; ccac, ‘Bonn Communiqué’ (n87) 2.
ccac, ‘Paris Communiqué’ (n87) 1 (emphasis added).
ccac, ‘Marrakech Communiqué’ (n87) 1 (emphasis added).
ccac, ‚Paris Communiqué’ (n87) 2.
ccac and who, Reducing Global Health Risks through Mitigation of Short-Lived Climate Pollutants: Scoping Report (ccac and who 2015) 2.
amap, ‘The Impact of Black Carbon on Arctic Climate’ (2011) <
amap, ‘Arctic Climate Issues 2015’ (n104).
Interview 3.
ipcc, Assessment Report 5 (cup 2014) 44.
ipcc, 1.5°C (n50) 19.
Interviews 3, 5, and 6.
Interview 6.
ipcc, Climate Change 2021: Technical Summary (cup 2021) 9.
ccac, ‘Marrakech Communiqué’ (n87) 2.
Interviews 3, 5, 6, and 7.
Meeting of the Parties to the Montreal Protocol Decision xxviii/1 (15 October 2016).
Inverviews 2, 3, 5, 6, and 7.
ibid.
Global Methane Pledge, ‘Fast Action on Methane to Keep a 1.5°C Future within Reach’ (2022) <
ipcc, Climate Change 2021 (n111) 9; Interviews 3, 4, and 5.
Interviews 3 and 5.
Interviews 5 and 6.
Interview 6.
Interview 7.
Annex: List of Interviews
- –Interview 1:
With a former senior amap official; conducted 19/11/2019
- –Interview 2:
With a European negotiator for the Montreal Protocol; conducted 03/03/2022
- –Interview 3:
With a climate scientist and expert on black carbon, involved in Arctic Council, unep, and ipcc assessments; conducted 11/03/2022
- –Interview 4:
With a scientist and national official involved in the Arctic Council’s work on slcps; conducted 17/03/2022
- –Interview 5:
With the former director of an ngo involved in the ccac with long-time experience in promoting slcp governance; conducted 18/03/2022
- –Interview 6:
With an expert in air pollution regulation serving on the ccac’s advisory committee; conducted 09/06/2022
- –Interview 7:
With an expert in air pollution and former delegate to the ccac of one of its founding governments; conducted 08/07/2022
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