Forerunner city or net-zero opportunist? Carbon dioxide removal in Stockholm, residual emissions and risks of mitigation deterrence

The City of Stockholm aims to achieve net-zero emissions by 2030 by compensating for residual emissions using bioenergy with carbon capture and storage (BECCS). Relying heavily on negative emissions to reach the target, the city's strategy presents an interesting case of net-zero climate policymaking. Based on the analysis of interviews, City Council debates


Introduction
Far-reaching mitigation activities in cities are increasingly identified as indispensable to halt global warming, and some cities are positioned to lead climate change mitigation [1].Approximately 70 % of people are projected to live in cities by 2050 [2], underscoring not only the necessity of engaging cities in climate change mitigation but also the potential of urban planning to influence emissions from citizens and municipal actors [1].Many cities have developed their own climate targets, which often are more ambitious than targets at national levels [3].As such, many cities have positioned themselves as forerunners in the global response to climate change, and one such city is the capital of Sweden, Stockholm.
The greenhouse gas (GHG) emissions budget associated with halting global heating at 1.5 • C is being spent at a frantic rate.A commonly shared outlook is that any realistic attempt to achieve the 1.5 • C goal requires both radical emission reductions and deployment of carbon dioxide removal (CDR) methods to counterbalance historical as well as future residual emissions.Bioenergy with carbon capture and storage (BECCS) is highlighted in Intergovernmental Panel on Climate Change (IPCC) reports as a CDR method with theoretical potential for large-scale removal [4].
Large-scale implementation of BECCS, as often depicted in global integrated assessment models, has been heavily questioned due to its lack of realism [5].Because of this criticism, plans using climate targets that rely on CDR may be scrutinised regarding their impact on near-term emission reductions.Referring to "moral hazard" [6] or "mitigation deterrence" [7], the critical literature argues that the potential of CDR can displace immediate efforts for near-term mitigation.Studies of mitigation deterrence have explored the reasons and mechanisms behind how the promises of CDR can hinder climate action, shedding light on the risks associated with pursuing technologies that claim to substitute for other methods of emission reduction.The literature largely focuses on CDR and the risk of foregone emission reductions when CDR acts as a substitute for other climate change measures [8][9][10].However, empirical cases that can support these claims or provide insights into the dynamics behind the systemic impacts of CDR on climate change mitigation are scares in the literature addressing these apprehensions [8].As a logical consequence of the discussion of mitigation deterrence, the assumptions hidden behind the classification of "hardto-abate" or "residual" emissions have also been questioned, since these classifications are used to justify the need for CDR methods to precede the reduction of anthropogenic emissions [11,12].Residual GHG emissions can come from agriculture, industrial processes, gas leaks, waste incineration, and other sectors, but the definition of residual emissions varies across countries [11].
This article is focusing on Stockholma growing municipality that was home to 10 % of Sweden's 10.5 million inhabitants in 2023.The municipality aims to become a climate-positive city by 2030 and to phase out fossil fuels 1 by 2040 [13].In the late 2010s, BECCS became a new component of the city's strategy to reach its climate target.The municipal energy utility Stockholm Exergi aspires to capture approximately 800 000 tonnes of carbon dioxide (CO 2 ) per year from a biomassfired combined heat and power plant in Stockholm [14].Stockholm is therefore a ripe and unique case for analysing how CDR methods are used to meet climate targets.
Climate change is governed at multiple levels of society, for example, through the UN, supranational entities (e.g., the EU), nation states, and sub-national organisations (e.g., provinces and municipalities).The multi-level governance setting will influence the view of what constitutes residual emissions and how CDR methods may be used to balance these.Therefore, municipal climate governance and mitigation deterrence in Stockholm will only be possible to understand if linkages between different levels of governance are analysed.By scrutinising a local climate policy discourse, this study adds the perspectives of public actors currently involved in processes of adapting the climate change governance of the City of Stockholm to include CDR as well.The prospect of removing CO 2 from the atmosphere to produce negative emissions could change the overall local climate policy: it could make climate targets more ambitious [15], but could also be used to compensate or create headroom for delayed emission reductions [16,17].
In the literature on cities and climate change, cities are viewed as both key actors in mitigation and constrained entities with limited capacity to act.CDR is viewed as indispensable in order to achieve ambitious climate targets, but also as a potential loophole to claim leadership while in effect postponing much-needed emission reductions.However, studies looking at how cities and local governments relate CDR to other strategies to reach net-zero targets are lacking.The aim of this article is accordingly to analyse residual emissions and CDR in a netzero strategy in the making, at the city level in Stockholm, with the intention to substantiate the scholarly understanding of mitigation deterrence empirically.This was done through interviews with politicians and civil servants working on climate and energy issues in addition to scrutinising the political climate debate on residual emissions and CDR in the City Council and in key policy documents.
The analytical ambitions are guided by the following research questions: 1. How do actors in the City of Stockholm perceive their ability to govern the reduction of gross GHG emissions, and how do they justify the anticipated future residual emissions?2. How have the perceptions explored through research question one been influenced by developments in the prospects for gross emission removals in Stockholm, and what are the consequences for mitigation deterrence in Stockholm's net-zero strategy?
The next section provides background on municipal governance and Stockholm's emissions, followed by section three presenting the methodology, including analytical departure points from multi-level governance and mitigation deterrence theory and method of data collection and analysis.Section four presents results concerning actors' perceived ability to govern emissions through direct and indirect abilities to govern, and through governance by providing enabling conditions for mitigation measures.Section five gives an account of how plans to implement BECCS in Stockholm have impacted the city's net-zero strategy, including views on how future residual emissions could be compensated for with CDR.Section six presents the main conclusions.

Municipal governance and emissions in Stockholm
Municipalities in Sweden are self-governing local authorities with a high degree of constitutionally protected autonomy [18].The Swedish political governance system is decentralised with large municipal-level autonomy [19].Nevertheless, Swedish municipalities differ in their size and capacity to introduce policies to mitigate climate change [20,21].Moreover, municipalities lack direct ability to govern all emissions within their territory, for example, with emissions from industry being governed by the EU Emissions Trading System.
In 2023, Stockholm undertook a process of updating its municipal environmental programme.The environmental programme is a governance tool for coordinating activities concerning climate mitigation and other environmental issues.Reforming the programme has included updating Stockholm's climate targets and the associated carbon budget.The reform process has been governed by a political mandate that the city should contribute its fair share to fulfilling the Paris Agreement, and the city's environmental administration has been tasked with drafting suggestions for new targets and carbon budgets.The mandate has triggered discussion within the administration of how to interpret the equity principles of the United Nations Framework Convention on Climate Change and the Paris Agreement.
GHG emissions from the City of Stockholm were 1.542 million tonnes of CO 2 equivalents (CO 2 e) in 2022, according to the city's reporting, and territorial emissions from the transport sector made up more than half of these emissions [22].Despite a steadily growing population, total emissions from heating buildings have decreased by 80 % since 1990.However, emissions from transport have decreased by only 15-20 % since 1990.Overall, emissions per capita decreased from 5.4 tonnes of CO 2 e per capita reported in 1990 to 1.6 tonnes per capita in 2022.When it comes to the City of Stockholm organisation, the emissions were 92 000 tonnes of CO 2 e in 2022, thus less than 10 %, with a downward trend across all sectors within the organisation, for example, from the heating of buildings and emissions from road traffic.A snapshot from 2022 is presented in Fig. 1.

Analytical departure points
Mitigation deterrence is defined as the possible reduced ambition or delay of climate change mitigation measures due to promises or plans to leverage unproven or speculative measures, including CDR methods [7].The phenomenon occurs due to various social, political, and economic mechanisms, including different perceptions and ideas about the future.These mechanisms, driven by economic interests and specific discursive frames, favour some climate change mitigation solutions over others [7,17].Technologies evolve alongside political and innovation regimes, highlighting how technologies gain support if they align with existing political and economic institutions [9].According to Markusson et al. [9], narrow framings of CDR methods as easily substitutable for 1 The City of Stockholm uses the term "climate positive" instead of "net-zero" for their 2030 target.For the 2040 target, the City of Stockholm uses the terms "fossil-free" and "fossil fuel-free" to indicate that no fossil fuels will be used within the city boundaries after 2040.
A. Olsson et al. emission reduction methodsand therefore signalling the possibility of cost-optimisationimpact how mitigation deterrence plays out and how climate change mitigation is governed.McLaren [10] estimates that mitigation deterrence could cause a 1.4 • C increase in global warming.However, it is very difficult to empirically determine causal links between the deployment of certain technologies and decreased efforts to reduce emissions, due to the counterfactual nature of this exercise, and the empirical ambitions of any studies of the matter are further complicated by different understandings of how to define delays in emission reductions [8].Nevertheless, an important concern is that relying on CDR in emission pathways becomes an issue if actors underestimate the urgency of emission reductions in the present due to reliance on CDR promises in the future [23].The risk that certain emissions may be falsely perceived by certain actors as hard to abate, and thereby exempted from reduction requirements without proper debate, has been identified as prominent in this discussion [12].
McLaren [10] distinguishes among three types of mitigation deterrence.The first type is substitution and failure, as when a particular relied-on technique such as BECCS fails to materialise at the scale or level of effectiveness expected, and it had substituted for other mitigation measures that could have been taken.The second type is when rebounds and indirect impacts happen due to an intervention.Rebounds could occur due to unanticipated emissions from the construction of infrastructure for CO 2 transportation, or if CDR methods require Fig. 1.Greenhouse gas emissions in Stockholm [ktCO 2 e], 2022.Emissions from heating and electricity are based on use data rather than production data, and are estimated using a Nordic production mix for electricity and regional emission factors for district heating.Source: City of Stockholm [22].
A. Olsson et al. increased use of electricity and heat.The third type refers to foregone or delayed mitigation in the present due to the promise of future climate interventions.Compared with the first type, which refers to emission reductions that are formally substituted by CDR methods that are unsuccessful in removing emissions, the third type occurs due to promises of emission removals.
Few empirical studies have investigated actors' perspectives on CDR and mitigation deterrence.One study that explores stakeholders' views, but in an experimental setting, is by McLaren et al. [17], who conducted workshops with stakeholders including non-governmental organisations (NGOs), academics, policymakers, and industries in the UK using scenarios to discuss mitigation deterrence.In another study, Otto et al. [24] interviewed NGOs in Germany to study the framing of CDR and mitigation deterrence.In their study of EU policies for CDR, Brad and Schneider [25] discussed missed opportunities to prevent mitigation deterrence when selecting climate targets and designing policies.These studies show that there are risks of mitigation deterrence, for example, when CDR is framed as a necessity that is within reach.However, the literature on mitigation deterrence lacks a concrete case of CDR in a local context [8].Therefore, this study adds an example of how BECCS in the City of Stockholm has led to risks of mitigation deterrence.
Markusson et al. [7] stress the significance of situating types of mitigation deterrence, such as those identified by McLaren [10], in a political regime, i.e., "the social structures and systems of power relations that enable governance over society" (p.8).To understand the specific context of climate mitigation in a municipality, it is therefore necessary to relate theory on mitigation deterrence to how decisions are made in specific political contexts.To this end, in this article, the theory of multi-level governance is used.Multi-level governance theory emerged in the 1990s to provide analytical tools with which to assess the rapidly evolving EU [26].This body of theory was designed for analysing vertical linkages between the authority of international organisations, nation states, and sub-national entities.Viewing policy development as a continuous process of negotiations between actors at multiple and heavily nested levels of territory, this theory broke with the tradition of viewing governance as the authority of the governments of nation states [27].The problematisation of state-centric analysis provided by emphasising vertical interlinkages was soon followed by increasing attention to the horizontal coordination of governance activities as well, which contributed to the broader shift in studies of international relations from government to governance [27].
This study uses multi-level governance theory to describe linkages that connect institutional levels of governance as perceived by civil servants and politicians in Stockholm.As such, the paper goes beyond McLaren's [10] three categories of mitigation deterrence, highlighting the mechanism of how mitigation deterrence may occur in a specific case.The linkages are understood in terms of modes of governance.Bulkeley and Kern [28] introduce four governing modes observed in municipalities: "self-governing, the capacity of local government to govern its own activities; governing by provision, the shaping of practice through the delivery of particular forms of service and resource; governing by authority, the use of traditional forms of authority such as regulation and direction which persist despite reforms; and governing through enabling" (p.2242).Regulation is usually beyond the mandate of Swedish municipalities; however, they can implement national regulations, such as environmental zones for vehicles [29].Thus, all modes of governance identified by Bulkeley and Kern [28] are applicable to Swedish municipalities and are used here to categorise the governance modes discussed and deployed in Stockholm.The governance modes correlate with direct and indirect municipal spheres of influence over emissions [30].The municipality can directly govern emissions that arise from activities that are a direct consequence of the municipal organisation, including territorial emissions and emissions outside the municipal territory [30].To manage these emissions, the municipality can use the self-governing mode of governance [28].The municipality can indirectly govern emissions that arise from activities that the municipality can impact through policy action, directorship, funding, etc. [30]; the corresponding modes of governance are to govern by authority and provisioning [28].In addition to direct and indirect influence, it is also possible to govern by sermons.This means governing via information and awareness campaigns, education programmes, nudging strategies, and supporting networks and civil society organisations aligned with municipal goals [31].In terms of modes of governance, Bulkeley and Kern [28] calls this governing through enabling (Fig. 2).

Method
This research is based on two sets of empirical material: (1) interviews with politicians and civil servants and (2) transcripts of debates in the Stockholm City Council.The interviews were conducted with municipal-level politicians and civil servants involved in the processes of revising Stockholm's climate targets and action plan.Their views of constraints on and opportunities to govern emissions and the role of the impending incorporation of CDR are therefore important in this study.A total of 32 people were contacted, resulting in thirteen semi-structured interviews via video calls in May and June 2023.At this time, Sweden was governed by a three-party minority coalition (liberal-conservative) between the Moderate, Christian Democratic, and Liberal parties, with parliamentary support from the Sweden Democrats (social-conservative and nationalist).Stockholm, in contrast, was governed by a three-party majority coalition between the Social Democratic, Green, and Left parties.Two of the respondents were from the Left Party, two from the Social Democratic Party, one from the Green Party, and one from the Centre Party.Seven Stockholm civil servants were interviewed in addition to the six politicians.The respondents are referred to with a "P" for "politician" and a "C" for "civil servant" followed by a number for each respondent.A list of all respondents is available in the Appendix Table A1.
Transcripts of all formal debates in Stockholm City Council's public meetings were analysed in addition to the interviews.The transcripts cover the period from January 2015 to October 2023, comprising more than 100 sessions of the Council.Text-searches were used to identify the climate-related segments of the Council's debates.Official reports from the City of Stockholm, as well as official documents associated with the Council, were also used in this study.These documents were used to trace the decision process regarding Stockholm's climate targets and the debate concerning the deployment of BECCS.Comments from representatives of a broader set of political parties are present in this material than in the interviews, so this material supplements the interviews by offering perspectives from other political parties.The transcripts also made it possible to follow the CDR discourse in more detail and presumably with higher accuracy due to that many of the politicians currently in office were not present in the early debate around 2015.It was also possible to fact check statements and to receive a deeper Fig. 2. Integrating the four modes of governance identified by Bulkeley and Kern [28] with the levels of ability to govern municipal greenhouse gas emissions discussed by Robinson and Gore [30].This figure is inspired by the City of Gothenburg [32].© Authors via Canva.com.
A. Olsson et al. understanding of points made by respondents regarding City Council debates.
The semi-structured interview methodology applied [33] includes an interview guide with a set of general questions about central issues covered in multi-level governance theory.These questions cover: vertical relationships of governance between the City of Stockholm and the UN, the EU, and Sweden; modes of governance and use of specific instruments and measures, such as emissions budgets, regulations, and economic policy incentives; the role of CDR in Stockholm's climate policy; views of Stockholm's responsibility to act; and horizontal relationships of governance, such as the distribution of responsibility and accountability within Stockholm and inter-municipal cooperation.The interview transcripts were inductively coded by two authors independently and the recurring patterns were then compared and discussed among all authors.The document analysis followed the same coding structure, exploring views among the politicians in the City Council of the overarching topics covered by the interview guide.
Although efforts have been taken to balance the lack of representation from certain political parties in the interviews, through the complementary study of transcripts of the City Council debate, interview material from all parties could have presented a more complete picture.Additional interviews with investors and implementers of CDR could also have enriched the study.The reader should bare these limitations in mind when presented with the results.

Governing emission reductions and justifying residual emissions
Countries define residual emissionsi.e., emissions that are claimed to be hard to abate and should be possible to negate using CDR methods under a net-zero targetin different ways [11].Since anticipated future residual emissions can be large relative to current emissions, it is important to address the assumptions behind the justifications of them.Scrutinising these justifications is key to understanding what net zero means in a municipality such as Stockholm.In Stockholm, an anticipated residual is justified in relation to views of the ability to govern GHG emissions, both directly and indirectly, as well as through providing enabling conditions (see Fig. 2).

Direct ability to govern emissions: from waste management
When it comes to the municipality's direct ability to govern emissions, a specific policy area that several respondents highlighted is municipal solid waste.Plastic waste is incinerated to produce heat and power as part of the municipal solid waste management system.While the municipality can govern these emissions, a lock-in effect due to large investments can be observed.Despite direct control over plastic use in its organisation and over the waste management system, emissions from incinerating plastic are perceived by respondents as partly beyond the reach of both direct and indirect municipal governance: "We can increase the amount of plastic that is source-separated, and we can advise people to use less plastic, but what is available on the market is governed by the EU or globally" (C4).According to C1, Stockholm has invested in large facilities for waste incineration, which will surely be used in the future.Thus, even if plastic waste recycling is increased, resulting in less plastic available for incineration, waste will be imported to the incinerators to enable operation at full capacity.In fact, Swedish heat and power producers are already importing 1.4-1.6 million tonnes of nonhazardous solid waste per year to meet the waste incinerator capacity of 7.1 million tonnes per year [34].To reduce emissions from incinerating plastic waste, EU policy is an important enabling factor.According to C2, "the EU will need to regulate plastic made from fossil feedstock to reduce the share of fossil fuels in waste incineration".C4 agreed and added that plastic is an issue that connects all levels of governance.Some respondents also pointed to a challenge since currently the only viable alternative to incineration is landfilling, and, according to P2, "it is better to incinerate the plastic that is not recyclable and use the energy for heating and electricity than for plastic to end up in nature.The problem is not incineration, but that fossil-based plastic is put in circulation in society in the first place". 2As waste incineration is seen as a necessity in the foreseeable future, management of the resulting emissions has spurred debate on carbon capture and storage (CCS).In the Council debate, the construction of a new combined heat and power plant was supported by the Left Party only due to the possibility of using CCS to lower emissions (Stockholm City Council protocol 2022-05-09).The new power plant is designed to have the capacity to burn both biomass and up to 900 000 tonnes of refuse-derived fuels 3 annually [36].The promise of CCS has worked as political glue to facilitate bipartisan support for this facility, despite worries about fossil-fuel lock-in (see [37]).
The issue of waste incineration alludes to the difficulty of determining what should be considered residual emissions, and to what extent restrictions due to the state of technological knowledge and economic factors should be considered [11].CCS technology makes it possible to reduce emissions from waste incineration.However, economically, covering the cost of CCS relies on promises of technological progress, potential state aid, a high price on emissions of fossil CO 2 , as well as access to affordable sites to store CO 2 .Nevertheless, the sole promise of CCS, perceived as a self-governance mode, makes it possible to perpetuate investments in waste incineration.In fact, even in the absence of CCS, the respondents stressed that incinerating waste is the responsible way to deal with waste management since landfilling is a worse alternative.This argument was used by many respondents to justify why emissions from the incineration of fossil-based plastic would be part of the residual in 2030.

Indirect ability to govern emissions: from road transport
Stockholm must govern emissions outside its direct control, with uncertain impacts on emission outcomes.According to C3, the municipality uses all tools available for the indirect governance of emissions, such as city planning, traffic planning, and public procurement.C4 pointed out that the types of emissions that the city tries to reduce through indirect governance modes are hard to follow up quantitatively: "When closing a coal-fired power plant, it is easy to see the direct effect, but when it comes to reducing car traffic […] we do not know if it is better to build bicycle lanes or to put all money into a new subway".
Several respondents viewed the transport sector as at least partly beyond municipal control.However, one respondent said that Stockholm has the capacity to implement a more sustainable transport system with lower emissions and infrastructure that enables low-carbon behaviours, and that such a system change could be a model that spreads to other parts of the country (P3).Another respondent claimed that the city should do everything within its power to reduce emissions from road traffic, but not be held accountable if emissions do not decrease (C7).Several respondents agreed that meeting the target of reducing emissions from road transport by 80 % by 2030 compared with 2010 is a difficult challenge for Stockholm.One respondent highlighted the fragmented nature of infrastructure policy: "The municipality does not own all the roads in its territory.Region Stockholm is responsible for some, and the Swedish Transport Administration for some.Similarly, when it comes to electric vehicle charging infrastructure, the municipally owned parking company is responsible for the general supply of 2 The landfilling of organic waste has been prohibited in Sweden since 2005 [35].However, the alternative waste management option for waste imported to Sweden from other countries may still be landfilling. 3Refuse-derived fuel is produced by separating non-combustible materials from biomass and fossil-based plastics to produce fuel with a higher heating value.
A. Olsson et al. charging stations, but the environmental administration is responsible for residential areas.As a politician it is hard to get a grip on this, despite our ability to govern" (P4).
The partial lack of direct control over transport-related emissions has led to the perception that the transport sector is likely to contain residual emissions in 2030 and beyond.However, despite the perceived lack of influence, the respondents mentioned several possible ways to use authoritative modes of governance, for example, by introducing strict environmental zones that ban most internal combustion engines from entering the city centre.To reach its own climate targets, Stockholm is relying on other municipalities, and on the regional and national governance levels.According to C4, Stockholm climate policy is dependent on regulation at the national level: "For traffic in the city centre, for example, we can implement environmental zone class 3, 4 but we are dependent on state regulation to be able to do it".Emissions from the transport sector arise not only from local traffic but also when cars and trucks enter the municipality from outside the territory.National and EU policies govern the biofuel quota, i.e., the amount of biofuel that must be added to fossil fuels at the filling station, having a direct impact on emissions from the transport sector.According to P6, "our entire SEK 1 billion investment in the better recycling of plastic waste, which may reduce emissions by 35 000 tonnes [of CO 2 per year], will be lost since the increase in emissions from the proposed changes to the vehicle fuel quota system will be 40 000 tonnes [of CO 2 per year in Stockholm]".In contrast to the constraining linkages with the state, linkages with Region Stockholm are suggested by respondents to provide some enabling characteristics.According to C2, "the Region should get a lot of praise since they have phased out fossil fuels from the bus fleet.They have done a tremendous job and have been early too.This has contributed to Stockholm being notable [for its emission reductions]".

Ability to govern emissions by providing enabling conditions for mitigation measures
In Sweden, municipalities levy a flat income tax, but for the most part are prohibited from steering consumer behaviour with, for example, a value-added tax or a tax on GHG emissions.However, P6 pointed out other ways that municipalities can influence citizens' choices: "We are closer to the public, and I think we have a very important role in showing leadership […] we need to send the signal that we will do everything within our power to reduce emissions".P3 pointed out that the most important aspect of climate policy in Stockholm is to show that it is possible to be a wealthy city with high mitigation ambitions.
The forerunner ambitions extend to the use of CDR methods.As stated by one respondent, "it is important that we get started with BECCS so that it can be spread all over the world and show that it works and is possible" (P2).As such, BECCS serves a symbolic function attributed with significance far beyond the local context.The respondents claimed that Stockholm could contribute to international climate efforts not only by demonstrating leadership and reducing its net emissions, but also by demonstrating that it is possible to achieve ambitious climate targets and inspiring others to follow suit.

Compensating for residual emissions with carbon dioxide removals
The respondents agreed that CDR would be necessary to compensate for residual emissions.According to the respondents, there are two main reasons for classifying emissions as residual at the municipal level: first, challenges governing emissions from waste incineration due to lock-in effects and, second, the indirect and uncertain ability to govern emissions from road transport.The justification of what is likely to constitute residual emissions in 2030 is grounded in values and interests [12], but manifested more tangibly in the perception of residual emissions as hard to abate due to the modes of governance available at the municipal level [28].
According to P2, "we need to use all the mitigation tools available, and we will not be able to reach our climate goals if we don't use negative emissions."Respondent C3 pointed out that everyone was counting on negative emissions by 2030 as fundamental for reaching the net-zero target.The possibility of BECCS removing 800 000 tonnes of CO 2 per year from Värtaverket aligns with Stockholm's plan to reduce emissions to 700 000 tonnes per year by 2030.If BECCS was not part of the equation, the possibility of achieving net-zero emissions by 2030 would likely not have been viewed as realistic.As such, the ability to reach the target hinges not only on active emission reductions, but also on realising one centralised initiative: the execution of carbon capture at the biomass boiler in Värtaverket and the possibility of transporting the captured CO 2 to a geological and permanent storage location outside Sweden.
The importance of BECCS for achieving the target warrants scrutiny.Most respondents were almost entirely uncritical of the BECCS plan and its feasibility, even though a few, such as C2, raised critical questions: "It is very important that we achieve negative emissions, because emission reductions are not enough, but they should never be seen as a way to get out of reducing emissions".One politician added that BECCS did not exist yet and was a future promise (P6).Another politician highlighted the local risk of transporting CO 2 from Stockholm: "If something happens, then it is a huge environmental catastrophe" (P5).A front-end engineering design study contracted by Stockholm Exergi and conducted by Petrofac identifies the risk of the intermediate storage of liquid CO 2 in a densely populated area [38].While the risks associated with temporary buffer storage and transport were mentioned by one respondent, the risks associated with the final geological storage of CO 2 were not discussed in the interviews.As such, these response patterns mirror a general tendency in science and public debates in the 2010s to downplay storage-related risks and instead highlight the potential climate benefit of deploying BECCS [39].Strategies to achieve the city's net-zero target if BECCS fails or is delayed are completely lacking, which makes Stockholm's goal achievement highly vulnerable to actions taken by other levels of governance, such as the delivery of state aid from Sweden or support from the EU.

The rise of carbon dioxide removal methods in Stockholm
In 2015, Stockholm City Council adopted the goal of becoming entirely fossil fuel free by 2040 [40].In addition, the Stockholm municipal organisation aimed to be fossil fuel free by 2030 (Stockholm City Council protocol 2018-10-10).The official city strategy for how to become fossil fuel free concluded that the municipality has a limited ability to impact certain residual emissions, and therefore introduced the idea of compensating for these emissions through CCS or biochar [40].
In the 2019 city budget, plans to develop a BECCS pilot plant at Värtaverket were mentioned with the loose aim of it being up and running by 2025 [41].At that time, much of the CDR discourse in the Council meetings concentrated on biochar production, given the positive experience with a small test facility in Stockholm.However, the focus shifted from biochar to BECCS after a research BECCS facility was inaugurated at Värtaverket in December 2019, i.e., six years earlier than previously anticipated.This development led local politicians to bring forward the date for the net-zero target in Stockholm.The discussion started in late 2021 with the Social Democratic Party in opposition suggesting that Stockholm could be climate positive by 2035, instead of 2040, due to the rapid decrease in emissions after closing the coal-fired power plant in the city (Stockholm City Council protocol 2021-11-17), which also happened a few years ahead of schedule [41].Around the 4 Only electric, fuel-cell, or certain gas vehicles meeting the Euro 6 standard are allowed to enter zone 3. ).The Social Democratic and Left parties, which would go on to form a coalition with the Green Party after the election in September 2022, approved of this new ambition, and formally acknowledged it in the budget adopted in 2023 [13].Thus, the goal adopted in 2019 -to become climate positive by 2040 [42] became more ambitious with the new goals of becoming climate positive by 2030 and completely fossil fuel free by 2040 [13].
State aid has been instrumental in supporting the development of BECCS in Stockholm.The Swedish Energy Agency has provided approximately EUR 900 000 in funding to the BECCS research facility through the Industrial Leap Fund [43].Additionally, the state intends to provide support to full-scale BECCS facilities [44].Respondent P5 pointed out that Stockholm Exergi is a likely beneficiary of this state aid given its extensive experience with CO 2 capture.Several respondents also noted that the local net-zero strategy depends heavily on this BECCS facility.Stockholm Exergi [45], in turn, has underscored that investments in a full-scale BECCS facility require state aid.
However, national state funding is limited; P4 pointed out that Stockholm municipality and Stockholm Exergi can apply for external funding, for example, from the EU.Stockholm is participating in the EU Mission: 100 Climate-Neutral and Smart Cities by 2030, giving it the opportunity to apply for enabling grants from the EU [46].Funding awarded to Stockholm Exergi by the EU Innovation Fund of EUR 180 million played a part when the net-zero target year was moved from 2040 to 2030 (Stockholm City Council protocol 2022-04-25).According to Stockholm Exergi [45], this funding will cover around 15 % of the operating costs; according to the EU Innovation Fund, the grant will cover 30 % of all relevant costs, including both capital and operating expenditures [47].
Debate in Stockholm City Council clearly shows that BECCS played a crucial role when deciding how and when to reach a balance between emissions by sources and removals by sinks in the City of Stockholm's territory.Biochar as a CDR method became marginalised in Stockholm City Council debate after the schedule for full-scale BECCS was advanced to an earlier date.Two respondents mentioned biochar by referring to its marginal potential as a CDR method, compared with the promised potential of BECCS (P2, C2).However, respondents from the Left Party were more positive about the large-scale deployment of biochar in the city.The timeline of the Stockholm targets is illustrated in Fig. 3.

Reliance on carbon dioxide removal accentuates the risk of mitigation deterrence
BECCS constitutes an opportunity for Stockholm, and since Stockholm is a wealthy city with forerunner aspirations, most respondents in this study pointed out that the city has the capacity to act to implement BECCS.As shown above, all respondents agreed there is a need to compensate for residual emission to reach the climate target in 2030.However, the relatively large BECCS potential may also muffle further queries as to the nature of residual emissions, i.e., whether such emissions are unavoidable or just inconvenient.The large BECCS potential may not only enable moving the target to an earlier date, but it may also lessen the pressure to reduce emissions from fossil fuels.There is also a risk that the material promises of CDR may fail or be delayed for several reasons.Over-optimism or an unrealistic schedule may make it difficult to reach the goals.The EU state aid regulation is currently a barrier to the state support system for BECCS, potentially delaying the announced reverse auction scheme.Lack of access to geological storage capacity may become another barrier [39,48].Additionally, the deployment of other CDR methods, such as biochar, has been crowded out by the seemingly large potential of BECCS, which leads to a less resilient CDR portfolio.The promise of BECCS and CCS has also led to a process whereby the goal and meaning of a fossil fuel-free city become less comprehensible, reducing that target's prominence in the political discourse.If emissions are deterred based on the promise of BECCS, and if BECCS turns out to fail or is delayed, Stockholm will have painted itself into a corner.
The categories of mitigation deterrence suggested by McLaren [10] address risks or uncertainties of consciously relying on CDR for climate target compliance.They do not, however, explain the mechanism by which mitigation deterrence happens.To understand perceptions of residual emissions and how mitigation deterrence may occur in the case of Stockholm, it is important to understand why BECCS is presented as the better choice to the actors in this study compared to reducing residual emissions.In this municipal setting, climate change is high on the political agenda and local goal compliance means going beyond the nationally required targets.The target-setting process undertaken by Fig. 3. Timeline for progress towards the Stockholm net-zero target.© Authors via Canva.com.

A. Olsson et al.
Stockholm is clearly an opportunity to act, seized by the city in a particular context in which forerunner cities serve as an ideal and the ambition to govern emissions is high.In addition, we find no expressed intention in the empirical material to use CDR to avoid undertaking reductions of residual emissions.A broad view of mitigation deterrence was proposed by Markusson et al. [7], in which attention is paid not only to actors' explicit intentions (to deter or postpone), but also to the political context and potential unintended deterrence.With this broader view in mind, we propose that the mechanism that is at play in the Stockholm case is constituted by (1) constraints on local action emanating from governance at the national and the EU levels, and (2) the forerunner appeal that BECCS as a novel technology has.BECCS is a new radical exiting possibility, which should be compared to the same old tedious work involved in reducing residual emissions.In this situation, Stockholm focusses on horizontal governance, engaging their own energy utility Stockholm Exergi to invest in BECCS, instead of vertical governance intended to affect national and EU policy to reduce emissions.
Since the BECCS potential is rather large, emissions that are far below the mark of 800 000 tonnes CO 2 per year become insignificant to policymakers.The rhetoric around reaching the removal side of the netzero equation is dominating the discourse, while residual emissions are being shadowed.Net-zero is in vogue, and it therefore speaks louder than the rather demanding efforts to reduce residual emissions.Thus, BECCS becomes the centrepiece of the strategy and emissions from the transport sector and incineration of waste are increasingly viewed as inevitable, but also relatively insignificant in the net-zero scheme.In a multi-level governance perspective, important constraints imposed by other levels of governance may be perceived as challenging.Established multi-level diplomacy to enable reduced residual emissions, such as lobbying in Brussels and affecting the Swedish government via organisations such as the Climate Municipalities [20], is arguably less novel than BECCS and may therefore have lost some of its forerunner appeal.
In this respect and given the importance of CDR in the Stockholm net-zero strategy, several respondents discussed the ownership of the CDR process: "Do we own these [negative] emissions and should the municipality become an actor that buys and sells certificates?Is it reasonable that a municipality implements a BECCS facility, or should we only facilitate other actors to do it?"(C1).According to C3, Stockholm is following accounting principles when it sums territorial gross emissions and gross removals to claim net-zero status.However, the accounting principles and ownership of CO 2 removals were unclear to some respondents: "It is a bit confusing, and we would like someone to clarify this issue" (C3).The respondent wanted clearer advice from academia on how system boundaries apply to CDR, as well as more coherence between the EU and the national way of accounting for negative emissions (C3).
In the council debate on how to compensate for residual emissions with CDR, the Social Democrats in opposition proposed an inquiry to find a way of financing BECCS by taxing emissions, a sort of local compensation scheme [49].However, the 2020 majority wanted to hold off the inquiry and referred to the city management office (Stadsledningskontoret), which stated: "The financing suitable for the city is not clear at present, and according to the city management office, it is too early to investigate a local climate compensation scheme for the financing of BECCS" [50].Instead of this proposed financing scheme, Stockholm Exergi is currently dependent on state aid in addition to leaning towards a model in which actors on the international voluntary offset market may "co-claim", i.e., create one type of CO 2 removal certificate for state actors and a separate one for private actors on the voluntary market [45,p. 7].
The proposed financing of BECCS in Stockholm thus promotes special conditions for the deployment of this technology compared with, for example, authoritative measures intended to reduce emissions from road transport or other sectors.Since the international trading of carbon removals may attract additional funding, BECCS is an investment opportunity and is highlighted as such by its proponents [45].As shown by how Stockholm has changed its climate target to fit available technologies, this business opportunity is not part of an innovation narrative or an imaginary in the sense described by McLaren et al. [17] and as such (intentionally or unintentionally) used to deflect attention from the residual emissionsbut is instead viewed as a possible achievement, a type of forerunner badge.The respondents in this study stressed that BECCS enables the city to be even more ambitious than would otherwise be possible, with a chance to proudly wear the net-zero badge ten years earlier than previously expected.
In the case of Stockholm, the consistent lack of critical reflection on potential ways that BECCS may fail is striking.Discussions of risks that may arise at the various stages of a BECCS system are missing in the council debates and were rarely mentioned by respondents.While several important aspects of residual emissions from road transport and waste incineration had been considered, related issues concerning BECCSsuch as financing, intermediate storage in an urban environment, transport, and geological storagewere left to technical experts to determine.Additionally, no record of political controversies related to the difference between a net-zero target and a fossil fuel-free target is present in the material analysed here.It seems that the actors have chosen to set the boundaries for their reflection on BECCS very narrowly, almost at the plant itself at Värtaverket in Stockholm.The perceived lack of ability to govern emissions can partly explain how residual emissions are created at the municipal level, but it does not explain this lack of problematisation of BECCS.
The absence of critical reflection in the data presented here stands in stark contrast to the controversial debate in the 1980s that preceded the construction of a coal-fired power plant near the current BECCS initiative.The debate and decisions about Värtaverket in the 1980s also attracted international attention because the chosen technology, pressurised fluidised bed combustion (PFBC), was untested and would lead Sweden down a unique technological path.Advocates of this path argued that there were no other alternatives to nuclear power, which was to be phased out in Sweden.Opponents, representing a wide range of actors, including engaged citizens, instead emphasised that the technology was untested, was supported by optimistic calculations, and entailed environmental risks associated with a centrally placed facility that could be seen as a risky experimental plant.In response, proponents of the technology reiterated the claim that the criticism was mainly based on misinformation and that more acceptance could be achieved if accurate information was disseminated.In the end, the facility was built with PFBC technology in 1990, despite some authorities recommending against it and even though the initiative, in several crucial respects, did not align with the national energy policy, which clearly signalled the reduced use of fossil fuels [51,52].
The current lack of critical reflection is likely not due to a lack of awareness of the global nature of climate mitigation policymaking.The political awareness of citizens' emissions being more than just the territorial emissions is clear in the empirical data.Instead, past research has underscored the challenges associated with high expectations [53,54].High expectations can create a flawed foundation for decisionmaking, leaving stakeholders ill-equipped to handle future issues.This can result in disillusionment and decreased support for the technology at hand.Additionally, the performative nature of high expectations regarding the future of BECCS might lead to downplaying of the potential of other mitigation alternatives.This situation could give rise to moral hazard: BECCS might be viewed as societal insurance against severe climate change, serving as a rationale for avoiding more profound transformations.Considering recent significant setbacks in the development and implementation of CCS [55], including Vattenfall's discontinued CCS project in Germany around 2010 and Norway's prematurely aborted "moon landing" in Mongstad [56], to mention just two cases, the phenomenon of technological optimism points to the need to discuss mitigation deterrence through the lens of sociology of expectations.Indeed, several papers are embarking on this venture [e.g., A. Olsson et al. 57,58,59], pointing to how the mitigation deterrence literature may be developed further.

Conclusions on the Stockholm climate policy strategy and risks of mitigation deterrence
Based on the material assessed here, there is a definite risk of mitigation deterrence in Stockholm.It is important to note, however, that mitigation deterrence does not have to be intentional; it can also be a consequence of a technological trajectory, or, as suggested here, the consequence of an opportunity to act in one direction while simultaneously unintentionally blurring other pathways.To begin with, there are arguments suggesting that the Stockholm case might not represent intentional mitigation deterrence since the view that BECCS is indeed realisable was primarily used to increase the climate ambition rather than create headroom for more residual emissions.However, there is a risk of unintentional mitigation deterrence if the municipality's plans for BECCS fail or are delayed.The material also indicates that BECCS may have displaced other CDR initiatives, such as biochar, and underpins justifications for the continued high use of waste incineration for district heating and electricity production.It would be unfortunate if further discussion of how to address hard-to-abate emission sources were hampered by the tick-box nature of net-zero target fulfilment based on technologically optimistic prospects of BECCS.Not fully utilising options to reduce emissions and use other CDR methods than BECCS, even if difficult, represents a lost opportunity to mitigate climate change.This article adds to the mitigation deterrence literature by stressing how a municipality perceives itself caught in the web of multi-level governance.Rather than addressing constraining linkages that impact residual emissions by vertical governance at the national and EU levels, Stockholm takes the horizontal path which is enabled by popularisation of BECCS as a forerunner strategy, with risks of mitigation deterrence, but also potential for CDR.Taking the view that BECCS is an important mitigation measure in its own right, rather than a special type of negative emissions with the ability to cancel out emissions, would be a strategy to deal with this issue [60].In line with this, setting separate targets for CDR and for emission reductions would deal with some of the risk of mitigation deterrence [61].However, separate targets would not eliminate the risk.If an overarching net emissions target governs climate policy, specified in separate targets for emission reductions and removals, the risk of mitigation deterrence is capped by the CDR target.If the CDR target turns out to be overoptimistic and this is acknowledged too late to be addressed by additional emission reductions, then the residual emissions would become too high to achieve the net target.Insufficient emission reductions would have been legitimized by an overoptimistic CDR potential.Separate targets, therefore, increases transparency and caps the risk of mitigation deterrence, yet require additional safeguards against overoptimism.One way to address this would be to supplement separate targets with risk analysis, which may motivate exploring more options to reduce the residual as well as to expand the portfolio of methods used to achieve CDR.
It is also important to note that technological optimism is often necessary for gathering the resources and taking the risks that new projects often require.So, our discussion should not be viewed as an argument against investing in BECCS in Sweden.Indeed, BECCS is often presented as a necessity if we are to achieve ambitious climate stabilisation targetsan argument strengthened by referring to depleting carbon budgets and more stringent climate targets.Since this trend is established and BECCS is one of the main technological options for managing CO 2 emissions, the construction of BECCS as essential by the participants in this study is not surprising (see [57]).Note, however, that this logic is true also for fossil fuels with CCS or other uncertain mitigation potentials; CCS has been used in Stockholm to legitimise investments in waste incineration, including future incineration of fossilbased plastics.If CCS does not deliver, just like if BECCS does not deliver, Stockholm will struggle to meet its climate targets.The concept of mitigation deterrence, therefore, should not be limited to anticipations of CDR but also to emission reductions; both may turn out to be overoptimistic, resulting in stranded assets or failure to achieve targets.
Nevertheless, it is very concerning that if BECCS fails to deliver the negative emissions it promises, the residual emissions accepted through BECCSmost notably emissions from road transport and waste incinerationare not balanced by sinks.If the concept of BECCS means accepting the balancing of more residual emissions than otherwise allowed, the Stockholm case could indeed lead to mitigation deterrence.This can only be determined ex post, and even then, causal links will be difficult to establish.The risk of not reaching the 2030 target is very real and is with the current climate policy strategy completely dependent on the success of the BECCS project.This dependence warrants a critical discussion.If the political process of determining residual emissions is not opened-up, climate targets may become hollow promises that rely on technological fixes in the future.
Finally, the question in the title of this paper is intentionally provocative.We have not answered the question of whether the City of Stockholm is a forerunner or a net-zero opportunist.However, forerunner ambitions should not be limited to achieving net-zero targets, they must also address the issue of residual emissions in depth.The clear implication from this paper is that Stockholm will only retain its status as climate policy forerunner by sedulously maintaining the downwards trend of GHG emissions.

Declaration of competing interest
The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Mathias Fridahl reports a relationship with City of Stockholm Environment and Health Administration, Environmental Analysis that includes: funding grants.If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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. Olsson et al. same time, Stockholm Exergi communicated the possibility of sequestering 800 000 tonnes of CO 2 per year by 2025.Soon thereafter, the ruling majority proposed that the target year for a climate-positive Stockholm should be 2030 instead of 2040 (Stockholm City Council protocols 2021-11-17 and 2022-02-21