•First estimation of committed emissions based on actual industry equipment data•The median historic blast furnace campaign length is 17 years•CO2 emissions of 21 Gt to be expected for immediate blast furnace phase-out case•10 years of inaction and steel consumes 12% of the remaining 1.5°C carbon budget Stronger climate policy has pushed the steel sector to start implementing lower-emission technology, but existing large-scale industrial assets have long economic lifetimes that are impeding decarbonization. Furthermore, socio-economic and political considerations such as local jobs and value creation are deterring policy makers to retire polluting production. We show that the opportunity to reduce such committed emissions is larger than previously estimated if equipment-level analysis is conducted and reinvestments in the coal-based global blast furnace fleet are avoided. This approach can be also applied to other emission-intensive industrial assets and their respective investment cycles. To safeguard a chance to meeting the Paris Agreement target a focus on industrial renewal is thus needed. This includes better data transparency on the age of industrial assets and regulatory measures that co-evolve with a policy also taking into account a just transition, demand reduction, and research, development, and demonstration. Iron and steel production is responsible for 7% of global greenhouse gas emissions. Earlier literature finds that the long economic life of steel production equipment impedes decarbonization in line with climate targets. Here, we estimate the cumulative emissions from existing primary steel production equipment if operated as historically observed, based on furnace-level data of historical operating patterns. We find that the emissions commitment of current primary steel equipment is significantly smaller (21 Gt CO2eq) than previously suggested (52–65 Gt CO2eq). Consequently, we argue that future emissions from steel are driven not by long-lived capital but by the deployment pace of novel technologies and renewable energy provision, and a reduction of steel and energy demand. Without rapid progress in these aspects, the operation of current steel production equipment is likely to consume significant amounts of the remaining carbon budget. We recommend monitoring of emission-intensive asset aging and regulation of their operation. Iron and steel production is responsible for 7% of global greenhouse gas emissions. Earlier literature finds that the long economic life of steel production equipment impedes decarbonization in line with climate targets. Here, we estimate the cumulative emissions from existing primary steel production equipment if operated as historically observed, based on furnace-level data of historical operating patterns. We find that the emissions commitment of current primary steel equipment is significantly smaller (21 Gt CO2eq) than previously suggested (52–65 Gt CO2eq). Consequently, we argue that future emissions from steel are driven not by long-lived capital but by the deployment pace of novel technologies and renewable energy provision, and a reduction of steel and energy demand. Without rapid progress in these aspects, the operation of current steel production equipment is likely to consume significant amounts of the remaining carbon budget. We recommend monitoring of emission-intensive asset aging and regulation of their operation. 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Zheng Y. Caldeira K. Shearer C. Hong C. Qin Y. Davis S.J. Committed emissions from existing energy infrastructure jeopardize 1.5 degrees C climate target.Nature. 2019; 572: 373-377https://doi.org/10.1038/s41586-019-1364-3Crossref PubMed Scopus (176) Google Scholar, 25Erickson P. Kartha S. Lazarus M. Tempest K. Assessing carbon lock-in.Environ. Res. Lett. 2015; 10https://doi.org/10.1088/1748-9326/10/8/084023Crossref Scopus (71) Google Scholar, 26Davis S.J. Caldeira K. Matthews H.D. Future CO2 emissions and climate change from existing energy infrastructure.Science. 2010; 329: 1330-1333Crossref PubMed Scopus (713) Google Scholar, 27Davis S.J. Socolow R.H. Commitment accounting of CO2 emissions.Environ. Res. Lett. 2014; 9084018https://doi.org/10.1088/1748-9326/9/8/084018Crossref Scopus (118) Google Scholar Committed emissions are defined as the cumulative GHG emissions resulting from operating current fossil infrastructure until the end of its expected economic lifetime.27Davis S.J. 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Climate policy, stranded assets, and investors’ expectations.J. Environ. Econ. Manag. 2020; 100: 102277https://doi.org/10.1016/j.jeem.2019.102277Crossref Scopus (16) Google Scholar However, no study has yet quantified the committed emissions from industry based on the lifetimes of actual industrial equipment that needs to be replaced. The literature on committed emissions accounting has largely focused on the power sector and only a few studies have extended their scope to industrial assets.6IEAIron and Steel Roadmap. International Energy Agency, 2020Google Scholar,24Tong D. Zhang Q. Zheng Y. Caldeira K. Shearer C. Hong C. Qin Y. Davis S.J. Committed emissions from existing energy infrastructure jeopardize 1.5 degrees C climate target.Nature. 2019; 572: 373-377https://doi.org/10.1038/s41586-019-1364-3Crossref PubMed Scopus (176) Google Scholar,25Erickson P. Kartha S. Lazarus M. Tempest K. Assessing carbon lock-in.Environ. Res. 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Committed emissions from existing energy infrastructure jeopardize 1.5 degrees C climate target.Nature. 2019; 572: 373-377https://doi.org/10.1038/s41586-019-1364-3Crossref PubMed Scopus (176) Google Scholar,35Smith C.J. Forster P.M. Allen M. Fuglestvedt J. Millar R.J. Rogelj J. Zickfeld K. Current fossil fuel infrastructure does not yet commit us to 1.5 degrees C warming.Nat. Commun. 2019; 10: 101https://doi.org/10.1038/s41467-018-07999-wCrossref PubMed Scopus (64) Google Scholar or other not clearly specified assumptions.6IEAIron and Steel Roadmap. International Energy Agency, 2020Google Scholar,25Erickson P. Kartha S. Lazarus M. Tempest K. Assessing carbon lock-in.Environ. Res. Lett. 2015; 10https://doi.org/10.1088/1748-9326/10/8/084023Crossref Scopus (71) Google Scholar In this paper, we estimate the emissions commitment from global primary steel production equipment through a modified approach to committed emissions accounting for industrial assets that is based on actual historic operating patterns of steel production equipment. By doing so, we show that the socio-economic inertia of steel assets is a much smaller obstacle to steel decarbonization than often assumed. Our main argument is that the blast furnace relining (the reoccurring investment between furnace campaigns) is the main driver of committed emissions from steel production. In other words, the investment in a blast furnace relining at the end of the campaign represents the junction at which the branching off onto a low-emission technology pathway is most feasible for integrated steel producers. In the following we first develop the argument that decarbonizing industrial assets follows a logic of industrial renewal rather than whole plant retirement. We then analyze historic blast furnace operational patterns based on a global furnace-level dataset and use the results to estimate the emissions commitment of current primary steel production equipment. From its first presentation,26Davis S.J. Caldeira K. Matthews H.D. Future CO2 emissions and climate change from existing energy infrastructure.Science. 2010; 329: 1330-1333Crossref PubMed Scopus (713) Google Scholar the goal of committed emissions accounting (CEA) was to inform public policy and investors on the future emissions of current investments into long-lived fossil infrastructure.27Davis S.J. Socolow R.H. Commitment accounting of CO2 emissions.Environ. Res. Lett. 2014; 9084018https://doi.org/10.1088/1748-9326/9/8/084018Crossref Scopus (118) Google Scholar,30Pfeiffer A. Hepburn C. Vogt-Schilb A. Caldecott B. Committed emissions from existing and planned power plants and asset stranding required to meet the Paris Agreement.Environ. Res. Lett. 2018; 13054019https://doi.org/10.1088/1748-9326/aabc5fCrossref Scopus (63) Google Scholar,35Smith C.J. Forster P.M. Allen M. Fuglestvedt J. Millar R.J. Rogelj J. Zickfeld K. Current fossil fuel infrastructure does not yet commit us to 1.5 degrees C warming.Nat. Commun. 2019; 10: 101https://doi.org/10.1038/s41467-018-07999-wCrossref PubMed Scopus (64) Google Scholar This body of literature has shown that the world is already locked into substantial climate warming from current assets—even if no more GHG emitting equipment is realized. A similar approach investigates the implications of treating the remaining carbon budget for the 1.5°C goal as a hard target, i.e., that all emitting equipment be retired when this budget is exhausted.29Pfeiffer A. Millar R. Hepburn C. Beinhocker E. The ‘2°C capital stock’ for electricity generation: committed cumulative carbon emissions from the electricity generation sector and the transition to a green economy.Appl. Energy. 2016; 179: 1395-1408https://doi.org/10.1016/j.apenergy.2016.02.093Crossref Scopus (107) Google Scholar This would mean that assets are potentially abandoned before the end of their economic lifetimes26Davis S.J. Caldeira K. Matthews H.D. Future CO2 emissions and climate change from existing energy infrastructure.Science. 2010; 329: 1330-1333Crossref PubMed Scopus (713) Google Scholar and before they have generated the expected returns and recouped investments. These assets are then referred to as impaired or stranded.32Johnson N. Krey V. McCollum D.L. Rao S. Riahi K. Rogelj J. Stranded on a low-carbon planet: implications of climate policy for the phase-out of coal-based power plants.Technol. Forecasting Soc. Change. 2015; 90: 89-102https://doi.org/10.1016/j.techfore.2014.02.028Crossref Scopus (82) Google Scholar, 33Caldecott B. Introduction to special issue: stranded assets and the environment.J. Sustain. Finan. Invest. 2017; 7: 1-13https://doi.org/10.1080/20430795.2016.1266748Crossref Scopus (38) Google Scholar, 34Sen S. von Schickfus M.-T. Climate policy, stranded assets, and investors’ expectations.J. Environ. Econ. Manag. 2020; 100: 102277https://doi.org/10.1016/j.jeem.2019.102277Crossref Scopus (16) Google Scholar A key input to committed emissions accounting is the expected economic lifetime of an investment.27Davis S.J. Socolow R.H. Commitment accounting of CO2 emissions.Environ. Res. Lett. 2014; 9084018https://doi.org/10.1088/1748-9326/9/8/084018Crossref Scopus (118) Google Scholar Most CEA studies have so far focused on the power sector and assumed that the economic lifetime of assets such as coal power stations entails the retirement of all the equipment at the site in question. Although this may be a reasonable assumption for the power sector—for example when a coal power plant is retired—we argue that a different approach is needed to quantify the emissions commitment of industrial sectors. Industrial sites such as steel mills can be over one hundred years old and will have undergone multiple cycles of repair and reinvestment during this time. As CEA was designed to “inform public policy by quantifying future emissions implied by current investments” (Davis and Socolow27Davis S.J. Socolow R.H. Commitment accounting of CO2 emissions.Environ. Res. Lett. 2014; 9084018https://doi.org/10.1088/1748-9326/9/8/084018Crossref Scopus (118) Google Scholar: p.1), an analysis concluding that steel mills will be emitting until the end of the industrial site will not be of much service of climate policy makers wanting to act quickly. What is needed, instead, is a choice of expected economic life that takes into account the timing and economics of the asset reconfigurations that are needed to bring the steel sector onto a low-emission pathway. Decarbonizing steel and other industries require the replacement or significant redesign of certain equipment in existing plants but does not necessarily mean that all current production sites need to be abandoned (see Figure 1). While it is probable that decarbonization of the global steel sector will entail the retirement of old steel plants and the establishing of new, greenfield steel mills, in the short term the conversion of existing sites are likely to dominate. This is due to large sunk costs in downstream equipment and the presence of skilled and knowledgeable workers and staff as well as political interests in sustaining jobs and value creation locally. Steel plants are part of an established value chain, with both upstream suppliers of iron ore that will remain also in a decarbonized future and with significant value in downstream assets—such as casting and rolling—that are often located close to main customers and that can be retained in all low-emission technology pathways for the steel sector. As shown in Figure 1, a transition from the traditional integrated route to, for example, steel production based on the hydrogen direct reduction process,14Vogl V. Åhman M. Nilsson L.J. Assessment of hydrogen direct reduction for fossil-free steelmaking.J. Cleaner Prod. 2018; 203: 736-745https://doi.org/10.1016/j.jclepro.2018.08.279Crossref Scopus (112) Google Scholar will require the replacement of equipment in the process stages of energy and iron ore preparation, ironmaking, and steelmaking, while up- and downstream assets as well as auxiliary equipment at the production site can be repurposed and thus their value retained. A detailed techno-economic assessment by the IEAGHG,36IEAGHGIron and Steel CCS Study. Techno-Economics Integrated Steel Mill, 2013https://ieaghg.org/publications/technical-reports/reports-list/9-technical-reports/1001-2013-04-iron-and-steel-ccs-study-techno-economics-integrated-steel-millGoogle Scholar for example, has found the value of retainable assets (1,817 million USD as defined in Figure 1) to be close to half of total investment costs for a greenfield integrated steel mill. The major capital expenditure that drives investment cycles in a steel mill is the so-called relining of the blast furnace.36IEAGHGIron and Steel CCS Study. Techno-Economics Integrated Steel Mill, 2013https://ieaghg.org/publications/technical-reports/reports-list/9-technical-reports/1001-2013-04-iron-and-steel-ccs-study-techno-economics-integrated-steel-millGoogle Scholar During a relining, production at the steel mill is halted, and the refractory material that separates the furnace walls from its hot contents is repaired or replaced. The production outage distinguishes the relining from the maintenance of other equipment at the steel mill, which does not require halting production. During relining production typically ceases for several months before production can be resumed, starting a new campaign, i.e., the productive time period between relinings. The combination of investments of a magnitude of several hundred million USD36IEAGHGIron and Steel CCS Study. Techno-Economics Integrated Steel Mill, 2013https://ieaghg.org/publications/technical-reports/reports-list/9-technical-reports/1001-2013-04-iron-and-steel-ccs-study-techno-economics-integrated-steel-millGoogle Scholar,37Wörtler M. Schuler F. Voigt N. Schmidt T. Dahlmann P. Lungen H.B. Ghenda J.-T. Steel's contribution to a low-carbon Europe 2050.https://www.bcg.com/publications/2013/metals-mining-environment-steels-contribution-low-carbon-europe-2050Date: 2013Google Scholar and the absence of revenues during the production stoppage make the blast furnace relining the single most important reinvestment in steel production. To illustrate, a typical relining of 3 months for a large blast furnace (4 Mtpa capacity) would result in foregone revenues of one billion USD. Capital expenditures for relining lie in the order of one-third to one-half of constructing a new blast furnace (USD 280–300 million, adjusted for inflation).36IEAGHGIron and Steel CCS Study. Techno-Economics Integrated Steel Mill, 2013https://ieaghg.org/publications/technical-reports/reports-list/9-technical-reports/1001-2013-04-iron-and-steel-ccs-study-techno-economics-integrated-steel-millGoogle Scholar,37Wörtler M. Schuler F. Voigt N. Schmidt T. Dahlmann P. Lungen H.B. Ghenda J.-T. Steel's contribution to a low-carbon Europe 2050.https://www.bcg.com/publications/2013/metals-mining-environment-steels-contribution-low-carbon-europe-2050Date: 2013Google Scholar At the same time, ironmaking in blast furnaces is the main source of GHG emissions in steel production. All low-emission pathways for steel require the replacement or at least significant modifications to the blast furnace, which can only be implemented once the furnace is shut down (even for CCS technology that necessitates complex integration with the blast furnace). The moment just before a relining is the time in the investment cycle when the blast furnace is relatively most depreciated, and thus, the investment decision is most likely to favor alternative technology. As production will be halted any way, the regular interval of blast furnace relining constitutes the most suitable and most probable timing for an integrated steelmaker to shift to a low-emission steel production pathway. In the case of a Northern European steelmaker, for example, “[t]he blast furnace was fully refurbished as recently as 2011 […] to last until the conversion to electric arc furnace in 2025.” 38Moggridge M. SSAB shuts down blast furnace ops in Oxelösund. Steel Times International, 30th August, 2018.https://www.steeltimesint.com/news/ssab-shuts-down-blast-furnace-ops-in-oxeloesundDate: 2018Google Scholar The choice to reline an existing blast furnace, on the other hand, will lead to a lock-in into carbon-intensive steel production for the next blast furnace campaign. We therefore argue that the blast furnace campaign is an appropriate proxy for the lifetime in CEA for steelmaking, as it represents the most probable investment