Net zero
Kirstine Lund Christiansen
Related terms: carbon neutral, climate neutral, carbon dioxide removal, negative emissions, residual emissions
In recent years, the idea of net-zero emissions – or simply net zero – has become the lodestar and focal point of climate mitigation efforts. The concept entails a state in which no net emissions are released to the atmosphere, as any carbon released is balanced by the removal of a corresponding amount of carbon from the atmosphere.
The concept originates in the scientific modelling communities that sought to identify at what point global average temperatures stop rising (Allen et al. 2024). In several scientific articles from around 2009, the community found that global temperatures stop rising once global emissions reach zero – or once a balance between emissions and removals is struck (for example, Matthews et al. 2009; Zickfeld et al. 2009; see also Allen et al. 2024).
Though rooted in a scientific and global context, net zero has since moved into a political context characterized by individuation and accounting logics. First, net zero was, implicitly, adopted politically within the Paris Agreement’s Article 4. Here, the notion of balancing emissions and removals of carbon was evoked as a global goal to be reached in the middle of the century to ensure that the temperature targets of the agreement were not exceeded (UNFCCC 2015). Later, the Glasgow Climate Pact of 2021 explicitly recognised that net zero carbon dioxide emissions must be achieved around mid-century to limit global warming to 1.5°C (UNFCCC 2022). Thus, net zero became politically conceptualized as a global target for international climate governance (Allen et al. 2022; Fankhauser et al. 2022; Green and Reyes 2023).
Once recognized as a key global target, net zero was quickly recast as a target for individual actors (Allen et al. 2022; Fankhauser et al. 2022). Not only did Parties to the UNFCCC (i.e., country governments) set net-zero targets to support the Paris Agreement, but other actors like city councils and companies also started setting net-zero targets. Thus, in the late 2010s and early 2020s, a plethora of countries, cities, states, regions, and companies across the world committed to the net-zero agenda and set targets for when they seemingly want to have no negative impact on the climate (Hale et al. 2022; Arendt 2024; Green, Hale, and Arceo 2024).
While the widespread adoption of net-zero targets can be interpreted as broad-based support for the Paris Agreement, the reconceptualization of net zero as a goal for individual entities (e.g., countries, cities, or companies) to reach also illuminates political challenges. For example, from the point of view of climate justice, the adoption of net-zero targets at the individual company (or even country) level may lead to actors claiming a limited supply of carbon dioxide removal to compensate for emissions they themselves deem societally necessary or too costly to abate (Broekhoff 2021). As is currently often the case, if carbon removals are sold to the highest bidder through markets, it will likely be the emissions of the wealthy who are compensated for rather than subsistence emissions of those most marginalised (Carton, Hougaard, and Christiansen 2021; Armstrong and McLaren 2022). This illustrates how governing net zero is a deeply political issue.
(This essay is based on research for my PhD thesis and thus draws on Christiansen 2025.)
References
Allen, Myles, David J. Frame, Pierre Friedlingstein, Nathan P. Gillett, Giacomo Grassi, Jonathan M. Gregory, William Hare, et al. 2024. “Geological Net Zero and the Need for Disaggregated Accounting for Carbon Sinks.” Nature 638: 343-50.
Allen, Myles, Pierre Friedlingstein, Cécile A.J. Girardin, Stuart Jenkins, Yadvinder Malhi, Eli Mitchell-Larson, Glen P. Peters, and Lavanya Rajamani. 2022. “Net Zero: Science, Origins, and Implications.” Annual Review of Environment and Resources 47 (1): 849-87.
Arendt, Rosalie. 2024. “Residual Carbon Emissions in Companies’ Climate Pledges: Who Has to Reduce and Who Gets to Remove?” Climate Policy 0 (0): 1-16.
Armstrong, Chris, and Duncan McLaren. 2022. “Which Net Zero? Climate Justice and Net Zero Emissions.” Ethics & International Affairs 36 (4): 505-26.
Broekhoff, Derik. 2021. “For Corporate Net-Zero Targets, Focus on the Big Picture.” SEI, 11 May 2021.
Carton, Wim, Inge-Merete Hougaard, and Kirstine Lund Christiansen. 2021. “We Can’t Let Markets Decide the Future of Removing Carbon from the Atmosphere.” The Conversation, 16 November 2021.
Christiansen, Kirstine Lund. 2025. “Legitimising Voluntary and Market-Based Climate Action: Corporate Narratives, Nature-Based Offsetting and the Greening of Capitalism.” PhD dissertation, Copenhagen: University of Copenhagen.
Fankhauser, Sam, Stephen M. Smith, Myles Allen, Kaya Axelsson, Thomas Hale, Cameron Hepburn, J. Michael Kendall, et al. 2022. “The Meaning of Net Zero and How to Get It Right.” Nature Climate Change 12 (1): 15-21.
Green, Jessica F., Thomas N. Hale, and Aldrick Arceo. 2024. “The Net Zero Wave: Identifying Patterns in the Uptake and Robustness of National and Corporate Net Zero Targets 2015–2023.” Climate Policy 0 (0): 1-14.
Green, Jessica F., and Raúl Salas Reyes. 2023. “The History of Net Zero: Can We Move from Concepts to Practice?” Climate Policy 23 (7): 901-15.
Hale, Thomas, Stephen M. Smith, Richard Black, Kate Cullen, Byron Fay, John Lang, and Saba Mahmood. 2022. “Assessing the Rapidly-Emerging Landscape of Net Zero Targets.” Climate Policy 22 (1): 18-29.
Matthews, H. Damon, Nathan P. Gillett, Peter A. Stott, and Kirsten Zickfeld. 2009. “The Proportionality of Global Warming to Cumulative Carbon Emissions.” Nature 459 (7248): 829-32.
UNFCCC. 2015. “Paris Agreement.” United Nations.
UNFCCC. 2022. “Glasgow Climate Pact.” Glasgow: United Nations Framework Convention on Climate Change.
Zickfeld, Kirsten, Michael Eby, H. Damon Matthews, and Andrew J. Weaver. 2009. “Setting Cumulative Emissions Targets to Reduce the Risk of Dangerous Climate Change.” Proceedings of the National Academy of Sciences 106 (38): 16129-34.