Rethinking Highest Possible Ambition

2025 is now projected to be the second or third warmest year on record, surpassed only by 2024, the hottest year so far, when global temperatures reached 1.6°C above pre-industrial levels. Although the long-term global warming trend so far remains below the Paris Agreement’s 1.5°C target, current emission trajectories suggest with relative certainty that we will surpass 1.5°C in the near future. The Intergovernmental Panel on Climate Change (IPCC) defines the temporary exceedance and return to the 1.5°C as “overshoot”. Overshoot brings several new governance challenges with it. One of these is the need for even more mitigation actions as emissions must not only be reduced to achieve net-zero but rather net-negativity in order to return to 1.5°C as quickly as possible. In light of overshoot, the need for states to employ their highest possible mitigation ambition (HPA) is amplified. However, as I will illustrate, it is not always applied, particularly in the agricultural sector, where HPA calls for stronger and more immediate mitigation action.

Agricultural emissions often remain unaddressed in mitigation actions. Many Nationally Determined Contributions (NDCs) and Long-term Low-emission Development Strategies (LT-LEDS), the main mechanisms for parties under the Paris Agreement to communicate their medium- and long-term climate plans, broadly acknowledge the need to reduce agricultural emissions. Yet they rarely set specific reduction targets for the sector, and even when such targets are included, they often lack credible and detailed plans to achieve the projected reductions. This is underscored by the 2024 NDCs Synthesis Report, which indicates that agricultural emissions continue to go unaddressed, and policy coverage is limited. A 2024 FAO report further reveals an implementation gap in the sector, as commitments made in NDCs also do not translate into actions.

States classify a large portion of agricultural emissions as “hard to abate”, framing them as residual emissions which must be compensated through removals. However, all IPCC emissions reduction pathways consistent with 1.5°C, which indicate limited overshoot, include substantial reductions of agricultural emissions. As other sectors decarbonise more rapidly, persistent agricultural emissions pose a significant obstacle to achieving the Paris Agreement’s 1.5°C target, underscoring the growing importance of reducing emissions in this sector to restoring a pathway consistent with returning to 1.5°C as quickly as possible.

So how should HPA be understood in the context of addressing agricultural emissions under the Paris Agreement? Following the ICJ Advisory Opinion on Climate Change, the notion of HPA has attracted growing scholarly attention as a potential tool to shape the content of states’ NDCs. While it does not create new legal obligations for states, it establishes strong normative expectations and sets a standard for action within the regime.

Introducing a sectoral perspective for mitigation

The notion of HPA is connected to the obligation that each party must communicate and maintain successive NDCs (Article 4.2 Paris Agreement). In its recent Advisory Opinion, the ICJ confirmed that the content of NDCs is not completely up to the discretion of each party. Instead, parties must exercise due diligence, taking into account HPA, progression and Common But Differentiated Responsibilities (CBDR) mentioned in Article 4.3 of the Paris Agreement, when constructing their NDCs to ensure they fulfil their obligations under the Paris Agreement. HPA is an indicator for this due diligence standard. It implies that parties must raise their ambition to the highest level they can feasibly achieve, in light of their responsibilities, capabilities, and the best available science (see also Voigt et al.).

Determining HPA is tied to “best available science”. More concretely, this means that parties’ NDCs must make an adequate contribution to the temperature target. Collectively, as the ICJ has pointed out, all NDCs targets must be aligned with the long-term high-level temperature goal of the Paris Agreement . To achieve this, the best available science suggests that the global reduction of emissions in all sectors is essential. HPA further suggests that parties must comprehensively assess all available mitigation options and their associated potential (see also Voigt et al.). This is inherently sectoral, as options must be assessed beyond overarching framework laws; sector-level policies often provide more specific guidance on emission reductions. Here, the notion of HPA further connects with the obligation of conduct under Article 4.2 of the Paris Agreement. In addition to preparing NDCs, parties are also required to actively pursue domestic measures to achieve the goals they set. Only through such measures can credibility be established that states are committed to their HPA. Since the best available science suggests that mitigation is necessary across all sectors, measures should ensure reductions in the relevant sectors.

Ultimately, the expectation of HPA may introduce a sectoral narrative into the Paris Agreement, which is otherwise not sector-specific; it does not prescribe emission reductions for a particular sector. The introduction of a sectoral perspective is relevant, as it may help to translate the Paris Agreement’s high-level, long-term objectives into specific actions and may thereby support its implementation, especially in light of increased mitigation needs in a world of overshoot. This is particularly relevant given that governments do not control all levers of emission reduction. Many mitigation actions must be undertaken by other actors, creating a need for governments not only to assess all options internally but also to establish enabling conditions and incentives for the necessary social and technological transformations. Setting clear short- and long-term sectoral targets in NDCs can facilitate this process.

The implications of HPA for the agricultural sector

With regard to agriculture, many states have not been following the two expectations following from HPA which I just elaborated. Rather, many states characterise agricultural emissions as “hard to abate” and therefore residual, introducing a narrative of burden-shifting with regard to mitigation in the sector. Burden-shifting in the mitigation context, that is the practice of transferring emission reduction burdens from one sector to another rather than resolving the underlying issue, would not be problematic if other sectors could reduce emissions beyond their own or if abundant, low-cost, and permanent removals were available. However, neither condition reflects reality. No global sector is currently achieving the reductions needed for 1.5°C, and many rely on carbon dioxide removal technologies whose large-scale deployment remains highly uncertain. In this context, burden-shifting is unjustifiable, as it places unrealistic expectations on carbon dioxide removal and on sectors that have yet to meet their own mitigation requirements.

A recent example of such burden-shifting in the agricultural sector can be seen in New Zealand, where the government lowered its 2050 biogenic methane reduction target from 24–47% to 14–24% below 2017 levels. The change was justified using the controversial ‘no additional warming’ metric, which the Climate Change Commission and international scientists have deemed scientifically flawed and inconsistent with international obligations. Rather than achieving substantial methane reductions within the agricultural sector to remain aligned with 1.5°C pathways, the resulting shortfall in GHG emission reduction is effectively transferred to other sectors and to carbon dioxide removal efforts, which must now bear the additional mitigation burden.

In the case of agriculture, burden-shifting to the extent it is done currently might arguably not be in line with the highest possible mitigation ambition necessary in the sector. From the perspective of the best available science, current NDCs generally indicate that mitigation targets and measures in the agricultural sector require significant strengthening, among other things, to set the right conditions for other actors to reduce emissions from the sector. However, determining the highest possible mitigation ambition is not based solely on the best available science but is also societally determined. It is important to note that raising targets and adopting additional measures to reduce agricultural emissions will require profound societal transformation, as achieving rapid and sustained reductions in the sector demands both supply-side actions and demand-side changes in consumption.

Still, the ICJ Advisory Opinion paved the way for considering agricultural consumption activities, as it affirmed that the material scope of its inquiry with regard to state obligations in the context of climate change covers all human activities, including both consumption and production activities. By emphasising the need for states to assess all possible mitigation options and to set sectoral targets to create the right conditions for other actors to reduce emissions, HPA can serve as a narrative to promote stronger supply-side action while also integrating demand-side mitigation considerations for the agricultural sector, particularly in the NDCs of Global North countries. While the reduction of agricultural emissions will always need to be in line with ensuring food security, emissions can and need to be reduced further than at present for the sector to contribute meaningfully to 1.5°C pathways.

Conclusion

Ultimately, the notion of HPA, particularly when viewed in the context of overshoot, may impose strong expectations for sectoral mitigation targets and measures in all sectors, despite the Paris Agreement being agnostic to sectors. It can help to build a narrative emphasising the need for states to address mitigation comprehensively across all sectors and GHGs. A sectoral perspective may thus be essential to achieve the deep emission reductions required in the near term to minimise the magnitude and duration of overshoot.

With regard to mitigation in the agricultural sector, this post highlights the burden-shifting currently taking place in the sector, which appears inconsistent with the notion of the highest possible mitigation ambition under the Paris Agreement. HPA suggests that targets and measures in NDCs must be strengthened with respect to agriculture. This also points to the need for incorporating more demand-side measures for the agricultural sector into the NDCs of wealthier countries. While the level of HPA and what it entails for agricultural emissions reduction must ultimately be determined by each state party within its own societal context, HPA imposes a strong expectation for more mitigation targets and measures across all sectors under the Paris Agreement, thereby exposing the currently weak targets and measures brought forward in NDCs, especially by Global North countries, in the agricultural sector.