Climate litigation and ‘fair share’: how fast should the government act to combat climate change?

1. Introduction

Governments are obligated to take effective measures to counter the serious adverse effects of climate change. This was clarified by the European Court of Human Rights ("ECtHR") in the Swiss KlimaSeniorinnen ruling of Tuesday 9 April 2024. But this conclusion has not brought climate litigation to a halt. In various court cases, environmental organisations are demanding that the government accelerate climate action to achieve climate neutrality as soon as possible (e.g. by 2030). In this article, we address three of these cases: (i) the case of Bonaire and Greenpeace v. the Netherlands before the District Court of The Hague; (ii) the case of an environmental organisation v. four Belgian governments before the Brussels Court of Appeal; and (iii) the request for an advisory opinion of the International Court of Justice. These cases could have major implications for Dutch climate policy. 

First, this article addresses the relevant legal framework laid down in (i) the United Nations Framework Convention on Climate Change ("UNFCCC"); and (ii) the Paris Agreement (section 2). It then addresses the Urgenda judgment of the Dutch Supreme Court and the aforementioned Swiss KlimaSeniorinnen case, in which the legal duty to combat climate change was adopted (section 3). Next, this article analyses the three cases mentioned above (section 4). This article concludes with a short analysis of the potential impact of these climate lawsuits for companies (section 5). 

2. 'Equitable' distribution of efforts in respect of climate change in the UNFCCC and the Paris Agreement

The UNFCCC sets out general obligations and principles to protect present and future generations from climate change. The UNFCCC provides, for instance, that governments must mitigate climate change and its adverse effects on the basis of equity. In doing so, developed countries should take the lead, taking into account the specific needs and special circumstances of developing countries (Article 3 UNFCCC). The Paris Agreement also refers to equity and the principle of common but differentiated responsibilities and respective capabilities (Article 2(2) Paris Agreement). 

The UNFCCC and the Paris Agreement do not provide detailed guidance on how to achieve an equitable distribution of the global effort to combat climate change. Certain provisions provide starting points, but need further elaboration: according to Article 4(3) of the Paris Agreement, for example, states should consider the highest possible level of ambition when formulating their nationally determined contributions. Furthermore, the Paris Agreement and the UNFCCC stipulate that developed states must take the lead by undertaking economy-wide absolute emission reduction targets and mobilising climate finance from a wide variety of sources (Article 4(4) and Article 9(3) Paris Agreement, respectively; Article 3(1) UNFCCC). Finally, developed countries should provide support to developing countries (Article 4(5) Paris Agreement; Article 4 UNFCCC). 

In a 2022 report, the Intergovernmental Panel on Climate Change ("IPCC") argues that other mechanisms and actors (the judiciary and climate scientists) have an important role to play in developing these equity principles (IPCC 2022, AR6, Working Group III, Mitigation of Climate Change, p. 1468):

"Equity is critical to addressing climate change, including through the Paris Agreement" (Klinsky et al. 2017), however, since the political feasibility of developing equity principles within the climate change regime is low, the onus is on mechanisms and actors outside the regime to develop these (Lawrence and Reder 2019). Equity and fairness concerns are being raised in national and regional courts that are increasingly being asked to determine if the climate actions pledged by States are adequate in relation to their fair share (The Supreme Court of the Netherlands 2019; European Court of Human Rights 2020; German Constitutional Court 2021), as it is only in relation to such a 'fair share' that the adequacy of a State's contribution can be assessed in the context of a global collective action problem (Section 13.5.5). Some domestic courts have stressed that, as climate change is a global problem of cumulative impact, all emissions contribute to the problem regardless of their relative size and there is a clear articulation under the UNFCCC and Paris Agreement for developed countries to 'take the lead' in addressing GHG emissions (Preston 2020). Given the limited avenues for multilateral determination of fairness, several researchers have argued that the onus is on the scientific community to generate methods to assess fairness (Herrala and Goel 2016; Lawrence and Reder 2019). Peer-to-peer comparisons also potentially create pressure for ambitious NDCs (Aldy et al. 2017)." [emphasis added]

3. Climate change mitigation and the judiciary 

In the Urgenda Judgment, the Dutch Supreme Court ruled that the determination of “the share to be contributed by the Netherlands in the reduction of greenhouse gas emissions is […], in principle, a matter for the government and parliament.” However, the Supreme Court found that, “under certain circumstances, there may also be such clear views, agreements and/or consensus in an international context about the distribution of measures among countries that the courts can establish what – in accordance with the widely supported view of States and international organisations, which view is also based on the insights of climate science – can in any event be regarded as the state’s minimum fair share” (paragraph 6.3). In this regard, the Supreme Court assumed a reduction percentage of 25-40% in 2020 for the Netherlands (as laid down in Annex II to the Effort Sharing Regulation for Annex I countries) and assumed that this percentage corresponds to the Netherlands' capabilities and responsibilities (paragraph 7.3.4). As a result, the Supreme Court held that the lower limit of the Netherlands' obligation implies a reduction of at least 25% in 2020. The Supreme Court did not express an opinion on the extent to which the Dutch government should reduce its greenhouse gas emissions after 2020.

In the case of Verein KlimaSeniorinnen Schweiz and Others v. Switzerland before the ECtHR (application number 53600/20), the claimants point, among other things, to findings by Climate Action Tracker on Switzerland's fair share. Climate Action Tracker concluded that Switzerland could meet its fair share only by reducing its greenhouse gas emissions to well below zero: "[...] that to do its fair share to limit global warming to 1.5oC, Switzerland had to reduce its GHG emissions to significantly below zero by 2030”, paragraph 78). However, the ECtHR is cautious and does not (extensively) address the extent of Switzerland's fair share. The ECtHR concludes that Switzerland is not meeting its climate obligations because the Swiss CO₂ Act of 2011 was inadequate and the Swiss Climate Act of 2022 lacked concrete measures. Incidentally, the Court’s ruling does take into account the fact that, under its current policies, Switzerland would exhaust its remaining carbon budget by 2034, with the ECtHR referring to the fair share approach equal per capita emissions and to the fair share principle of common but differentiated responsibilities: 

"569. [...] In a scenario with a 34% reduction in CO2 emissions by 2030 and 75% by 2040, Switzerland would have used the remaining budget by around 2034 (or 2030 for an 83% change). Thus, under its current climate strategy, Switzerland allowed for more GHG emissions than even an "equal per capita emissions" quantification approach would entitle it to use. 

571. [...] the principle of common but differentiated responsibilities under the UNFCCC and the Paris Agreement [...]. This principle requires the States to act on the basis of equity and in accordance with their own respective capabilities. Thus, for instance, it is instructive for comparative purposes that the European Climate Law provides for the establishment of indicative GHG budgets." 

The equal per capita emissions approach is one of the equity approaches that climate science believes can serve as a basis for a reduction commitment as shown below. This approach distributes the remaining carbon budget equally among the world's population. This means that the carbon budget per country is determined by the number of inhabitants multiplied by the budget available per individual. In the next section, we address the climate case of Bonaire and Greenpeace v. the Netherlands and the different equity approaches from climate science.

4. Ongoing climate cases

In a number of ongoing cases, the issue of the extent of a state's obligation to mitigate climate change and the associated greenhouse gas reduction pathway plays a (central) role. Below, we address (1) the climate case of Bonaire and Greenpeace v. the Netherlands; (2) the case of VZW Klimaatzaak and others v. Belgium; and (3) the request for an advisory opinion to the International Court of Justice on the obligation of states in respect of climate change.

1. Climate case of Bonaire and Greenpeace v. the Netherlands

In the climate case of Bonaire and Greenpeace v. the Netherlands, eight residents of Bonaire and Greenpeace Netherlands argue that the Dutch State is committing a tort by failing to implement effective climate policies. In short, they are claiming on the one hand the adequate protection of Bonaire and its residents against the consequences of climate change (adaptation), and on the other hand that the Netherlands reduce its greenhouse gas emissions faster than planned (mitigation). They argue that the current Dutch climate policy does not meet what can at least be considered a fair share obligation of the Netherlands and that the Netherlands should take its fair share of the global effort to reduce greenhouse gas emissions, given its historical emissions. 

According to the claimants, the state must take all measures to reduce national greenhouse gas emissions. To this end, they are primarily demanding that national emissions be reduced to net zero by 2030, alternatively a (net) emission reduction in 2030 of 95% compared to Dutch emissions in 1990, and as a further alternative a (net) emission reduction in 2033 of 94%, including a 100% CO2 reduction, in 2033 compared to 1990 (page 211). Within these emission reduction targets, national emissions may according to the claimants be reduced by the emission reductions achieved abroad through Dutch international climate finance efforts. These demands exceed the current ambition of the Dutch government to be (net) climate neutral by 2050. 

To calculate the fair share of the Dutch State, the claimants are relying on insights developed in climate science. They cite, among other things, the Research by Rajamani et al. (2021), the International Institute for Applied Systems Analysis (IIASA) Report (2023), the NewClimate Institute Report (2022) and the Climate Action Tracker website (2021), from which the claimants derive the following principles:

• Rich countries should be expected to do relatively more than poor countries. According to the claimants, this follows from the equity principle and the principle of common but differentiated responsibilities ('CBDR'). These two principles were identified in the study by Rajamani and others as 'fairness principles guaranteed under international law' (together with the principles of sustainable development, special circumstances, do not harm and precaution). According to the claimants, the principles of equity and common but differentiated responsibilities justify the difference in responsibility: countries have contributed differently to climate damage through current, historical and foreseeable emissions, so they also bear different degrees of responsibility (paragraph 26.3).

• Long-term target of 1.5°C determines the remaining global carbon budget to be distributed. In this regard, the claimants are arguing that the IPCC scenarios should not serve as the basis for a fair share allocation because the IPCC does not take into account 'fairness principles' (paragraph 26.8). 

• A country should observe the highest possible level of ambition, despite the fact that a country's contribution depends on its specific circumstances. The claimants point out that this also underlies the methodology on which the Climate Action Tracker is based (paragraph 26.10). 

• If the state does not provide sound reasons as to why its own contribution satisfies the fairness principles, that in itself may be a ground for finding that a state does not do is fair share. The claimants point out that this was explicitly established in the Urgenda judgment (paragraph 26.12). 

• Effort sharing approaches that cannot serve as a basis for the reduction obligation are 'grandfathering' and 'least-cost'. This, according to the claimants, follows from the study by Rajamani and others, because the approaches of 'grandfathering' (distribution of carbon budget in proportion to historic emissions) and 'least-cost' (reduction obligation based on cost-effectiveness) allegedly do not take into account the principles of equity and CBDR and allegedly are not be in line with the principles of the UNFCCC and the Paris Agreement (paragraph 26.16). 

• Effort sharing approaches that can serve as a basis for the reduction obligation are 'responsibility', 'capability' and 'equal per capita emissions'. These approaches, according to the study by Rajamani and others, are based on one or more principles of international law, the claimants argue. Responsibility means that countries with higher historical emissions get a relatively small proportion of the remaining budget, capability means that countries with higher wealth can and should contribute more, and equal per capita emissions means distributing the remaining carbon budget equally among the world's population (paragraph 26.18). 

• If every country were to choose the most favourable effort sharing approach, the 1.5°C target will be exceeded. A state's fair share depends on the effort sharing approach used to calculate that fair share. The claimants indicate that, for example, the equal per capita approach for a country with high (historical) emissions leads to a significantly more favourable result than if that country's fair share is calculated based on historical responsibility (paragraph 26.19).

The claimants conclude that even if the Netherlands were to calculate its fair share solely on a per capita basis, Dutch emissions would have to be reduced by at least net 94% by 2033. According to the claimants, this follows from the various fair share analysis reports. Approaches that take into account both historical emissions and capacity to contribute, as well as per capita approaches, lead to a 95% reduction, and approaches based on (only) historical emissions and/or capacity conclude that the carbon budget available for the Netherlands has already been exhausted (paragraph 26.60).

2. VZW Klimaatzaak and others v. Belgium

In the Belgian case of VZW Klimaatzaak and others v. Belgium, the Brussels Court of Appeal (the "Court") addresses the extent of Belgium's fair share. 

In this case, the claimants argue that the Belgian authorities should have adopted a more ambitious climate policy. The claimants explicitly address Belgium's fair share and argue that the governments should have opted for an 81% (secondary 61%) reduction of greenhouse gas emissions by 2030 compared to 1990. They also refer to Rajamani's study and argue that developed states, with a high historical responsibility and GDP per capita, have in fact already consumed their fair share of emissions and should in principle net stop emitting from 2030 onwards (paragraph 186). On the basis of the equity approach of equal per capita emissions, which the claimants argue is 'minimally consistent with equity', the claimants demand an 81% reduction in greenhouse gas emissions in 2030 compared to 1990. Based on the equity approach grandfathering, a 61% reduction in greenhouse gas emissions in 2030 compared to 1990 has been set by the claimants, which the claimants say is the "minimum minimorum" to effectively address the climate emergency and is beyond any margin of appreciation (paragraph 189).

However, the Court is cautious, stating that the principle of separation of powers prohibits the Court from setting a greenhouse gas reduction rate that it considers desirable or equitable in the light of Belgium's historical responsibility for greenhouse gas emissions. The Court can only assess whether the State has taken sufficiently appropriate and reasonable measures, taking into account the knowledge available at the time (paragraph 190). Furthermore, in the absence of a political consensus as to which allocation key is 'fair', the Court can only take into account an allocation key that is least restrictive for the state (paragraph 192). 

On the basis of the best available climate science, the precautionary principle and the international political consensus, the Court cannot conclude in this case that only a scenario of a 61% reduction in greenhouse gas emissions by 2030 compared to 1990 would be compatible with the state's obligations under Articles 2 and 8 of the ECHR (paragraphs 195 and 214). The Court considers that given (i) the consensus within the European Union to reduce greenhouse gas emissions by at least 55% by 2030 compared to 1990, and (ii) the fact that the Belgian State is in a more favourable position than many other European states in terms of its ability to contribute, there is no doubt that the 55% reduction is a minimum if it wishes to comply with its obligations to protect human rights (paragraph 202). 

As a result, the Court ruled on 30 November 2023 that the climate policies of the Federal State and the Brussels and Flemish regions were unlawful. It ordered a reduction of at least 55% in greenhouse gas emissions by 2030. On 18 April 2024, (only) the Flemish region appealed the Court’s decision.

3. Request for an advisory opinion of the International Court of Justice

On 29 March 2023, the United Nations General Assembly adopted a Resolution requesting an advisory opinion of the International Court of Justice on the obligations of states in respect of climate change. The request specifically asks for an opinion on the responsibility that states bear with regards to vulnerable states, including small island developing states, and to present and future generations affected by the adverse effects of climate change. 

States had until 15 August 2024 to submit written statements. Sixty-two states made use of this opportunity. The first public hearing in the case is scheduled for 2 December 2024. 

5. Finally, what are the potential implications for companies?

In the cases addressed above the question is raised whether developed countries should not be climate neutral (long) before 2050 already, given their fair share. Although these cases are brought against governments, they are also relevant for companies, as these cases can force governments to take more stringent mitigation and adaptation measures. If the courts explicitly rule that climate neutrality must be achieved earlier (than 2050), this could lead to stricter regulations and reduction obligations for companies. It is therefore important for governments and companies to monitor these cases.