What is the scope of States’ obligations regarding climate change? On 9 April 2024, the Grand Chamber of the European Court of Human Rights (ECtHR) issued a landmark ruling addressing this question in the European context. The Klimaseniorinnen v Switzerland case was the first to bring to the fore the connections between the effects of climate change on human health and the rights protected by the European Convention on Human Rights (Convention). The petitioners, an NGO representing more than 2,000 Swiss senior women as well as individual members of the organisation, argued that the Swiss government’s failure to implement sufficient measures to mitigate climate change infringed upon their rights to life and health as protected under Articles 2 and 8 of the Convention. In a sophisticated 260-page decision, the Grand Chamber of the ECtHR sided with the petitioners. Importantly, it found a violation of Article 8 (right to respect for private and family life), which it interpreted as ‘encompassing a right for individuals to effective protection by the State authorities from serious adverse effects of climate change on their life, health, well-being and quality of life’ [519].

The Klimaseniorinnen case serves as a prominent illustration of the ‘Paris effect,’ which refers to the influence of the 2015 Paris Agreement on climate-related legal proceedings. While State Parties to the Paris Agreement agreed to ‘pursue efforts’ to limit global warming to 1.5°C above pre-industrial levels, this goal was not binding. However, the Klimaseniorinnen indeed ‘sharpened the Paris Agreement’s teeth’ as the Grand Chamber not only reaffirmed this target but also imposed on States a duty of appropriate and consistent conduct in pursuing that goal.

Specifically, the Grand Chamber adopted a set of five criteria to assess State compliance with their obligations under the European Convention. It held that States must: (1) have ‘due regard to the need’ to specify a target timeline for achieving carbon neutrality; (2) establish intermediate greenhouse gas (GHG) emissions reduction targets and pathways; (3) provide evidence showing whether they have duly complied with these targets; (4) keep the relevant GHG reduction targets updated with due diligence; (5) and act timely, appropriately and consistently when devising and implementing the relevant legislation and measures [550]. These criteria are to be considered together and a shortcoming in one aspect will not necessarily amount to a violation of Article 8.

The Grand Chamber noted that the exact measures and methods adopted by States to comply with this obligation fall within their wide margin of appreciation. However, borrowing from the Paris Agreement again, it endorsed the principle of equity enshrined in this instrument, according to which States ought to act within their respective capacities [572]. In the case of Switzerland, the Grand Chamber found that the ‘absence of any domestic measure attempting to quantify [its] remaining carbon budget’ could not be viewed as complying with the State’s Article 8 obligations [572]. The Grand Chamber further cited Switzerland’s past failure to meet GHG targets and its failure to act in good time and in an appropriate and consistent manner [573], concluding that there was a violation of Article 8.

The outcomes of this landmark case are far-reaching. At the European level, not only will Switzerland need to revise its climate policies to meet the Court’s requirements, but this decision also provides an unprecedented roadmap for ECHR Member States to comply with their obligations under the Convention. This decision is thus likely to spur Member States into taking tangible actions to protect the environment, to avoid facing similar litigation.

Further, on the international plane, this decision can be expected to hold persuasive value in the context of ongoing climate-related proceedings. While not binding on other international courts, the Grand Chamber’s decision appears particularly well-documented and is anchored in an extensive review of relevant international, regional, and domestic instruments and case law [121-272]. It provides insightful interpretations of key global instruments – such as the Paris Agreement – that will also be considered by other international and regional bodies tasked with adjudicating similar questions. This decision thus constitutes a significant milestone promoting constructive judicial dialogue, enabling the consolidation of a consistent and coordinated legal framework regulating States’ obligations in combatting climate change.