Guest Commentary: The Meaning of “Fair Share” in Climate Ambition Litigation under the Paris Agreement

By Will Donaldson*

On June 15, 2022, the Municipal Court of Prague sided with a Czech climate NGO in Klimatická žaloba ČR v. Czech Republic, ordering the Czech government to create a more ambitious emissions reduction plan based on its obligations under the Paris Agreement (Press Release of Czech Climate Litigation). The Court drew on IPCC reports and the EU NDC to determine that the Czech Republic must take measures to reduce its emissions by 55% by 2030 compared to 1990 levels (Opinion, unofficial translation, paragraph 251). The court’s decision adds to a list of successful climate ambition cases that began with the Netherlands’ Urgenda decision in 2007. These cases, and pending cases in South Korea, Canada, the European Court of Human Rights, and Italy, face down a daunting question: what is a country’s “fair share” of effort to combat climate change?

The “fair share” question is difficult to answer because it requires a court to translate broad principles into a country-specific quantitative assessment of emissions reduction. Countries that signed the Paris Agreement have a duty to mitigate their emissions in order to keep global warming below 2°C, but that duty is not identical for each country. Principles of international environmental law such as equity and common but differentiated responsibilities (CBDR), adopted by the Paris Agreement and other international climate declarations, place a heightened duty on developed countries to combat climate change. Yet, these principles do not spell out to what extent a developed country’s “fair share” of effort is greater than the effort required by an average country (Will and Magner-Nestler).

Courts, litigants, and scholars have taken various approaches to fill this gap. In Urgenda, the Supreme Court of the Netherlands reasoned that even though reducing the Netherlands’ emissions would have little effect on a global scale, it is still responsible for its fair share. Lauded as a courageous decision, Urgenda laid the foundation for future ambition lawsuits by rejecting the drop-in-the-bucket argument and using climate science and international agreements to impose a specific emissions mitigation obligation on the Netherlands (Backes and van der Veen).

In Do-Hyun Kim et al. v. South Korea (pending), the plaintiffs argue that South Korea must adopt a more ambitious climate target based on a comparison to global averages. The plaintiffs calculated how much global emissions targets must decrease, in aggregate, to keep warming below 2°C. South Korea is especially obligated to reduce its emissions, since its per capita CO2 emissions are 2.7 times higher than the global average and its historic emissions are the 16th highest in the world. The plaintiffs concluded that South Korea should reduce its emissions target by at least as much as the necessary global average reduction, which would still require South Korea to adopt a more ambitious emissions target (Do-Hyun Kim Supplemental Complaint page 59).

Scholars and organizations such as Climate Action Tracker (CAT) have developed a sophisticated burden-sharing methodology to assign a fair share to each country. The first step in this approach is to assign a “fair share range” to each country based on the available effort-sharing literature, including IPCC reports. Next, CAT determines where on the range a country’s current climate target lands. Finally, assuming that every country’s target will fall on the same place on its range, CAT calculates the level of temperature change that would result. Professor Lavanya Rajamani and others has refined this analysis, distinguishing effort-sharing methodologies that accord with international law and those that do not to create more accurate fair shares. The plaintiffs in A Sud et al. v. Italy relied on a report of Climate Analytics, one of CAT’s parent organizations, in their complaint. The plaintiffs in Duarte Agostinho and Others v. Portugal and 32 Other States, before the European Court of Human Rights, also relies on CAT’s analysis to define fair share for 32 members of the EU.

While it remains to be seen whether the courts will side with the plaintiffs in these pending cases, the decision in the recent Czech Republic case is an encouraging sign because it accepted the binding nature of the Paris Agreement, found that climate change interferes with individuals’ rights, and because it engaged in transjudicial dialogue.

The Municipal Court of Prague found that the Paris Agreement Article 4(2) imposes an obligation on the Czech Republic to implement mitigation measures aimed at achieving its NDC (paragraph 248). The Czech Republic never established an NDC of its own, but the court determined that the EU-wide NDC requiring a collective 55% reduction in greenhouse gas emissions by 2030 must be interpreted to apply to individual EU members including the Czech Republic, since the Czech Republic is a direct participant in the Paris Agreement (paragraph 251). Therefore, the court ordered Czech Ministries to take mitigation measures to reduce greenhouse gas emissions by 55% by 2030, compared to 1990 levels (paragraph 328). The court also enjoined the Czech government from continuing to interfere with the plaintiffs’ rights. The Czech Constitution and the EU’s Charter of Fundamental Rights and Freedoms create a right to a favorable environment. The court interpreted this right to mean a right to live in climatic conditions “which allow the unhindered exercise of the needs of human life” (paragraph 213). The court found that this right was interfered with by the consequences of climate change, pointing to specific findings in the IPCC Sixth Report which describe climatic conditions in Europe. Even though the worst consequences of climate change have not occurred, any finding of a change for the worse can establish interferences (paragraph 223). The Czech Court also cited the Netherlands’ Urgenda decision and the United States Supreme Court’s decision in Massachusetts v. EPA.

The Decision in Klimatická žaloba ČR v. Czech Republic was a major victory for the climate and a valuable precedent for similar cases in Europe and around the globe. Even though the opinion of one national court is not binding on others, the Czech court’s engagement with transjudicial dialogue may encourage judges in the pending cases to draw on decision form other jurisdictions as well. Since climate change requires a global solution, transjudicial dialogue will be pivotal to mitigating climate change equitably and effectively.

* This blog post was edited by Maria Antonia Tigre. Will Donaldson is a law student at Columbia Law School and interned with the Sabin Center during the summer of 2022.

Global Climate Litigation Fellow at Sabin Center for Climate Change Law at Columbia Law School | Website | + posts

Dr. Maria Antonia Tigre is the Global Climate Litigation Fellow at the Sabin Center for Climate Change Law at Columbia Law School.