The Erga Omnes Character of Climate Change Mitigation: a New Dimension to the Doctrine of Necessity?

By Aaryyan Aathreya

Aaryyan Aathreya is a second-year law student from School of Law, SASTRA University India. He is passionate about Public International Law and International Dispute Settlement.


Climate change is unequivocally one of the most challenging issues that the international community has been mandated to deal with. International Environmental Law (‘IEL’) is faced with a diabolical paradox insofar as mitigating the adverse effects of climate change is concerned. 

On the one hand, there is judicial ambivalence regarding the legal character of norms that underlie climate change mitigation obligations under relevant international instruments. For instance, the International Court of Justice (‘ICJ’) has characterized the precautionary principle as an “approach” rather than a principle of IEL, in the Pulp Mills and Construction of a Road cases. In the case concerning the Gabcikavo-Nagymaros Project, the ICJ had regarded sustainable development as an “objective” as opposed to a principle. 

On the other hand, there has been a proliferation of decisions and resolutions adopted by the Conference of Parties (‘COP’) of Multilateral Environmental Agreements (‘MEA’) that require state parties to reduce the negative impact of climate change mitigation activities— albeit their legal character is normative at best. In accordance with the principle of common but differentiated responsibilities, developed state parties are required to take the lead in combating climate change and developing state parties are obligated to contribute only in accordance with their respective capabilities and common but differentiated responsibilities. However, with the enactment of the Paris Agreement, the gap between developing and developed state parties has reduced. Several developing countries have submitted and continue to submit their Nationally Determined Contributions (‘NDCs’), in accordance with their obligations under Article 4 of the Paris Agreement.

 However, in light of the judicial ambivalence regarding principles of IEL and the several COP decisions under MEAs, how should countries characterize climate change mitigation obligations as a norm of IEL and thereby successfully resolve the conflict between obligations under climate change treaties and other MEAs? 


Apart from the UNFCCC, its Kyoto Protocol and the Paris Agreement, other key MEAs whose decision-making bodies have inter alia dealt with climate change include, but are not limited to, the Convention on Biological Diversity (CBD), Convention on the Conservation of Migratory Species and Wild Animals (CMS) and the Convention on the Conservation of Bats in Europe (EUROBATS)

From as early as 2008, the COP to the CBD had adopted decisions to warn state parties of the potential negative impacts of climate change mitigation activities. In its decision IX/16, the COP had urged state parties to increase the positive and minimise the negative impacts of climate change mitigation activities. This has been successively reaffirmed using stronger language by the COP of the CBD in 2010, 2014, 2016 and 2018

The Secretariat to the CMS has adopted resolutions 7.5, 11.27 and 12.21 that call upon state parties to minimize negative effects of climate change mitigation measures because they allegedly have the most immediate negative impact on migratory species. In a similar vein, the COP of the EUROBATS, in resolution 8.7, has also urged state parties to adopt mitigation measures whenever activities are undertaken by state parties to mitigate climate change. There is also growing scientific evidence regarding the potentially harmful impact of mitigation activities on migratory species and the biodiversity as a whole. 

Despite the precarious stances adopted by decision-making bodies of these MEAs, the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) states— “mitigation involves some level of co-benefits and risks due to adverse side effects but these risks do not involve the same possibility of severe, widespread, and irreversible impacts as risks from climate change.” According to Conclusion 12 of the International law Commission’s Conclusions on the Creation and Identification of Customary International Law, resolutions adopted by intergovernmental organizations or conferences do not in themselves constitute customary international law— they may indicate towards the creation of customary international law in the future. Therefore, given the proliferation of decisions and resolutions adopted under the auspices of various MEAs that call upon state parties to minimize the negative impact of mitigation activities, there may be potential disputes regarding the specificities of such requirements in the future. 


Theoretically, there exists an ambiguity with respect to the legal character of erga omnes obligations and its enforcement before international adjudicatory bodies. Scholars,, such as Fitzmaurice, such as Fitzmaurice, have argued that the legal character of international obligations pertaining to climate change are not traditionally bilateral in character but have to be placed within the paradigm of obligations erga omnes. In para 31 of the judgement in the Barcelona Traction case, the ICJ had distinguished between obligations owed vis-à-vis another state and obligations owed to the international community as a whole. It is the latter set of obligations that are regarded as obligations erga omnes. Contrary to the claim that it is quixotical to attribute responsibility for ambiguous obligations, it has been extensively suggested by scholars and organisations, that there is growing evidence that the duty to mitigate the adverse effects of climate change is erga omnes in character. 

The phraseology of Article 2 of the UNFCCC and Paris Agreement, which prescribe the objective of both the agreements, indicate that the obligations under them are owed to the international community as a whole. Furthermore, the IPCC 5th Assessment Report elaborately details the consequences of delaying additional mitigation measures to 2030, including the costs that it would entail for all states— financially and environmentally. 

Although climate change mitigation was not mentioned as an example of an erga omnes obligation by the ICJ when it rendered its Barcelona Traction judgement, it would, in all likelihood, be characterized as an erga omnes obligation since all states have a legal interest in the protection of the environment. If international adjudicatory bodies were to accept this characterization, it would no longer require them to determine the question of the prevalence of one MEA over another and would rather place climate change mitigation on an independent and higher pedestal under IEL. 


Although the doctrine of necessity under international law has been regarded as a virtual subterfuge, it is contributory to, and not subversive of international law, to the extent that it adequately compliments climate change mitigation measures. Customary international law and Article 25 of the ARSIWA preclude wrongfulness when there is a grave and imminent peril against an essential interest of a state, provided that it does not impair the rights of any state and the measure adopted by the state is the only means of doing so.

 According to the ICJ in para 54 of the Gabcikavo-Nagymaros Project judgement,, a “peril” appearing in the long term might be “imminent” as soon as it is established, at the relevant point in time, however far off it might be, if it is not thereby any less certain and inevitable. Since dangerous levels of anthropogenic emissions are very likely to have adverse effects on the environment and climate change is an incumbent concern, albeit its consequences may drastically appear only in the long term, it is a grave and imminent peril.

 In para 53 of its Gabcikavo-Nagymaros Project judgement, the ICJ held that the environment constitutes an essential interest of a state. However, by recognizing climate change mitigation obligations as obligations erga omnes, adjudicatory bodies and states could go one step further to argue and adjudge that mitigation activities not only protect the essential interest of a state, but that of the international community. 

With several means to mitigate climate change, the onus would be on each state to demonstrate how a particular activity is the only means available for the state pursuing the activity. If a state can successfully establish a causal link between the principle of sustainable development and the activity being pursued, it would be a strong defense in its favour under international law.

Finally, rather than impairing a state’s rights under various MEAs, climate change mitigation activities protect the rights of other states due to its erga omnes character. Consequently, wrongfulness may be precluded, if adjudicatory bodies are satisfied with such a characterization based on the facts and circumstances of each case. 


Climate change as a concern of International law has existed ever since the 1990s with the enactment of the UNFCCC Agreement. However, there has never been a dispute before the ICJ solely concerning climate change mitigation activities. Given the uncertain status of several norms of International Environmental Law in general, and norms that underlie climate change mitigation in particular, recognizing the erga omnes character of climate change mitigation activities would provide a new dimension to a general defence (the doctrine of necessity) under International law that has, until recently, only been cautiously explored. 

One thought on “The Erga Omnes Character of Climate Change Mitigation: a New Dimension to the Doctrine of Necessity?

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s