Introduction

1The outcome of climate change negotiations, United Nations Framework Convention on Climate Change 1992 (UNFCCC), Kyoto Protocol 1997 and the Paris Agreement on Climate Change 2015, didn’t envisage reducing greenhouse gases in proportion and within a time-frame that would be sufficient in ensuring a stable climate to allow ecosystems to adapt naturally to climate change which would help economic development to grow sustainably. This lack of progress relating to mitigation also owing to anthropocentric approach to deal with environmental issues led to political and scholarly interest in alternative responses to climate change, adaptation and climate geo-engineering. The latter is the focus of this paper, which is defined as “deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change” (The Royal Society, 2009). The Intergovernmental Panel on Climate Change (IPCC) divides climate geo-engineering into two categories. The first is Carbon dioxide removal (CDR) that is techniques that aim at removing the carbon dioxide (CO₂) directly from the atmosphere by either increasing natural sinks for carbon or by using chemical engineering to remove the CO₂ with the intent of reducing the atmospheric concentration of CO₂. The second is Solar radiation management (SRM), which “involves reflecting more sunlight from reaching the Earth’s surface” (IPCC, 2014). The SRM comprises atmospheric, terrestrial and space-based approaches. The paper focuses on climate geo-engineering which uses atmospheric means to inject sulfate aerosols into stratospheric layer also called Stratospheric aerosol injection (SAI), which should increase the capacity of the Earth to reflect sunlight from reaching the Earth.

2The SAI activity designed to induce change to the stratosphere by its very nature will have trans-boundary consequences, which is violation of the universally accepted customary (ICJ, 1996, § 29) international environmental law rule of no-harm. Those conventions which are indirectly applicable in regulating SAI – i.e. Environmental Modification Technique Convention (ENMOD) 1977, United Nations Convention on the Law of the Sea (UNCLOS) 1982, London Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1972 (London Convention) and the Protocol 1996 – are outside the scope of this paper. The no-harm rule is the fulcrum around which paper revolves. Since there is no dedicated convention to deal with geo-engineering, the objective of the paper is to understand and analyze the extent to which no-harm rule can be relied upon in meeting the pre-operational phase and post-operational situations of SAI activity. In the paper, the words climate engineering or geo-engineering and SAI or solar geo-engineering have been interchangeably used.

3The no-harm rule is a due diligence obligation comprising a number of prevention duties. One of them is conducting Trans-boundary Environmental Impact Assessment (TEIA). The latter has been affirmed by the International Court of Justice (ICJ) in a number of decisions (Pulp Mills case, ICJ, 2010, § 203-210; Costa Rica v. Nicaragua and Nicaragua v. Costa Rica, ICJ, 2015, § 101-105 and § 142-162) as part of customary international law. As the effects of environmental degradation are generally felt after some years, another relevant procedural tool known as the post-environmental impact assessment (EIA) monitoring needs to be considered for regulation of trans-boundary harm. The paper also dwells on the responsibility of private persons who might be involved at some stage in the acts of geo-engineering.

4Since the SAI activity is likely to have harmful consequences for one or more States, it is important that it is preceded by a liability regime to compensate for the damage. The issue of liability is not settled in situations of non-accidental damage or for acts not prohibited by international law. The paper touches on Draft Articles of International Law Commission (ILC) to understand the status of liability when an act, not prohibited by international law, results in trans-boundary harm.

5The capacity of no-harm rule to independently respond to geo-engineering linked trans-boundary harm is doubted amongst scholars. The paper finds in interactional international law theory an interpretive tool to defend as to why no-harm rule will still remain as the mainstay to regulate the behavior of States in addressing significant trans-boundary concerns.

No-harm rule and SAI activity

6The legal responsibility emanates from the breach of positive obligations undertaken by States or imposed on them by international law. In environmental issues, responsibility emanates from the breach of customary international obligation or from the breach of treaty obligation. Since there is no specific treaty governing geo-engineering, it is pertinent to rely on the no-harm rule to regulate the behavior of States engaged in SAI. This rule involves to put certain limits to the SAI activities and foresees some impact in terms of responsibility of States. The rule says that States have a duty to prevent or minimize significant trans-boundary harm to the territory of other States or areas beyond national jurisdiction. The significance of the rule can be measured from the evidence that it has been able to make judicial tribunals and international environmental lawyers rely on it in understanding trans-boundary pollution and in the management of shared natural resources. Since the legendary Trail Smelter arbitration award 1941 (United States v. Canada, 1938 and 1941), the rule has been recognized as part of the customary international law in a number of judgments (ICJ, 1996, § 29).

7In the Corfu Channel case, a dispute between Albania and Britain, the ICJ posits knowledge as the basis of state responsibility. The ICJ held Albania on the ground, inter alia, of “every State’s obligation not to allow knowingly its territory to be used for acts contrary to the rights of other States” (ICJ, 1949, p. 22). The word “knowingly” is clarified by Judge Alvarez in his opinion in the case saying “Every State is bound to exercise proper vigilance in its territory. A State which fails to exercise this vigilance, or is negligent in its exercise, will find its responsibility involved in case of injury caused in its territory to other States or to their nationals” (ICJ, 1949, p. 44).

8The Principle 21 of the Stockholm Declaration 1972 and the Principle 2 of the Rio Declaration capture the substance of state responsibility. The overwhelming influence of the rule is further affirmed through its progressive inclusion it in recurrent treaty provisions, in recommendations made by international organizations, resolutions adopted in the international conferences, and the other texts that can be said to represent state practice.

9As per the rule, the States are obliged to conform to the established procedural international environmental law rules of conduct, the duty to notify, duties relating to the ongoing exchange of information, the duties to consult and to negotiate in good faith, the duty to warn, and the duties relating to the settlement of disputes.

10However, it is generally recognized that the no-harm rule prohibits only the causing of significant harm. The 1996 Working Group on international liability for injurious consequences arising out of acts not prohibited by international law clarified “significant” as something that was not de minimis or not negligible but more than “detectable” and need not be at the level of “serious” or “substantial” (ILC, 1996, p. 108). Further, the harm must lead to real detrimental effects on such aspects as human health, industry, property, the environment or agriculture in other States which could be measured by factual and objective standards.

The risks of SAI and Trans-boundary Environmental Impact Assessment

11Similarly, in domestic law, a counterpart to EIA has emerged in international law known as the Trans-boundary Environmental Impact Assessment (TEIA). The latter is a procedure to evaluate how a proposed measure or project or activity will impact the environment beyond the borders of the State conducting the activity. Though it is still naïve in international law, the TEIA has been upheld by the ICJ in the Pulp Mills case as part of “the general international law where there is a risk that the proposed industrial activity may have a significant adverse impact in a trans-boundary context, in particular, on a shared resource” (ICJ, 2010, § 204). In the Court’s understanding a party would be considered to have failed to comply with due diligence, and the duty of vigilance and prevention which it implies, if a party planned works posing risks to the regime of the river or the quality of its waters did not undertake an environmental impact assessment on the potential effects of such works (ICJ, 2010, § 204).

12The Espoo Convention (Convention on Environmental Impact Assessment in a Trans-boundary Context) does lay down certain essential elements of a trans-boundary EIA, but the Convention does not bind them as they are not parties to it (UNECE, 1991). The Court pointed out that Principle 5 of the 1987 United Nations Environment Programme (UNEP) Goals and Principles of Environmental Impact Assessment, which are relevant as technical guidelines, merely provide that the environmental effects in an EIA should be assessed with a degree of detail commensurate with their likely environmental significance (UNEP, 1987). Therefore, the specific content of an EIA is for each State to determine in its domestic legislation or in the authorization process for the project. However, the Court was quite unequivocal in its finding that “an environmental impact assessment must be conducted prior to the implementation of a project” (ICJ, 2010, § 205). Though the deployment of the technique of geo-engineering is still in abeyance, the Court has sent a clear message to the entrepreneurs of geo-engineering to be ready for TEIA.

13In addition, several principles reflect the international law obligation to require TEIA. Principle 4 of the 1987 UNEP Draft Principles provides for EIA of planned measures that create the risk of trans-boundary harm. Principles 11 and 12 require notification, exchange of information, and consultation between States on activities likely to have significant trans-boundary environmental effects. The United Nations General Assembly (UNGA) took note of the Draft Principles and requested all member States to use them as guidelines in the formulation of bilateral or multilateral conventions regarding natural resources shared by two or more States, without prejudice to those principles already part of customary international law.

States, private persons and trans-boundary harm

14The forces of globalization and the States in pursuit of faster economic development have launched liberalization on a large scale, which has allowed private individuals to get actively involved in project designing, project development and project implementation. The private actors are being sponsored by the States in areas otherwise were in exclusive domain of States. As geo-engineering might be initiated by private actors or given the nature of geo-engineering private actors are likely to be sponsored by States, it merits explanation the extent to which private actors would be required to comply with the obligations of due diligence. As a general rule, the conduct of private persons or entities is not attributable to the State under international law. Circumstances may arise, however, where such conduct is nevertheless attributable to the State because there exists a specific factual relationship between the person or entity engaging in the conduct and the State.

15The advisory opinion given by the Seabed Disputes Chamber of the International Tribunal for the Law of the Sea (ITLOS) in February 2011 in Responsibilities and obligations of States sponsoring persons and entities with respect to activities in the Area (deep-seabed and sub-soil thereof) clarifies the responsibility of sponsoring States with reference to private actors. The Chamber relies on the recent ICJ judgment in Pulp Mills case to clarify the connection between “responsibility to ensure” and due diligence with reference to States sponsoring private persons in the Area. The Chamber finds the following paragraph of ICJ’s judgment suitable for its purpose: “It is an obligation which entails not only the adoption of appropriate rules and measures, but also a certain level of vigilance in their enforcement and the exercise of administrative control… such as the monitoring activities” (ICJ, 2010, § 197). Such pro-activity is something that the Chamber clearly expects from sponsoring States in regulating all stages of activities in the Area.

16The Chamber recognizes that the sponsoring State is under a due diligence obligation to ensure a potential contractor undertakes such an assessment prior to the submission of an application for a plan of work to the Authority (ITLOS, 2011, § 142).

Post-environmental impact assessment monitoring of measures

17EIA is a pre-operational phase procedural tool to predict the effects of a proposed measure and it cannot tell the effects to be entailed by a project after a decade or so. It is significant to note that the ICJ has recognized in the Gabčíkovo-Nagymaros case between Hungary and Solovakia that both “the awareness of the vulnerability of the environment and the recognition that environmental risks have to be assessed on a continuous basis have become much stronger” (ICJ, 1997, § 112) in international law, and thus should be taken into account by States when implementing existing obligations or contracting new ones. It is not disputed that customary international law obliges States to share and exchange information relevant for supervision and assessment of environmental impacts on a regular basis. The obligation of no-harm rule obliging States who have to undertake invasive projects to take all appropriate measures to prevent trans-boundary harm. With respect to particularly invasive or potentially very harmful developments, this aspect of the no-harm rule may require States to monitor continuously such developments to ensure that they do not cause significant trans-boundary harm.

18There is provision for post-EIA in the Convention on Non-navigational Uses of Water 1997 which requires its member States to exchange readily available data in the environment of international rivers to which they are riparian on a regular basis (Article 9). In international maritime law, the post-EIA monitoring is well established (UNCLOS, 1982, Article 204[20]). The Espoo Convention says in Article 7(1) that State Parties have to undertake continuous supervision of particularly invasive measures. The Chamber notes in the advisory opinion, discussed above, the Regulations relating to polymetalic nodules impose a direct obligation on sponsoring States (and contractors) to work with the Authority to ensure the “establishment and implementation of programmes for monitoring and evaluating the impacts of deep seabed mining on the marine environment” (ITLOS, 2011, § 142). Under general international law, there is no corresponding treaty provision that provides for post-EIA monitoring. A general requirement of post-EIA monitoring is derived from more general principles of international environmental law; those being the obligation to conduct trans-boundary EIA, the obligation to exchange information on a regular basis or the due diligence aspect of the obligation not to cause significant trans-boundary harm. The obligation to exchange information and the no-harm rule provide rudiments that could evolve into an obligation of post-EIA monitoring under customary international law (Bremer, 2017, p. 90).

Doctrine of necessity and non-compliance with no-harm rule

19Climate change poses an existential threat to mankind. Whether it fits in the category of grave and imminent peril does not get unanimous support. In future, geo-engineering (SAI) might be defended on the ground of necessity. The general defense of necessity is still controversial in international law (Agius, 2009). However, the concept codified by the International Law Commission (ILC) receives support by a number of scholars (Crawford, 2010, p. 179). Necessity as identified and codified by the ILC precludes the wrongfulness of an act inconsistent with an international obligation of the State only when the act is the only means to safeguard an essential interest against a grave and imminent peril; and does not seriously impair an essential interest of the State or State towards which the obligation exists, or of the international community as a whole (ILC, 2001, Article 25).

20It is important to note that in the Gabčíkovo-Nagymaros project case 1997, the ICJ with reference to the ILC concept stated that the defence of necessity was in fact recognized by customary international law and was available to States in order to evade international responsibility for wrongful acts (ICJ, 1997, § 40). In the Construction of Wall case 2004, the plea of necessity was taken by Israel (ICJ, 2004, § 136). All these cases point out the reasonableness of the doctrine of necessity. There are few cases of state practice where necessity has been successfully invoked which received international and political support. For instance, the Torrey Canyon incident did not evoke protests of the affected party, the ship owner, or other governments; it is the case to which scholars primarily refer to illustrate the state of necessity (Shaw, 2003, p. 712).

Would the victims of geo-engineering be eligible for compensation?

21The issue of compensation is salient in the context of potential harm from deployment of SAI technique or outdoor experiment of it. The States facing harm to be released from SAI activity might ask for ex ante assurances of compensation. In order to generate support for solar geo-engineering activity amongst States, it is important that there should be assurances of compensation in a situation of injury. The focus of international law has been on preventing problems and ex post on offering platforms to resolve disputes, not on liability or other processes that involve potential blame. One reason for this is that the States do not want to divert its focus and precious resources from economic development and people’s welfare and they are not interested in enumerating harm and attributing them. All these are likely to result in political tension. The next two paragraphs are aimed at understanding mostly from the yardstick of state responsibility debates in International Law Commission as to what international law might offer to a solar geo-engineering victim.

22The Stockholm Conference encouraged States “to develop further the international law regarding liability and compensation for the victims of pollution and other environmental damage caused by activities within the jurisdiction or control of such States” (1972, Principle 22). In the Chorzów Factory case, the Permanent Court of International Justice (PCIJ) made it very clear: “It is a general principle of law that every violation of an engagement involves an obligation to make reparation” (1928, § 73). The procedural tools emanating from due diligence obligation do not guide on the extent to which purely environmental harm would be compensable. It is a widely held view that the responsibility of States for trans-boundary harm depends on a breach of treaty, customary norm or the commission of prohibited act. There have been a handful of cases relating to trans-boundary harm that have actually given rise to formal dispute settlement and the issuance of compensation to the affected parties (Trail Smelter arbitration award, 1941; ICJ, 1949). Most trans-boundary concerns are resolved through negotiation or adoption of an agreement that regulates the issue at hand.

23In 1978, the ILC launched an arduous effort called Liability for Injurious Consequences for Acts not Prohibited by International Law to settle the issue of liability arising out of trans-boundary harm (§ 178). The ILC’s 1996 Draft Articles provide for strict liability, which means whether a State has exercised due diligence or not, it will be held liable (Article 1). As regards compensation, the Draft Article says on the nature and extent of compensation or other relief for a significant trans-boundary harm caused by an activity, that it should be settled by the State of origin and the affected party through negotiation, having regard to various factors mentioned in Article 22 and in accordance with the principle that the victim of harm should not be left to bear the entire cost. In effect, what was required as part of a balance of interests between the parties was equitable compensation rather than full compensation. The 1996 Draft Articles did not generate support amongst the sceptics in the run-up to its adoption by the UNGA and it was suspended in 1997 on further consideration of liability for damage. The 2001 ILC’s Draft Articles on the Prevention of Trans-boundary Harm contains little of relevance to liability, except for a non-discrimination principle which governs trans-boundary access to judicial or other procedures for preventive remedies and redress, and saving clause for obligations under other treaties or customary international law (Crawford, 2010, p. 97). In the March 2003 report, the Special Rapporteur for the topic, P. S. Rao, gave the reason why strict liability was not considered. He said:

State Liability and strict liability are not widely supported at the international level, nor is the liability for any type of activity located within the territory of a State in the performance of which no state officials or agents are involved. […] The case law on the subject is scant and the basis on which some claims of compensation between States were eventually settled is open to different interpretations. […] The role of customary international law in this respect is equally modest. (ILC, 2003, § 3)

24The focus of the Commission has shifted from liability to loss allocation among different actors involved in the operations of the hazardous activities. As solar geo-engineering holds potential for both relative benefit and harm, it would be preferable to shift from liability to loss allocation among different actors. In solar geo-engineering experiment and deployment, there might be both state and non-state actors which necessitate striking a balance of interests rather than making claims for compensation against an actor or States.

Compensation re-incarnated in Costa Rica v. Nicaragua judgment

25There are handful of cases where compensation has been awarded for trans-boundary harm to the injured party by the injurer. The Costa Rica v. Nicaragua is the first ever case adjudicated by the ICJ involving a claim for compensation for environmental damage (ICJ, 2018). In the case, ICJ adjudicated competing claims to a portion of the border area between the two States along the San Juan River, as well as allegations brought by each State accusing the other of violating the obligation to exercise due diligence to avoid causing significant trans-boundary harm. In the case, Costa Rica asked the Court to order Nicaragua to:

[…] make reparation in the form of compensation for the material damage caused to Costa Rica, including but not limited to: (i) damage arising from the construction of artificial canos and destruction of trees and vegetation on the ‘disputed territory’; (ii) the cost of the remediation measures carried out by Costa Rica in relation to those damages (ICJ, 2015, § 49).

In a separate phase of proceedings, the ICJ in an unappealable decision pronounced monetary compensation for environmental harm to Costa Rica, awarding the sum of US $ 378,890 and defended it by saying that it is consistent with the principles of international law governing the consequences of internationally wrongful acts, including the principle of full reparation (ICJ, 2018, § 156). The Court made it very clear that compensation is due for damage caused to the environment, in addition to expenses incurred by an injured State as a consequence of such damage.

26There are three elements in the judgment: first, the internationally wrongful acts on the part of Nicaragua, second, the Court seeking to establish whether there existed a direct and certain causal link between environmental harm in Costa Rica and Nicaragua’s wrongful acts and third, the Court’s embracing of overall valuation approach instead of clinical valuation approach in calculating the costs of damage to Costa Rica’s ecosystems, might help in a situation when a State does solar geo-engineering activity without conforming to due diligence standards proportionate to the size of the activity. Non compliance with due diligence obligation amounts to wrongful acts resulting in environmental damage to a neighbouring country that gives rise to an obligation of reparation. While assessing damage to environment, the Court applied overall valuation approach which is grounded in equitable consideration and that might find favour with solar geo-engineering actors, an act that involves both relative benefit and harm. Compensating for environnmental damage could generate support for solar geo-engineering.

Enforceability of no-harm rule

27The previous precedents try to understand the formulation, content and the scope of topic, applicability of no-harm rule in influencing the behavior of state and non-state actors of SAI involving release of potential trans-boundary effects by it. It also discusses the ex ante and ex post assurances, which are offered by the duty of conduct and the duty of result respectively in regulating the trans-boundary effects of hazardous activity, which also include SAI.

28Although the no-harm rule is a binding rule of customary international law, the potential of the no-harm rule to respond independently to the risks of SAI is downplayed owing to the fact that it lacks clarity and specific guidance on how the States should proceed with geo-engineering (Bodansky, 1996, p. 312). In Bodansky’s view, States have a wide discretion in their interpretation of the no-harm rule with respect to geo-engineering. He is of the view that at best general principles (including no-harm rule) may provide a frame of reference within which States can debate geo-engineering governance (Bodansky, 1996, p. 312-313).

29J. Brunnée and S. J. Toope (2010) have developed interactional international law which demonstrates that the no-harm rule has capacity to generate legal obligation that can influence the behaviour of state and non-state actors. The theory draws on the constructivist school of international relations theory and L. L. Fuller’s criteria of legality. Constructivists argue how shared norms emerged from shared social understandings which are fostered by social structures. In interactional law theory, the legitimacy of legal norms, and hence their capacity to generate a sense of legal obligation are contingent on whether they meet three key elements: (a) shared understandings, (b) Fuller’s eight criteria of legality, and (c) a practice of legality (Brunnée, & Toope, 2010, p. 53-54). Shared understandings are a common understanding between actors on the need for a legal norm and what the norm entails. According to Brunnée and Toope, shared understandings are background knowledge or norms that shape how actors perceive themselves and the world, how they form interests and set priorities and how they make or evaluate arguments. Interactional law theory holds a strong sense of legal legitimacy and legal obligation norms must also satisfy Fuller’s eight criteria (Brent, McGee, & Maguire, 2015): (i) General applicability of rules (Brunnée, & Toope, 2010, p. 46-47); (ii) Promulgation of rules so that subjects are aware of the law (p. 49-51); (iii) Rules must be imposed prospectively (p. 51-62); (iv) Laws need to be clear to be correctly applied (p. 63); (v) Legislator must avoid laws to contradict one another (p. 65); (vi) Law should not demand the impossible of the subject (p. 70); (vii) Laws should remain constant over time and should not be changed too frequently (p. 79); (viii) Those responsible for making and enforcing law should comply with the law to maintain the integrity with a system (p. 81).

30According to Fuller, norms that satisfy the eight criteria of legality generate fidelity to law (1969, p. 39-41). As per the interactional international law, no-harm rule will generate fidelity to law in situations of geo-engineering as it meets the three criteria. Meeting of the three key elements together will generate a sense of legal obligation without an element of coercion or without any anticipated gain based on cost-benefit analysis resulting ultimately in automatic compliance with standard of care required in situations of geo-engineering. Since Trail Smelter award till date, the decisions of arbitration awards and the ICJ decisions have upheld no-harm rule consistently. The decisions have further identified some more procedural duties in those decisions that have strengthened belief in the capacity of no-harm rule to put some constraints on States’ behavior. The ILC’s Draft Articles relating to non-accidental harm (for acts not prohibited by international law) also say that the no-harm rule only applies to harm above a certain threshold. The States generally use the term “significant” to define harm above a certain threshold which means there is a magnitude of harm beyond which States do not tolerate trans-boundary harm. But it is not clear what it means in practical terms and how it is to be applied in the context of specific threats of trans-boundary harm, such as those arising from SAI. The understanding amongst States that harm above a certain threshold must be shared by them is evidenced by a 1985 survey of state practice by the ILC. The ILC, in its commentary on Draft Articles, has given meaning of “significant”, which is something more than “detectable” but need not be at the level of “serious or substantial” (1996, p. 108). The harm must lead to a real detrimental effect, which must be susceptible of being measured by factual and objective standards.

Conclusion

31In the absence of a treaty governing SAI, the States are going to rely on no-harm rule when it is facing damage to human health, industry, property, environment or agriculture. The ICJ’s decision to compensate Costa Rica for damage caused to its environmental goods and services (2018, § 75) sets an example that would guide the potential victims of geo-engineering. The dispersed nature of effects by SAI is going to result in contestation of breach of threshold by the victim State and the State of origin. The ILC’s definition of significant or defining of threshold as something which is more than detectable but need not be at the level of serious or substantial is going to be relied upon by the victim State. The removal of subjectivity and accommodating all possibilities in terms of further refining the legal content of no-harm rule so as to allow the no-harm rule in addressing the risks of SAI can be met by having a treaty on geo-engineering.