Fact check: What international regulations or agreements address geoengineering and weather modification?

1. Why the ENMOD Treaty Still Dominates the Legal Conversation

The primary binding international instrument directly addressing environmental modification for hostile purposes is the 1976 UN Convention prohibiting military or hostile uses of environmental modification techniques; it forbids weaponization while explicitly allowing peaceful applications, leaving broad latitude for non‑military geoengineering activities ^[1]. This creates a legal baseline: hostile uses face prohibition, but peaceful research or climate interventions are not banned by ENMOD. The treaty’s age and specific remit mean it does not contemplate modern climate interventions like SRM, so while ENMOD is legally significant, it is insufficient to govern contemporary geoengineering research, deployment choices, or cross‑border impacts ^[1].

2. Drafts and Non‑Binding Guidance Fill Some Gaps but Lack Force

A 1980 draft by the World Meteorological Organization and UNEP proposed cooperation between states in weather modification, providing a normative foundation for international collaboration and transparency but did not create binding obligations ^[2]. That draft has informed discussion and demonstrates early multilateral awareness of weather modification risks and the need for coordination. However, reliance on such drafts means governance remains largely aspirational: states can endorse cooperative principles without committing to enforceable standards or dispute mechanisms, which leaves substantive regulatory gaps for research protocols, environmental assessment, and liability.

3. Recent Scientific Advisories Demand a Global Review Mechanism

A May 2025 scientific brief by the UN Secretary‑General’s Scientific Advisory Board focused on Solar Radiation Modification and explicitly highlighted the absence of a comprehensive international framework to govern SRM research or deployment ^[3]. The brief called for a structured global review process that would evaluate SRM alongside mitigation and adaptation strategies, reflecting a scientific consensus that governance must be anticipatory and inclusive. This advisory perspective frames SRM as a policy decision requiring global scrutiny, yet it stopped short of proposing legally binding instruments, underlining the persistent gap between scientific recommendation and treaty‑level action ^[3].

4. Governance Advocacy Groups Push for Inclusive, Prudent Decision‑Making

Policy and civil‑society analyses, such as the 2018 Carnegie Geoengineering Governance Initiative report, stress the need for informed, prudent, and inclusive decision‑making before any large‑scale geoengineering is undertaken ^[4]. These reports catalogue potential ecological and geopolitical risks as well as possible benefits, urging multilateral deliberation and participatory governance to avoid unilateral deployments. The advocacy community’s emphasis on transparency and stakeholder engagement reflects a normative push for democratic legitimacy, yet it competes with state interests and technical actors who may prefer flexible, non‑binding arrangements—highlighting a governance tension between precaution and operational agility ^[4].

5. Biodiversity Frameworks Introduce Sectoral Constraints

There are regulatory frameworks under biodiversity conventions that address climate‑related geoengineering activities insofar as they affect ecosystems, signalling that sectoral treaty regimes are beginning to incorporate geoengineering considerations ^[5]. These frameworks tend to emphasize biodiversity protection and risk assessment, suggesting that any geoengineering proposal must account for ecological impacts. The emergence of such sectoral constraints creates a patchwork where different treaties impose overlapping but not comprehensive rules: ecosystem safeguards exist in some fora, yet a unified governance architecture for SRM or other climate interventions remains absent ^[5].

6. Where the Analyses Agree—and Where They Split

Across the documents, there is clear agreement that no single, enforceable international governance regime currently regulates geoengineering comprehensively; ENMOD covers hostile use, draft WMO/UNEP texts and biodiversity frameworks provide partial guidance, and scientific bodies call for new review mechanisms ^{[1] [2] [3] [5]}. Divergence appears in tone and prescriptions: advocacy reports emphasize participatory global governance and precaution ^[4], while drafts and sectoral rules indicate incremental, issue‑by‑issue governance. The practical implication is legal fragmentation: states and institutions will continue to negotiate responsibilities and norms through a mixture of treaties, soft law, and scientific advisories.

7. What the Existing Record Omits and Why That Matters

The assembled analyses reveal notable omissions: there is little in the cited material about enforcement mechanisms, liability regimes, compensation for transboundary harms, or concrete operational thresholds for governance activation ^{[2] [1] [3] [4] [5]}. These gaps matter because SRM or other geoengineering techniques could produce cross‑border impacts requiring dispute resolution and liability rules. Without those elements, the international system depends on voluntary cooperation and reputational pressures rather than enforceable obligations, leaving open the possibility of unilateral action or contested deployments that could trigger diplomatic crises and environmental harms.