jus ad bellum

Geoengineering Wars and Atmospheric Governance

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Published my latest article, written with Scott Moore of UPenn, “Geoengineering Wars and Atmospheric Governance,” in the The Harvard International Law Journal. A copy can be downloaded from SSRN here. Here is the abstract:

The increasingly harsh and unevenly distributed heat-related harms caused by climate change, together with frustration over the collective inability to respond to the crisis, are likely to make unilateral geoengineering efforts increasingly attractive. Stratospheric aerosol injection (“SAI”) is a form of solar radiation modification that is effective, technically feasible, and within the financial means of many states and even non-state actors. Yet, there are virtually no global governance structures in place to specifically regulate such activity, and existing international law would provide only weak constraints on unilateral SAI efforts. These features create incentives for unilateral action in what is known as a “free driver” problem: few constraints on a unilateral action that has low direct cost combined with immediate direct individual benefit despite widely distributed risks and indirect costs.

There would be significant collateral environmental and climatic harms associated with SAI. That, coupled with the high risk of unilateral action, is reason enough for both caution and stronger governance. But another risk posed by any unilateral SAI effort—one that is underappreciated and under-theorized—is that of armed conflict. We explore how and why states would likely perceive the potential risks associated with unilateral SAI effort as constituting a threat to national security, and in the absence of adequate legal and institutional mechanisms to constrain such unilateral action, might well contemplate the use of force to defend against the perceived threat. The Article explores and explains how and why the jus ad bellum regime is unlikely to prevent states from engaging in unauthorized use of force against unilateral SAI actors. (click “read more” below for full abstract).

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Discussing Kursk on Asymmetrical Haircuts: The International Justice Podcast

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It was a pleasure to be a guest on Asymmetrical Haircuts: The International Justice Podcast, to discuss the legal issues implicated by the Ukrainian incursion into the Kursk region of Russia in August of 2024, in the episode “Justice Update – Ukraine (Almost) Joins the ICC, and Invades Russia,” Sept. 6, 2024.

What was the International Legal Basis for the Strike on al-Zawahiri?

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(Published in Just Security, Aug. 9, 2022)

The killing of al-Qaeda leader Ayman al-Zawahiri in a CIA drone strike has been touted as a political win for President Joe Biden, a vindication for an over-the-horizon counter-terrorism strategy, and even as “justice served.” Yet there appears to be little interest in whether it was lawful. The media has not seriously raised the question, the punditry has not addressed it, and the government has not yet provided any official legal basis for the killing (to be fair, some law and policy blogs, such as Lawfare, Just Security, and Articles of War, have begun to address it). This disregard is problematic, as there are indeed serious questions as to the lawfulness of this strike – and people should be demanding answers.

Let us acknowledge up front that Ayman al-Zawahiri was the second-in-command of al-Qaeda at the time of the 9/11 terrorist attacks on the United States – which were heinous crimes, terrorist acts, and amounted to an “armed attack” against the United States under international law.

Nevertheless, his killing some 21 years later requires a legal justification under international law. What is more, the drone strike also constituted a use of force against Afghanistan, with which the United States is no longer engaged in an armed conflict – and so that too requires legal justification. This essay briefly reviews the international law regimes that are implicated (leaving aside entirely the domestic law considerations, such as the 2001 Authorization for Use of Military Force), and some of the questions regarding the lawfulness of the strike that arise under each regime – and argues that these questions are important.

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Geoengineering and the Use of Force

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(Published in Opinio Juris, Jan. 20, 2021).

It is now widely accepted that the climate change crisis is going to contribute to increasing levels of armed conflict among and within states in the coming decades. Less widely considered is the effect the crisis may have on the jus ad bellum regime. In a two-part essay in Opinio Juris (and in a much longer law review article), I have suggested that there will be growing pressure to relax the jus ad bellum regime when the more dire consequences of the climate change crisis begin to manifest themselves. That is, there will be mounting claims that the threat or use of force may be justified against those “climate rogue states” perceived to be recklessly and unlawfully contributing to the growing threat to international peace and security.

This argument may seem rather radical and unlikely from today’s perspective. But in this essay, I will examine how the case of geoengineering may help to illustrate just how some of the threats posed by climate change will create real tension for the jus ad bellum regime. The essay explores the hypothetical situation in which one country moves to unilaterally engage in a geoengineering scheme that many other states think will cause catastrophic harm to the climate and the ecosystem. How would the international community likely respond, and with what implications for international law?

Geoengineering

As most readers will know, the term geoengineering refers to large-scale intervention and manipulation of the environmental systems for purposes of either reducing the pace or countering the effects of climate change. There are many different avenues being explored, ranging from different methods of carbon dioxide removal (CDR), to various forms of solar management regulation (SRM). The latter is a broad category of methods that aim to lower or maintain the temperature of the Earth’s atmosphere by reducing the exposure of the Earth’s surface to the full brunt of energy from the sun.

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