Courageous advisory opinions in the realm of climate change. How to proceed?

• Introduction

The advisory opinions concerning climate obligations of the International Court of Justice, the InterAmerican Court of Human Rights, the Tribunal for the Law of the Sea (ITLOS), and the judgment of the European Court of Human Rights (ECHR) in Klimaseniorinnen v Switzerland are groundbreaking. They emphasise, inter alia, the urgent need to majorly reduce GHG emissions at great pace.

There are no one size fits all climate obligations: the common but differentiated responsibilities and respective capabilities (cbdrc) feature., which “reflects the need to distribute equitably the burdens of the obligations in respect of climate change, taking into account, inter alia, States’ historical and current contributions to cumulative GHG emissions, and their different current capabilities and national circumstances, including their economic and social development” (ICJ at 148). The Courts embrace environmental rights and rights of and obligations towards future generations. The IACtHR adopts the right to a healthy climate (at 298-316) and a healthy environment (at 364-376; see also ICJ at 387-393).The opinions and the judgment offer a valuable framework for further developing the law. International adjudicators cannot, however, map detailed obligations of specific countries. The flipside of the coin is that – mostly national – courts have ample maneuvering room to decide future cases. Hence, time will tell how they will shape the law. This may impede a level playing field, the price of obstruction by some powerful players in the international arena.

• Mitigation

Keeping the increase of global temperature close to 1.5C global (a Herculean task) requires phasing out global GHG emissions within a few years. That is not going to happen. Global emissions are still rising. The impressive reductions globally effectuated by renewable energy and more efficiency are insufficient to counterbalance the shortfall by some major emitters and global economic growth. To present-day US government, money is the only value. On their bandwagon, other high emitters follow(ed) suit. In many countries the transition towards renewable energy is fraught with difficulties: lack of materials, particularly rare metals, people and (allegedly) money. Investors have become reluctant to invest in the transition, seeing that climate policies of quite a few countries are unpredictable and not credible: investors need stability. Data centers and AI require increasingly colossal amounts of energy. Hence, in any credible scenario the remaining carbon budget is very limited.

Society (mostly top-end developed countries) keeps focusing on the short term, at the same time paying lip service to the rights of nature, future generations, and the 1.5C-goal, or hide behind fig leafs: unfortunately, we have a few other priorities right now, but don’t worry, we will comply with our obligations. The past is prologue. A focus on the corporate world is potentially more promising. Enterprises can be sued before courts in multiple countries. However necessary in case of laggards, litigation is not the panacea. Litigation is costly, judgments are largely unpredictable and their delivery takes time. Enforcement may be problematic.

The better strategy might be to bring about a coalition of the willing from the corporate world, NGOs, international institutions and like-minded countries. They should determine the maximum reductions reasonably achievable in light of the cbdrc; the bar should be set high. A quid pro quo, e.g. a waiver oflitigation in case of compliance, may serve as an incentive to reach agreement and to comply with the same.

In the meantime credible experts, which should seek input from major stakeholders, could explore:

• – how to balance inter- and intra-generational interests and those of nature. Naturally, there is no answer that will appeal to all players. More likely than not, the interests of future generations and nature will come off worst because achieving the required reduction of global emissions would result in an almost standstill of the global economy. We should acknowledge that inconvenient truth and be prepared to answer the question: why shouldn’t we do more? Why is that truly impossible?
• – strategies to reduce GHG emissions, e.g. by phasing out fossil fuel subsidies (see ICJ at 427 and IACtHR at 143), high taxes, or other disincentives, on unnecessary air and sea travel, the consumption of meat, energy consuming, but unnecessary, products/services such as computer games and misusing AI for useless questions. (See for a comparable approach concerning other energy consuming activities IACtHR at 353).
  The money should be invested in reduction measures and/or put in a fund to alleviate the climate burden of vulnerable countries and nature. Most of these ideas are not new, but we need strategies to get the job done. Der Worte sind genug gewechselt, Laßt mich auch endlich Taten sehn! (Goethe).
• – strategies to discourage, or price, doing business with obvious laggards and perhaps also enterprises based in countries that are an obstacle to meaningful progress. That will ignite anger from one or more powerful countries. Hence, single countries put themselves at a competitive disadvantage if they would put such measures in place. The goal can probably be achieved by a coalition of the willing.
• – strategies to persuade investors to be reluctant to buy equity issued by States and enterprises which do not have a credible and by and large sufficient trajectory to curb their GHG emissions and comply with this trajectory, or create obstacles to the transition towards renewable energy.
• – the possible adverse consequences of specific rules and judgments. For instance: will enterprises move their production and/or seat to countries where sustainability is a curse, climate cases don’t stand a chance, or so-.called liberal judges face serious threats? Such a relocation would be detrimental to the climate and an undeserved gain for the relevant countries.

In some countries obtaining permits for the transition is a time consuming exercise. Some courts, probably not only in the Netherlands, confine themselves to a focus on the relevant domestic rules. They don’t balance these rules and the many sources of international and human rights law that require a swift transition. Courts should prioritise climate cases and be creative to get rid of unnecessary procedural obstacles to grant meaningful permits to effectuate the transition towards renewable energy. (Compare ICJ at 253, IACtHR at 540, 541, 544, 545 and ITLOS at 235.) Some of these recommendations seem low hanging fruit.

• Climate losses

 Future generations and our planet will be aghast by the world they have inherited: a planet scourged by a series of unprecedented natural disasters and a largely ruined biodiversity. The ensuing losses, not least the global cost of adaptation and the loss of biodiversity, will be astronomically high. The subsequent COPs leave little hope that international consensus how to distribute the burden can be reached, let alone to provide the money. 

International law creates climate obligations towards all States (the erga omnes-feature; see ICJ at 439 ff). Liability is based on wrongful acts (ICJ at 427). Liability for “damage caused to the environment, “in and of itself” — which may include “indemnification for the impairment or loss of environmental goods and services in the period prior to recovery” — and expenses incurred by injured States as a consequence of such damage” requires “full compensation”  (ICJ at 443 ff, in particular 443 and 450). “[R]eparation must “wipe out all the consequences of the illegal act and reestablish the situation which would, in all probability, have existed if that act had not been committed”” (at 450). “[E]xpenses incurred by injured States as a consequence of such damage” is a bit ambiguous, probably because the questions posed by the UN General Assembly seem to focus on “significant harm to the climate system and other parts of the environment” (ICJ at 1, pp. 8 and 9 supra a and b).( See also IACtHR at 278, 302, 303, 350, and 556-559). The ICJ doesn’t (explicitly) address the obligations under violated international law for other losses.

 It would be weird if, e.g., a low end emerging country, that has violated its reduction obligations, would have to contribute to the losses of a top-end affluent country, inter alia because the latter’s losses will be disproportionally high seeing the prices in that country; prices that (largely) flow from a carbon-intensive economy. The argument that the obligation can be offset against a counterclaim of the relevant country is unconvincing. It would mean that the vulnerable country would have to bear its own losses and have to contribute, albeit to a lesser extent, to the losses of a top-end affluent country.

More likely than not, enterprises will have to bear the brunt of such litigation. They already are defendants in claims for damages initiated by alleged US victims before US courts; see extensively https://www.climatecasechart.com/search?cpl=category%2FSuits+against+cor porations%2C+individuals&cpl=category%2FClimate+damage and IACtHR at 171. Seeing that the US majorly contributed to climate change, it would be unacceptable if US victims could reap most of the – unavoidably not unlimited – fruits of liability law, even less so in light with the US’ current stance concerning climate change. There are more reasons why liability law is an unattractive solution in most instances. It would be useful to discern the pros and cons.

In the meantime vulnerable countries and nature cannot be left to their own devices; in the same vein the separate opinions of the ICJ Judges Charlesworth (at 17 ff) and Yusuf (at 36 ff). They cannot wait until hell freezes over. Workable solutions to shoulder their losses have to be explored; see for elaboration Jaap Spier and Sam Wiegers, Climate Change: A Tragedy of Errors and Looking Away (L’Ircocervo 24 (2025) n. 1 p. 169- 206, https://lircocervo.it/).

• The role of courts

However important ground-breaking climate judgments are, one swallow doesn’t make a summer. Enlighted judges should – and some, such as Brian Preston, already do – publish, lecture and teach about viable avenues to deliver judgments that make a difference. They don’t need to pierce to the converted. Traditional judges who believe that the law can only be found in “the books” should be their audience. If one or more ideas gain sufficient, preferably wide, support, they may gain the status of an opinio iuris. The Oslo Principles and the Climate Principles for Enterprises, both available at https://climateprinciplesforenterprises.org/ offer recommendations and a host of references to the work of others.

The former ECHR judge Tulkens observed that “[t]he ECtHR should lie between conviction and responsibility. On the conviction side, it should be borne in mind that Convention rights are not Dead Sea Scrolls. We are not museum curators but actors. We are here to think human rights, to bring them to life … [and ensure that] these rights will have a meaning in the present reality” (Judicial Activism v Judicial Restraint: Practical Experience of This (False) Dilemma at the European Court of Human Rights, (European Convention on Human Rights Law Review 3 (2022),https://brill.com/view/journals/eclr/3/3/article-p293_002.xml?srsltid=AfmBOopbL7u3YK1oJBxeKbBtKxaP2khEYySQBSHN PoxfvCXCfKLWLRh z, p. 299).

At the end of the day, judges cannot ignore the outer limits of what is possible, unavoidably too little. In the same vein the ICJ: “a State acts wrongfully if it fails to use all means at its disposal to bring about the objective envisaged under the obligation, but will not act wrongfully if it takes all measures at its disposal with a view to fulfilling the obligation even if the desired objective is ultimately not achieved” (at 208, emphasis added; see also at 135). This is a sobering thought, not least to nature and future generations. That, I’m afraid, is an inconvenient truth in our wicked world: “[w]e tend to support our past decisions even if new information suggests they were wrong, we tend to think that examples that come readily to mind are more common than they are, and we are irrationally impatient” (Mark Carney, Values, William Collins, 2021, p. 46). “Irrationally”; we don’t have time for patience. When in our wheelchairs, grandchildren will pose very intrusive questions.