Ocean Acidification

Global warming threatens to eradicate Earth’s tropical corals. As legal interventions addressing climate change expand, fossil fuel companies’ historical awareness of their products’ damaging effects is increasingly important. We searched historical documents using a large-language-model-based agent, finding that carbon majors were aware by the 1980s of prospective impacts of fossil fuels on corals from ocean acidification, marine heatwaves, sea-level rise, and intensified storms and later funded efforts downplaying such impacts.

Introduction

The world’s tropical coral reefs are under imminent threat of collapse from global warming. Living corals have declined by approximately 50% worldwide since the 1990s, with global warming now the greatest threat to future survival¹. Global warming kills corals primarily through increased ocean temperatures and more frequent and intense marine heatwaves, which cause coral bleaching (loss of coral symbionts), exacerbated by ocean acidification (from increased carbon dioxide levels), which weakens coral health, and intensified storms (from increased sea surface temperatures), which physically destroy coral assemblages, all ultimately caused by fossil fuels¹. Approximately one billion people worldwide depend directly on coral reefs for livelihoods, food security, and protection from storms and coastal erosion, and coral reefs provide shelter and nourishment to over 30% of the world’s named marine species². Economically, coral reefs provide an estimated 10 trillion USD per year in ecosystem services, including tens of billions of dollars per year in coral reef tourism³, and potential efforts to restore reefs lost over the last decade alone have been estimated to cost around 1 trillion USD². Mass coral bleaching and mortality from marine heatwaves driven by global warming is ongoing⁴. The Intergovernmental Panel on Climate Change (IPCC) predicts mortality of 70—90% of the world’s reef-building corals at global warming of 1.5 °C and mortality of more than 99% at 2 °C¹.

Legal interventions may play a critical role in helping to protect the world’s coral reefs and associated ecosystems (for example, by securing funding for reef monitoring and rehabilitation) and in compensating affected communities for economic losses associated with climate-change-driven coral impacts. In this context, the history of fossil fuel industry awareness of the foreseeable impacts of climate change on coral reefs is highly relevant. Climate lawsuits against governments, fossil fuel producers, and other parties have expanded in number and sophistication over the past decade⁵ and have recently cited impacts on coral reefs⁶. Additionally, the 2024 and 2025 advisory opinions from the International Tribunal for the Law of the Sea (ITLOS)⁷ and the International Court of Justice (ICJ)⁸ on climate change clarified, respectively, that greenhouse gases are marine pollutants under the United Nations Convention on the Law of the Sea (UNCLOS) and that best efforts to attain the 1.5 °C warming limit of the United Nations Framework Convention on Climate Change (UNFCCC) Paris Agreement are legally binding on governments under international law, strengthening the basis for legal actions seeking to mitigate global warming and obtain reparations for damages. Research on the fossil fuel industry’s internal knowledge of global warming⁹, public-facing denial and minimization of the problem^10,11, and false assurances to be solving it¹² has clarified global warming as not only a scientific and technological problem but also one of corporate corruption subject to legal correction and remedy¹³. Such research has so far informed dozens of ongoing legal actions seeking industry accountability for climate change¹⁴.

Franta B., Patakota M. & Rutherford J., 2026. Assessing early oil industry awareness of the impacts of fossil fuels on coral reefs using a novel AI agent. npj Ocean Sustainability 5: 32. doi: 10.1038/s44183-026-00215-z. Article.