Climate change is the most urgent of multiple global crises now threatening human health. To minimize climate chaos and avoid dangerous tipping points, global CO₂ emissions need to fall by at least 9% every year until 2030 to keep global warming below 1.5°C above pre-industrial levels. Yet in 2023, CO₂ emissions increased by 1% – to around 40 billion tons a year. In 2024, the remaining carbon budget to “keep 1.5 alive” was around 200 billion tons. On present trends, it will be exhausted by 2030. We are heading for global ecological, social, and political catastrophe within our children’s lifetimes — and quite possibly our own.

How can global health law advance climate action and justice? Three lessons stand out.

First, Prof Larry Gostin and colleagues urged the international community over 15 years ago to focus on climate change adaptation as well as mitigation. They called attention to the disproportionate burdens of climate change on the world’s poorest and most vulnerable populations, exacerbating global health disparities. Keep in mind that G20 countries have contributed nearly 80% of historical CO₂ emissions, while least-developed countries have contributed 4%. Given these inequitable causes and consequences of climate change, states have obligations of international cooperation and assistance when in a position to assist; yet rich states have so far failed to take adequate, timely action to reduce greenhouse gas emissions and assist poorer states.

Second, Gostin and colleagues have long noted that states’ obligations to address the health impacts of climate change are grounded in international human rights treaties as well as national constitutions and laws. In response to government inaction, affected communities and populations (including young people, women and girls, Indigenous peoples, and other poor and marginalized communities in both developed and developing states) have taken legal action in national and international courts and tribunals. These human rights claims have often been persuasive, establishing legal obligations for climate action.

Third, assembling compelling science-based legal evidence of harms to human health, both physical and mental, requires close collaboration between health experts, legal professionals, and affected communities. The global response to HIV — long grounded in human rights, gender equality, and the leadership of people living with HIV and affected communities — demonstrates what can be achieved: global and national responses affirmed the rights and meaningful participation of people living with HIV and affected communities; billions of US dollars were raised and disbursed annually by the Global Fund and bilateral donors for HIV prevention and treatment, largely in the Global South; and the reform of World Trade Organization patent rules facilitated access to lower-cost HIV treatments. Despite these promising advancements in the HIV response, the more recent experiences in the COVID-19 response present a stark warning — where a lack of global solidarity led to vaccine hoarding by some rich states at the expense of Global South communities.

Prof Gostin’s decades-long contribution to global health law offers inspiration for climate action, and also lessons we ignore at our mutual peril.