Climate Change, Health Impacts, and State Obligations under International Law


The Sabin Center has recently published two reports on the connection between climate change, health impacts, and State obligations under international law. These reports are aimed at providing insights on issues to be analyzed by the International Court of Justice (ICJ) in its upcoming advisory opinion on climate change, and otherwise enhancing the capacity of judges, advocates, and governments to engage in legal proceedings involving questions about State obligations to protect health in the context of climate change. The first report, Climate Change and Human Health, synthesizes the latest scientific research on the human health effects of climate change and identifies State obligations to address those  effects under international law. The second report, Public and Human Health Implications of Climate Mobility, examines the critical nexus of climate change, mobility, and health, and describes State obligations to protect the health of migrants and people who are displaced by climate change.

Context for the Reports

 On March 29, 2023, the United Nations General Assembly adopted a resolution requesting an advisory opinion from the ICJ on the obligations of States with respect to climate change. The General Assembly requested that the ICJ render an opinion on: (i) the obligations of States under international law to ensure the protection of the climate system and other parts of the environment from greenhouse gas (GHG) emissions, and (ii) the legal consequences for States that have caused significant harm to the climate system. The ICJ is currently accepting written comments on this matter through August 15, 2024.

The ICJ advisory opinion is one of multiple legal proceedings aimed at clarifying State obligations under international and human rights law with respect to climate change. The International Tribunal for the Law of the Sea (ITLOS) recently issued an advisory opinion clarifying that State parties have treaty obligations (under the United Nations Convention on the Law of the Sea) to “take all necessary measures to prevent, reduce, and control marine pollution from anthropogenic GHG emissions.” The InterAmerican Court of Human Rights (IACtHR) has been asked to issue an advisory opinion on State obligations to protect human rights in the context of climate change. Other regional and domestic courts are also weighing in in these issues. In April, the European Court of Human Rights (ECtHR) issued a landmark decision recognizing that climate change threatens human rights and outlining minimum requirements for State action to control GHG emissions. Going forward, courts and tribunals will inevitably face additional questions about the specific nature of State obligations with regards to GHG mitigation, adaptation, and responsibility for climate change-related harms.

 Key Findings from the Reports

The existing scientific evidence makes it clear that climate change has significant adverse effects on human health and the underlying determinants of health, including transboundary effects that are highly inequitable in nature. Some of the primary drivers of harmful health effects include food insecurity and malnutrition; water insecurity; increases in food-, water- and vector-borne diseases; extreme weather events; ecological degradation; deterioration of air quality; and forced displacement and migration.

In some cases, the relationship between climate change and health impacts is relatively direct (e.g., death and injury from extreme heat). But climate change also disrupts human and natural systems in ways that create more indirect, long-term, and systemic risks to health. Climate change effects often interact in ways that create cascading and compounding hazards for human health. The effects on human mobility and displacement are a prime example: climate change contributes to human migration and displacement, while also intensifying the health-related risks that migrants and displaced people encounter in transit, and imposing additional stress on destinations that receive migrants and displaced people.

There are significant disparities in terms of exposure to health-related hazards from climate change, with lower-income regions and countries that have historically contributed less to climate change experiencing some of the most severe impacts on human health.  In addition, there are certain individuals and groups that are disproportionately affected by health hazards due to unique vulnerabilities. These include children, women, elderly and disabled people, indigenous people, subsistence farmers, and people who lack access to shelter, among others.

Based on the evidence of health impacts, the report on Climate Change and Human Health identifies a number of legal obligations for States that can be inferred from general principles articulated in customary international law, treaty law, and human rights law. For example, evidence of health-related harms provides ample support for recognizing a general duty on the part of States to mitigate their contributions to climate change, consistent with their duty to prevent harm to other States under international law, as well as their treaty obligations under the United Nations Framework Convention on Climate Change and the Paris Agreement. The evidence also provides a basis for recognizing State obligations to pursue adaptation measures where necessary to prevent or mitigate transboundary health effects from climate change, to provide international assistance and support in efforts to address the health effects of climate change, to provide compensation for their contributions to climate-related losses and damages (including health-related damages), and to assess and disclose the effects of State actions on climate change and health outcomes.

The report on Public and Human Health Implications of Climate Mobility provides a more in-depth assessment of health impacts associated with climate change-related displacement and migration, and characterizes State obligations to protect the health and well-being of migrants and displaced people. The report underscores the paramount importance of mitigating climate change to prevent forced displacement, but also finds that irreversible environmental changes necessitate anticipatory measures to protect migrants and displaced people, both in transit and in destination communities. States must uphold refugee and human rights law, refrain from returning people to danger, offer safe mobility pathways, and guarantee non-discriminatory access to resources and services essential to protect human and public health

The full reports can be downloaded from our website here.