The global climate crisis is an existential threat for the planet. In 2022, climate and ocean surface temperatures were 1.15 ± 0.13°C higher than pre-industrial average values, indicating that we are in the warmest period in recorded history. Such temperature changes carry myriad risks with respect to extreme climate events, animal life, and human populations [1]. Climate scientists point to human activity as the central cause driving these changes. The release of greenhouse gases (GHG) such as carbon dioxide (CO2), methane, and chlorofluorocarbons constitutes the major cause of the global temperature increase [2].

Health care systems contribute substantially to GHG release globally [3]. Despite accounting for more than 18% of gross domestic product, the field of medicine receives less focus than other industries with respect to GHG emissions [4]. The urgency of the present climate situation demands that we in medicine reflect on our own contributions to the coming crisis. Clinical trials represent one space for reflection.

While they are indispensable methodological instruments for generating high-level evidence, clinical trials are exceptionally resource-intensive, accounting for billions of dollars in spending [5], [6]. In the context of the climate crisis, there is increasing focus on their environmental costs.

Here we provide an overview of the complex relationship between clinical trials and the environment. We highlight prior work that has quantified GHG emissions and propose strategies to minimize the carbon footprint of medical research.