In this publication, co-authors Dr. Wendy Levinson and Dr. William Silverstein highlight Choosing Wisely Canada’s national effort to reduce unnecessary tests, treatments, and procedures in health care, which not only improves patient safety but also helps mitigate the climate crisis. Collaborating with 21 professional societies, Choosing Wisely Canada has developed 41 actionable recommendations to decrease the environmental impact of clinical care. These recommendations target five areas of planetary harm: medications, energy use, waste reduction, travel, and purchasing. Examples include reducing the use of high-emission anaesthetic gases, promoting virtual care when appropriate, and avoiding unnecessary medical waste.