Several years ago Praveen Kalra, MD, was doing research to prepare a talk about anesthesia when he read a report that stunned him: It said that each year, emissions from anesthetics used in surgeries harm the climate as much as the carbon dioxide emissions from 1 million cars.

“Wait, is this true?” wondered the Stanford University Medical Center (SUMC) anesthesiologist. Kalra knew that most anesthesia gases are not metabolized by the patient, but instead are exhaled and captured in ventilation systems that expel the gas out of the building and into the atmosphere. But he had not known the extent of the environmental damage. He dug for more information and found another unpleasant surprise: One of the common anesthetics used at SUMC, desflurane, produces greenhouse gas emissions at a rate 2,500 times higher than carbon dioxide.

Kalra led an effort for the California medical center to eliminate desflurane in favor of far less environmentally damaging anesthesia drugs such as sevoflurane. That change eliminated 1,200 tons of greenhouse gas emissions in 2020, Stanford Health Care reports.

As hospitals increase efforts to reduce their carbon footprints, the SUMC experience illustrates the creative ways they are making progress, in addition to high visibility, high impact projects like switching to solar power and installing energy-efficient windows. While such major investments are essential, they must be supplemented by countless changes in the most fundamental ways that hospitals carry out their business — like re-sterilizing unused surgical tools and using hot water from a city’s woodchip incinerator to heat buildings.

Creative thinking is especially important after 61 of the nation’s largest hospitals, health sector companies, and nonprofits, including the AAMC, joined the Biden administration’s Health Sector Climate Pledge last month to reduce their greenhouse gas emissions by 50% by 2030 and to reach net-zero emissions by 2050.

Meeting that pledge will have a big environmental impact, given the health sector’s outsized contribution to greenhouse gas emissions around the world. A 2019 report, Health Care’s Climate Footprint, led by the international nonprofit Health Care Without Harm, concluded that “if the health sector were a country, it would be the fifth-largest emitter [of greenhouse gases] on the planet.” The biggest contributor is the United States, accounting for 27% of the global health care carbon footprint, the report said.

Hospital systems that have been working to reduce their greenhouse emissions shared their lessons about what works, in terms of both physical changes and new approaches for working with staff and communities.