It is time for the health sector to respond to the reality of climate change by taking a moral and tangible leadership role in mitigation efforts around the globe, beginning with its own policies and practices.

No one knows the precise size of the health sector's global climate footprint, but we know that it is substantial. In all industrialized and many developing countries, provision of health-care services is a massive energy-intensive activity. The health sector is also a major consumer of water, computers, medications, food and other resources. This consumption enlarges the health sector's climate footprint beyond the mark made by energy.

Many health systems, particularly in Europe and North America, have begun to develop comprehensive strategies to reduce their climate footprint and move toward climate-neutrality. Many others are taking steps to address a particular aspect of the problem. Reducing the health sector's climate impact, however, is as complex as the broad diversity of health systems that exist in the world.

For instance, in many parts of the world it is necessary to improve the delivery of health care and this may require an increase in energy consumption. However, if such increases are accompanied by a focus on energy efficiency and the deployment of clean, renewable energy-generation technologies, then the delivery of higher-quality health care can coincide with a climate protection strategy.