The Lancet Countdown on health and climate change: from 25 years of inaction to a global transformation for public health.

Executive summary The Lancet Countdown tracks progress on health and climate change and provides an independent assess­ ment of the health effects of climate change, the implementation of the Paris Agreement, 1 and the health implications of these actions. It follows on from the work of the 2015 Lancet Commission on Health and Climate Change, 2 which concluded that anthropogenic climate change threatens to undermine the past 50 years of gains in public health, and conversely, that a comprehensive response to climate change could be "the greatest global health opportunity of the 21st century". The Lancet Countdown is a collaboration between 24 academic institutions and intergovernmental organ isations based in every continent and with representation from a wide range of disciplines. The collaboration includes climate scientists, ecologists, economists, engineers, experts in energy, food, and transport systems, geographers, mathematicians, social and political scientists, public health professionals, and doctors. It reports annual indicators across five sections: climate change impacts, exposures, and vulnerability; adaptation planning and resilience for health; mitigation actions and health co­benefits; economics and finance; and public and political engagement. The key messages from the 40 indicators in the Lancet Countdown's 2017 report are summarised below.