A collaboration between The Lancet and University College London, UK, resulting in the first UCL Lancet Commission report, setting out how climate change over the coming decades could have a disastrous effect on health across the globe. The report examines practical measures that can be taken now and in the short and medium term to control its effects.

Climate change could be the biggest global health threat of the 21st century. Effects on health of climate change will be felt by most populations in the next decades and put the lives and wellbeing of billions of people at increased risk. During this century, the earth’s average surface temperature rises are likely to exceed the safe threshold of 2°C above pre-industrial average temperature.

This report outlines the major threats—both direct and indirect—to global health from climate change through changing patterns of disease, water and food insecurity, vulnerable shelter and human settlements, extreme climatic events, and population migration. Although vector-borne diseases will expand their reach and death tolls, the indirect effects of climate change on water, food security, and extreme climatic events are likely to have the biggest effect on global health.

A new advocacy and public health movement is needed urgently to bring together governments, international agencies, non-governmental organisations, communities, and academics from all disciplines to adapt to the effects of climate change on health.