The effects of climate change on health are already here, from increasing food prices to floods. Doctors led the charge on tobacco—we must do the same for climate change.

It is the defining issue for health in the 21st century. By reducing our greenhouse gas emissions as health professionals, as well as citizens, we will also prevent disease.

The world is close to the critical thresholds of two degrees of global warming and 450 ppm (parts per million) of carbon dioxide equivalent emissions. We have 5-10 years to stabilise emissions to prevent catastrophic climate change. This requires action now.

Each person in the UK is directly responsible for about 10 tonnes of carbon emissions a year, divided evenly between energy consumed in buildings; transport (including one tonne on air travel); food production, distribution, and retailing; and consumption of goods and services other than food. About half of these emissions come from the home, and half from work and community infrastructure.

Our priorities require little money. Most mean …