Climate change is the greatest public health crisis of the 21st century. As consistently trusted messengers to the public, doctors and nurses have a crucial role to play in raising public awareness of the health threat posed by climate change and catalyzing action. The Medical Society Consortium on Climate and Health (Consortium) organizes major medical societies representing over 700,000 physicians and health professionals to carry three simple messages:- Climate change is harming Americans today, with people of color and communities living in poverty experiencing greater harm.- The way to slow or stop these harms is to decrease the use of fossil fuels and increase energy efficiency and the use of clean energy sources.- These changes in energy choices will improve the quality of our air and water and bring immediate health benefits.