In June, the American Medical Association, American Academy of Pediatrics and American Heart Association were among a long list of medical and public health groups that issued a call to action asking the U.S. government, business and leaders to recognize climate change as a health emergency. The World Health Organization calls climate change “the greatest health challenge of the 21st century,” and a dozen U.S. medical societies urge action to limit global warming. Some medical societies provide patients with information that explains the related health risks. But none have guidelines on how providers should talk to patients about climate change.