Climate change is real and is harming people’s health, according to a new report released Wednesday by the American Geriatrics Society and the 11 other organizations that are members of the Medical Society Consortium on Climate and Health.

“We — physicians in medical societies representing over half of the nation’s doctors — see a need to share our growing understanding and concern about the health consequences of climate change with all Americans,” the authors wrote in “Medical Alert: Climate Change is Harming Our Health.”

The elderly and people with chronic health conditions are among those who are most harmed by the extreme heat, weather emergencies and contaminated water or food that can be caused by climate change, according to the report.

The effects are going to get worse “unless we take concerted action,” the groups said.