Jonathan Patz

APHA member Jonathan Patz, director of the Global Health Institute at the University of Wisconsin-Madison, presents during last week’s Climate & Health Meeting in Atlanta. By Lindsey Wahowiak, courtesy APHA.

The science is clear. Climate change is happening and it’s affecting our health.

That was the convincing message delivered by a panel of experts presenting at last week’s Climate and Health Meeting in Atlanta, hosted by APHA and others. Simply put, a changing climate affects our food supply, the spread of infectious disease, our water systems and air quality, and much more. All have significant impacts on human health.

“It’s the most important environmental health problem of our times,” said APHA member Jonathan Patz, MD, MPH, of the University of Wisconsin-Madison and a lead author of a report from the Intergovernmental Panel on Climate Change, who moderated the session “Connecting Climate Change and Public Health: State of the Science.”

Patz and other experts presented a staggering scientific case for climate action.

Extreme weather

In New York City, within 30-50 years, we could see a dramatic rise in the number of heat waves annually. “By mid-century that could triple to 39 days [each year],” said Patz.

APHA member Kim Knowlton, DrPH, with the Natural Resources Defense Council, explained how extreme heat increases premature death and illness: Our heart beats faster. We breathe more rapidly to cool ourselves when it’s hot out. This can lead to heat cramps and fatigue, or to more serious fainting and heat stroke, which can be fatal.

“It’s not just the heat exposures, it’s the vulnerabilities,” said Knowlton. Children, outdoor workers, athletes, seniors, poor and homeless people, and pregnant women are all at greater risk. “Preterm birth is linked to extreme heat,” she said. Many medications such as high blood pressure and allergy medicines make one more susceptible.

Climate change also increases the frequency and intensity of extreme weather events. Hurricanes, heavy rainfall and drought affect communities present immediate risks to health and can contribute to population displacement and uprooting of families.

Food supply

Our food supply is also affected by climate change. Not only are crop yields influenced by extreme weather fluctuations, but they also affect the nutritional value of our food and how we produce it.

“Climate change affects the quantity, quality and locations of where our food is produced,” said Samuel Myers, MD, MPH, of Harvard University. “As temperatures rise, parts of the world will simply become incompatible with prolonged physical labor.”

“We’re faced with uncomfortable requirements,” said Myers. We will need to significantly increase food production to keep up with demand, while food production will shift away from population centers to more hospitable regions nearer the Earth’s poles.

Infectious disease

Disease pathogens and disease transmission are likewise impacted by climate change. According to Glenn Morris, MD, MPH, with the University of Florida, “as we begin to see changes in our environment, we see new niches” for these pathogens to exist.

He outlined several examples: Vibrio species, which are agents for cholera, diarrheal disease and sepsis, live in water. Morris said we’ve seen rates of growth increasing rapidly with even moderate increases in sea surface temperature.

“One of the problems we’re seeing in Florida is Cyanobacteria,” he said. Driven by temperature, these agents can cause algal blooms harmful to marine ecosystems. Warming temperatures may permit seasonal expansion of vector species, he said. Elevated temperatures may expand the range of the vector such as mosquitoes or ticks.

Mental health

It’s not just physical well-being at risk. Climate change also threatens mental health.

Rising temperatures increase conflict between individuals and between groups, said Lise Van Susteren, MD, an advisory board member with the Center for Health and the Global Environment at the Harvard T.H. Chan School of Public Health. She called climate change both a multiplier and a root cause of climate anxieties that can contribute to an explosion of refugees, destabilization and political turmoil.

“In times of peril and adversity, people regress,” she said. Fears turn to anger and aggression. And it can lead to domestic violence, child abuse, trauma and sorrow.

Even those not directly impacted are affected. “It is painful to see people drowned, burned and flooded, right?” she asked.

The Climate and Health Meeting was hosted by APHA, former Vice President Al Gore and his Climate Reality Project, Harvard Global Health Institute and the Center for Health and the Global Environment at the University of Washington.

The meeting is part of APHA’s Year of Climate Change and Health, aimed at raising awareness of the impact of climate change on health and mobilizing action. The yearlong initiative culminates with the APHA 2017 Annual Meeting and Expo in November, themed Creating the Healthiest Nation: Climate Changes Health.

To view an archived recording of the meeting, visit