Aaron (Ari) Bernstein, MPH ’09, has studied the health effects of climate change from many angles. As associate director of the Center for Health and the Global Environment at the Harvard Chan School, he has explored the public health effects of such environmental stresses as global warming and loss of biodiversity and has shared the science with students, educators, policymakers, and the public. As a hospitalist at Boston Children’s Hospital, he has treated young patients with asthma and infections connected to environmental degradation. He spoke recently with Madeline Drexler, editor of Harvard Public Health, about the public health threats that await humanity if it fails to reverse climate change.
Q: Right now, what is the most salient public health problem tied to climate change?
A: If you want to find some of the least healthy people on the planet, you can find them among those who have been forced to move from their homes. This happened in Syria, where the 2006 to 2011 drought forced pastoralists who lived in rural areas to give up their herds and move to cities, where they were not welcome. In a politically unstable country, that was the last straw on the camel’s back that turned the tide to violence.
It also happened in Somalia, where the drought that began in 2011 precipitated a famine, displacing millions of people into neighboring countries that could scarcely afford to take them in. The trauma, violence, infectious disease, mental health problems, and nutritional deficiencies of migration: This is a pattern we will continue to see. And these severe droughts are expected to be more common as climate change unfolds.
Q: From a public health point of view, will removing carbon from the atmosphere equally benefit rich and poor countries?
A: If we mitigate greenhouse-gas emissions, the health benefits in developing nations will actually be far greater than in developed countries. Think about events like Hurricane Matthew, which struck Haiti this fall. Forecasting models tell us that although hurricane frequency is likely to decrease, hurricane intensity is likely to increase over this century—we’re expecting more intense storms.
In a place like Haiti, there’s mass deforestation, huge potential for mud- slides. You throw at it this enormous storm with 145-mile-per-hour winds and 40 inches of rain—the consequences are wildly, wildly more severe for a place like Haiti than if that same storm with the same intensity hit any U.S. city.
Q: You’ve pointed out that some greenhouse gases directly influence plants. Why is that important to human health?
A: Greenhouse gases not only warm the atmosphere and alter the water cycle—they have direct effects on many species, including plants. If you elevate the concentration of atmospheric carbon dioxide, that changes the nutritional profile of certain staple food crops.