Aaron Bernstein, MD, MPH, is a faculty member at Harvard Medical School’s Center for Health and the Global Environment and a pediatric hospitalist at Children’s Hospital Boston. He strives to promote a deeper understanding of the health effects of global environmental change, and is coauthor of Sustaining Life: How Human Health Depends on Biodiversity (Oxford University Press, 2008).
Remember last July? It was hot. During a three-day swelter early in the month, the mercury topped 100°F in Boston for only about the twelfth time in the past century. I wasn’t surprised when I found myself caring for many kids at Children’s who wound up with asthma attacks that left them gasping for air, while just trying to enjoy a summer day. Heat catalyzes the production of ground-level ozone, a potent lung irritant. It also poses particular troubles for kids with other chronic illnesses, including diabetes and kidney disease, in addition to causing dehydration and heatstroke.
Heat waves are nothing new, of course. But they are becoming more common and more severe with each successive year, owing to a build-up of greenhouse gases in Earth’s atmosphere, carbon dioxide (CO2) being the most important.
The burning of fossil fuels that began in the Industrial Revolution has produced enough greenhouse gases so far to warm the Earth’s temperature by 1.3°F. That increment may seem inconsequential, especially when held up against daily fluctuations in temperature, but it isn’t. If you collected daily temperatures you’d find that they distribute on a bell-shaped curve:
If you shift this distribution just a small amount, even 1°F, you can double the number of extreme heat days. That’s why 100-degree days are now occurring roughly every few years in Boston, whereas at the start of the last century they occurred once per decade. Presuming we don’t markedly reduce greenhouse gas emissions, our best estimates indicate that by 2100, we will have as many 100-degree days each summer as we’ve had in all of recorded temperature history to date.
The very gases that cause climate change, and in particular CO2, cause other health problems for kids. Take allergies. CO2 stimulates pollen production from some of the most allergenic plants around, like ragweed. If greenhouse gas emissions continue unabated, we can expect each ragweed plant to boost its pollen production — already estimated to have doubled since the Industrial Revolution — by a further 50 percent or more by 2100. Warming has also promoted an earlier start to spring and a later finish to fall that have translated into a longer allergy season and more days of misery for allergy sufferers.
As temperatures rise, more water evaporates from the Earth’s surface. This intensifies the water cycle, resulting in heavier individual downpours and longer intervals between them. This spells both more floods and more droughts. Floods cause property loss, injuries and outbreaks of waterborne disease, and the recent swelling of the Mississippi and Lake Champlain may be common events in the near term. Droughts, especially when joined with heat waves, wilt crops. Several studies have found that on the whole, climate change has already hindered and will continue to constrain our ability to grow food.
Climate change is also well on its way to being the leading cause of biodiversity loss. Biodiversity, or the variety of life on Earth — including all its genes, species and ecosystems — sustains essential life support systems, including the provision of air, water, and food, and also provides us with a source of medicines, many of which I regularly use each day.
These are but a small sampling of what’s at stake with climate change. As a pediatrician, there’s only so much I can do with a prescription pad to protect children’s well-being. For some matters, and climate change is one of them, I recognize that we must act in other ways to ensure the healthiest possible future. That’s why I cheer reasonable measures to reduce the release of greenhouse gases into our atmosphere, primarily from the burning of fossil fuels such as oil, gas, and coal.