Climate change is one of the most important issues of our time — one that has serious implications for human health on this planet. That’s why health care professionals are key among those hoping that policymakers meeting this week in Paris for the 21st United Nations Conference on Climate Change will make some concrete solutions for stemming the disastrous effects of climate change on public health.
The Paris talks, which began on Monday (Nov. 30), will go on until Dec. 11, and a World Health Organization-led event addressing climate change’s impact on health will take place on Dec. 8. The WHO has been pushing the importance of health as part of the climate change agenda for over a decade, and the event is designed to promote the message that a strong and effective international climate treaty is critical to public health.
“Climate change threatens human health and well-being in many ways, including impacts from increased extreme weather events, wildfire, decreased air quality, and illnesses transmitted by food, water, and diseases carriers such as mosquitoes and ticks,” says George Luber, PhD, associate director for climate change in the Division of Environmental Hazards and Health Effects at the Centers for Disease Control and Prevention’s National Center for Environmental Health.
If countries around the world — the U.S. included — don’t address the health component of climate change, “some existing health threats will intensify and new health threats will emerge,” he tells Yahoo Health.
Consider that between 1999 and 2009, extreme heat — one key aspect of climate change — caused 7,800 deaths in the U.S., according to the CDC, and an analysis of 2012 data showed that the number of such deaths is only increasing as summer temperatures rise. Extreme heat also results in increased incidences of heart disease, respiratory disease, and stroke, Luber says.
But it’s not just heat — air pollution is another important consequence, leading to about 200,000 premature deaths a year. As the winters have shortened, pollen seasons have lengthened, thereby exacerbating seasonal allergies. And increased rainfall is leading to mosquitoes and other disease-carrying pests finding new homes in parts of the world where the illnesses would have otherwise been uncommon.
As of this week, for example, the Brazilian health ministry reported more than 1,200 cases of the mosquito-borne Zika virus — which is transmitted by a mosquito from Africa that also carries dengue, yellow fever, and the chikungunya virus — in the country. The virus was first detected in Brazil in April.
In North America, the vector-borne diseases to watch out for include Lyme, dengue fever, West Nile virus, Rocky Mountain spotted fever, plague, and tularemia (a serious bacterial infection that comes from animals), Luber says. And vector-borne diseases that aren’t currently common in the U.S. — such as chikungunya, Chagas disease (caused by a parasite found in the feces of the triatomine bug), and Rift Valley fever viruses (which are most commonly found in domesticated livestock — can soon be threats. “Climate change effects on the geographical distribution and incidence of vector-borne diseases in other countries where these diseases are already found can also affect North Americans, especially as a result of increasing trade with, and travel to, tropical and subtropical areas,” Luber says. “Ticks that carry Lyme disease may also grow in number and the geographic area Lyme is found is growing, with 50 to 90 more cases per 100,000 people than in 1991.”
Research has established a link between climate change and the increase in Lyme disease. According to a 2014 study in the journal Environmental Health Perspectives, warmer temperatures in the Northeast U.S. over the past years has allowed new populations of Ixodes scapularis ticks to establish themselves in regions that were once too cold. The warmer temperatures allow ticks to reach adulthood faster, the study says, and more ticks also stay alive when it’s hotter.
Clearly, human health and climate change are inextricably linked, says Jeffrey Shaman, PhD, associate professor of environmental health sciences at Columbia University. The effects of climate change on health run the gamut from increased mortality as a result of extreme heat, to the rise of different kinds of pathogens afflicting plants and other food sources, to the forced migration of people whose habitats have been devastated by extreme weather, and who may carry with them different illnesses to wherever they migrate to, he tells Yahoo Health.
“For 10,000 years, we existed in a relatively stable climate that allowed for the consistent cultivation of agriculture and staple food sources, and offered us an environment that wasn’t so variable and therefore wasn’t difficult for humans to thrive in,” Shaman says. “We work very well in a stable environment and when we know the rules of the game, but we are now changing the rules of the game.”
Scientists like Shaman say that short-term variations in climate, warming included, are normal. But it’s the longer-term trend — caused primarily by rising levels of carbon dioxide and other heat-trapping gases in the atmosphere — that is a concern because it intensifies the warming effect.
This warming has led to rising sea levels, extreme heat waves, milder winters, and serious melting of snow and ice in the poles, as well as fires and drought. It’s resulted in terrific storms, vast amounts of seasonal and unseasonal rainfall and flooding, all of which impact health in some way, because “the process that is stirring the pot makes systems that worked well before less likely to do so,” Shaman says.
Human beings have played a major role in contributing to the levels of carbon dioxide in the atmosphere, to our own detriment. In Indonesia, for example, forest fires have been raging for months, because of clearing land for new plantations for palm oil, the country’s chief export. The resulting haze has forced endangered orangutans and other species to flee the forests and has also led to an unprecedented rise in respiratory illnesses.
According to the WHO, 7 million people died from air pollution (both indoor and outdoor) in 2012. Coal emissions are largely responsible for outside air pollution. Exposure to the tiny particles found in coal and other fossil fuel emissions increases the risk of death from heart disease, according to a new study from researchers at the NYU Langone Medical Center. These particles contain arsenic, selenium, or mercury, which contribute to the development of potentially fatal heart and lung diseases because they are small enough to slip past the body’s defenses and be absorbed into the bloodstream and deep into the lungs, the study says.
Here in the U.S., increasing ground-level ozone — a key component of smog — has human effects in the form of diminished lung function, increased hospital admissions, and emergency room visits for asthma, Luber says. Indeed, asthma prevalence (the percentage of people who have ever been diagnosed with asthma and still have asthma) increased nationwide from 7.3 percent in 2001 to 8.4 percent in 2010, according to the CDC.
Minimizing or controlling the health effects of climate change depends, to a large degree, on the measures that countries and states take to identify the variety and scope of climate impacts and their associated potential health outcomes. States (such as Arizona, Michigan, and Minnesota) and cities (such as San Francisco) have developed comprehensive heat alert plans, Luber says, while New York City, Maine and Michigan now track extreme heat-related health conditions. Vermont has created the “Tick Tracker,” a web-based surveillance system to track tick-borne disease using reports from residents (in 2014, 294 ticks were reported and geographically tracked, including 176 deer ticks, which can spread Lyme disease). Meanwhile, Minnesota developed and is conducting training to help local health departments monitor air quality, track asthma and allergies, and improve energy efficiency to reduce production of harmful air pollutants. And North Carolina identified that it is vulnerable to storm surge, and is at high risk for flooding, drinking water outages, and waterborne disease.
At the individual level, activities that reduce carbon pollution often provide co-benefits in the form of preventive health measures, Luber says. “For example, reliance on cleaner energy sources for electricity production and more efficient and active transport, like biking or walking, can have immediate public health benefits, through improved air quality and lowered rates of obesity, diabetes, and heart disease,” he says.
But above all else, Luber believes that information is key, because unfortunately, most Americans still don’t associate health with climate change.
“Most believe it will affect people in a different time or place,” Luber says, “but diverse groups of Americans find information on health impacts to be helpful once received, particularly information about the health benefits of reducing carbon emissions and adaptation.”
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