Climate Change and Health Series – How Does Climate Change Impact Public Health?
The highlight of my career (thus far) has been to work at the intersection of climate change, public health and equity between 2017 and 2020. This included serving on an interdepartmental Climate Health Action Team at a local health department and six-month practicum project supporting development of climate change and health messaging tailored to specific populations.
Key takeaways from those efforts included: 1: most people in the United States accept that climate change is real with immediate and long-term impacts. 2: the attitudes of many Americans regarding climate change tend to be interwoven with their political and religious beliefs and perceived connection to nature. 3: few people in the United States are aware of climate change-related health impacts. 4: national, state and local public health agencies have only recently begun integrating consideration of climate change into programs, services and messaging. 5: placing climate change messaging within a health impact context can effectively build knowledge and motivate behavior change.
My goals for this post are to address key takeaway #3 in building awareness of connections between climate change and health impacts, how severe these impacts are projected to be in the future and how these impacts are/will disproportionately affect certain populations more than others.
Temperature and extreme heat
Arguably, the most direct connection between climate change and health is temperature. Annual temperatures in the United States have increased over the past few decades and 1.8 degrees relative to last century. Average temperatures are expected to increase by at least 2.5 degrees over the next several decades and between 3-12 degrees by 2100 depending on global emission levels. This may seem like a modest rise overall but will not be uniformly distributed and extreme heat events (temperatures dramatically above normal for a specific geographic area) are also projected to worsen significantly. Direct heat-related health impacts include heat stroke, exhaustion, and dehydration. Studies have also linked extremely hot days with increased demand for emergency medical services, hospitalizations and premature deaths. Equity consideration: Dense urban areas with limited green space and a high concentration of concrete and asphalt can be 5-10 degrees warmer than suburban and rural areas, placing populations who live there, including a disproportionate number of African Americans (52% more likely than whites), Asians (32%) and Latinos (32%) at highest risk during heat waves.
Extreme weather events
The historic winter storm that hit Texas in mid-February caused widespread power and water outages, significant crop loss and the premature deaths of over 75 people. It was also the latest example of an alarming rise in the number of global natural disasters. A United Nations report cited 7,348 major natural disasters occurred between 2000 and 2019, as compared to 4,212 natural disasters in the previous 20 years. Climate-related natural disasters have also risen 83 percent over the past two decades. Extreme weather events have several direct and down stream impacts on public health. There is the immediate loss-of-life and serious injuries, which often disproportionately impact the most overburdened populations, for example those experiencing homelessness, occupying substandard housing, limited-English proficient (less likely to receive emergency messaging). Major disruptions of agriculture, as resulted from the Texas winter storm, with the near or total loss of 37 major crops, also have broad impacts which most threaten at-risk communities. For example, food banks already facing unprecedented demand due COVID-19, are expecting to provide less food as a result of the storm.
Vector-borne diseases
Warming temperatures are expanding suitable habitat for insects such as mosquitos and ticks which can carry malaria, West Nile, Lyme disease and other serious illnesses. Lyme disease is transmitted to humans through tick bites – historically, ticks were only found in the Northeastern U.S. but have increasingly been identified in the Midwest. Unsurprisingly, expanded tick habitat has resulted in more cases of Lyme disease. The number of annual cases of Lyme disease in the United States has risen from around 10,000 in 1991 to 28,000 in 2018. A study by Carnegie Mellon University predicts that at the rate of current warming, the number of Lyme disease cases will increase by 21 percent by 2050. Agricultural workers are at especially high risk of contracting Lyme disease. This includes migrant, seasonal farmworkers who may have limited access to healthcare, are more likely to be uninsured with less financial resources to afford antibiotics critical for treatment and generally less likely to report potential cases.
Extreme precipitation
Rainstorms are increasing in strength due to climate change. This is especially relevant in the Pacific Northwest, where a study by Seattle Public Utilities found that extreme rainstorms have grown 30 percent stronger over the past 15 years. Heavy precipitation is a direct contributor to waterborne disease outbreaks, with a study published in the American Journal of Public Health reviewed finding over 50 percent of waterborne disease outbreaks in the United States were preceded by a precipitation event. According to the CDC, waterborne illnesses such as “swimmer’s ear,” Norovirus, Giardiasis and Cryptosporidiosis impact over 7 million people each year in the U.S.
These are only a few key examples of how climate change is impacting public health. Other less direct connections, which may be topics of future posts, include climate change and global/local food systems, workplace and population displacement. Overall, climate change will present added challenges for already overburdened populations, who have contributed the least to the problem but face the greatest impact(s).