SGIM Forum

Sign of the Times: Part II

Health Impacts of Climate Mobility in the United States

Dr. Parekh ( is a second-year internal medicine resident at the Boston Medical Center. Dr. Dresser ( is a climate and human health fellow in the Department of Emergency Medicine at Beth Israel Deaconess Medical Center and a clinical fellow at Harvard Medical School. Dr. Kimball ( is an assistant professor in the Section of General Internal Medicine at Boston University School of Medicine and is the director of the Immigrant & Refugee Health Center at Boston Medical Center.

Movement of people in response to climate change, referred to as climate mobility, is increasingly expected to play an important role in reshaping American demographics in coming decades. Gradual alterations in temperature and sea level, combined with sudden natural disasters, such as hurricanes and wildfires, will push increasing numbers of people to migrate. This process may drastically shift population centers around the country and will likely worsen health outcomes. This column will discuss the myriad economic and health-related impacts of climate mobility on social determinants of health for those who are displaced.

A patient we will call Vanessa illustrates the potential for profound social and health-related sequelae of climate mobility in the United States. Vanessa had recently moved to her uncle’s house in Los Angeles after her home in Northern California burned down during one of the most destructive wildfire seasons ever recorded. Shortly after starting the school year, Vanessa developed acute anxiety, palpitations, dizziness, and bilateral lower limb paralysis. She revealed that her uncle had been sexually abusing her and was ultimately diagnosed with conversion disorder. While the proximal factors in her presentation are all too commonly seen in clinical practice, the distal precipitant of her situation was wildfire and subsequent movement to a new location. In this situation, climate-related hazards created social disruption, leading to a tragic outcome.

Versions of Vanessa’s story may become increasingly common as more Americans are exposed to the hazards of climate change. Climate change will contribute to disasters, disasters will push people to move, and the displaced will suffer new or exacerbated health problems. Data from the National Oceanic and Atmospheric Administration (NOAA) shows that severe weather events in the United States have already become more frequent, destructive, and deadly, killing an additional 235 people per year.1 This trend is expected to continue as wildfires, tropical storms, droughts, and other disasters become more common and intense.

Concerning as they are, mortality figures fail to capture the social and economic impacts of climate change in the United States. Recent modeling suggests that by the end of the century, up to 13 million Americans could be displaced by sea level rise alone.2 More than 2.5 million people in Florida could be displaced, devastating regional economies, and upending countless livelihoods. Almost half of the communities threatened with inundation from sea level rise are socioeconomically disadvantaged, restricting their ability to adapt to climate risks. Neighborhoods on the front lines of climate change may also face economic depression; there is already evidence of decreased market valuations in Floridian coastal properties.3 These changes will place additional financial strain on an already vulnerable population and threaten to worsen preexisting disparities.

How will health outcomes change for the displaced? Like Vanessa, many will suffer from the predictable distress caused by economic, ecologic, and physiologic stress. Extreme weather events and migration have been associated with increased incidence of domestic violence, suicide, post-traumatic stress disorder, depression, and worsening of existing psychiatric illnesses.4 Human pathogens will have new opportunities due to a combination of flood-related damage to sewage and sanitation infrastructure and increasing suitability for vector-borne diseases. In the absence of adaptation strategies, extreme heat could cause 36,000-98,000 deaths annually by 2100, representing a 3- to 8-fold increase.5

Physician lives and practices will also be affected. For example, Floridian physicians disproportionately practice in coastal areas with 14.6% of them living in or around Miami in 2017. These physicians may choose to relocate their practices as sea levels rise, and floods and hurricanes cause property damage. Out-migration of physicians could reduce access to health care for patients who are unable or unwilling to move, leading to disparities in care. Similarly, patients who move to new areas will likely encounter barriers to healthcare access, especially if they travel across state lines. Large-scale episodic environmental and health disasters will also become more common—Hurricanes Katrina and Maria are examples—with resulting damages to tertiary care centers and reduced health access for thousands.

While many studies have estimated the number of people who may be displaced, determining where they will go is more challenging. One model predicts a significant population shift from coastal regions to inland cities, such as Atlanta, Denver, Chicago, and Austin.2 As a result, this could increase the burden on state and federal safety net institutions and worsen preexisting housing crises. Climate mobility may also be visible in rural areas, as economic opportunities dissipate due to increasing climate-related problems with agriculture and families relocate to metropolitan areas with more opportunities. More research must be done to verify how climate mobility will affect rural America, and whether these patterns may worsen preexisting gaps in healthcare access.

It is also unclear who will migrate. Will wealthy individuals be the first to leave threatened areas or will they use their capital to adapt to hazards that would cause others to emigrate? Will the elderly and infirm be unable to leave high-risk neighborhoods? Will communities of color be disproportionately left behind or displaced? Changing population demographics in specific catchments could alter risk pools, affecting the cost of private health insurance. These questions have profound implications for equitability and affordability of health care.

Climate mobility poses a complex problem for healthcare, as many of the specifics necessary for policy and financial decision-making—the who, when, and where—are unknown. More research must be done to establish how health systems will be affected by climate change and increased mobility. Physicians must ask themselves how their practices may be affected by climate migration, and how they may best safeguard the health of their patients. Health professionals should advocate for policies that increase community adaptability to climate change and encourage responsible land use, and use their votes at the city, state, and national level to agitate for a future that anticipates and protects Americans from the hazards of climate mobility.


  1. NOAA National Centers for Environmental Information (NCEI). U.S. billion-dollar weather and climate disasters: Overview. DOI: 10.25921/stkw-7w73. Accessed February 15, 2021.
  2. Shindell D, Zhang Y, Scott M, et al. The effects of heat exposure on human mortality throughout the United States. Geohealth. 2020;4(4):e2019GH000234.
  3. Honkaniemi H, Juarez SP, Katikireddi SV, et al. Psychological distress by age at migration and duration of residence in Sweden. Soc Sci Med. 2020 Feb 20;250:112869. doi: 10.1016/j.socscimed.2020.112869. Online ahead of print.
  4. Keys BJ, Mulder P. Neglected no more: Housing markets, mortgage lending, and sea level rise. Natl Bureau of Econ Research. Working Paper No. 27930. Published October 2020. Accessed February 15, 2021.
  5. Hauer M. Migration induced by sea-level rise could reshape the US population landscape. Nature Clim Change. 7, 321–325 (2017). Accessed February 15, 2021.


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