COMMENTARY ON COVID-19, CLIMATE CHANGE, AND HUMAN HEALTH

Jay Lemery, Kim Knowlton, Cecilia Sorensen, and Hanna Linstadt

The COVID-19 pandemic has demonstrably exposed the fault lines in our public health infrastructure and exacerbated the underlying disparities in our communities. For those of us studying climate change and human health, the parallels are all too easy to make: a public health disaster hampered by a lack of preparation and coordination; health effects spilling over to have dire economic consequences; a disproportionate burden falling upon communities of color, those with the fewest resources and the smallest contribution to the causation of the problem.

But in other ways, there has been a remarkable divergence in the public response toward the pandemic and climate change. We have witnessed an historic mobilization of resources and public policy measures, despite the significant effects these global phenomena have had on business as usual and societal norms. Massive economic stimulus packages passed rapidly, with widespread consent from a historically gridlocked, partisan legislature. Prodigious sums of public funds were allocated toward the accelerated development of diagnostics, treatments, and vaccines.

Despite the criticisms that more could be done, there is no doubt our world changed overnight, and that our society mobilized rapidly to address the crisis. We contrast the pandemic response to the slow-motion climate change crisis, for which, despite being evident for decades, effective action remains elusive.

In crisis comes opportunity. Looking to the world we will create after coronavirus disease 2019 (COVID-19), we believe there are historic opportunities to reinvigorate and enhance the resilience of our communities and institutions. We have a once-in-a-generation mandate to reconsider our public health and economic operating systems, and in turn, change the trajectory of our next public health crisis-a rapidly changing climate.

Understanding that the science and impacts of the pandemic are rapidly changing, we have nevertheless endeavored to provide a brief inventory and overview on the many facets of COVID-19 and climate and health issues. We cite the interactions between COVID-19 and climate-related health conditions and how the global recovery from the pandemic has the potential to improve public health and to limit the effects of climate change in the future.

Climate Change Exposure Pathways and COVID-19

Increasing Temperature

Hotter temperatures are known to worsen chronic conditions like cardiovascular disease and respiratory disease, as well as diabetes-related conditions and cerebrovascular disease (Crimmins et al. 2016). Data on environmental temperatures and COVID-19 infections are conflicting. Some studies show that the transmission of the virus may actually decrease with rising temperatures (Le et al. 2020; Liu et al. 2020; Prata, Rodrigues, and Bermejo 2020), so it is possible the increased average temperatures globally could have a positive effect on slowing the spread of COVID-19. On the other hand, there are also studies that refute this notion (Global Heat Health Information Network 2020; Xie and Zhu 2020). Thus, it is currently unclear what the true effect of rising temperatures has on the transmission and/or severity of COVID-19.

Air Quality

Initial data have shown that people with certain underlying respiratory diseases or cardiovascular disease may be at risk for more severe illness from COVID-19 (Centers for Disease Control and Prevention 2020c). Air pollution exposure increases a person's risk of developing an underlying respiratory disease (Crimmins et al. 2016). This history of exposure may lead to more severe disease when infected with COVID-19. Even exposures to a small increase in air pollution-specifically fine particulate matter-have been shown to increase the COVID-19 death rate (Wu, Nethery, Sabath, Braun, and Dominici. 2020).

Concomitant Stressors

The pandemic is already straining the health care and emergency response systems of many regions and countries (Boccia, Ricciardi, and Ioannidis 2020; Uppal et al. 2020). Simultaneously, climate-driven severe weather events such as wildfires, flooding, and hurricanes continue to occur, resulting in injuries and illnesses that also strain the resources of existing health care systems (Crimmins et al. 2016). When faced with "double disaster" scenarios, the health care system is at risk of becoming overburdened to the point at which it is unable to provide the necessary care.

COVID-19 also affects the public health response to disasters like extreme weather events. For example, it is typical for evacuated or displaced persons in an extreme weather event to congregate in large shelters or community centers. However, many of these shelters have needed to reduce their capacity to allow for recommended social distancing (Wendle 2020), creating a challenging problem in the way we respond to disasters. Simultaneously, a large majority of public health and community time and resources are currently being diverted to address the COVID-19 pandemic, leaving less available to address chronic climate change-fueled stressors such as extreme heat, wildfires, and more. There is an imperative to enact an "all hazards" approach to public health risk reduction that encompasses all types of public health emergencies and addresses vulnerabilities within the system as well as within communities.

Climate Change and Future Pandemics

New and Emerging Pathogens

Anthropogenic forces that contribute to climate change also lead to changes in the geographic distribution of certain species (Crimmins et al. 2016), which can place these species in closer contact with humans. Deforestation and clearance of natural habitat for agricultural purposes not only leads to increasing CO2 levels and loss of biodiversity but also to more frequent interactions between wild animals and humans, subsequently increasing the risk of novel disease transmission to humans (Rohr et al. 2019). Improving forest management practices may help prevent spillover of yet unknown pathogens while simultaneously helping to address climate change.

Migration and Vulnerable Populations

Loss of land and employment from climate-related extreme weather events, such as floods, drought, and hurricanes can lead to forced migration (United Nations High Commissioner for Refugees n.d.). There were 24.8 million disaster-related displacements in 2019 (Internal Displacement Monitoring Centre 2019). When populations are displaced, they most often end up in very densely populated settlements (Refugees International 2020), and increased density in housing leads to increased risk of spread of communicable disease (Snyder 2018). This is particularly problematic in the era of COVID-19. Living in densely populated communities can make practicing social distancing extremely difficult, and access to health care is often scarce in these communities (Snyder 2018). Poor infrastructure resulting in a lack of clean, reliable water supply for sanitation and hygiene also increases the risk for COVID-19 outbreaks within communities (Poole, Escudero, Gostin, Leblang, and Talbot 2020).

Even in nonmigrant populations the social determinants of health, including socioeconomic factors, ethnicity, age, and health status increase the exposure to climate change-related negative health impacts (Crimmins et al. 2016). For example, communities of color and people living in poverty are at higher risk of exposure to air pollution (United Nations Environment Programme 2019), suffer higher rates of chronic disease, and lack access to health care (Islam and Winkel 2017). According to the Centers for Disease Control and Prevention (CDC), the pandemic has revealed a similar pattern of vulnerability. The CDC states that "long-standing health and social inequities have put some members of ethnic minority groups at increased risk of getting sick and dying from COVID-19" (CDC 2020b). Initial data shows that non-Hispanic American Indian or Alaska Native persons, non-Hispanic black persons, and Hispanic or Latino persons have COVID-19 hospitalization rates about five times that of non-Hispanic white persons (CDC 2020a). In the United States, racial/ethnic minorities have a disproportionate burden of underlying comorbidities and simultaneously suffer from poorer socioeconomic status and are more likely to live in crowded urban conditions, making it incredibly difficult to practice social distancing or work from home (Webb Hooper, Nápoles, and Pérez-Stable 2020).

Water

Climate change threatens water security, as increasingly unpredictable weather conditions and extremes in precipitation will limit reliable access to safe water and sanitation (United Nations Water n.d.b). Access to basic sanitation and water is a fundamental precondition for adequate public health and is vital to prevent the spread of COVID-19 as well as innumerable current and future pathogens (United Nations Environment Programme n.d.; United Nations Water n.d.a).

Crucial Turning Point

COVID-19 has held a mirror up to the inherent injustices of our society. The frightening reality is that in aggregate, our collective society appears to be one that does not invest in public health; one that has not addressed deep racial and socioeconomic inequalities; has an indifference to science; eschews public education; and allows those most vulnerable to bear the greatest burden of a global pandemic disease, all to...