Over the past few years, a plethora of research has come out linking climate change to adverse health outcomes around the world. In 2021, a worldwide group of medical research professionals suggested that rising temperatures associated with climate change was the greatest threat to global public health. Illustrating the growing potential consequences of climate change, 2021 marked some of the most frequent extreme and costly climate events in the United States in the past decade. Climate and climate change related health risks disproportionately impact historically marginalized and under-resourced groups, who have the least resources to prepare for and recover from these disasters. As climate-related events become more common, the impacts on health and health care will increase in both frequency and intensity. This brief provides an overview of the impact of climate and climate change on health, identifies who is at increased risk for negative health impacts associated with climate and climate change, explains why there is a growing focus on climate change and health, and reviews recent federal efforts to address climate change and health equity.
How Do Climate and Climate Change Affect Health?
Climate and weather can negatively impact individual and population-level health through multiple pathways. The Centers for Disease Control and Prevention (CDC) notes that different climate drivers, including increasing temperatures, precipitation extremes, extreme weather, and rising sea levels, affect health through a range of exposure pathways, including extreme heat, poor air quality, reduced food and water quality, changes in infectious agents, and population displacement (Figure 1). These exposures may lead to negative health outcomes such as heat-related and cardiopulmonary illnesses; food-, water-, and vector-borne diseases, and worsened mental health and stress.
Climate-related health threats are expected to increase going forward. For example:
Climate change has caused longer, more frequent, and more intense heat waves, which are likely to result in more heat-related illnesses and deaths. Studies have found that exposure to extreme heat makes people sick and may also cause death. In the United States, more than 65,000 people visit the emergency room for heat-related stress and approximately 702 people die from heat exposure each year.
Increasingly frequent extreme weather events due to climate change cause direct loss of life and negatively impact health through the damage they cause. Over the past twenty years, major storms such as hurricanes Katrina, Rita, Sandy, Harvey, and Maria, have resulted in massive loss of life and billions of dollars of damage. In addition to the immediate hazards created by the storms, the flooding and damage they cause to infrastructure can lead to the spread of waterborne diseases and contamination from industrial and agricultural waste runoff; compromise emergency response efforts; limit access to basic needs, including food, water, and housing; and disrupt access to health care and prescription medications. For example, in a survey of Katrina evacuees in Houston shelters, KFF found that, immediately after the hurricane, 25% of evacuees reported going without needed medical care and about a third (32%) went without their needed prescription medicines. Moreover, impacts extend beyond the immediate aftermath of storms. KFF survey data of New Orleans residents one year after Hurricane Katrina found that 32% said their life remained “very disrupted” or “somewhat disrupted” by the storm, with this share rising to 59% of African American residents in Orleans Parish. More than a third (36%) of those living in the Greater New Orleans area reported their access to health care deteriorated since the storm, 19% reported declines in their physical health, and 16% reported deterioration in their mental health. Ten years after the storm, KFF survey data of New Orleans residents who lived in the area during Katrina reported lingering mental health effects, including problems sleeping. In Puerto Rico, there was an excess mortality of 2,975 deaths as a result of Hurricane Maria. KFF interviews with Puerto Ricans two months after Hurricane Maria found that participants were continuing to face challenges meeting basic needs, and daily life remained challenging due to lack of electricity. In a KFF survey of Puerto Ricans one year after the storm, a quarter said their lives were still somewhat or very disrupted and about a quarter said they or a household member had a new or worsened health condition since the storm.
Worsening air quality also may negatively impact health in a variety of ways. Research suggests that climate change may contribute to increases in particulate matter and ground-level ozone—key components of smog and harmful air pollutants. The CDC notes that prolonged exposure to ozone can lead to worse lung function, an increase in cardiovascular- and respiratory-related hospital visits and admissions, and an increase in premature deaths. The Organization for Economic Cooperation and Development predicts that global annual health care costs associated with air pollution will increase from $21 billion in 2015 to $176 billion in 2060. Increases in wildfires due to changes in rain patterns and warmer summers may worsen air quality through the emission of particulate matter and other ozone-forming gases in smoke, which contribute to increased incidences of respiratory and cardiovascular illnesses. Moreover, longer and more intense pollen seasons stemming from longer warmer periods and increased carbon dioxide concentrations may negatively impact respiratory health, particularly for allergy and asthma sufferers. The CDC reports that medical costs associated with pollen exceed $3 billion each year and result in fewer productive work and school days.