03. CLIMATE-RELATED HEALTH IMPACTS
The consequences of climate change in Montana—including more frequent and intense heat waves; and increases in spring flooding, late-summer drought, extreme weather events, and wildfires—have recognized potential to impact human health (Ebi et al. 2018). Though little studied for Montana to date, climate change is known to be adversely impacting global health, including some Americans, now. For example, an increase in climate-related extreme events has led to increased emergency room visits and hospital admissions in the US (Ebi et al. 2018). Those adverse impacts are expected to increase over coming decades (Wuebbles et al. 2017).
Figure 3-1 depicts how climate pressures (also called stressors), following multiple exposure pathways, can lead to specific health outcomes for people. Those outcomes, discussed in this section, include heat-related illness; vector-borne diseases; mental health impacts; physical trauma, injuries, and death; respiratory, cardiovascular, and gastrointestinal conditions; and adverse effects on pregnancies and birth outcomes.
While climate change affects all parts of the world, the severity of specific health impacts will vary by the specific climate pressure, as well as by location. Coastal regions, for example, will endure the most damage from sea-level rise, whereas inland states like Montana will be impacted most by the adverse effects of heat waves and reduced air and water quality (from wildfire smoke, desertification, land degradation, and other factors [Hughes and Diaz 2008; Sharratt et al. 2017]). In the subsections that follow, we describe some of the exposure pathways and health outcomes resulting from climate change as shown in Figure 3-1. Some of the discussion may apply globally, but we emphasize those pathways and outcomes more likely to impact Montanans.
Climate change is increasing the intensity and frequency of heat waves (Meehi and Tebaldi 2004; Reid et al. 2009). Globally, 157 million more people were exposed to extreme heat in 2017 than in 2000 (Watts et al. 2018). Assuming no changes in the current trend of emissions, the Union of Concerned Scientists projects that by mid century “the number of people [in the United States] experiencing 30 or more days with a heat index above 105°F in an average year will increase from just under 900,000 to more than 90 million—nearly one-third of the US population” (UCS 2019). Similarly, by the end of the century parts of Montana could see as many as 54 additional days over 90oF (32oC) (Whitlock et al. 2017; Section 2).
Multiple studies have demonstrated increased mortality associated with heat waves (Knowlton et al. 2009; Ostro et al. 2009; Isaksen et al. 2016), which is the major cause of weather-related deaths in the United States (NWS undated) (see sidebar). Gubernot et al. (2015) find that people who work in agriculture or construction jobs have the highest risk for heat-related death; that risk may be even higher for employees of Montana businesses such as farms and small construction firms that have no backup personnel. This finding should concern Montanans given that agriculture and construction are integral to our state’s economy.
In addition, American Indian ceremonial practices (e.g., sundances) become more difficult during extreme heat and expose participants to risk for heat-related conditions (Doyle et al. 2013).
Which is More Deadly—Extreme Heat or Extreme Cold?
This seemingly simple question actually has no clear answer. Temperature extremes in both directions kill hundreds of people in the US each year, but determining the actual death toll is subject to large errors. Two US agencies, using different methods and datasets, came to opposite conclusions about which is more deadly:
- NOAA’s monthly publication Storm Data (NOAA-NCEIa) regularly reports many more deaths per year as heat-related than as cold-related (NOAA-NCEIb). For example, their annual summary for 2011 indicates 206 deaths from extreme heat versus 29 from extreme cold.
- The Centers for Disease Control and Prevention’s Nationa