How Concerned Should We Be About the Effects of Heat Waves?

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July 2023 was the hottest month recorded on the planet. Areas where heat waves were never an issue before are being repeatedly hit by extreme temperatures, and many lack the means to protect their residents from harm. With all of this, the negative physical consequences of heat stress (heat stroke, worsened symptoms of cardiovascular and metabolic disease, neurological impairment) have become hard to ignore, affecting more and more individuals across the globe. But the heat doesn’t just affect us physically—it also affects us psychologically. So just how concerned should we be about the effects of heat exposure on our physical and mental well-being?

Heat waves affect some of us more than others.

The short answer is that while we should all be concerned, not everyone will be equally affected by heat exposure. A recent commentary and review in the journal American Psychologist highlighted how the short- and long-term effects of climate change will disproportionately influence communities that are most vulnerable or sensitive and those who are unable to adapt to these stressors (Pearson et al., 2023). For example, children, older adults, individuals who are pregnant, and those with chronic medical conditions are more likely to experience harm from extreme weather events, such as heat waves. However, while this increased vulnerability may have negative consequences, the ability to adapt and protect oneself and one's community can mitigate these negative effects.

Unfortunately, there are widespread disparities in the extent to which communities can actually adapt to environmental stressors. Redlining and other systemic racist practices in the United States have led to major inequalities in generational wealth, access to resources, and the presence of tree canopy and urban greenspaces (Nardone et al., 2021; Locke et al.., 2021). When people lack air conditioning (AC) or the ability to pay for it, and there aren’t cooling effects of urban greenspaces to buffer against hot temperatures, individuals in these communities have less adaptive capacity.

In other words, the people most likely to experience illness due to heat stress are those who are more at risk for harm and are not in a position to cool their environments when that heat wave occurs. This combination of vulnerability and lack of heat adaptation ability has severe consequences, such as increased heat-related emergency department visits in racialized and lower-income communities (Li et al., 2021). However, even though many individuals are unlikely to need emergency treatment for heat-related medical issues, this doesn’t mean that the impact of heat exposure is negligible for everyone else.

Heat stress takes a toll on our minds, too.

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In part, this is because people don’t just respond to heat stress with physical symptoms, but it can also affect us psychologically—it affects our mood, our cognition, and our interactions with others. It even impacts children’s learning and performance in school (Park et al., 2020). Unfortunately, while we know that exposure to heat stress in a laboratory study or everyday life can have an impact on our minds and our mental well-being, we don’t really know the extent to which they occur in heat waves, what individual traits or dispositions might make people more susceptible to the psychological impacts of heat, or whether most people are truly aware of the psychological toll that heat stress is having on them.

Circling back to this idea that vulnerability may matter less as long as communities can minimize their exposure (adaptive capacity), this uncertainty creates a new issue. While many of the acute physical symptoms of heat exposure (e.g., nausea, dizziness) are apparent, the psychological effects may be less obvious, and there may be variability in the extent to which people realize they are being affected by the temperature. And if people aren't aware of the psychological impact, they may not take action to seek out cooler spaces (such as libraries, other temperature-controlled indoor public spaces, or designated cooling centers) or use their AC if they have it.

Ultimately, it’s up to psychologists and other scientists to generate a more comprehensive understanding of the different impacts that heat stress can have on individuals. But, in the meantime, it is probably better for all of us to play it safe and minimize our heat exposure however we can. Your body and brain will be better for it.

Note: If you're worried about heat and don't know how to protect yourself, the U.S. Centers for Disease Control and Prevention website has helpful advice: https://www.cdc.gov/disasters/extremeheat/faq.html