How do we manage a hotter reality and deadly heatwaves?

The heatwave that struck the Pacific Northwest and Canada at the end of June 2021 brought temperatures never experienced in the region, breaking records by up to 11 degrees Fahrenheit. The heatwave, virtually impossible without human-caused climate change, is part of a pattern of more frequent, intense and long-lasting heatwaves that comes with our changing climate.

While the event was shocking, in many ways it should not have been a surprise. The heatwave was typical of responses and impacts to heatwaves observed in other well-resourced countries — but still poorly prepared for our new reality. Forecasts days before the event warned of record-shattering temperatures. City departments and outreach organizations began ad hoc discussions of what could be done in regions that have no heat action plans and low air conditioning prevalence.

Actions taken, particularly establishing cooling centers, undoubtedly saved some lives. But there were more than 2,000 heat-related emergency department visits in Washington alone and health care services were overwhelmed. Far worse, the death toll stands at over 1,000, of which more than 800 occurred in British Columbia, where the heat was most intense and insistent; the overall toll is certain to rise as deaths from heart attacks, respiratory disease and other causes are connected to the extreme heat. This was a massive disease outbreak, and nearly all these deaths could have been prevented.

Experience in hundreds of cities worldwide demonstrates that preparedness — in the form of heat early warning systems and action plans — saves lives. For example, mortality during the 2006 heatwave in France was markedly lower than expected based on the devastating 2003 heatwaves — the difference was the result of a national heatwave plan and associated preventive measures. 

Heat action plans include two basic components: early warning and response systems, and longer-term plans for modifying the built environment to be more resilient in a warmer future. 

Meteorological forecasts generally give adequate warning of extreme heat, and we know from epidemiological studies who is at risk and at what temperatures. Early warning and response plans move beyond decisions on the temperature threshold at which warnings are issued, to a comprehensive all-of-society approach that considers and bolsters local capacities. Plans should include at least:

• • an alert system
• • identification and mapping of high-risk residents (e.g., elders, those living alone, those with chronic diseases or disabilities, those in hotspot neighborhoods, the homeless and outdoor workers)
• • education and capacity building activities in advance of the heat season
• • a communication plan designed to reach both high-risk residents and those who provide outreach and support (e.g., buddy systems and disaster registries)
• • plans for working with service providers and bolstering response capacity
• • establishment of cooling centers and strategies for getting people to them
• • opportunities for people to cool off safely in outdoor settings
• • plans for modifying certain outdoor activities such as school sports practices and construction work
• • contingency plans for power outages
• • monitoring, evaluation and learning from such events

These plans need to be co-designed and co-implemented involving not just health departments and meteorological services, but also emergency managers, fire and emergency medical services, utilities, social services, schools and universities, hospitals, and agencies and organizations working with marginalized communities, elderly care, and the unhoused. Systems will vary from location to location. State and national agencies can facilitate coordination and help ensure consistency of information provided. Plans need to be developed in advance and tested through drills and table-top stress tests. After heat events, comprehensive evaluation should be pursued.

Longer-term built environment strategies range in scale from buildings to entire metro regions. 

At the building scale, “cool roofs” that reflect rather than absorb heat and outdoor window shades can help maintain cooler internal temperatures and reduce cooling needs.  Air conditioning, preferably using energy-efficient heat pumps, saves lives during heat waves. 

At the neighborhood scale, smart surfaces like light-colored pavement reduce heating, and shade over sidewalks and in other public spaces helps protect people from heat.  Vegetation is important; parks and streets with plenty of tree canopy can be more than 10 degrees cooler than unvegetated parts of a city.  Bodies of water also provide a cooling effect; pools and “spray parks” can give relief, though drowning risk needs to be addressed.  These features help to counteract the “heat island effect” — whereby cities are substantially hotter than surrounding countryside because of dark surfaces, lack of vegetation, and local heat generation.  In cities where heat is accompanied by increasing water scarcity — say, across much of the U.S. Southwest — design strategies need to reckon with multiple tradeoffs.

It’s not just the heat: vulnerability is increasing. Around the world, more people are living in cities (a process partly driven by rural-to-urban migration when climate change ravages agriculture) — and cities are especially susceptible to extreme heat. 

Some of the fastest-growing cities in the U.S. are in our hottest places. Populations are aging — and older people are at particular risk.  Water supplies are dwindling, constraining basic protective actions such as planting and maintaining tree canopies.  And poverty, another risk factor during extreme heat, remains a persistent problem.  Before the COVID-19 pandemic, 34 million Americans, or 10.5 percent of the population, were officially classified as living in poverty, and more than twice that number lived in near-poverty.  These numbers are likely to have increased since the starts of the pandemic.  Poverty substantially increases the risk of dying in a heat wave. Strategies like avoiding power shutoffs for unpaid bills during high-heat periods and subsidizing utility bills can help.

This is, by any measure, an emergency.  We need to manage the unavoidable, with heatwave preparedness systems and by building our communities in ways that help us withstand more extreme heat.  But at the same time, we need to look at root causes: our ongoing contributions to a hotter, more dangerous world, from burning fossil fuels.  Halting these practices is primary prevention — the definitive long-term solution to places too hot to bear.

Kristie L. Ebi, Ph.D., MPH, is a professor at University of Washington’s Center for Health and the Global Environment. She has been conducting research and practice on the health risks of climate variability and change for nearly 25 years, focusing on understanding sources of vulnerability; estimating current and future health risks of climate change; designing adaptation policies and measures to reduce risks in multi-stressor environments; and estimating the health co-benefits of mitigation policies.

Howard Frumkin, MD, MPH, DrPH, is a  public health physician, former dean of Public Health at the University of Washington and former director of CDC’s National Center for Environmental Health.

Jeremy Hess, MD, MPH, is a practicing emergency medicine physician and professor of emergency medicine and public health. He directs the University of Washington’s Center for Health.