Although almost all heat-related deaths are preventable, heat waves kill thousands of people worldwide every year. Right now, an extreme heatwave in India and Pakistan, affecting about 1 billion people, is “testing the limits of human survivability,” warns Chandni Singh, a lead author of the Intergovernmental Panel on Climate Change’s Sixth Assessment Report. In April, the average high temperature for northwest and central India was the highest in 122 years.
In recent years, similar extreme conditions have occurred in the United States, Australia, Europe, Scandinavia and Japan, resulting in thousands of hospitalizations and deaths. Extreme heat is also associated with an increase in preterm birth, low birth weight babies and stillbirth; reduction in labor productivity; higher rates of chronic kidney disease of unknown cause; and suicide increases.
Extreme temperatures are therefore a “social” problem. Such conditions not only harm human health, they also adversely affect infrastructure, crop yields and poultry mortality, threaten livelihoods and undermine food security. The 2021 Pacific Northwest and western Canada heat dome was a case in point.
It was an event that would have been virtually impossible without climate change. Temperature extremes were about 41 degrees Fahrenheit above previous records, resulting in about 1,000 additional deaths and a 69-fold increase in heat-related emergency room visits. Yields from wheat and cherry crops plummeted, and millions of mussels, clams and oysters were cooked in their marine habitats, threatening food security and livelihoods for indigenous peoples and low-income communities.
Already almost 40% of heat-related deaths are due to climate change. And as climate change is projected to increase the frequency, intensity and duration of heat waves, the need for additional measures to protect people will only become more urgent. Without immediate and significant investment to improve community and health system resilience, heat-related deaths will increase.
Well-communicated, evidence-based action plans are needed to keep people calm and reduce hospitalizations and deaths. In addition to early warning and response systems, life on a warmer planet requires longer-term planning. That means providing more blue and green space, changing building materials, and focusing on ways to cool people rather than the environment.
Early warning and response systems need more than a single threshold to determine the onset of a heat wave. Effective systems should also include collaborative processes and take into account local capacities and constraints. Health ministries need to work closely with hydro-meteorological services, police and fire services, emergency services, aged care agencies and trusted voices for vulnerable populations (e.g. adults over 65) and marginalized communities.
Effective early warning systems are already in place around the world, including in resource-poor areas like Ahmedabad, India. In addition, organizations such as the Global Heat Health Information Network collect and share data on local and national experiences and best practices. The demand for additional guidance is growing rapidly, along with the increasing frequency and severity of heat waves.
Nevertheless, most of today’s early warning systems do not explicitly take into account the risks of a changing climate. To be more adaptable, planners should have timelines for reviewing changes at the beginning and end of the summer season and form regional partnerships to ensure a consistent message. Early warning systems are also needed that take multiple thresholds into account, such as: B. Temperature measurements combined with local knowledge of vulnerable populations.
For example, early warnings could be issued several days before the peak of a heat wave to warn at-risk groups such as older adults, young children and pregnant women. A second warning could then be issued at slightly higher temperatures for outdoor workers and those involved in sports or similar activities, followed by a third warning for the general public at the usual threshold for declaring a heatwave. These warnings would need to be paired with effective communication so that people are properly motivated to take the appropriate actions to stay cool.
Even after these improvements, early warning systems should then be tested to determine their resilience to unprecedented heat. This could be done through exercises to identify weak points. Such testing should include not only heatwaves, but also compound risks such as a heatwave combined with wildfire or a heatwave coinciding with a pandemic like the Pacific Northwest experienced in 2021. Vulnerability mapping can be a powerful tool to help decision-makers determine where interventions are most needed to protect human health and well-being.
A much warmer future requires urgent and immediate investment, building on best practices and lessons learned from existing thermal adaptation plans. Effective models need to be scaled to improve resilience and sustainability. Unprecedented higher temperatures are survivable, but not if we don’t prepare for them.
Kristie L. Ebi is Professor of Global Health and Environmental and Occupational Medicine at the University of Washington.
