Research published Monday highlights an alarming trend: countries like Mexico, Kenya, Italy, and others are experiencing extended periods of heat stress compared to several decades ago. The study reveals that heat stress is now affecting regions previously unaffected. Over the past six decades, extreme feels-like temperatures, heat stress days, and tropical nights have increased dramatically due to global warming, which is attributed to fossil fuel combustion.
The researchers moved beyond studying temperature alone and employed feels-like temperatures to gauge impacts on individuals. They used the Universal Thermal Climate Index to model the human body’s response to temperature, humidity, wind speed, and other factors. Heat and humidity pose threats because they hinder sweat evaporation, a natural cooling process, making humid heat waves more perilous than dry ones.
Research shows worsening heat stress in traditionally warm regions and beyond. Previously, studies assessed the role of human-driven climate change in rising temperatures. Estimates suggest that by 2024, people worldwide experienced an additional 41 days of dangerous heat. Projections indicate an increase of nearly two months of extremely hot days annually by century’s end.
For instance, volunteers in Milan, Italy, are providing essentials to the homeless amid heat waves. Margarita Salazar, 82, tries to cool down in Veracruz, Mexico, during scorching weather. Researchers examine heat stress levels ranging from strong (≥ 32°C/89.6°F) to very strong (≥ 38°C/100.4°F), and extreme (≥ 46°C/114.8°F).
Detailed projections estimate up to 50 more days of strong heat stress annually since the 1970s in areas like Namibia, Angola, Tanzania, Kenya, Uganda, Mexico, and Central America. Southern European countries like Spain, Italy, Greece, and Turkey may see up to 40 additional days compared to the 1970s.
In the U.S., regions are experiencing at least 15 more days of strong heat stress, with southern states, including Texas and Florida, witnessing close to 25 days of very strong heat stress. Heat stress seasons are elongating.
The study’s lead author, Rebecca Emerton, a senior scientist at the European Centre for Medium-Range Weather Forecasts, noted the expanding footprint of heat stress into areas where it was previously rare or non-existent.
According to the study, feels-like temperatures during the ten warmest nights each year have risen more quickly (0.32°C/0.58°F per decade) than during the ten warmest days (0.27°C/0.49°F per decade). This means inadequate recovery from daytime heat during nights.
Now, over a billion more people endure at least one day of extreme heat stress annually compared to the 1970s. Future impacts hinge on global response. Jennifer Francis, a climate scientist at the Woodwell Climate Research Center, stated that the study provides concerning details about rising dangers for billions due to increasing temperature and humidity.
Emerton emphasizes the necessity for actions such as mitigation of future warming, adaptation strategies, heat health action plans, early warning systems, and climate risk assessments.
Alexa St. John, a climate reporter for the Associated Press, contributes further insights. Follow her for updates: @alexa_stjohn.
The Associated Press’ climate and environmental coverage is financially backed by various foundations; however, AP maintains editorial independence. More information on AP’s standards and supporters is accessible at AP.org.
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