One of the many effects of climate change is the increase in temperatures. In Puerto Rico, heat waves are becoming more frequent and extensive. Given this reality, it is crucial to understand the risk that citizens face.
Beyond temperature, there are various factors that affect the thermal sensation or the heat index, that is, how the heat feels. For example, it has been shown that cement and asphalt retain heat for longer, which affects urban areas and creates "islands" of extreme heat. Thermal sensation is also influenced by socioeconomic and demographic factors.
In San Juan, due to its high population density and size, heat vulnerability maps already exist. These maps combine information on temperature, social conditions, and environmental characteristics to identify the communities most exposed to extreme heat and with fewer resources to cope with it. In this way, they help prioritize actions such as tree planting, the creation of cool spaces, and the preparation of health services.
However, in other municipalities, such as Ponce, this type of analysis is incomplete. Given that Ponce is drier, it records higher temperatures; also, it has more inhabitants with high levels of poverty compared to the metropolitan area, which makes the development of heat vulnerability models critical for public health in the southern region.
A group of scientists, led by Dr. Laura Cabrera Rivera and mentored by Dr. Pablo Méndez Lázaro –both from the Department of Environmental Health of the Graduate School of Public Health of the Medical Sciences Campus of the University of Puerto Rico–, completed a detailed statistical analysis to create a heat vulnerability map for Ponce. The findings of their analysis were published in the "Urban Climate" journal last January.
“Our research group, the ‘Caribbean Collaborative Action Network’ (CCAN), part of the Climate Adaptation Partnerships program of the National Oceanic and Atmospheric Administration (NOAA), works on various initiatives to help Puerto Rico adapt and prepare for extreme heat. This phenomenon increasingly affects essential sectors of our daily lives and especially vulnerable populations, such as older adults and children,” said Méndez Lázaro.
The scientists measured or obtained information on different variables, including soil temperature, amount of vegetation, presence of cement and asphalt, population density, and conditions such as poverty and aging, to develop a heat model. Then, they used this information to create an interactive map showing how heat vulnerability is distributed across the different communities of Ponce.
“To truly understand heat vulnerability, it's not enough to just measure temperature. It is essential to integrate factors such as vegetation cover, impervious surfaces, population density, and social conditions, because these are the elements that determine who is most exposed and who has less capacity to protect themselves from extreme heat,” explained Cabrera Rivera.
With the urban heat models that CCAN has developed, the next step is to collaborate directly with agencies and decision-makers to create mitigation strategies based on scientific evidence.
Méndez Lázaro summarized some of these initiatives. For example, reforestation activities are carried out in schools, led by the Department of Education, to create cooler and healthier spaces. In addition, CCAN offers training workshops to educators, first responders, Emergency Management personnel, the Hospital Association, and groups of older adults, so that each sector can better prepare for the challenges of extreme heat.
With 78 municipalities on the island, the efforts of Cabrera Rivera, Méndez Lázaro, and their CCAN colleagues are just beginning. Their plan is to expand the heat vulnerability maps to other cities in Puerto Rico.