By Pablo A. Méndez-Lázaro

Climate change presents evolving challenges to human health and to the distribution and diversity of living natural resources (IPCC, 2007; Bozzi and Dubrow, 2020). Some of these challenges are due to changing temperatures and weather patterns (Villarini et al. 2011). Extreme events, such as heat waves, widespread flooding, or very strong storms, are of interest to scientists and managers because of their potential to cause extensive damage and impacts on people, infrastructure, and nature (McPhillips et al. 2018; Gould et al. 2018).

Extreme heat episodes are becoming more common worldwide, including in tropical areas (Mendez-Lazaro et al. 2017). Higher frequency, duration, and intensity of extreme heat episodes are triggering public health issues in most mid-latitude and continental cities. Along with heat intensity and duration, factors such as time within the year, repetition, time between adjacent events, and acclimatization of individuals are important determinants of the health outcomes of extreme heat episodes. According to the Intergovernmental Panel on Climate Change (IPCC) Working Group 1 Sixth Assessment Report (AR6), which focused on small islands, warming will continue in the 21st century for all global warming levels and future emissions scenarios, further increasing heat extremes and heat stress (IPCC, 2021).

There is also concern that climate change can re-introduce diseases into geographic areas where they had been previously eradicated. Rising average temperatures can lead to the expansion of the geographic range of many vectors, to decreasing extrinsic incubation periods of many pathogens, and to an increased rate of contact of mosquitoes (such as Aedes aegypti and Aedes albopictus) with prey, including humans. Climate change has led to increased risk of exposure of human populations to airborne allergens and vector-borne diseases such as West Nile virus, malaria, dengue fever and chikungunya, particularly in tropical communities (Githeko et al., 2000; Brunkard et al., 2008; Portier et al., 2010; Méndez-Lázaro et al. 2014).

Changing patterns and frequency of prolonged heat episodes, ground level atmospheric ozone concentration or smog, and dust and other aerosols that trigger asthmatic responses are also conditions of concern (Shamir and Georgakakos, 2014). Small tropical islands, such as Puerto Rico, are particularly vulnerable because of extreme events associated with changes in both terrestrial and marine weather.

Air pollution is another significant public health problem, responsible for a growing range of health impacts in many regions of the world and in the Caribbean. Problems related to air pollution and climate can have serious impacts on the economy and public health (Méndez-Lázaro et al. 2014; Méndez-Lázaro et al. 2017). Globally, the largest dust sources are in the northern hemisphere, with major contributions from the Sahara and Sahel regions in North Africa. Air pollution, variability in aerosols from natural sources, and trends in environmental variables due to climate, can interact with various socio-economic factors in numerous ways to affect public health. Some interactions, such as those that influence the timing of dengue fever, the emergence of epidemics, or extremes in urban heat, can impact the economy and social fabric of communities (Méndez-Lázaro et al., 2014).

Over 20 million tons of mineral dust from Africa is transported every year by the trade winds to the Caribbean, and is ultimately deposited over a large area, spanning Brazil to the southeastern USA. In Puerto Rico, Saharan dust is positively associated with cardiovascular and respiratory conditions (Lillianne et al. 2019). African dust outbreaks (a natural source of degraded air quality) are also associated with increased to excessive risk of emergency room visits and hospitalizations related to asthma in children in Trinidad & Tobago (Gyan et al., 2005), Guadeloupe (Cadelis et al., 2015), and Grenada (Akpinar-Elci et al., 2015).

On the other hand, the coronavirus SARS-CoV-2, which is responsible for the present COVID-19 pandemic, increases the risk of mortality due to severe respiratory illness and cardiac injury (de Ángel Solá et al. 2020). This novel virus is particularly concerning in lower and middle-income countries that are exposed to powerful natural hazards and are at high risk for emergence of other pathogens. Their lower preparedness for public health emergencies can lead to disproportionately higher mortality rates. According to the 4th U.S. National Climate Assessment, “high levels of exposure and sensitivity to risk in the U.S. Caribbean region are compounded by a low level of adaptive capacity, due in part to the high costs of mitigation and adaptation measures relative to the region’s gross domestic product” (Gould et al. 2018).

Addressing climate change and extreme weather events requires new geospatial and communications approaches to facilitate efforts from public health practitioners and emergency response planners (White-Newsome et al. 2013; Wolf and McGregor, 2013). These strategies need to link human health, rapid and synoptic environmental monitoring, and the research that helps improve the forecast of hazardous conditions for human population segments or for other organisms. Knowledge of risks and availability of mechanisms to apply the information in effective ways by working with the public are essential (Buczak et al. 2012; White-Newsome et al. 2013; Garni et al. 2014).

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Pablo Méndez-Lázaro (Ph.D.) is currently an Associate Professor at the Department of Environmental Health of the University of Puerto Rico, Graduate School of Public Health. He is an active Member of the Puerto Rico Climate Change Council, and one of the six (6) scientists nominated by the Governor of Puerto Rico and confirmed by both the Senate and House of Representatives of Puerto Rico for the Executive Committee on Climate Change Adaptation Plan. Dr. Méndez-Lázaro is currently PI and Co-PI on NASA research projects exploits new technologies in ways that benefit all segments of socio-ecological and technological systems by applying Earth Observing Data and Remote Sensing to research on public health and vulnerable populations. He was recently invited by the U.S. Global Change Research Program to serve as the Chapter Lead for the US Caribbean Chapter of the Fifth National Climate Assessment.

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