*3.3. Heat Accumulation*

Ltd.

Ltd.

The HA maps for RCP 8.5 show that the areas with the highest HA (purple and deep purple) were again within the western portions of Trinidad. Port of Spain and Diego Martin Regional Corporations were the hottest regions in Trinidad. However, there were even larger areas of the warmest regions (purple and deep purple) in 2090 under RCP 8.5 compared to all other RCPs. The highest HA values were approximately 2319-degree days in 2090 under RCP 8.5 (Figures 7–11 below).

**Figure 7.** Heat accumulation in Trinidad for RCP 8.5 in 2014. Source: Authors' compilation based on data from the Trinidad and Tobago Meteorological Services and CLIMsystems **Figure 7.** Heat accumulation in Trinidad for RCP 8.5 in 2014. Source: Authors' compilation based on data from the Trinidad and Tobago Meteorological Services and CLIMsystems Ltd.

based on data from the Trinidad and Tobago Meteorological Services and CLIMsystems

**Figure 7.** Heat accumulation in Trinidad for RCP 8.5 in 2014. Source: Authors' compilation based on data from the Trinidad and Tobago Meteorological Services and CLIMsystems

Ltd.

Ltd.

Ltd.

Ltd.

**Figure 8.** Heat accumulation in Trinidad for RCP 8.5 in 2018. Source: Authors' compilation based on data from the Trinidad and Tobago Meteorological Services and CLIMsystems **Figure 8.** Heat accumulation in Trinidad for RCP 8.5 in 2018. Source: Authors' compilation based on data from the Trinidad and Tobago Meteorological Services and CLIMsystems Ltd.

**Figure 9.** Heat accumulation in Trinidad for RCP 8.5 in 2030. Source: Authors' compilation based on data from the Trinidad and Tobago Meteorological Services and CLIMsystems **Figure 9.** Heat accumulation in Trinidad for RCP 8.5 in 2030. Source: Authors' compilation based on data from the Trinidad and Tobago Meteorological Services and CLIMsystems Ltd.

10

**Figure 10.** Heat accumulation in Trinidad for RCP 8.5 in 2050. Source: Authors' compilation based on data from the Trinidad and Tobago Meteorological Services and CLIMsystems

**Figure 9.** Heat accumulation in Trinidad for RCP 8.5 in 2030. Source: Authors' compilation based on data from the Trinidad and Tobago Meteorological Services and CLIMsystems

Ltd.

Ltd.

Ltd.

**4. Discussion**

*4.1. Heat Trends*

4.1.1. Land Surface Temperatures

are warmer than the surrounding areas (Figure 3).

**Figure 10.** Heat accumulation in Trinidad for RCP 8.5 in 2050. Source: Authors' compilation based on data from the Trinidad and Tobago Meteorological Services and CLIMsystems **Figure 10.** Heat accumulation in Trinidad for RCP 8.5 in 2050. Source: Authors' compilation based on data from the Trinidad and Tobago Meteorological Services and CLIMsystems Ltd.

**Figure 11.** Heat accumulation in Trinidad for RCP 8.5 in 2090. Source: Authors' compilation based on data from the Trinidad and Tobago Meteorological Services and CLIMsystems **Figure 11.** Heat accumulation in Trinidad for RCP 8.5 in 2090. Source: Authors' compilation based on data from the Trinidad and Tobago Meteorological Services and CLIMsystems Ltd.

Trinidad show striking similarities in distribution. The hottest regions in Trinidad are demonstrably centred around urbanization. This is a visible indicator that urbanization and urban infrastructure in Trinidad plays a significant role in heat absorption and retention. Landsat thermal imagery showed that the western portions of Trinidad are warmer compared to the surrounding areas. This is indicative of the presence of a surface urban heat island (SUHI) as the urban regions

The comparative maps of land surface temperature and urban development in

The urban environment can be characterized by a conglomeration of

anthropogenic surfaces, vegetation, and water features. All of these urban features dictate and influence temperature regimes within the environment and can create a separate microclimate (Le and Tran 2019; Giyasova 2021,). Urban areas, particularly those within the tropics, have experienced population movements, urban growth, and industrialization which have led to elevated temperatures and the creation of urban heat islands (UHIs) such as the UHI in San Juan, Puerto Rico (Molina et al. 2020). Similarformations of UHIs are possible within other Caribbean SIDS. Thermal imagery indicated that the majority of the developed western portion of Trinidad is warmer than the rural undeveloped regions in Trinidad. Anthropogenic infrastructure within urban areas can result in increased temperatures due to the

#### **4. Discussion**

#### *4.1. Heat Trends*

#### 4.1.1. Land Surface Temperatures

The comparative maps of land surface temperature and urban development in Trinidad show striking similarities in distribution. The hottest regions in Trinidad are demonstrably centred around urbanization. This is a visible indicator that urbanization and urban infrastructure in Trinidad plays a significant role in heat absorption and retention. Landsat thermal imagery showed that the western portions of Trinidad are warmer compared to the surrounding areas. This is indicative of the presence of a surface urban heat island (SUHI) as the urban regions are warmer than the surrounding areas (Figure 3).

The urban environment can be characterized by a conglomeration of anthropogenic surfaces, vegetation, and water features. All of these urban features dictate and influence temperature regimes within the environment and can create a separate microclimate (Le and Tran 2019; Giyasova 2021). Urban areas, particularly those within the tropics, have experienced population movements, urban growth, and industrialization which have led to elevated temperatures and the creation of urban heat islands (UHIs) such as the UHI in San Juan, Puerto Rico (Molina et al. 2020). Similar formations of UHIs are possible within other Caribbean SIDS. Thermal imagery indicated that the majority of the developed western portion of Trinidad is warmer than the rural undeveloped regions in Trinidad. Anthropogenic infrastructure within urban areas can result in increased temperatures due to the increased surface areas of buildings that absorb thermal radiation and reduce wind speeds. The thermal characteristics of urban surface materials allow for increased heat storage and higher heat capacities and conductivities than vegetated surfaces. Urban areas also have vast amounts of impervious surfaces such as asphalt/pitch and concrete that decrease cooling. (Vujovic et al. 2021). Persons living within highly urbanized regions are exposed to greater health risks due to heat stress and heat strokes with most heat mortalities occurring in highly urbanized cities as a result of the urban heat island effect (Heaviside et al. 2017; Piracha and Chaudhary 2022). The most vulnerable groups include the elderly, the very young, the chronically ill or disabled, expectant mothers, and the socially isolated. Low-income and minority groups are also high-risk groups since they lack the social and financial capacity to withstand adverse climatic conditions (Heaviside et al. 2017; Piracha and Chaudhary 2022). It is therefore necessary for accurate temperatures to be disseminated to the general public so that they can undertake the necessary measures and precautions to protect themselves from the health risks and impacts associated with elevated temperatures, particularly in regions of high population densities such as Port of Spain. It is understood that humidity is an important factor in assessing heat-related impacts on human health as well as the quantification of the UHI effect. Therefore,

further studies should be conducted inclusive of humidity for heat index and HI effect calculations in order to quantify the heat-related health impacts within urban regions in Trinidad.

#### 4.1.2. Heat Index

The maximum HI in Trinidad has increased significantly from 1976 to 2015, particularly during the wet season. The increasing heat index found in this study was similar to findings in other parts of the Caribbean, including islands in both the Greater and Lesser Antilles, where the HI has notably increased over a 35-year period (Ramirez-Beltran et al. 2017). Additionally, observations in other parts of the Caribbean revealed that the maximum HI was higher during the wet season, similar to the findings in this study (Ramirez-Beltran et al. 2017). Temperatures in Trinidad and Tobago are generally higher during the wet season due to higher levels of humidity (TTMS 2023).
