Future Projections of Sea Surface Temperature (SST) in the MDR and Wider Caribbean Region: Utilizing CMIP6 GCM Ensembles

As the Earth's climate undergoes dramatic shifts due to anthropogenic influences, certain regions are increasingly subjected to harsher climatic extremes. This study focuses on the critical role of sea surface temperature (SST) variations in shaping regional climate patterns, particularly within tropical regions such as the Main Developing Region (MDR) and the Caribbean. These regions are climatically sensitive and hold significant ecological and economic importance. While the implications of warming SSTs in these regions, particularly during the Late Rainfall Season (LRS; August, September, October, November), are not fully understood, the 2023 IPCC report emphasizes that the impacts of climate change will intensify with increasing greenhouse gas concentrations. Thus, understanding future SST projections in these areas is crucial for anticipating potential effects on weather patterns, ecosystems, and socio-economic activities. This study leverages models from the Coupled Model Inter-comparison Project Phase 6 (CMIP6) to project SSTs in the North Atlantic and wider Caribbean region under SSP2-4.5 and SSP5-8.5 scenarios. We utilized 14 CMIP6 models for individual analysis and conducted a multi-model ensemble to mitigate uncertainties and biases, providing a more accurate representation of future regional SSTs. The historical period from 1982 to 2011, using the NOAA OISST dataset, was employed for model validation, performance assessment, and robustness evaluation.

Our study period is divided into two distinct temporal segments: mid-century (2036-2065) and future (2071-2100). Results indicate good model performance, albeit with some biases. Pearson correlation coefficients (R) were 0.84 for the LRS and 0.85 for the annual cycle, suggesting that the CMIP6 models capture approximately 72% of the variance in observed SSTs. Furthermore, a root mean square error (RMSE) value of 0.17 indicates that, on average, the CMIP6 ensemble mean predictions deviate from observed SSTs by 0.17°C. These statistical evaluations imply that the climate models effectively simulate the overall trends and variability of SSTs in this region with good accuracy. Projected spatial results for the mid-century and future LRS show the highest SST increases concentrated in the Caribbean Sea and Gulf of Mexico. Climate change projections highlight significant warming in these areas and parts of the western Atlantic Ocean, with temperature decreases towards the east. Findings, as illustrated in Figure 1, suggest that climate models project an overall increase in SSTs in the region during the LRS by the mid-21st century, with an exponential increase in SSTs in the future under each SSP scenario compared to the historical period. The Caribbean Sea and Gulf of Mexico are expected to experience the most substantial warming, potentially impacting various aspects of regional climate, including rainfall patterns, hurricane intensity, and marine ecosystems. By providing accurate SST projections, this research supports efficient adaptation and mitigation efforts addressing climate change impacts. Understanding how warming SSTs affect marine ecosystems and human life is crucial, particularly in assessing potential links to heat stress, marine heatwaves (MHWs), and hurricanes. This work contributes to this goal in sensitive regions with high number of vulnerable populations.