Since 2011, the coasts of North America, Mexico, and the Caribbean have experienced an unusual increase in the arrival of Sargassum. A large amount of Sargassum has caused significant economic losses in the tourism sector of the Dominican Republic as well as the entire Caribbean region. The present article discusses the possible factors contributing toward this unusual increase. Large Sargassum masses are generated in the Sargasso Sea. In this region, several current systems converge with the North Atlantic Subtropical Anticyclone (NASH), which has an area of displacement extending from Brazil to Africa. Sargassum is transported toward Africa, where it meets the Northern Equatorial Recirculation Region (NERR) before recirculating back toward the Caribbean in a clockwise pattern (Putman et al., 2018; Wang, 2007). Upon returning to the Caribbean and Gulf of Mexico, Sargasso grows flowers and distributes across the region. The effect of the North Atlantic Oscillation (NAO) is also analyzed as well as the possible influence of Sahara dust, which acts as a source of nutrients for the growth and development of Sargassum. In the Dominican Republic, the species found in the current study included Sargassum fluitans and Sargassum natans. As for the species Sargassum polyceratium var. ovatum, the variety ovatum has not been reported before on the coasts of the Dominican Republic. Key words: Sargassum arrival, Caribbean, Dominican Republic, Azore High.

There is no doubt that global warming is altering weather patterns and climatic trends all over the world, yet how Earth's changing climate is affecting hurricanes is still not fully understood. Hurricanes are powerful tropical cyclones (TCs) that develop in the warm waters of our planet's oceans. They are known as typhoons in the West Pacific and cyclones in the Indian Ocean. Hurricanes are mostly powered by warm tropical waters, and it is well established that ocean temperatures in areas where TCs form have been rising since the mid-20th century [1]. In recent years we have witnessed powerful hurricanes that have exhibited record-breaking, rapid intensification. They have produced extreme rainfall that has led to flash floods and landslides, and have caused severe storm surges that have impacted many coastal environments and communities. Over the past three decades the Caribbean in the North Atlantic basin has been particularly affected by hurricanes, creating hazardous conditions and putting water resources in jeopardy. Many studies have examined the relationship between climate change and hurricane frequency and intensity in the North Atlantic basin. The results of these analyses suggest that warmer sea surface temperatures (SSTs) associated with climate change are a major factor in the increased frequency of hurricanes [2]. Several studies have found that the total number of major hurricanes in the North Atlantic is increasing [3] and that this is associated with higher SSTs and more humid environments [4]. However, other researchers have found that the increase in the total number of hurricanes may be associated with an undercounting of storms in the pre-satellite era [5] and that it may also be related to teleconnections like the El Niño Southern Oscillation (ENSO) and the Atlantic Multidecadal Oscillation (AMO), which promote changes in vertical wind shear and SSTs that could enhance or suppress TC development [6]. A recent study has found an increase in the total number of off-season TCs [7], that could be associated with climate change. The latest research suggests that both climate change (higher ocean heat, sea surface temperature and cloud cover moisture) and climatic variability (ENSO and AMO) might explain the increase in the total number of tropical cyclones and major hurricanes in the North Atlantic (Fig 1A), with climate change factors being more statistically significant [4]. Even though recent research has found that the total number of tropical cyclones has increased in the North Atlantic, it is still not clear how much of that increase in activity and intensity can be attributed to climate change. Researchers have found that the increase in hurricane intensity in the Atlantic basin is strongly correlated with an increase in the late summer / early fall SSTs that have been attributed to climate change [8] When researchers examined the total power dissipation and accumulated cyclone energy (ACE) by TCs, they found that storm intensity (Fig 1A

Climate change might increase the frequency and severity of longer-lasting drought in the Caribbean, including in Hispaniola Island. Nevertheless, the hydroclimate changes projected by the state-of-the-art earth system models across the island remain unknown. Here, we assess 21st-century changes in hydroclimate over Hispaniola Island using precipitation, temperature, and surface soil moisture data from the 6th Phase of the Coupled Model Intercomparison Project (CMIP6). The resulting analysis indicates, as with the previous 5th Phase of CMIP (CMIP5) models, that Hispaniola Island might see a significant drying through the 21st century. The aridity appears to be robust in most of the island following the Shared Socioeconomic Pathways (SSP) 5–8.6, which assumes the “worst case” greenhouse gas emissions into the atmosphere. We find a significant reduction in both annual mean precipitation and surface soil moisture (soil’s upper 10 cm), although it appears to be more pronounced for precipitation (up to 26% and 11% for precipitation and surface soil moisture, respectively). Even though we provide insights into future hydroclimate changes on Hispaniola Island, CMIP6’s intrinsic uncertainties and native horizontal resolution precludes us to better assess these changes at local scales. As such, we consider future dynamical downscaling efforts that might help us to better inform policy-makers and stakeholders in terms of drought risk.

The 2020 hurricane season in the North Atlantic basin was the most active on record, with 30 named tropical cyclones. In this study, climate trends in oceanic and atmospheric parameters (including the sea surface temperatures, ocean heat content, cloud cover, mid-level humidity, vertical wind shear, and sea level pressure) were used to model the tropical cyclone, hurricane, and major hurricane frequency in the post-satellite era (1966–2020). The relationships between storm frequency and climate variability factors (including the El Niño Southern Oscillation, the North Atlantic Oscillation, the Atlantic Multidecadal Oscillation, and the Atlantic Meridional Mode) were also examined. This was performed to determine the factors that exerted the greatest influence on the most active hurricane seasons on record. Mann–Kendall trend tests, Pearson’s correlations tests, stepwise Poisson linear regression models and spatial analysis techniques were used to identify the climate change and variability factors that best explained the tropical cyclone frequency in the North Atlantic. Our results show that hyperactive hurricane seasons, such as that of 2020, tend to be associated with higher cloud cover development, lower sea level pressure patterns, higher sea surface temperatures, positive phases of the Atlantic Multidecadal Oscillation and the Atlantic Meridional Mode, and weaker wind shear environments. Seasons with more major hurricanes had higher ocean heat contents and weaker wind shear environments. The 2020 and 2005 seasons had similar cloud cover and sea level pressure patterns, yet the wind shear was lower in 2020 than in 2005, which was associated with La Niña dominant conditions that could explain why 2020 surpassed 2005 in the total number of storms.

This study investigates the temporal trends and correlations between Saharan dust mass concentration densities (DMCD) and Sargassum concentrations (SCT) in the tropical North Atlantic. Average DMCD data for June, July, and August from 1980 to 2022, alongside SCT data for the same months from 2012 to 2022, were analyzed using Mann–Kendall tests for trends and lagged regression models to assess whether higher Saharan dust levels correlate with Sargassum outbreaks in the region. A comprehensive analysis reveals a significant upward trend in Saharan dust quantities over the study period, with the summer months of June, July, and August exhibiting consistent increases. Notably, 2018 and 2020 recorded the highest mean DMCD levels, with June showing the most significant increasing trend, peaking in 2019. These findings are consistent with previous studies indicating a continuous elevation in Saharan dust concentrations in the tropical atmosphere of the North Atlantic. Simultaneously, Sargassum concentrations also show a notable increasing trend, particularly in 2018, which experienced both peak SCT and elevated DMCD levels. Mann–Kendall tests confirm statistically significant upward trends in both Saharan dust and Sargassum concentrations. Simple linear regression and lagged regression analyses reveal positive correlations between DMCD and SCT, highlighting a temporal component with stronger associations observed in July and the overall June–July–August (JJA) period. These results underscore the potential contribution of elevated Saharan dust concentrations to the recent surge in Sargassum outbreaks in the tropical North Atlantic. Furthermore, the results from forward stepwise regression (FSR) models indicate that DMCD and chlorophyll (CHLO) are the most critical predictors of SCT for the summer months, while sea surface temperature (SST) was not a significant predictor. These findings emphasize the importance of monitoring Saharan dust and chlorophyll trends in the Eastern Caribbean, as both factors are essential for improving Sargassum modeling and prediction in the region. This study provides valuable insights into the climatic factors influencing marine ecosystems and highlights the need for integrated environmental monitoring to manage the impacts on coastal economies.

In recent years, the coasts of the Caribbean, West Africa, and the Gulf of Mexico have faced a massive influx of pelagic Sargassum (Sargassum natans and S. fluitans), driven by climatic and oceanographic changes. These algae, once confined to the Sargasso Sea, now proliferate in a new source region: the Greater Atlantic Sargassum Belt (GASB), fed by river nutrients from the Amazon and Orinoco, equatorial upwellings, Saharan dust, and a small contribution from the Gulf of Guinea transported by trade winds. This alga is transported to the Caribbean by key currents such as the North Equatorial Current, the Caribbean Current, and the Gulf of Mexico Loop Current. These combine with climate patterns such as the North Atlantic Subtropical High (NASH), the North Atlantic Oscillation (NAO), and the Atlantic El Niño mode, which affect the routes and intensity of the blooms. Peaks occur between April and September, with critical years such as 2015, 2018, and 2025, when more than 33.5 million metric tons were estimated. Although satellite monitoring has improved, challenges remain, such as low resolution in turbid waters and the lack of models that integrate physical, chemical, and biological variables. Given the scale of this phenomenon, stronger regional cooperation between governments and the community at large is needed, along with effective early warning systems. This paper attempts to analyze some of the most relevant studies on the mechanisms of Sargassum transport to the Caribbean, providing scientific insights into evidence-based management.