Rising sea level and increasing tropical cyclone frequency are threatening the population of San Andrés Island, Colombia, western Caribbean

Matthias Bernet,Liliana Torres Acosta

doi:10.1051/bsgf/2022003

Abstract

The Colombian island of San Andrés is a popular tourist destination located about 195 km offshore of the east coast of Nicaragua in the southwestern Caribbean Sea. Together with Providencia and Santa Catalina, San Andrés is part of the UNESCO Seaflower Biosphere Reserve. With a 26 km2 surface area and 78 000 inhabitants, San Andrés is one of the most densely populated islands in the Caribbean with on average ∼ 3000 inhabitants/km2. The majority of the population and the mass tourism are concentrated in the low-elevation (0.5–6 m) areas, particularly in the north and along the east coast of the island. These areas are prone to flooding during storm events such as hurricanes Eta and Iota in 2020. A review of the geological, environmental and the socio-economic situation of the island, and the record of tropical cyclones since 1911, shows why the local population has become increasingly vulnerable to storm events and rising sea level. Tropical cyclones may form locally in the southwestern Caribbean or originate in the eastern Caribbean/Atlantic Ocean. The latter tend to be stronger and cause more damage when they reach San Andrés. The HURDAT2 dataset shows that the frequency of storm events affecting San Andrés has increased in recent decades, with six storms over the past 20 years, including three category 4-5 hurricanes since 2007. Increasing storm frequency and intensity may be linked to increasing sea surface temperatures caused by anthropogenic global warming, although the changes described here may be limited to a relatively small geographical region, as opposed to representing basin wide tropical cyclone behavior. The growing population density since the 1950s has augmented the potential for disaster.

Highlights

San Andrés Island is located about 195 km to the east of the coast of Nicaragua (Fig. 1), and is part of the San Andrés, Providencia and Santa Catalina archipelago that belongs to Colombia
San Andrés Island can serve as a model for studying how the geological, environmental and socio-economic conditions define the vulnerability of the local population to environmental hazards such as storm events and rising sea level
Since 1911 San Andrés Island has been affected on average by a tropical cyclone once every eight years, but over the past 20 years the frequency has increased to one tropical cyclone every three years

Summary

Introduction

San Andrés Island is located about 195 km to the east of the coast of Nicaragua (Fig. 1), and is part of the San Andrés, Providencia and Santa Catalina archipelago that belongs to Colombia This archipelago forms the UNESCO Seaflower Biosphere Reserve (Gómez-López et al, 2012; Gavio and Mancera Pineda, 2015; Londoño-Diaz and Varas-Morales, 2015). San Andrés Island can serve as a model for studying how the geological, environmental and socio-economic conditions define the vulnerability of the local population to environmental hazards such as storm events and rising sea level. Rising sea level will increase the potential for catastrophic storm surges for low-lying coastal communities (Smith, 2001) This is one of the aspects that we will discuss in the case of San Andrés, as the impacts of such hazardous events will likely be compounded by their combined effects such as extreme rainfall, high windspeeds, storm surges, wave action (coastal erosion), landslides, disruption of infrastructure, and electricity and drinking water supply during and after storm events. One important question that arises in this context is, if the increasing disasters are linked to an increase in storm activity alone or because more and more people are living in areas exposed to storm hazards? For appreciating the vulnerability of the population of San Andrés Island, we review here the current geological, environmental, and socio-economic conditions of the island, and examine the record of storm events affecting the island over the past 110 years in relation to global warming induced increasing sea surface temperatures (Schmidt et al, 2006; Glenn et al, 2015; Taylor and Stephenson, 2017) and the apparent increasing storm frequency and intensity in the Caribbean (Vecchi and Knutson, 2008; Brun and Palmer, 2015; Xu et al, 2016; Knutson et al, 2021; Vecchi et al, 2021)

Geological setting and environmental conditions

Population and socio-economic history and development

Environmental hazards

Global warming, sea level rise and storm events

Protection from the barrier reef

Socio-economic factors contributing to the vulnerability of the population

Findings

Future storm events

Conclusions