According to a recent study conducted by the University of Bristol and published in Environmental Research Letters, people who live in the world’s smallest countries—those that contribute the least to climate change—are already suffering significantly from its effects, and this burden is only expected to increase.
The image identifies where all 57 SIDS are located globally, including in the more concentrated regions of the Pacific (in red) and Caribbean (in black). Most SIDS are very small, meaning they have previously been missed out in global flood risk studies. Image Credit: University of Bristol
According to the study, an average of 20 % of the population in Small Island Developing States (SIDS), or about 8.5 million people, are now at risk of both inland and coastal flooding. As per the results, this percentage triples to more than 60 % of the population for the Bahamas, Guyana, and Tuvalu, three of the 57 countries that are centered in the Pacific, Caribbean, Indian Ocean, and South China Sea.
In the midst of record-breaking rainfall and devastating scenes in Valencia, Spain, the findings further highlight the severe risk of flooding for people in all parts of the world.
Flooding is now an alarming real-world threat for so many people globally. This study demonstrates that the often-overlooked Small Island Developing States are already subject to a disproportionate level of flood exposure, despite contributing the least to climate change.
Leanne Archer, Study Lead Author and Research Associate, Cabot Institute for the Environment, University of Bristol
Future projections also indicate that, even under the most optimistic global warming scenarios, the number of people impacted by rising sea levels, storm surges, and extreme rainfall events—including tropical cyclones—will increase substantially. In comparison, the scale of people likely to be affected far exceeds flood exposure levels in developed countries like the United States and the United Kingdom, where approximately 13 % and 8 % of the population are currently impacted, respectively.
Leanne added, “The findings should be a call to action to support these nations in adapting to and mitigating against these extreme repercussions, even under the lowest emissions scenario, which put life and livelihoods in peril.”
Small Island Developing States (SIDS) are a group of island nations and territories, with populations ranging from about 1,000 to 7 million people, identified by the United Nations (UN) as particularly vulnerable to climate change. While coastal flooding poses a significant risk due to population concentration along coastlines, recent findings reveal that inland flooding is actually the predominant issue for SIDS, accounting for 81 % of the overall population exposure to flood risks.
“Previous studies have only focused on coastal flooding, representing a significant underestimation of exposure. This is also the very first time a comprehensive picture of flood risk has been mapped across all 57 Small Island Developing States because the populations are so small, they haven’t met the minimum catchment size of previous major global studies. The modeling provides striking evidence demonstrating that climate change has an unjust and unequitable impact on the places and people, who have contributed least to the greenhouse gas emissions, fueling the problem,” Leanne further added.
By increasing the magnitude of numerous factors, such as rainfall, river flow, extreme wave heights and water levels, storm surges, and sea level rise, climate change is making flooding in SIDS more likely.
A fifth (21 %) of SIDS populations are predicted to be at risk of flooding, even if global warming is kept to a 1.5 °C increase by 2100. According to the study, this number could increase to almost a quarter (23 %), in the worst-case scenario of more than 4 °C warming. Last month, a United Nations report warned that if governments do not do more to reduce carbon emissions, global warming could reach 3.1 °C.
Belize, the Turks and Caicos Islands, and the Maldives were among the countries predicted to be most at risk, regardless of how much the world warms.
The study, conducted in collaboration with the University of Southampton, made use of Fathom’s Global Flood Map, a water risk intelligence firm that combines global population datasets with a high-resolution global hydrodynamic flood model.
This study fills an important gap in research, including direct measures of flood hazard and exposure which are essential to adequately reduce loss and damage from flooding in the Small Island Developing States. The results are a timely warning to the world’s political leaders and policy makers that global commitments to significantly reduce carbon emissions must be backed up by action, in order to reduce potential loss and damage from flooding in Small Island Developing States, which contribute least to harmful carbon emissions.
Paul Bates, Study Co-Author and Professor, Hydrology, University of Bristol
The University of Bristol’s research is driven by a commitment to finding bold solutions to significant global challenges. This study aligns with key research themes, including net zero, climate change, and social justice, reflecting the Cabot Institute’s strong emphasis on addressing urgent issues related to environmental change, natural hazards, and disaster risk.
Journal Reference:
Archer, L. et. al. (2024) Population exposure to flooding in Small Island Developing States under climate change. Environmental Research Letters. doi.org/10.1088/1748-9326/ad78eb