The double burden of inequality and flood losses

Our analysis of over 500 major flood events in advanced economies indicates that the human toll of floods tends to be higher in more unequal countries. We argue that the increasingly uneven distribution of wealth deserves more attention within international disaster risk research and policy arenas.
The double burden of inequality and flood losses

New York Times columnist David Brooks (2005) captured the essence of inequalities and flood impacts when commenting on the aftermaths of Hurricane Katrina: “Floods wash away the surface of society, the settled way things have been done. They expose the underlying power structures, the injustices, the patterns of corruption and the unacknowledged inequalities.

The flooding of New Orleans following Katrina has since become a textbook example of how marginalized neighborhoods often bear the brunt of disaster impacts due to societal structures. Almost two decades later, the world has witnessed many more examples of this tendency. Disasters continue to lay bare existing inequalities in ruthless ways, and inequality is now recognized as one of the key driving factors of disaster risk (UNGA, 2016).

Our recent article in Nature Sustainability dives into the ways economic inequality within countries can influence flood mortality. While there are many dimensions of inequality, we focus on economy due to the widening gap between rich and poor within many countries worldwide. Understanding the dynamics between economic inequality and human losses from floods thus becomes vital, especially in light of the intensifying rainfall patterns brought about by the climate crisis.

But how could economic inequality within a country influence its flood mortality rates? Research suggests that several factors can come into play, relating to both poverty and the asymmetries per se (Adger and Kelly, 1999; Anbarci, Escaleras and Register, 2005; Kahn, 2005; Collins, 2009; Tselios and Tompkins, 2019). High levels of income inequality often imply that a significant portion of the population lives in poverty, making them more vulnerable during and after a disaster. For instance, individuals living in poverty may lack the necessary resources to prepare for or evacuate during a flood. Power asymmetries typically lead to spatial marginalization in the urban landscape, which can increase the disaster risk. This occurs when resources, services, and flood protection infrastructure are concentrated in high-income neighborhoods, leaving low-income areas behind and at higher risk.

To better understand the relationship between economic inequality and flood mortality, we conducted a comprehensive analysis of over 500 major flood events in 67 middle- and high-income countries over the past three decades. Our objective was to determine whether the link between economic inequality and flood mortality would persist after controlling per capita GDP and the number of people living in affected areas. Our study reveals a striking association between economic inequality and human losses caused by floods. Simultaneously, most countries in our sample experienced widening income gaps during the study period. While our data do not allow us to establish causality, our findings emphasize how economic inequality seems to play a more central role in explaining human flood losses compared to the GDP.

Income inequality and flood fatalities in 67 middle- and high-income countries. This map displays 573 major flood disasters (dots) that occurred between 1990 and 2018, with the size of the dots indicating the number of reported flood fatalities and the colour of the countries indicating their average level of income inequality across the study period. A higher Gini index indicates higher inequality. Figure from Lindersson et al. (2023)

Looking ahead, it is essential for researchers to delve deeper into the ways in which economic inequality amplifies the human losses from floods. By doing so, we can develop more efficient strategies for disaster risk reduction that take into account the socioeconomic disparities that exist within and between countries. One way to achieve this is by conducting large-scale studies that broaden their focus beyond inter-country inequality and also examine intra-country inequality. Our recent article highlights the importance of not only analyzing the vulnerability of poor countries but also the vulnerability of marginalized individuals in rich countries. By adopting this approach, we can better identify and address the root causes of vulnerability to floods and other hazards.

Addressing the root causes of vulnerability is, at the end of the day, absolute key to reduce the human toll from disasters. This is especially true when crafting policies for disaster risk reduction. For instance, floodplain regulations aimed at decreasing the human exposure to floods will never be completely successful if a significant portion of the population is living in unofficial conditions. To truly minimize the impact of disasters, it is crucial to improve the everyday lives of the most vulnerable individuals – in poor countries as well as in rich ones.

Article reference:

Lindersson, S., Raffetti, E., Rusca, M. et al. The wider the gap between rich and poor the higher the flood mortality. Nat Sustain (2023). 

References in this blog post

  • Adger, W. N. and Kelly, P. M. (1999) ‘Social Vulnerability to Climate Change and the Architecture of Entitlements’, Mitigation and Adaptation Strategies for Global Change, 4(3), pp. 253–266. doi:
  • Anbarci, N., Escaleras, M. and Register, C. A. (2005) ‘Earthquake fatalities: the interaction of nature and political economy’, Journal of Public Economics, 89(9), pp. 1907–1933. doi:
  • Brooks, D. (2005) ‘The Storm After the Storm’, The New York Times, 1 September.
  • Collins, T. W. (2009) ‘The production of unequal risk in hazardscapes: An explanatory frame applied to disaster at the US–Mexico border’, Geoforum, 40(4), pp. 589–601. doi:
  • Kahn, M. E. (2005) ‘The death toll from natural disasters: The role of income, geography, and institutions’, Review of Economics and Statistics. MIT Press, pp. 271–284. doi:
  • Tselios, V. and Tompkins, E. L. (2019) ‘What causes nations to recover from disasters? An inquiry into the role of wealth, income inequality, and social welfare provisioning’, International Journal of Disaster Risk Reduction, 33, pp. 162–180. doi:
  • UNGA (2016) Report of the open-ended intergovernmental expert working group on indicators and terminology relating to disaster risk reduction. A/71/644.

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