Study Analyzes Future Displacement Risks Due to Flooding from Overflowing Rivers

Annually, millions of people across the globe get displaced from their homes as a result of extreme weather due to climate change.

Flooding is one of the main causes of population displacement. Image Credit: Keystone.

The International Red Cross and Red Crescent Movement reports that in the past six months alone, 10.3 million people have been displaced due to climate-related events—four times those displaced by conflict and war at the same time.

Flooding is one of the major causes of such displacement. A new example is a scenario in eastern Australia, where tens of thousands of people have had to leave their homes toward safety from the 100-year flood.

An international research group under the guidance of the Weather and Climate Risks Group at ETH Zurich very recently published a new study targeted at offering better insights into future displacement risks as a result of flooding from rivers that overflow their banks.

The study assesses the impact of climate change as well as socioeconomic and demographic factors on such risks.

Population Growth Greatly Increases Risk

The team used a range of climate, hydrology, and population distribution models to show that if the population stays stable at its present level, the threat of flood-related displacement increases by over 50% (when compared to 2010 levels) for each degree of global warming.

But the global population is constantly increasing. Despite this increase continuing toward a more sustainable path, the threat of displacement will still increase considerably: supposing that the world fulfills the Paris Agreement’s goal of restricting global warming to a maximum of 2°C, the worldwide averaged risk is predicted to increase by up to 110% by the end of the 21st century.

Yet under “business as usual” climate-change conditions and in case the gap between rich and poor keeps increasing, the risk is predicted to increase much more drastically. In such a case, the team estimated that the risk of displacement as a result of flooding would be nearly 350% more.

Rapid Action Required

The authors of the study note that it is not yet too late to mitigate and deal with the risk of flood-related displacement through spatial and urban planning measures and protective infrastructure like dams.

Our findings highlight the need for rapid action on both climate mitigation and adaptation agendas in order to reduce future risks, especially to vulnerable populations. Floods often affect the most socio-economically vulnerable groups, who tend to live in more hazard-prone areas.

Pui Man Kam, Study Lead Author, ETH Zürich

Kam is a doctoral student in ETH Professor David N. Bresch’s group.

The team utilized a global climate-, hydrology- and inundation-modeling chain to perform their study to measure the impact of global warming on displacement risk for both present and predicted future population distributions. The study was recently published in the Environmental Research Letters journal.

Because floods are a major driver of displacement and due to the fact that they are influenced by climate change, it is imperative that we have a better understanding of how the risks are changing.

Pui Man Kam, Study Lead Author, ETH Zürich

Journal Reference:

Kam, P. M., et al. (2021) Global warming and population change both heighten future risk of human displacement due to river floods. Environmental Research Letters. doi.org/10.1088/1748-9326/abd26c.

Source: https://ethz.ch/en.html

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