Plastic waste puts millions of the world’s poorest at greater risk of flooding

A devastating 2005 flood that killed 1,000 people in the Indian city of Mumbai has been blamed on a tragically simple problem: Plastic bags had blocked storm drains, preventing monsoon flood water from draining out of the city.

Now a new report, in an attempt to quantify this problem, estimates that 218 million of the world’s poorest people are at risk of more severe and frequent flooding caused by plastic waste.

The number is equivalent to the population of the UK, France and Germany combined. About 41 million of these are children, the elderly and people with disabilities, according to the report. Three-quarters of those most at risk live in Southeast Asia and the Pacific region.

Researchers from Resource Futures, an environmental consultancy, and Tearfund, an international Christian charity, found that communities in Cameroon, Nigeria, the Democratic Republic of the Congo (DRC), Ghana, Bangladesh and Indonesia experienced more severe flooding due to the blockage of plastic waste drainage systems in recent years. In these communities, plastic waste has been a risk multiplier for flooding, they said.

To identify those most at risk, they used a study on flood risk and poverty published in 2022 by Jun Rentschler and others that identified 1.8 billion people at high risk of flooding across 188 nations. They narrowed their analysis to only low- and middle-income countries with urban drainage, solid waste management, and inadequate sanitation. To focus on populations most at risk from plastics that exacerbate flood risk, they also excluded countries with poorly managed waste of less than 1kg per person per year and focused on urban slums.

Rich Gower, senior economist and political partner at Tearfund, said: Across the globe, from Brazil to the DRC, Malawi to Bangladesh, we see plastic pollution making floods worse. Without decisive action, this problem will only get worse.

Plastic waste pollution has doubled in the last decade and is projected to triple by 2060. Only 9% is recycled globally.

Gower said: The purpose of the report is to give an order of magnitude to the number of people at risk. What we are saying is that plastic pollution affects the poorest and most marginalized communities the hardest. We’ve seen it with the burning of plastics and now we’re seeing it with the risk of flooding. These communities bear the brunt of the plastic pollution.

The authors pointed out the limitations of the estimate. It was based on the best data available, they said, admitting that no detailed data is available on the impacts of plastic-aggravated flooding. Nor, they said, was there sufficient modeling of the links between plastic pollution, flooding and health. But they had applied multiple conservative assumptions and sensory checks, and considered the estimate realistic and conservative, they said.

Gower urged governments, who are meeting in Paris next week to start negotiations on a legally binding plastics treaty, to consider these hardest-hit communities. Through the plastics treaty, world leaders have a once-in-a-lifetime opportunity to end this crisis by reducing plastic production and making sure the rest is collected and recycled safely, he said.

Brendan Cooper, a consultant at Resource Futures, said he used Rentschler’s flood risk study as a starting point. Then we broke it down into those more in line with plastic-aggravated flooding, Cooper said. We have found that urban areas have high levels of poorly managed waste.

While the figures were estimates, he said, they were a conservative estimate.

Densely populated slums of South Asia, East Asia and the Pacific and sub-Saharan Africa were likely to suffer the worst effects of plastic-aggravated flooding due to poorly planned and rapid development, with limited infrastructure for flood mitigation , according to the report.

It showed that plastic pollution in slums in many low- and middle-income countries was making floods more severe by blocking drainage systems, resulting in health problems, including gastrointestinal diseases such as cholera and diarrheal diseases.

The researchers excluded coastal communities and small island developing states from the survey, as coastal flooding is unlikely to be exacerbated by plastic waste.

More than 1 billion people live in slums globally, and it is projected to reach 3 billion by 2050. The most commonly observed plastic objects blocking drainage systems, according to the report, are bottles, nylon strings, fishing industry, plastic bags and sachets.

The study said that the accumulation of plastic pollution could raise water levels by one meter within the first hour of a flood.