It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
On today’s episode of the Mongabay Newscast, we take a look at two stories that show the effectiveness of combining traditional Indigenous ecological knowledge and Western science for conservation and restoration initiatives.
Our first guest today is Dr. Gary Paul Nabhan, an ethnobotanist at the University of Arizona. He tells us about eelgrass, an ancestral food of the Comcaac people in the state of Sonora in Mexico. Nabhan tells us why eelgrass is making a big comeback as a sustainable source of food for the Comcaac community and gaining international attention in the process.
We also speak with Sara Iverson, a professor of biology at Canada’s Dalhousie University, about a research project called Apoqnmatulti’k that aims to better understand the movements of lobster, eel, and tomcod in two important ecosystems on Canada’s Atlantic coast. Iverson tells us why those study species were chosen by the Mi’kmaq people and why it’s so important that the project combines different ways of knowing, including Western science and traditional Indigenous knowledge.
Today we’re taking a look at two stories that show the effectiveness of combining traditional Indigenous ecological knowledge and Western science for conservation and restoration initiatives. Listen here:
Earlier this month, we featured indigenous aquaculture projects on this podcast, looking at mussel farms in New Zealand and clam gardens in British Columbia, Canada. Today we’re sticking with aquatic environments and taking a look at two more projects, one focused on seagrasses in Mexico and the other on fish along the Atlantic coast of Canada.
Our first guest is Dr. Gary Paul Nabhan, an ethnobotanist at the University of Arizona. He tells us about eelgrass, an ancestral food of the Comcaac people in the state of Sonora in Mexico. Nabhan tells us why eelgrass is making a big comeback as a sustainable source of food for the Comcaac community and gaining international attention in the process.
We also speak today with Sara Iverson, a professor of biology at Canada’s Dalhousie University, about a research project called Apoqnmatulti’k that aims to better understand the movements of lobster, eel, and tomcod in two important ecosystems on Canada’s Atlantic coast. Iverson tells us why those study species were chosen by the Mi’kmaq people and why it’s so important that the project combines different ways of knowing, including Western science and traditional Indigenous knowledge, which a Mi’kmaq elder dubbed ‘two eyed seeing.’
A researcher snorkels over a seagrass meadow. Image courtesy of Seawilding.
BUGS!
Macro portraits reveal the glamor and peril of endangered insects
Photographer Levon Biss captures the exquisite majesty of bugs—and the pressures that threaten them.
BY LAUREN J. YOUNG | PUBLISHED JUN 28, 2022 This large stick bug, up to seven inches long, might seem hard to miss in the wild, but the insect slips under the radar, resembling lichens and leaves. Levon Biss
The Lord Howe Island stick insect might look more lobster than bug. Nicknamed the “land lobster,” this critter can grow up to seven inches long and gleams like polished obsidian among tree trunks and twigs, blending into the forest environment. For decades, Lord Howe Island, a small volcanic isle just northeast of Sydney, Australia, was the only known home of the species, Dryococelus australis. But in 1918, a shipwreck introduced predatory black rats that decimated the stick bug and many other native animals. Locals and biologists thought the insect was extinct until 2001, when a tiny population was discovered on a small nearby spired island, Ball’s Pyramid. Zoo and museum scientists are breeding the insects to restore this once-lost species and soon return it back to the wild—their original home on Lord Howe Island.
The Lord Howe Island stick insect represents one of 40 species brought to life in a new macrophotography exhibit, Extinct and Endangered: Insects in Peril, by photographer Levon Biss at the American Museum of Natural History in New York City. The large format photos not only reveal the insects’ diverse textures and minute hairs in vivid detail—they also shed light on these often overlooked creatures whose existence is threatened by human-induced climate change and other ongoing pressures.
“Right now, we’re just in the process of trying to quantify how much insects are in trouble,” says David Grimaldi, the museum’s invertebrate zoologist who curated the exhibit, in a video. “We have to rely on entomologists and other biologists to go out into the field and monitor insects, but we shouldn’t wait for the counts. We should start protecting natural areas.”
Insects make up 80 percent of animal life on Earth, shaping a significant slice of our ecosystem from pollinating crops to decomposing waste. In 2017, a study in PLOS One revealed that more than 75 percent of the total biomass of flying insects in protected nature reserves in Germany had been lost over 27 years—scratching just the surface ofan alarmingtrend of species diversity loss and insect population decline.
“Without hyperbole we’re in a very serious conundrum,” says Jessica Ware, entomologist and associate curator in invertebrate zoology at the museum, in AMNH’s press video. “Insects have undergone mass extinctions in the past, but right now the mass extinction that we’re seeing, that we’re witnessing, seems to be the largest that’s ever been recorded.”
With the power of macrophotography, Biss hopes that the insect portraits of Extinct and Endangered: Insects in Peril will be an eye-opening look at insects that showcases both their beauty and their value. These tiny creatures, Biss says in the video, go underappreciated despite being so important to humans and the planet.
“We need to understand that they’re important and we can’t just ignore them because they’re hard to see,” Biss says. “Hopefully people will walk away with an appreciation of them and they’ll marvel in them, and realize that they’re too beautiful to be lost, they’re too important to be lost.”
Images and specimen captions from Endangered: Insects in Peril are provided by AMNH.
Sabertooth longhorn beetle. Levon Biss
The sabertooth longhorn beetle, Macrodontia cervicornis, lives in the Amazon River basin and is among the longest beetles in the world. Habitat loss has contributed to its vulnerable status. The practice of collecting and selling these beetles—a single specimen can go for thousands of dollars—is another cause of their decline.
Stygian shadowdragon. Levon Biss
Dragonflies may be the most acrobatic fliers in the insect world, and stygian shadowdragons are no exception. Late in the twilight, they soar high above dark waters, swooping down to capture mosquitoes and other insect prey. Living near lakes and rivers in the eastern US and Canada, stygian shadowdragons, Neurocordulia yamaskanensis, start out life in the water. Females lay their eggs and larvae develop there, breathing through internal gills.
For now, their numbers appear stable in some parts of their range, but in other areas they have completely disappeared. In coming years, climate change could have many detrimental effects on remaining populations. Much remains to be learned about how dragonfly larvae manage in northeastern rivers and lakes, and if those waters warm dramatically, the larvae may not be able to survive. Depending on how the waters are affected by heat, drought and other factors such as water pollution, researchers have estimated that more than 50 percent of this dragonfly species’ preferred river habitat could be lost as the climate shifts.
Raspa silkmoth. Levon Biss
The raspa silkmoth, Sphingicampa raspa, lives in hot, arid areas of Arizona, West Texas, and in Mexico, and depends on the “monsoon” season as part of its life cycle. If these reliable yearly rainstorms are affected by climate change, it could imperil these and other southwestern moths and butterflies.
This colorful tiger beetle may look flashy, but in the pink sand dunes of its Utah habitat, its cream and green hues actually help the animal blend in. The cream forewings also help these beetles handle desert heat, by reflecting rather than absorbing sunlight. In the dunes, these tiger beetles are predators—note the insect’s curving mandibles, used to capture ants, flies, and other small prey.
The beetles’ tiny range lies on public lands, and researchers and wildlife officials there have closely monitored them for years. In low-rainfall years they have found the beetle population falls—a decline that may only become steeper with climate change. A different type of risk comes from people driving off-road vehicles over the dunes. To prevent the larvae in their burrows from being crushed, officials have set aside some conservation areas where the vehicles are now prohibited.
17-year cicada. Levon Biss
Every 17 years when the weather warms, millions of periodical cicadas (Magicicada septendecim) have a mass emergence, digging themselves out of the soil where they’ve been growing, climbing up trees, and splitting out of their skins into winged adults. But land clearing and development may destroy the underground nymphs before they can emerge and reproduce. And pesticides applied to lawns, golf courses, and parks seep into the ground where the nymphs feed.
Lauren J. Young is an Associate Editor at Popular Science where she covers health inequities, environmental justice, biodiversity, space exploration, history, and culture. Before joining PopSci in 2021, she was a digital producer and reporter at public radio’s Science Friday. Contact the author here.
GREEN CAPITALI$M
Spin-out company aiming to replace harmful plastic microbeads receives £1.3M investment
Sustainable cellulose start-up Naturbeads is poised to scale up
Naturbeads, a company set up by University of Bath researchers that aims to replace plastic microbeads with sustainable alternatives, is set to scale up its work after receiving £1.3M (€1.5M) in a recent funding round.
The investment from Italian Venture Capital fund Progress Tech Transfer, Eos Advisory and Proionic GmbH will allow Naturbeads to grow its work from pilot to demo plant scale and to expand the range of applications of its technology.
Naturbeads has developed a range of innovative and renewable biodegradable cellulose-based products that can be used in cosmetics, paints, coatings, additives for the oil and gas industry packaging and composites.
Following research carried out at Bath’s Centre for Sustainable and Circular Technologies (CSCT), the company was founded by Professor Davide Mattia from CSCT and the University’s Department of Chemical Engineering, the late Prof Janet Scott, formerly of CSCT and the Dept of Chemistry, and CEO Dr Giovanna Laudisio, an alumna of Bath’s School of Management.
Prof Davide Mattia said: “We are delighted to have received this investment, which will allow us to accelerate our work in providing a sustainable alternative to persistent microplastic beads. An estimated 30,000 tonnes end up in the world’s oceans each year, showing the clear need for technologies such as ours to be adopted quickly.”
Giovanna Laudisio added: “Raising funds for a hard tech start-up like Naturbeads is challenging but we are pleased that with this investment we are bringing on board two institutional investors like EOS and Progress Tech Transfer and a company like Proionic. I am confident that with their support we will be able to accelerate the commercialization of our technology and prevent hundreds of thousands of tons of microplastics from reaching the environment”.
Through a new collaboration with its subsidiary Naturbeads Italia and Professor Antonio Proto at the University of Salerno, the firm will explore the application of its technology in the tyre industry to reduce its contribution to microplastic pollution.
Alberto Calvo, partner of Progress Tech Transfer®, said: “We immediately understood the enormous potential of the technology developed by Naturbeads, which fits perfectly into our mission as early-stage, sustainability-driven investors. The company offers exciting prospects on global markets in a large number of industrial sectors which are desperately seeking for pragmatic solutions addressing the elimination of micro-plastics from their products, and Naturbeads is already positioned as a global technology leader in this arena.”
Andrew McNeill, Managing Partner of Eos Advisory, said: “Microbead plastic water pollution is a significant and hidden environment hazard that the world is only just starting to wake up to. As countries and industries restrict and ban their use, the market for biodegradable replacements is vast. What has really impressed Eos about Naturbeads is the people involved, the protections in place and the potential of this technology. This investment will support the scaling of Naturbeads production and route to market.”
Bernhard Ludwig, Executive Director of Proionic, said: “We are happy not only to supply the necessary solvent for the process but to further contribute to the development of what we consider a game-changing technology.”
Naturbeads has previously been funded by the University of Bath Impact Acceleration Account, Sky Ocean ventures, Innovate UK and the EPSRC.
Selenium removal from industrial wastewater focus of new research
Daniel Giammar, collaborators win prestigious NAWI grant
Beth Miller 06.21.2022
Industrial wastewater and agricultural draining waters can contain a variety of contaminants, such as the element selenium, that must be treated or removed. A multi-institutional team led by an engineer at Washington University in St. Louis seeks to refine a method that would remove selenium from wastewater efficiently and cost-effectively.
Daniel E. Giammar, the Walter E. Browne Professor of Environmental Engineering in the McKelvey School of Engineering, will lead the team on the new research with $1.25 million in total funding. The project is supported by the U.S. Department of Energy and through matching funds from Washington University in St. Louis and collaborators. The prestigious award is part of $17.7 million the Department of Energy awarded to 16 projects nationwide to bolster development of energy-efficient water-treatment technologies through the National Alliance for Water Innovation, led by Lawrence Berkeley National Laboratory.
Emerging technologies in selenium removal have focused on using electrocoagulation, a method that electrochemically introduces a metal ion, such as ferrous iron, to water to ultimately remove contaminants from wastewater in a few different ways: the release of ferrous iron from the anode introduces a reactive species that can remove dissolved selenium while reactions on the cathode may also be involved in selenium removal.
Over three years, Giammar and his collaborators from Lawrence Berkeley National Laboratory, Electric Power Research Institute and WaterTectonics plan to advance the use of iron electrocoagulation to remove selenium from water by tailoring the generation of solid particles to have targeted adsorption and reduction properties. They will evaluate their method in various settings, including batch reactors and in laboratory-scale continuous flow reactors with water from the power, mining and agricultural sectors, to develop a model to predict performance. In addition, they plan to develop a tool to assess the feasibility of electrocoagulation for this and two other NAWI projects underway at University of California, Los Angeles and Texas A&M University as well as for future research.
Also collaborating on the project is Jeffrey Catalano, professor of earth and planetary sciences at Washington University.
“Selenium is a challenging contaminant to remove from water, but it has rich chemistry to potentially be used in new technologies,” Giammar said. “The operation of selenium removal technologies is strongly dependent on context, which prevents a one-size-fits-all solution. We plan to address the need for modular technologies that can be operated autonomously and replace the need for chemical supplies with electricity.” The McKelvey School of Engineering at Washington University in St. Louis promotes independent inquiry and education with an emphasis on scientific excellence, innovation and collaboration without boundaries. McKelvey Engineering has top-ranked research and graduate programs across departments, particularly in biomedical engineering, environmental engineering and computing, and has one of the most selective undergraduate programs in the country. With 140 full-time faculty, 1,387 undergraduate students, 1,448 graduate students and 21,000 living alumni, we are working to solve some of society’s greatest challenges; to prepare students to become leaders and innovate throughout their careers; and to be a catalyst of economic development for the St. Louis region and beyond.
Study shows chemical's extent in the Fairbanks winter air
A chemical compound discovered in 2019 in the wintertime air of Fairbanks, Alaska accounts for a significant portion of the community's fine particulate pollution, according to new research that seeks to better understand the causes and makeup of the dirty air.
The finding is the first measurement of how much hydroxymethanesulfonate, or HMS, is in the Fairbanks air.
The compound constituted 3% to 7% of the total amount of particles less than 2.5 micrometers, or PM2.5, during pollution episodes. That amount is substantially higher than observed elsewhere, leading the research team to conclude that Fairbanks's extreme low temperatures are a factor in the compound's formation.
"People in the community really are not aware of this," said Jingqiu Mao, principal investigator on the research. "We feel it's important to inform the community about this new chemical compound in Fairbanks."
"Very little is known about the health impact of hydroxymethanesulfonate," he said. "This compound is new to us in the atmospheric chemistry and air quality communities. We didn't know this compound could be so abundant."
The research was published in May in Environmental Science & Technology and authored by James Campbell, a graduate student of Mao. The work included scientists from the University of Alaska Fairbanks Geophysical Institute, Georgia Institute of Technology, Johns Hopkins University and NASA's Goddard Space Flight Center.
The research paper is the first produced under a three-year National Science Foundation grant.
Fairbanks has been under mandate by the U.S. Environmental Protection Agency to improve its wintertime air quality and has been working for years to do so. The community and state face penalties for non-compliance.
The new HMS finding is also significant because recent studies have revealed that hydroxymethanesulfonate can easily be mistaken for sulfate, potentially making prior air pollution measurements inaccurate. Studying HMS also enables a better understanding of other chemical reactions in ambient aerosols in Fairbanks during the winter months.
Knowing the correct makeup of the fine particulate matter pollution is key to implementing appropriate air quality control measures, Mao said.
"A lot of sources contribute to PM2.5," he said. "But when you start thinking about improving air quality, which part should be dealt with first? And what are the consequences of that?"
The research team studied Fairbanks's air in two winters: January to March 2020 and December 2020 to February 2021. Data came from instruments placed near the UAF Community and Technical College in downtown Fairbanks and at a nearby state Department of Environmental Conservation site already measuring total PM2.5, sulfur dioxide and temperature.
Scientists have known that hydroxymethanesulfonate forms through the combination of sulfur dioxide and formaldehyde, which combine when they are attracted to liquid particles in the atmosphere.
Scientists don't know, however, to what extent factors such as the acidity of the atmospheric droplets, temperature and humidity lead to HMS formation.
They also don't know which source is most responsible for HMS formation in Fairbanks. Sulfur dioxide comes from combustion of fossil fuels, including heating oil and coal. Formaldehyde likely gets into the air from burning wood.
Studies have shown that wood smoke contributes 40% to 70% to the wintertime PM2.5 mass concentration in Fairbanks.
"Fairbanks is one of the few optimal places for HMS formation," Mao said. "And that is not necessarily a good thing."
More information: James R. Campbell et al, Source and Chemistry of Hydroxymethanesulfonate (HMS) in Fairbanks, Alaska, Environmental Science & Technology (2022). DOI: 10.1021/acs.est.2c00410
Here Comes the Sun – Daniel Weeks, Revision Energy and the Fight for a Livable World
Dan Weeks and his wife Dr. Sindiso Mnisi Weeks
By WAYNE D. KING, Radical Centrist
My conversation with Dan Weeks was a refreshingly optimistic moment in these troubling times. He’s no Pollyanna about the challenges that we face but he definitely sees the magnificent and expansive view from the summit, even as he recognizes the mountains still to climb.
A 12th-generation Granite Stater, Dan Weeks is well steeped in New Hampshire history but he is also a citizen of the world. Dan left New Hampshire after high school to serve with AmeriCorps and attend Yale and Oxford on scholarships. He lived and worked on four continents before returning to NH with his South African wife Dr. Sindiso Mnisi Weeks, a human rights lawyer and academic. Dan and Sindiso are the proud parents of three young children.
Today Dan is a director at ReVision Energy, an employee-owned solar company in Brentwood. and lives in Nashua with his wife and kids.
Dan is an outspoken clean energy advocate and entrepreneur on a mission to transition New England and the world from fossil fuels to renewable energy. As Vice President of Business Development at ReVision Energy, Dan leads commercial sales, project finance, and development for the region’s largest clean energy company while promoting climate action at the state and federal level. He has been named one of New Hampshire’s “Most Influential Business Leaders” by NH Business Review, “Young Professional of the Year” by Stay Work Play New Hampshire, and “Forty Under 40” by the New Hampshire Union Leader.
Flooding exacerbates pollution exposure in at-risk urban communities
Increased flooding in the U.S. is exposing more people to industrial pollution, especially in racially marginalized urban communities, according to new research from Rice University, New York University and Brown University.
Thomas Marlow, a postdoctoral fellow at NYU Abu Dhabi, said industrial activity has not only contributed to climate change, but also left behind enormous amounts of land-based contamination that will continue to put people at risk when floodwaters rise. Marlow is the lead author of "Future Flooding Increases Unequal Exposure Risks to Relic Industrial Pollution," published today in Environmental Research Letters.
"We wanted to investigate where those dynamics will affect different communities in the years ahead," he said.
The scholars focused on six different U.S. cities (Houston; Philadelphia; Minneapolis; Portland, Oregon; New Orleans; and Providence, Rhode Island), combining historical data on former hazardous manufacturing facilities with future flood risks projected down to the address level. They found that more than 6,000 former industrial sites likely still to be sources of significant ground pollution are at elevated flood risk over the next 30 years. These sites are disproportionately located in lower-income communities of color.
"We found that the sites of highest concern cluster and create zones of increasing risk in areas where more than 560,000 residents currently live," said Jim Elliott, professor and chair of sociology at Rice. "Analyses further indicate that racial minorities, those with lower incomes and those residing in multiunit housing disproportionately live in these areas, regardless of the city in question."
Scott Frickel, professor of sociology at Brown, said the findings show an urgent need for new cleanup strategies.
"Specifically, we need to rethink site-based strategies for cleaning up urban lands polluted by past industrial activities," he said. "This work must engage and include residents of historically marginalized communities in planning efforts as government agencies at all levels work to make their cities more resilient and environmentally just in the age of climate change."
"The good news is that if we act now, we can not only tackle the problem but also help build more just and resilient cities," Elliott concluded.
More information:Thomas Marlow et al, Future flooding increases unequal exposure risks to relic industrial pollution,Environmental Research Letters(2022).DOI: 10.1088/1748-9326/ac78f7
Flooding is among the most prevalent natural hazards, with particularly disastrous impacts in low-income countries. This study presents global estimates of the number of people exposed to high flood risks in interaction with poverty. It finds that 1.81 billion people (23% of world population) are directly exposed to 1-in-100-year floods. Of these, 1.24 billion are located in South and East Asia, where China (395 million) and India (390 million) account for over one-third of global exposure. Low- and middle-income countries are home to 89% of the world’s flood-exposed people. Of the 170 million facing high flood risk and extreme poverty (living on under $1.90 per day), 44% are in Sub-Saharan Africa. Over 780 million of those living on under $5.50 per day face high flood risk. Using state-of-the-art poverty and flood data, our findings highlight the scale and priority regions for flood mitigation measures to support resilient development.
Introduction
Globally, natural shocks are estimated to cause an average of over $300 billion in direct asset losses every year; this estimate increases to $520 billion when considering well-being (or consumption) losses1. While each country faces its individual set of natural hazards, including cyclones, earthquakes, or wildfires, floods are among the leading threats to people’s livelihoods and affect development prospects worldwide2. Especially in lower-income countries—where infrastructure systems, including drainage and flood protection, tend to be less developed—floods often cause unmitigated damage and suffering3. Recent disastrous floods in countries as diverse as Nigeria, Bangladesh, Vietnam, the United States, and the United Kingdom illustrate that the threat is a global reality. Rare, major floods and smaller, frequent events alike can revert years of progress in development4 and poverty reduction. Understanding the scale and distribution of risks is crucial for devising targeted mitigation measures and allocating adequate resources.
While the threat is already substantial, several ongoing trends could result in significant increases in flood risks in coming years. For a high-concentration climate change scenario, estimates from 11 climate models converge to the conclusion that flood frequencies in Southeast Asia, East and Central Africa, and large parts of Latin America could increase substantially by 21005. Even in an optimistic climate change scenario (RCP 2.6), sea levels are estimated to rise up to 0.55 m by 2100, putting especially large coastal cities at risk6. Land subsidence, often caused by unsustainable ground water extraction and drainage, has been shown to increase coastal flood risks at a rate four times faster than sea level rise7.
Flood risks are also driven by socioeconomic change, as the number of people, assets, and value of economic activities increase over time3. By one estimate, in the absence of risk-mitigating measures, socioeconomic growth could result in the absolute damages from flooding to increase by a factor 20 by 2100. Considering the compounded effect of these drivers in the world’s 136 largest coastal cities, one study has shown that population and asset growth, climate change, and subsidence are likely to contribute to a drastic increase in global average flood losses, from $6 billion per year in 2005 to over $60 billion in 20508.
Recognizing the severe impacts of disasters on socioeconomic development, many flood exposure assessments have been conducted at local and national scales, often leveraging the recent availability of high-resolution flood, asset, and population maps, enabling increasingly accurate risk assessments. Yet, local studies have focused predominately on high-income countries like the European Union, United States, and Japan, not least due to data availability and the large economic values at risk9,10. While studies exist for developing countries, attention is focused on large economic centers like Jakarta, Dhaka, Dar es Salaam, Accra, and Ho Chi Minh City11,12,13,14,15,16; few systematic assessments exist for the least developed countries and subregions, where floods are likely to have the most devastating impacts on livelihoods.
Overall, there is limited evidence on the global scale of flood exposure and how it relates to the incidence of poverty. Previous global flood risk assessments suffer from multiple limitations. By using global historical inventories of recorded flood events (e.g., from EM-DAT), studies have estimated exposure indicators at the country level17. Yet, the lack of data on the spatial distribution and coincidence of flood risk and populations means that this approach does not allow a robust estimation of exposure headcounts17,18. A more recent study documents the worrying trend of increasing flood exposure using satellite data for 2000 to 2018, though omits at-risk populations who remained unaffected during the study period and many events that remain undetected by the satellite observations19.
Studies that use relatively coarse (by current standards) spatial resolution flood hazard data tend to only represent major fluvial floodplains. This means they are unable to capture pluvial flood risk and flooding along secondary rivers, and thus drastically underestimate exposure3,5,20,21. One study projects that the global number of flood-exposed people will reach 1.3 billion by 205020, but our study shows that this threshold has already been exceeded by at least 39%. This illustrates the importance of high-resolution data to capture the highly localized nature of flood risks, and the tendency of people to avoid settling in the riskiest locations22. Other global studies have only focused on certain types of flood, rather than assessing the combined risks from fluvial floods (rivers exceeding their capacity due to excessive precipitation), pluvial floods (surface water build-up due to extended precipitation and insufficient drainage), and coastal floods (due to tidal or storm surges, or sea level rise)2,23,24,25,26,27. For instance, a recent study conducted a detailed global assessment of the risk of sea level rise to the world’s coastal population28, estimating that over 190 million people live in areas that could be inundated by sea level rise by 2100; but it does not consider inland flood risks. Other studies have only assessed risks for a subset of countries, falling short of full global coverage22. Most importantly, none of the existing global studies consider the intersection between flood exposure and poverty incidence, which is a crucial indicator for people’s vulnerability, resilience, and ability to cope with and recover from floods1. This study addresses these gaps.
We find that about 1.81 billion people, or 23% of the world population, are directly exposed to inundation depths of over 0.15 meters. This would pose significant risks to lives and livelihoods, especially of vulnerable population groups. The majority (1.24 billion) are located in South and East Asia, where China (395 million) and India (390 million) account for over one-third of global exposure. Low- and middle-income countries are home to 89% of the world’s flood-exposed people. Of the 170 million who face high flood risk and extreme poverty (living under $1.90 per day), 44% are in Sub-Saharan Africa. At least 780 million people face high flood risk, while living on less than $5.5 per day. We conclude that the number of people living in poverty and under severe flood risk is substantially higher than previously thought. Moreover, they are concentrated in vulnerable regions that face compounding risks from climate change, sociopolitical instability, and resource constraints that hamper effective risk management. By offering global, yet disaggregated, insights on flood risk exposure and poverty incidence, this study highlights the scale of the needs and priority regions for flood risk mitigation measures that can safeguard livelihoods and prevent prolonged adverse impacts on development.
Results
Here we present results from a high-resolution global exposure assessment for 188 countries, reaching within rounding errors of the entire world population. We assess people’s exposure to all current flood risks—that is, pluvial, fluvial, and coastal flooding. Flood data from Fathom-Global 2.0 are based on latest generation terrain and hydrographic models, while population density uses WorldPop 2020 maps calibrated on census and satellite data (Fig. 1). The global coverage of these datasets enables an overlay analysis with 3 arcseconds resolution (equivalent to about 90 × 90 meters at the equator), providing a more granular assessment than previous studies and eliminating the need for analytical assumptions besides the ones employed for producing the datasets. In addition, we use the latest edition of the World Bank’s Global Subnational Atlas of Poverty (GSAP), which harmonizes household survey data and offers poverty estimates with global coverage and statistical representativeness at the subnational level. Full technical details on data and computational process are provided in the “Methods” section.
Fig. 1: Flood exposed populations in the metropolitan region of Colombo, Sri Lanka.
Our estimates show that globally, 1.81 billion people (23% of the world population) live in locations that are exposed to a significant level of flood risk, facing inundation depths greater than 0.15 meters in the event of a 1-in-100-year flood, or at least medium risk (Fig. 1). In other words, considering a global population of 7.9 billion29, almost one in four of the world’s people are exposed to significant flood risk.
Regionally disaggregating global exposure headcounts, it becomes apparent that flood risks are particularly prevalent in certain regions. At 668 million people, the East Asia and Pacific region has the highest number of people exposed to significant flood risk, corresponding to about 28% of its total population. In the South Asia region, 576 million people are exposed to significant flood risk (about 30.4% of the population). Between 9–20% of the regional populations of Sub-Saharan Africa, Europe and Central Asia, Middle East and North Africa, Latin America and the Caribbean, and the United States and Canada are exposed to high flood risk. Figure 2 provides a full breakdown of regional exposure estimates in absolute and relative terms. In East Asia and Pacific, South Asia, and the Middle East and North Africa, regional exposure is driven by single countries, namely China, India, and Egypt.
Fig. 2: Population exposed to floods.
a shows the percentage of population exposed to at least medium-level flood risk at the subnational level. b displays the percentage of population exposed to different levels of flood risk in each region. c, d show the total number of people exposed to at least medium-level flood risk based on geographical region and countries’ income classification, respectively. EAP East Asia and Pacific, ECA Europe and Central Asia (ECA), SAR South Asia region, SSA Sub-Saharan Africa, MNA Middle East and North Africa, LAC Latin America and the Caribbean, CAN & USA United States and Canada, HIC high-income countries, UMIC upper middle-income countries, LMIC lower-middle-income countries, LIC low-income countries.
Our results also show that 1.61 billion (89%) of the world’s flood-exposed people live in low- and middle-income countries and about 193 million (11%) live in high-income countries (Fig. 2d). Considering that flood-exposed populations in high-income countries are more likely to benefit from flood protection systems, social postdisaster assistance, and other risk management support, these figures highlight the significant risks faced by developing countries. Full country-level results are provided in Supplementary Table 1.
Countries with the largest flood-exposed populations
Several countries stand out with particularly large populations directly exposed to high flood risk (Fig. 3a); and several factors explain this picture. Evidently, more populous countries are more likely to have large numbers of people living in direct exposure to flood risk. The two most populous countries, India and China, have the highest absolute exposure headcounts with 390 million and 395 million, respectively, and account for about one-third of all people exposed to flood risk globally. Yet, geographical features and urbanization patterns can drastically increase the size of exposed populations. The top 10 countries in terms of absolute exposure headcounts feature countries in which large population groups are concentrated along major river systems (e.g., Bangladesh, Egypt, Vietnam) or in coastal regions (e.g., Indonesia, Japan).
Fig. 3: Absolute and relative population exposure at country level.
a shows the ten countries with highest absolute number of people exposed (and as a percentage of the total population in parentheses). b shows the ten countries with highest relative population exposure. c–e show the ten countries with highest relative population exposure to different kinds of flood risks. Note: Countries or territories with populations of under 100,000 are omitted from this figure, in particular Andorra (24.3%, d) and Cayman Islands (6%, e).
However, focusing on absolute exposure headcounts risks overlooking countries with smaller populations yet large relative exposure. Figure 3b presents the top 10 countries in terms of percentage of population exposed to high flood risk, in all of which over one-third of the population is flood-exposed. The Netherlands has the world’s highest relative exposure to flood risk, with 58.7% of the population living in areas that would face inundation depths of over 15 cm in the event of a 1-in-100-year flood without considering flood protection systems. The country has some of the world’s most comprehensive flood protection systems, with protection against extreme events of up to 1-in-10,000-year return periods that can effectively mitigate the risks estimated in this study.
The same is not true, however, for most other countries with high exposure, particularly low- and middle-income countries, where flood risks coincide with poverty and vulnerability. Vietnam, where 46% of the population is located in flood zones, is a leader among developing countries in its efforts to mitigate natural risks. Its extensive sea dike system stretches over 2600 kilometers, exceeding many other countries’ protective infrastructure14. Yet the system is built to safety standards that only protect against 1-in-30-year coastal flooding, and would be overwhelmed by more severe events14.
Geographic and urbanization patterns are driving the high flood exposure relative to countries’ population size. Considering exposure to different flood types highlights these factors (Fig. 3c–e). Fluvial flood risks dominate in areas where large population shares are concentrated in low-lying river basins, such as the Brahmaputra (Bangladesh), Euphrates and Tigris (Iraq), Irrawaddy (Myanmar), Indus (Pakistan), Mekong (Cambodia, Laos, Vietnam), and Nile (Egypt, South Sudan). Pluvial flooding drives risks in mountainous regions where natural drainage capacity is more limited and flash flood risks are heightened (e.g., Nepal, Andorra), or in climates with intense rainy seasons that exceed drainage and soil absorption capacity (e.g., Bangladesh, Guyana, Myanmar, Suriname). Coastal flooding dominates in countries with expansive coastal urbanization (e.g., Guyana, Vietnam) and islands countries (e.g., The Bahamas, Fiji).
Flood exposure at subnational level
A spatially disaggregated view of flood exposure estimates highlights that, within countries, risks are concentrated in specific areas, such as the coast or river basins. Several subnational regions stand out with large, exposed populations (Fig. 4a). In the Indian states of Bihar, Uttar Pradesh, West Bengal—all located along the Ganges River—a combined 196 million people live in high-risk flood zones, accounting for 33–53% of the states’ respective populations. In Pakistan, ~48 million of Punjab’s 120 million people live in high-risk flood zones, corresponding to 38% of the province’s total population. Located at the confluence of the Ganges and Brahmaputra Rivers, almost two-thirds of the population of Bangladesh’s Dhaka Division are directly flood-exposed. In China, exposed populations are largest in provinces along the coast and Yellow River Valley.
Fig. 4: Absolute and relative population exposure at subnational level.
a shows the ten subnational administrative areas with highest absolute number of people exposed (and as a percentage of the total population in parentheses). b shows the ten ADM-1 areas with highest relative population exposure.
While these are all large subnational regions that often exceed the size of smaller countries, our results show that in smaller subnational areas, much larger population shares can be at risk (Fig. 4b). The world’s top 10 subnational areas in terms of relative exposure are all in Africa and Asia. Pool Department in the Republic of Congo is located along the Congo River, and we estimate that 91% of its population of 360,000 faces significant flood risk. The subnational areas with highest relative exposure in Africa are Chad’s capital region N’djamena, on the Chari River, and South Sudan’s Unity State, on the White Nile. In three Thai provinces, all located along the flood-prone Chao Phraya River, 70–80% of the population are at direct risk. With about 85% of their population living in flood zones, Vietnam’s Red River Delta provinces have some of the world’s highest exposure rates, and are the country’s main population and economic centers.
Economic risk, poverty, and flood exposure
Using the World Bank’s global collection of harmonized household survey data, this study is able to highlight two seemingly contrasting findings: monetary flood exposure emphasizes risks in high-income countries; yet the interaction of flood exposure and poverty emphasizes risk in low-income countries. In short, by relying solely on monetary risk estimates, planners would bias their attention toward areas with high-value assets and large resources. But in so doing, they risk overlooking areas with high socioeconomic vulnerability, where flood risk mitigation measures are most urgently needed to protect lives and livelihoods.
By combining the headcount estimates with per capita income levels, we translate flood exposure headcounts into estimates of the economic activity value that is directly exposed to flood risk. This monetary risk estimate suggests that $9.8 trillion of economic activity is directly located in areas with significant flood risks (note that this refers to exposed, not lost, economic activity, and does not distinguish people’s place of residence and work). This is equivalent to about 12% of global gross domestic product (GDP) in 202030. As Fig. 5 illustrates, monetary risk estimates highlight risks in higher-income countries, with the highest economic exposure in North America, Europe and East Asia, and Sub-Saharan Africa classified as having “low exposure” in monetary terms.
Fig. 5: Economic activity at risk, estimated by exposure headcounts multiplied by subnational income per capita.
a shows the economic value at risk at an ADM-1 level. b displays the total economic value at risk for each region. c lists the top 10 countries with the highest economic value at risk. HIC high-income countries, UMIC upper middle-income countries, LMIC lower-middle-income countries, LIC low-income countries.
Of the $9.8 trillion of economic activity in flood risk areas, 84% is located in high- and upper middle-income countries (following the World Bank’s income classification). High-income countries account for 37% of exposed economic activity, but only 11% of the world’s flood-exposed population. In contrast, low- and lower-middle-income countries account for 52% of exposed people, but only 16% of exposed economic activity. Among countries with the largest economic value at risk, China leads, with $3.3 trillion exposed, followed by the USA ($1.1 trillion) and Japan ($0.7 trillion); no low-income country is among the top 10 countries in terms of economic value at risk. In interpreting these results, it is important to note that flood risk exposure does not account for existing flood protection measures. Such measures tend to be better developed in high-income countries, meaning that the fraction of exposed economic activity lost during a flood tends to be higher in low-income countries1.
Floods have been documented to cause more long-lasting and devastating effects in low-income communities. Here, lower-quality buildings and assets mean damages are higher1; inadequate planning and drainage infrastructure exacerbate hazards; the lack of widespread formal banking means people cannot draw on liquid savings or affordable credit to cope and recover; social systems lack the resources and reach they need to support affected populations; and insurance markets are less developed. To understand where flood risks pose the largest threat to development outcomes, a systematic assessment of poverty rates is essential.
Our estimates show that of the 1.81 billion flood-exposed people globally, at least 170 million are living in extreme poverty (i.e., on less than $1.90 per day). Of these, 88% are located in Sub-Saharan Africa and South Asia (Fig. 6). Flood exposure coincides with poverty most widely in Sub-Saharan Africa, where 74.7 million people are both flood-exposed and living in extreme poverty; in South Asia, the figure is also 75.0 million, driven by India (66 million).
Fig. 6: Poverty and flood exposure.
a–c chart the share of total population exposed to significant flood risk and living with income below $1.90, $3.20, and $5.20 per day, respectively. d shows for each region the total number of people who are both exposed to significant flood risk and living in poverty. EAP East Asia and Pacific, ECA Europe and Central Asia, LAC Latin America and the Caribbean, MNA Middle East and North Africa, SAR South Asia region, SSA Sub-Saharan Africa.
The World Bank defines the $1.90 a day threshold as the most severe form of poverty, corresponding to a minimum subsistence level in low-income countries. However, floods are major livelihood shocks for all affected low-income households, even if they do not fall under the extreme $1.90 line. Hence, and given persistent poverty in middle-income countries, it is essential to consider less extreme poverty definitions. Indeed, when using less stringent poverty thresholds, the number of flood-exposed people in poverty increases significantly. We estimate that, globally, around 467 million people live in high-risk flood zones while living on less than $3.20 a day, increasing to 780 million if we consider incomes under $5.50 a day. This means that four out of every ten people exposed to flood risk globally are living in poverty (Table 1).
Table 1 Global flood exposure headcounts at different poverty thresholds for 2020.
The maps in Fig. 6 highlight that raising the poverty threshold shifts the geographic concentration of poverty and flood exposure from mainly Sub-Saharan Africa to include subnational regions in Egypt, the Middle East, South and East Asia, and Latin America. Increasing the poverty threshold from $1.90 to $5.50 doubles the number of people in Sub-Saharan Africa facing flood exposure and poverty from 75 million to 151 million. In SAR, the increase is sixfold, from 75 million to 464 million; in East Asia, it is eightfold, from 10 million to 81 million.
Among the top 10 countries where extreme poverty (at $1.90 threshold) and flood exposure coincide, seven are in Sub-Saharan Africa (Fig. 7a). With over 65 million, India has the highest number people exposed to flood risk and living in extreme poverty, though this represents only 16.8% of its total exposed population (390 million). As a share of the overall population, extreme poverty and flood exposure coincide most acutely in Sub-Saharan Africa (Fig. 7b); for these countries, 9–28% of the population faces significant flood risk while living in extreme poverty.
Fig. 7: Hotspots of coinciding poverty and flood exposure.
Top 10 countries in terms of the number (a) and share (b) of people who are exposed to significant flood risk while living in extreme poverty (at $1.90/day).
Overall, these results highlight that flood risks are substantial in many low-income countries. Our results also show that the risks are often concentrated in subnational regions within these countries—for example, there are provinces in South Sudan and Congo where over 50% of the population is both flood exposed and living in extreme poverty. Despite being typically overlooked by monetary measures of flood risk, these countries and regions face substantial vulnerabilities due to poverty and associated challenges surrounding social safety nets and infrastructure quality.
