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Rainfall in the northeastern state of Odisha might decrease by 12% if India’s river-linking plans are implemented.Credit: Asit Kumar/AFP via Getty

A gigantic plan to link several of India’s rivers and divert vast volumes of water for irrigation could result in reduced rainfall in already water-stressed regions, according to a paper1 published in Nature Communications last month. The water transfer could affect the climate systems driving the Indian monsoon and reduce September rainfall by as much as 12% in some of the country’s states, according to the study.The paper is one of a string of independent research studies into the controversial plan. Some scientists have cautioned that too little is known about the environmental effects of the river engineering project for it to be implemented.The plan, first suggested by the British during colonial rule and most recently refined in 2015-2016, is “probably the largest manipulation of India’s hydrology to ever be conceived”, says Jagdish Krishnaswamy, an eco-hydrologist at the Indian Institute of Human Settlements in Bengaluru.The Indian water ministry plans to create a network of 15,000 kilometres of canals and thousands of reservoirs to transfer 174 billion cubic metres of water annually — roughly equivalent to the yearly water use of neighbouring Pakistan — from regions with abundant water to those that are in need of it. The study’s authors write that the goal of the project “is to keep the maximum possible water — which earlier used to reach oceans from river basins — on the land to meet the growing water demand of the country”.Other studies have assessed the potential impacts of the project, including sediment deposition and the consequences for aquatic ecosystems, but this is the first to assess how the land and the atmosphere interact to affect the way in which water cycles between them.Subimal Ghosh, one of the authors of the study and a climate scientist at the Indian Institute of Technology Bombay in Mumbai, describes the water cycle as involving interaction between atmospheric moisture, oceans, plants releasing moisture and climactic patterns. He says his team aimed to study “how a river basin in one region impacts atmospheric processes and therefore impacts other regions as well”.“River interlinking plans may be useful but we need to have detailed assessments of climatic impacts,” explains Roxy Mathew Koll, a climate scientist at the Indian Institute of Tropical Meteorology in Pune, and another co-author of the study.More crops, more waterA core aim of the river-linking plan is to increase the area under irrigation by 35 million hectares. More crops would lead to higher levels of moisture being released from their leaves in a process known as evapotranspiration. With more moisture in the air locally, temperatures would reduce, and rainfall patterns and cloud formation would change.The team used computer modelling to examine the interplay between rainfall, humidity, soil moisture, temperature and wind speed across seven river basins for the monsoon months — June to September. The team did not model other months.The study found that the effect of the land–atmosphere interaction is highest in September. “September is when crops are at maturity and evapotranspiration is high,” explains Koll. This resulted in a reduction in September rainfall in the states of Rajasthan, Gujarat, Odisha and Andhra Pradesh of between 6.4% and 12%. The researchers also found an increase in September precipitation of up to 12% in northeastern states Bihar and Jharkhand and up to 10% in the central areas of Maharashtra and neighbouring Telangana.Reduced rainfall will translate to less flow in rivers in subsequent months, and this could exacerbate water stress in regions that are already arid, such as Rajasthan and Gujarat, the authors say.These effects do not factor in the impact of river flow into the ocean, which can also affect monsoonal rainfall, they also say.Nature asked India’s National Water Development Agency, which oversees the river-linking project, to comment on the study but did not receive a response.Scientists have welcomed the analysis. The paper highlights new implications of the project, says Krishnaswamy. “River linking may considerably reduce or neutralize the claimed benefits of inter-linking.”Rupa Kumar Kolli, a meteorologist at the International Monsoons Project Office at the Indian Institute of Tropical Meteorology in Pune describes the paper as “a very important contribution”. He says he hopes that the paper will prompt a more thorough analysis of the river-linking project before it can go ahead. “There is no going back once the project is implemented.” More

In the face of climate change, wine-growers in France will have to adapt their vineyards to a warmer, dryer world while preserving the heritage of their wine.Credit: PHILIPPE LOPEZ/AFP via Getty

When April nights dip below freezing, Claude de Nicolay knows she won’t be getting much sleep. At 4 a.m., she climbs out of bed and heads outside to light around 300 candles set up between the vines at Domaine Chandon de Briailles, a biodynamic vineyard in the Burgundy region in France that de Nicolay owns and manages. Spring buds are emerging earlier because of warming March temperatures, yet frosts are still common in April. The candles produce just enough heat to thaw the buds and protect them from being destroyed by the Sun’s rays come daybreak.Although the candles are “a lot of work”, de Nicolay chooses to use them, rather than electric heaters, because they help to minimize her contribution to climate change — the problem that has caused her vineyard to become dangerously out of sync with nature. “Agriculturalists are the first people who are affected,” de Nicolay says. “The future is really about how to be very gentle with the soils, to go back to more manual work, to stop using chemicals and to stop using too much energy.”Wine-growers around the world from California to South Africa are feeling the heat as global warming increases temperatures, throws patterns of precipitation out of whack and drives up the frequency and intensity of extreme weather events and wildfires. France’s wine sector faces extra vulnerabilities, thanks to its strict appellation d’origine contrôlée — a classification system with rigid rules about geography, grape varieties and production techniques. Under this system, “the origin becomes a sort of collective brand”, says Cornelis van Leeuwen, a viticulturist at Bordeaux Sciences Agro in Gradignan Cedex, France.France is the leading wine-producing country in terms of value. Last year, it exported wine worth €12.3 billion (US$13.3 million), accounting for about one-third of total global exports, according to the International Organisation of Vine and Wine, based in Dijon, France. This is in large part owing to the strong branding that the appellation system has created, exemplifying “how you find identity in a competitive world”, says Etienne Neethling, head of the international master programme in vine, wine and terroir management at the Higher School of Agriculture in Angers, France. Much of this has to do with terroir, which translates to ‘land’. But in the context of French wine, terroir refers to an entire philosophy of production: environmental factors, such as soil type, are understood to influence the flavour profile of the grapes. It also factors in where the product came from and who produced it and how — growers in different regions have different approaches to winemaking, and value different characteristics in their wine.Terroir and the appellation system might be canny cultural-marketing strategies, but both might prevent French wine-makers from being agile and innovative in the face of changing environmental conditions. The appellation system’s strengths could become weaknesses if the country’s wine regulators and makers adhere too closely to custom and do not keep pace with a rapidly changing world. “We are extremely vulnerable because of our strict regulations,” Neethling says.As climate change intensifies, French wine-growers have begun to advocate for legislative changes that reflect the realities of the pressures that they face in the field and cellar. In the meantime, they aren’t waiting for decisions to be formalized on paper, but are finding creative solutions that still adhere to the rules. As de Nicolay says, “We have to react quicker than our governments, because otherwise it’s going to be a real disaster.”Action imperativeCompared with the 1980s, the grape harvest in France is now starting around three weeks earlier1. “All producers have observed this earlier harvest,” says Jean-Marc Touzard, director of research at the Montpellier centre of the French National Research Institute for Agriculture, Food and Environment (INRAE).In 2019, Neethling and his colleagues conducted a survey of 3,636 wine-growers from 18 countries, which has not been published. Among the 1,298 French respondents, more than 80% were already noticing the impacts of climate change on vine performance and wine quality and were thinking about short- and long-term adaptation strategies. “Being reactive is no longer sustainable,” Neethling says. “We need to make sure our vineyards are the most climate-resilient possible.”
Science in France
In 2011, scientists and industry experts launched LACCAVE, a project aimed at examining the future of French winemaking. Sticking to business as usual, they found, was a strategy that “has no future”, says Touzard, who coordinated the project. The team also steered away from plans that relied solely on technology to save the day, he adds, because “it leads to artificialization of the wine industry” and “disconnection from the terroir”.Solutions will need to incorporate both science and centuries of wine-growing knowledge. For example, van Leeuwen and his colleagues have used chemical analysis to detect key molecules that influence aroma2. The findings could help wine-makers to more closely control the style and quality of their final product by basing decisions about harvest time on their grapes’ chemical profiles. A research team at the University of Bordeaux in France has used gas chromatography, a technique to separate and analyse vapourized compounds, and tastings by a panel of experts3 to explore and better understand the fruitiness of red wines produced from grape varieties that seem ideal for Bordeaux’s future climate.All solutions will need to be tailored to specific locations and driven by actions from a range of players, from individual growers and consumers to local and national authorities. This will all need to be done while “still trying to preserve the local identity of the wine”, Touzard says, yet at the same time accepting that “the taste, the flavour, will evolve”. The country’s wine-makers will walk a fine line between preserving the marketing advantages offered by time-honed knowledge and expertise and making sure that French vines aren’t left behind the rest of the world’s.Adaptive managementFrom 2009 to 2019, France’s Occitanie appellation — that is, the geographical area in which the region’s wine grapes are grown — lost 12% of its vineyard area, according to FranceAgriMer, a national platform that manages agricultural products. This was due to a number of factors, including growers abandoning some wine plots that were replanted with wheat — thanks in part to the changing climate — and producers switching to different grape varieties for similar reasons, and thus forfeiting their appellation label. “The landscape shift is thus still limited, but it has started and is set to increase,” Touzard says.As warming continues, Brittany and Normandy in the far north could become “a new picture of the French vineyard”, adds Hervé Quénol, the director of research at the French National Centre for Scientific Research in Rennes.In the heat-burdened southern regions of the Rhône Valley and Languedoc, wine-growers are contending with increasing droughts and a lack of water, leading to smaller berries and lower yields. “Yield is very responsive to weather and, in the long run, to climate,” says Karl Storchmann, an economist at New York University in New York City, who specializes in wine. The market reflects this: the price of land in the southern Languedoc region, for example, has been “sliding down like crazy”, Storchmann says, to less than half its equivalent value in 1991.

Buds on the vines are emerging earlier than ever — heat from candles can prevent frost from destroying them, without contributing much to climate change.Credit: PHILIPPE LOPEZ/AFP via Getty

In response to increasing drought, some southern appellations have relaxed rules that forbid irrigation. In 2000, just 4% of vineyards in Languedoc, Provence and the Rhône Valley were irrigated — they produced ‘table wine’, or wine that does not meet the appellation system’s quality standards. Today, 20% are irrigated, and they are allowed to do so in some cases under more flexible appellation rules. In certain areas, such as the Bouche du Rhône, 50% of vineyards are now irrigated. “We estimate that, in the south of France, the potential demand for irrigation could reach 50% of all vineyards by 2030,” Touzard says.Irrigation raises questions about sustainability, especially if the water is taken from non-renewable sources such as aquifers. Irrigation can make vines more susceptible to drought in the long run, because the plants’ roots do not grow as deep. “The big question is whether irrigation should be a priority for viticulture,” Quénol says, “specifically in the south of France, because there is not enough water.”In other regions, wine-growers are exploring solutions such as innovative soil management, changing their pruning regimes, introducing spatial variation between the vines based on microclimate or shifting to agroforestry by integrating trees and shrubs into their vineyards. Researchers at INRAE found that adding trees can lower a vineyard’s temperature by 2–4 °C. Agroforestry should be viewed as a long-term tool because, in the first years after planting, trees compete with vines for water, wine-growers have to invest time and effort into tending the saplings and rows of vines usually need to be removed to make room — translating to lost income in the near term. Eventually, the roots of the trees grow deep and no longer compete with the vines for water, and the trees will help with local climate mitigation. Following this strategy, and to boost biodiversity, de Claude and her colleagues have already begun planting fruit trees around their vines.Others are looking into changing the make-up of conventional blends. For example, Bordeaux wines are typically made mainly of cabernet sauvignon and merlot, and to a lesser extent petit verdot, cabernet franc, malbec and côt. However, “the emblematic merlot is clearly less adapted to climate change than cabernet sauvignon, so wine-growers could be tempted to increase the cabernet sauvignon proportion”, Touzard says.Another option is to introduce drought-resistant clones and varieties imported from hotter places such as Portugal, Italy and Greece. Since 2009, van Leeuwen has been investigating whether any of more than 50 varieties are better suited to Bordeaux’s warmer, dryer climate of the near future4. In 2019, the appellation of Bordeaux relaxed its rules to permit four new red varieties and two white ones. The appellation rules specified that, for now, growers can plant these varieties in only 5% of their vineyards, and these grapes can make up just 10% of any final blend.Some wine-growers have also had to start implementing changes in their cellars. Heat- and drought-stressed vines produce grapes that are less acidic and more sugary, leading to wine with different flavours and aromas and a higher alcohol content. In Languedoc, for example, the average alcohol content for red wine was around 11% in the 1980s; now, it’s 14%1. “The components of the berries are changing, which means changes in how the wine tastes,” Touzard says. “This could be a problem for specific markets with consumers who are really looking for traditional quality.”To try to balance out flavours and aromas, some French wine-makers are introducing new yeast strains during the fermentation process, fermenting the grapes at cooler temperatures, testing different types of storage aside from wood barrels and adding oenological innovations to better control acidity or reduce alcohol content. Still others are testing new blends incorporating grapes harvested at different dates, or ones made of different varieties. However, van Leeuwen points out that terroir is dynamic, and the taste of wine has always changed over time. “Consumers adapt to new styles,” he says.Optimism despite uncertaintyWhen Pablo Chevrot’s grandfather planted his first vines some 75 years ago at what is now Domaine Chevrot et Fils in Burgundy, he intended for his family to harvest grapes from those plants for up to a century. Some of those original vines are now collapsing — and given the pace of change, Chevrot knows that the ones he plants to replace them have little hope of ever making it to 100.If planetary warming exceeds 3–4 °C, then some wine-makers — especially those who are committed to the conventional terroir way of production — are likely to be out of a job. In this scenario, food security would probably become too pressing an issue to justify the water that goes into making a non-essential good such as wine. For the time being, Chevrot is doing what he can to ensure a viable future for his vineyard. “Nobody can ignore what is happening,” he says. “The doors are slowly opening for adaptation.”
Fungal findings excite truffle researchers and gastronomes
Chevrot, who has a degree in oenology, or the study of wine, stays on top of the scientific literature and is constantly experimenting with adaptations. “We’re working cleverly, but also going back to ancient ways,” he says. To deal with erratic frosts, he has begun pruning his vines later in the year, which postpones when buds first emerge from the vines. To cope with drought and high temperatures, he’s created higher canopies of leaves that provide more shade to the grapes. He works the land with horses, rather than tractors, to preserve the health of the soil, and six years ago he started to plant annual vegetation around the vines that helps to retain winter and spring water into the summer. In the summer, he cuts the annuals back to create “a sponge of organic matter” that continues to hold water and cool the soil, he says.More and more French wine-makers are following a similar path. “They’re recognizing that the more climate-resilient or smart the vineyard is, the better they will be able to adapt to climate change,” Neethling says. They’re also seeing the importance of regenerative farming that focuses on natural resources, he adds, and the need to mitigate their environmental impacts.Indeed, de Nicolay and her colleagues have been committed to a fully biodynamic approach since 2005. They are seeing positive results compared with their neighbours, who rely on machines and chemicals. When temperatures soar in mid-August, de Nicolay’s vines sport no yellow leaves — unlike those in nearby vineyards. “Wine-makers are asking how we do it,” she says. “They see our vineyard with much more life and strength against all these bad impacts.”For now, the extra effort and care are paying off. “What will happen in the next years, we don’t know,” de Nicolay says. “But we stay optimistic because we believe we are taking the right direction.” More

When I started studying snowmelt in 2009 in Utah and Colorado, I was most interested in quantifying the impact of warming temperatures on melt rates. But when I skied to research sites to collect snow samples, the mountainous landscapes were covered in dust; in Colorado, it was red from desert soils that had blown in. Fourteen years later, it’s clear that 2009 was one of the biggest years for dust deposition onto snow.Last month, we published research (O. I. Lang et al. Environ. Res. Lett. 18, 064045; 2023) that demonstrated how dust from the exposed Great Salt Lake bed falls in the Wasatch Mountains of Utah. Since 2009, I have spent every March through May skiing to remote sites in Utah and Colorado, where I monitor how dust layers evolve. I usually have to ski several kilometres, carrying a 27-kilogramme pack with a shovel to dig a snow pit, tools to cut snow wedges and measure their density, and containers to collect snow samples for analyses. One year, I hit a dusty patch of snow, broke my ski and sliced my leg open.In areas with heavy dust deposition, such as the southern Rocky Mountains, dust accelerates melt by one or two months. Warming air temperatures affect snow accumulation, but dust builds up over time and darkens the surface, which then absorbs more sunlight and hastens melt.We are now exploring different ice and snow landscapes — such as the Himalayas and the Andes — to study, for example, how black-carbon buildup following forest fires affects melting. In this picture from August 2019, I am in Greenland, measuring the ice’s surface reflectivity. Behind me, accumulated dark sediment flows into the stream.As we move into a future that is likely to be even dustier, I am trying to develop snowmelt models. We need to be able to predict snowmelt for many reasons, including to work out how to use water in the western United States as efficiently as possible. More

Damaged cars line a waterfront street in Lahaina, Hawaii. Toxins released by burnt items could infiltrate the city’s water supply.Credit: Paula Ramon/AFP via Getty

As search crews wrap up the hunt for people missing after fires swept the Hawaiian island of Maui, scientists are gearing up for a challenge facing survivors: water contamination. Early indications suggest that the local water system has been compromised in places, and the sheer scale of the damage could pose unprecedented threats to Maui’s diverse coastal ecosystem.So far, more than 100 people in Maui have been confirmed dead, making the wildfire that devastated the city of Lahaina the deadliest in modern US history. Hundreds more people are still unaccounted for. The fire damaged or destroyed an estimated 2,200 buildings, creating a toxic environment that is likely to affect water quality. The carcinogenic chemical benzene has turned up in the public water system in Lahaina, and local officials have advised residents not to drink tap water. Scientists also fear that contaminated run-off will flow onto the island’s sensitive coral reefs.“We have had large fire events before, but this is a different beast,” says Chris Shuler, a hydrologist with the Water Resources Research Center of the University of Hawaii at Manoa, in Honolulu. “There’s no playbook for this. Everybody is just figuring it out as we go,” adds Shuler, who is based on Maui.A fire’s toxic legacyWorking in parallel with local water officials, scientists at the University of Hawaii have already started testing for a variety of contaminants that could be released by the incineration of plastics, vehicles, household chemicals and other sources.Initial results might not be available for several days, but there is every reason to suppose that the water system in Lahaina has been contaminated, says Andrew Whelton, an engineer at the Purdue University in West Lafayette, Indiana, who specializes in disaster response. The problem, Whelton says, is that when multiple buildings are destroyed, the water system not only loses pressure but also can develop a vacuum that pulls pollution from burnt areas into water-delivery pipes. Those pollutants can then circulate through the water system as firefighters and residents open hydrants and taps to keep the flames at bay.

Volunteers unload bottled water from a boat in Maui, where some residents have been advised not to drink the tap water.Credit: Rick Bowmer/AP via Alamy

“The pipes and water volumes are designed to handle one or two structure fires,” says Whelton, who spent more than a week in Maui to help coordinate relief efforts with the University of Hawaii and government agencies. “They are not designed for an entire city to burn down.”The university is testing for benzene, formaldehyde and 86 other chemicals that are classified as volatile organic compounds. It is also checking for dozens of other contaminants. Test results from the inland community of Kula, where a second fire destroyed several hundred structures, have turned up little contamination thus far, Shuler says. But it could be several days before the university team gets its first test results from Lahaina, where the Maui County water department discovered benzene.Whelton says contamination is likely to show up in Kula as well. Hundreds or even thousands of samples will need to be tested to fully assess the risk across the island, he says.Reefs at riskScientists and government officials are already starting to think about longer-term impacts on the coral reefs, which are core to Lahaina’s economy and cultural identity. For Steve Calanog, incident commander for the US Environmental Protection Agency (EPA), that means working to prevent ashes tainted with contaminants such as asbestos, lead and arsenic from blowing into the ocean.Now that search and recovery operations are coming to an end, the EPA is preparing to move through the burnt zone to recover hazardous materials such as household chemicals, batteries and propane canisters. The agency then plans to spray cleared areas with a biodegradable soil stabilizer that will create a temporary crust on the ash piles. The material is commonly used for dust control in construction and other industries, but its application in wildfire recovery is relatively new. Calanog says that Lahaina represents a particular challenge, presenting a complex and often hazardous mix of urban fire debris that is sitting immediately next to coral reefs.
Controlling pollution and overfishing can help protect coral reefs — but it’s not enough
Other researchers are already starting to think about how to monitor fires’ impacts on the ocean. Scientists will be watching for everything from algal blooms to changes in acidification — as well as long-term changes in ocean nutrients and chemistry, which could drive a shift from a coral-based reef to one that is dominated by algae, says Andrea Kealoha, an oceanographer at the University of Hawaii’s Maui campus, in Kahului.Kealoha and her colleagues are applying for a National Science Foundation grant to investigate the ecosystem impacts. They are also hoping for a separate grant from the Federal Emergency Management Agency, so that they can monitor contaminants in fish populations to ensure that the fish are safe to eat.But for now, Kealoha is planning to test seawater samples that she collected off the coast a little over a week after the initial fire. Days before her sampling trip, according to the captain of the boat she was on, the ocean had been covered in ash and gleaming with oily substances. When she went out, however, the water was crystal clear, suggesting that the initial wave of pollution might have been carried farther out to sea by the winds.It will take time to gather the data and understand the impacts, she says, and people in Lahaina are already starting to ask questions. “The community wants to know about the long-term impacts to our waters and to our ecosystems,” she says. “It’s time to start addressing these questions.” More

A rescuer helps a woman with a child disembark from a rubber boat as trapped residents evacuate through floodwaters in Zhuozhou in northern China’s Hebei province, south of Beijing, Wednesday, Aug. 2, 2023. China’s capital has recorded its heaviest rainfall in at least 140 years over the past few days. Among the hardest hit areas is Zhuozhou, a small city that borders Beijing’s southwest.Credit: AP/Alamy

The floods that swept through China’s capital this week were exacerbated by urban development and insufficient drainage systems, researchers say.Typhoon Doksuri hit southern China’s coast in Fujian province on 28 July. It then rolled north to Beijing, dissipating to a lower grade of storm, but in the process dumping up to 745 millimetres of rain on the capital over 5 days — 4 times the city’s average August rainfall. The tail end of the storm also soaked the nearby city of Tianjin and the nearby Hebei province. The deluge of rain was the heaviest to hit Beijing in 140 years, leading to floods killing more than 20 people, destroying roads, cutting off power and forcing thousands of residents to evacuate. “We didn’t expect that the typhoon could impact such a large, vast area,” says Junqing Tang, who focuses on urban resilience and disaster risk reduction at Peking University Shenzhen Graduate School in Shenzhen, China.But as tragic as this week’s events have been, Beijing is no stranger to flooding and disaster. Floods that have resulted in injuries and casualties have hit the capital at least seven times over the past two decades. The deadliest of these occurred in July 2012, when 190 millimetres of rain drenched the city in a day, leading to flash floods that killed 79 people.One factor behind Beijing’s recent vulnerability to floods is its rapid development, says Shao Sun, a climatologist at the University of California, Irvine. Over the past three decades, the city’s population has almost tripled. The result is a concrete sprawl of buildings, roads and other infrastructure.“China’s rapid urbanization has led to a proliferation of impermeable surfaces,” he says. “Green spaces such as parks and gardens play a vital role in water retention. Their dwindling presence due to urbanization diminishes their capacity to effectively manage excessive rainfall.”Duafang Lu, who specializes in urban development in China at the University of Sydney in Australia, says that urbanization has also wiped out many of Beijing’s wetlands, which reduce flood risk by capturing and absorbing excess rainwater.The drainage systems in Beijing have also not kept pace with its rapid development, says Tang. Many of these systems were not designed to handle such huge volumes of water and are not maintained or upgraded on a regular basis. “This can lead to waterlogging and exacerbate the impact of floods,” he says.

A vehicle was left on a bridge, which collapsed by torrential rain in the suburbs of Beijing on August 1st, 2023. Flooding and fierce rain have killed at least 11 people.Credit: AP/Alamy

Sponge citiesThe Chinese government has taken steps to reduce the risk of urban floods. In 2015, it introduced a plan to construct ‘sponge cities’ that can retain and reuse 70% of rainfall. The aim is to ensure that 80% of urban built-up areas in these cities meet this target by 2030. Since then, some 30 cities — including Beijing — have been testing various approaches to mitigate floods, such as using permeable materials for roads and pavements, restoring wetlands and natural waterways, and creating more green spaces.Although the sponge-cities strategy is “very ambitious”, the approach was not designed to handle extreme weather events like the Doksuri storm, says Hongzhang Xu, who specializes in urban planning and infrastructure development at the Australian National University in Canberra. “Its design is based on average annual rainfall,” says Xu. And given Beijing’s low-lying location, drainage systems need to ferry excess rainwater quickly, he says. “The most important thing is to divert the water away as soon as possible.”Urban drainage in Beijing and other cities in China will need to be improved to withstand more frequent extreme weather as climate change intensifies, says Sun. Although this will be challenging, he says it would “significantly reduce the risk of urban waterlogging during the rainy season”. He adds that cities across China will need tailored flood-management strategies. “A one-size-fits-all approach is not the most optimal choice,” says Sun.Tang adds that Beijing and other Chinese cities will also need to create infrastructure that facilitates evacuations and provides information to help people respond to extreme weather. “At the end of the day, it’s people who react to those kinds of disasters,” he says. More

Fog-catching nets (seen here in Lima) can collect enough water for daily use. This technology has the potential to be used on larger scales.Credit: Klebher Vasquez/Anadolu Agency/Getty

This year’s United Nations water conference — the first in nearly 50 years — did not lead to a binding agreement. But the event, held in March in New York City, provided a wake-up call: water crises are worsening and need our urgent attention.As of last year, some 2.2 billion people still lacked access to safe drinking water, according to a July report from the World Health Organization and the UN children’s agency UNICEF (see go.nature.com/3djb6tb). And some 653 million people did not have hand-washing facilities at home.Fixing these problems is among the targets of the sixth of the UN Sustainable Development Goals (SDGs): to “ensure availability and sustainable management of water and sanitation for all” by 2030. This editorial is part of Nature’s series looking at each of the SDGs, set in 2015, at their halfway stage. We are focusing on questions and gaps that researchers can help to address.
Progress towards the Sustainable Development Goals
When the SDGs launched, there was optimism that the water goal could be reached, and progress has been made on some of its targets. Since 2000, an extra 2 billion people have gained access to safe drinking water, and by 2020, some 56% of all households had their waste water treated.But overall progress has not been fast enough, and, as early as 2018, UN-Water, which coordinates the UN’s work on water and sanitation, warned that the world was not on track. Countries are not prioritizing this goal, either at the national or the global level. By the UN’s own estimates, to achieve SDG 6, the world will need to spend US$260 billion per year by 2030 — mostly in Asia and Africa, where the numbers of people without safe drinking water are highest. International development assistance for water-related projects is currently around $9 billion annually, and has been falling since 2017. When there’s no policy strategy, it becomes hard to demonstrate research or pilot projects on large scales. Yet that is what needs to happen if clean water and sanitation are to become universal.Generations of water-stressed communities have applied the results of knowledge and innovation to get water. But there has been, at best, partial success for attempts to systematically share techniques that are known to work on local scales, such as condensing water from clouds with giant nets, used in Chile and Peru, or storing snow for use in dry periods, as practised in parts of China.It’s the same for newer technologies. For example, membrane distillation is a low-temperature method of desalinating water. It’s greener than existing methods because it uses less electricity, as chemical engineer Mohammed Rasool Qtaishat at the University of Jordan and his colleagues reported last year1. However, it is struggling to break out of the research and pilot phases and be deployed at larger scales. In a study2 published in March, Patricia Gorgojo, a chemical engineer at the University of Zaragoza, Spain, and her colleagues recommend improving communication between those who undertake small-scale studies and those who implement larger-scale demonstration projects, because the two often have different needs.
Global action on water: less rhetoric and more science
When it comes to research in its broader sense, results can be scaled up, as medical anthropologist Sera Young and her team at Northwestern University in Evanston, Illinois, show3,4. They have developed inclusive measures of the experience of being water-stressed, called water insecurity experiences (WISE) scales.SDG 6’s sanitation target calls for “special attention to the needs of women and girls”. But the UN’s annual progress reports do not include data on this topic. The principal reason seems to be that surveys are typically conducted at the household level — rather than at the individual level — and therefore cannot be disaggregated by sex or gender. This is where the WISE scales are effective: they can collect data at the household or individual level. They examine how water insecurity affects daily activities, health and well-being, from cooking, hand washing and laundry to personal hygiene and feelings of anger and anxiety. Respondents are identified according to age, gender and income, among other characteristics.The WISE scales are being used by some 100 national, intergovernmental, research and civil-society organizations around the world. Their use as a policy tool was demonstrated last year in Australia, which officially, has relatively low levels of water insecurity, with just 1% of the population affected. But some communities don’t recognize this picture. In 2022, Yuwaya Ngarra-li, a partnership between the Dharriwaa Elders Group — an Aboriginal cultural organization in the rural town of Walgett — and the University of New South Wales in Sydney applied the WISE methodology to a survey of 251 people and found that around 44% of respondents reported water insecurity and 46% food insecurity (see go.nature.com/3dciovf). The communities and Walgett Shire Council are exploring how to bring about improvements.As the world gets closer to the 2030 SDG deadline, more ideas will undoubtedly emerge, with promising potential. But SDG 6 will not be achieved without attention to scale. This is a large missing piece of the water and sanitation jigsaw. Ultimately, implementation is what matters. More

Indigenous mother Rosalia Gomez with her child in Santa Victoria Este, Argentina, where the authors worked in May 2022.Credit: Ronaldo Schemidt/AFP via Getty

Fieldwork can be a nightmare of logistics. Nobody would increase the burden by taking their children along — would they? We did just that, embarking on a four-day field campaign in a remote village with our three children, all under four. Not only did it work out, but we recommend it.We met in 2015, when we worked in the same laboratory at the University of Buenos Aires. Both of us are biologists: V.L.L. is an ecotoxicologist and M.L.L. studies the ecology of shallow lakes.We’ve both also been involved in other projects. M.L.S. has worked on a study of drinking-water quality in neighbourhoods of Buenos Aires for the past 15 years. V.L.L. has worked with rural and Indigenous communities as part of the Argentinian arm of the international organization Vía Campesina. We’ve formed a strong friendship and enjoyed holidays together with our partners before we became mothers.
Collection: Diversity and scientific careers
We supported each other in our shared desire to embrace motherhood as working scientists, which posed certain challenges. In 2019, M.L.S. began a three-month internship at Michigan State University in East Lansing, and her partner, Fede, took on full-time caring responsibilities for their six-month-old daughter, Maite, when the family moved to the United States. At the same time, V.L.L. relocated to Salta, Argentina — 1,490 kilometres from Buenos Aires — to live with her partner, Nacho, when their daughter, Julia, was just two months old.Family tripDuring the COVID-19 pandemic, we applied for funding to combine our scientific interests. The idea was to collaborate on the quality of drinkable water available to Indigenous and rural populations in Santa Victoria Este, a remote area of northern Argentina, bordering Bolivia and Paraguay. Santa Victoria Este encompasses approximately 6,430 square kilometres and is home to around 7,000 families, from the Wichí, Chorote, Toba, Chulupi and Tapiete communities. The zone is very arid, with little rain, so access to safe drinking water is a huge problem. This is probably one of the reasons for the infant death rate in the area — among the highest in the country.Beyond our scientific and social interests, we were personally motivated to find a way to ease tensions between motherhood and our scientific careers. The project involved a four-day research trip to the area. V.L.L. was still breastfeeding her second daughter — now one year old — and was committed to nursing throughout. For both of us, it was our first time so far from home since the children were born. So when the project was approved, we agreed with the rest of the team that we would embark on the trip as an extended family, with two little girls and a baby. Any scientific campaign requires teamwork; in this case, our daughters and husbands would be part of it.
Collection: Fieldwork
There were challenges. Our partners had to take leave from their jobs, for example. And Santa Victoria Este has a precarious health-care system and the potential for extreme temperatures. We felt guilty about exposing our daughters to possible risks, both on the journey and during our stay. The pandemic had heightened everyone’s fears. We took all the precautions we could, from using secure child seats on the journey to preparing a fully stocked first-aid kit.Despite the complexities involved, one driving force for both of us is the belief that our daughters will be happier if their mothers pursue their aspirations. We want to give them the message that they should chase their dreams and never feel limited by being women or having children. We also believe that, even though our children were very young at the time, living through such an adventure with their mothers was a valuable life experience.Toddlers on tourFinally, in May 2022, M.L.S., Fede and Maite flew from Buenos Aires to Salta, where they met up with the rest of the team. We spent two days finalizing our plans with the other team members. The care of the girls was included in the planning: we needed to make some adjustments to ensure the baby’s breastfeeding, as well as provide activities to keep the children entertained and happy. Slightly behind schedule owing to the unpredictability of family life, we loaded specially equipped car seats into the van, along with a tablet, toys, books, pencils, children’s music and other essentials. We also made sure to pack nappies, cleaning wipes and other necessary equipment for the baby. With everything in place, we embarked on an 8-hour drive. We planned stops to eat, use the toilet and stretch our legs. Fortunately, our children became friends, and played a lot during the long trip.
Training: Persuasive grant writing
Once on site, we worked with the whole team to take water samples at various locations. During the fieldwork, the children stayed in the village with their parents, playing among themselves, although Julia — then aged four and the oldest among them — joined us on some occasions. Before setting off, we had collaborated closely with local team members to establish a laboratory, providing the communities with the resources to conduct microbiological and chemical analyses of the water. Besides the results of the campaign, which provided valuable information about the drinking water, we anticipated establishing a local monitoring system. The communities of Santa Victoria Este have been organizing themselves to address their challenges. In 2020, they achieved a landmark victory when an international court ruled that the national government is obligated to ensure the restitution of lands to Indigenous communities, along with access to safe water and other rights. This historic ruling presents an important opportunity for us to support the local people’s empowerment and autonomy by providing them with equipment and training to monitor the water quality periodically.Motherhood and scienceOur experience fortified our conviction that it is possible to navigate the roles of mother and scientist committed to societal welfare simultaneously. We honed our ability to overcome obstacles, innovated effective solutions and, above all, relied on the unwavering support of our families and dedicated team as a real safety net. It was crucial that our partners acted as the main carers during the trip, and that the rest of the team was flexible and patient about our need to adjust plans during travel. This gave us the confidence to carry forward this ambitious project.Having the girls with us undoubtedly caused more tiredness (mental and physical), but the experience and lessons we gathered were very positive. Nothing we had done before could compare. For V.L.L., it was a relief to be able to continue breastfeeding, because neither she nor her daughter desired to end it prematurely.We hope that our story serves as an inspiration for other women in the scientific community, motivating them to pursue their professional aspirations while finding meaningful ways to meet the demands of motherhood. In this way, we can propel scientific progress, and foster the well-being of the communities we endeavour to serve. More

On a warm day in March, ecologist Valeria Souza went into a temazcal, or sweat lodge, in Texcoco, Mexico, to pray for the wetlands that she had been studying in the Chihuahuan Desert for the past quarter of a century. She had been performing this shamanic ceremony for years, asking for guidance to help save the scientifically treasured basin in the northern reaches of the country — known as Cuatro Ciénegas — from human exploitation. But this time was different.
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Souza, the region’s lead scientist, based at the National Autonomous University of Mexico in Mexico City, instead asked for permission to step away and forgiveness that she couldn’t do more. Despite the fight she’d put up, farmers and other local residents have been slowly draining water from the area for their crops and other sustenance. This has led to many of the basin’s pools drying up, turtles and plants dying, and prized microbes receding into the ground beyond researchers’ grasp. With climate change pushing the landscape’s temperatures ever higher, it has been an uphill struggle.Souza loves Cuatro Ciénegas. Researchers think that the isolated landscape has preserved microorganisms for hundreds of millions of years. “It’s a unique window into the past,” she says. But she is also tired, and says that it’s time to leave the task of protecting the basin to a new generation of scientists and advocates.A lost worldCuatro Ciénegas, which translates to ‘four marshes’, has long fascinated scientists. Although its name was inspired by springs located at the four cardinal points shaping the valley, in total, it contains more than 300 blue-green pools, or pozas, filled with microbes, bacterial mats and ancient microbial reefs called stromatolites. “It’s perhaps the most diverse place on the planet in terms of bacteria and archaea,” Souza says.

Valeria Souza, during a visit to Cuatro Ciénegas.Credit: Esteban Gonzalez de Leon

The wetland is fed by “an ancient sea” beneath the nearby Sierra de San Marcos y Pinos mountain, Souza adds. Rain on the mountain feeds the aquifer, which is heated by magma deep underground. The water then seeps upward, through ancient marine sediments, to form the pools.The region’s stromatolites have especially intrigued scientists. In other parts of the world, researchers usually come upon stromatolites as fossils — dried-out layers of ancient cyanobacteria containing trapped sedimentary grains. But those in Cuatro Ciénegas are alive, allowing scientists to study what early life on Earth must have been like. One way they do this is by extracting stromatolite DNA and analysing how it might have evolved.Drawn to the area in 1998, researchers funded by NASA’s Astrobiology Institute in Mountain View, California, went there to study the origins of life — with an eye towards understanding whether life could have once existed on Mars’s arid surface. James Elser, a limnologist who was one of the lead scientists on the project and who was at Arizona State University in Tempe, invited Souza to collaborate.Emptied oasisSouza confesses that the fight to save the place has been like a rock on her back.Because it is one of the most abundant sources of water in the Chihuahuan Desert, Cuatro Ciénegas has been tapped extensively by local residents. Three main canal systems — La Becerra, Santa Tecla and Saca Salada — siphon water from the wetlands, especially to grow alfalfa (Medicago sativa), a crop mainly used to feed cows.To halt this drainage, Souza brought in Mexican business magnate Carlos Slim, who partnered with the global wildlife charity WWF in 2009 to buy the land around the region’s largest lagoon, El Churince, and make it a protected area. She also successfully lobbied the dairy company Grupo LaLa, based in Gómez Palacio, to stop buying alfalfa from the region. But demand for water continues to soar, and the wetlands have steadily dried up.

This set of time-lapse aerial images shows El Churince, once the largest lagoon in Cuatro Ciénegas, dry up and disappear (images run from 1997 to 2022).Credit: Landsat data courtesy of the U.S. Geological Survey

By 2017, El Churince — which held the vast majority of fish species found in Cuatro Ciénegas and housed more than 5,000 species of bacteria, most of them only found in the region — was gone. Souza says that, after seeing the “graveyard of turtles and fishes” left behind, she mourned for years.Others have tried to protect the region. For instance, in 2000, the civil association Pronatura Noreste in Monterrey acquired the Pozas Azules ranch, whose roughly 2,700 hectares hold 100 of Cuatro Ciénegas’ pools. But the organization has similarly struggled to make headway. The land is protected, but the aquifer beneath it is not, says the association’s director, Rosario Alvarez.Souza would like to see Mexico’s National Water Commission (Conagua) take more stringent steps to protect the aquifer. The agency doesn’t keep a record of all the water that’s extracted from it, or the permissions for its use. This leads to over-extraction, which is collapsing the wetland, she says. “There is no inventory, and it’s urgent that [Conagua keep one] because the system cannot last five more years,” Souza adds.Conagua did not respond to Nature’s requests for comment.Saving an ancient worldSouza’s one hope is the generation of scientists and advocates she trained.When she became interested in Cuatro Ciénegas, she spent time educating children from the local school, CBTA 22, as well as the surrounding community, about the importance of preserving the wetland. Among the people she taught is Héctor Arocha, now a biotechnologist who is taking over research in the basin. Arocha works for 2040 Plan, a foundation in Cuatro Ciénegas that seeks to support the development of the community over the next 25 years.
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As part of that effort, on 4 April, Arocha opened Genesis 4C, the first scientific museum in the region, with the mission of creating a culture of conservation. “We gathered all the research that has been done in the valley in collaboration with Valeria and the whole team of researchers who have come over the years,” Arocha says. The museum has a research centre and plans to continue microbial-ecology projects on the origins of life, as well as to find uses for the wetland’s microorganisms in agriculture and medicine.Souza also sees ecotourism efforts in the area as promising. “Hoteliers and non-governmental organizations own the largest areas of Cuatro Ciénegas,” she says. One of the hotels, the María Elena, is donating to the 2040 Plan. There’s also an ecotourism park, called Las Playitas, that educates visitors about the marshes and donates money to the foundation.It’s hard to know whether the pools of Cuatro Ciénegas will survive, but Souza takes solace in the longevity of the bacteria that she loves. “Time is very relative” to the microbes living under the mountain, she says. The water in the pools might completely dry up, but the microorganisms are capable of patiently waiting millions of years underground before rising back up to the surface if the aquifer ever refills. Humans might never see that — “we will be extinct by then”, she predicts — but the microbes could endure. More