This week, some short reads

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Around half the world could lose easily accessible groundwater by 2050

In coming decades, major groundwater sources may become economically unfeasible — this could raise food prices and shift diets, among other impacts

By James Dinneen

15 May 2024

 

 

 

Reaching peak groundwater pumping could impact agriculture across the globe

Peter Bennett / Alamy

 

Groundwater extraction is set to peak globally within the next three decades as unsustainable pumping depletes accessible stores. This could reshape the food and water systems that serve at least half the world’s population.

Between 1960 and 2010, global groundwater extraction increased by more than 50 per cent, largely to irrigate crops. Today, one-fifth of all food is produced using groundwater. Much of this water is extracted from aquifers faster than they naturally refill, driving declining water levels. This causes the land to sink, contaminates the remaining water and harms ecosystems fed by the aquifers. It also increases the cost of extraction — wells must be drilled ever deeper and water pumps require more energy.

Previous studies projected this groundwater extraction would rise indefinitely, but they “did not have the human feedback in there”, says Hassan Niazi at Pacific Northwest National Laboratory in Washington state.

 

Niazi and his colleagues projected how decreasing water levels and rising pumping costs could affect extraction in the world’s major water basins this century. They used a model that incorporates the intricate relationships between groundwater extraction, economic development, energy systems and climate change. The researchers modelled 900 different scenarios to capture a range of possible futures.

On average across scenarios, they found the volume of groundwater extraction peaked around 2050 at 625 cubic kilometres of water — about twice as much as today. By century’s end, extraction declined to near present-day level. The peak’s timing and magnitude varied across scenarios, but nearly all forecasted a peak before 2100.

Some regions may face even quicker declines. In most scenarios, extraction peaked before 2030 in 10 per cent of studied water basins, including in large areas of India, Pakistan and China. Extraction in some basins appears to have already peaked. The researchers found declining extraction volumes in Missouri and California since 2010 and 2015, respectively.

“What is driving that peak really differs region to region,” says Niazi. In California, for example, increasing pumping costs appears to be the main cause. In South-East Asia, shifts in precipitation and hotter temperatures due to climate change play a larger role, he says.

 

The researchers were clear that it is impossible to drain all the planet’s groundwater – they project people will pump less than 1 per cent of the water present in the top 2 kilometres of Earth’s crust over the next century. But supplies that are economically or physically feasible to extract could run short, impacting agricultural and water systems.

Food prices could rise, for instance. That may spur more agriculture on rain-fed lands or compel drier countries to import water-intensive crops. Regions that haven’t pumped much groundwater might start pumping more.

“Those changes aren’t going to be easy,” says Peter Gleick at the Pacific Institute, a non-profit research organisation in California. “You can’t just move that agricultural production to somewhere else” in most cases, he says.

Alongside factors like climate change and a growing population, the impact on food availability could be “very alarming”, says Matti Kummu at Aalto University in Finland. Food producers should switch to less water-intensive crops and use groundwater more efficiently as soon as possible, he says.

 

Sunlight-trapping device can generate temperatures over 1000°C

A solar energy absorber that uses quartz to trap heat reached 1050°C in tests and could offer a way to decarbonise the production of steel and cement

By Chen Ly

15 May 2024

 

 

 

The heat-trapping device reached 1050°C in experiments

mark bulmer/Alamy

 

Engineers have developed a device that can generate temperatures of over 1000°C (1832°F) by efficiently capturing energy from the sun. It could one day be used as a green alternative to burning fossil fuels in the production of materials such as steel, glass and cement.

Manufacturing these materials involves heating raw materials to above 1000°C by burning fossil fuels, which is extremely energy intensive. “About half of the energy we use is not actually turned into electricity,” says Emiliano Casati at ETH Zurich in Switzerland. “It’s used to produce many of the materials that we need in our daily lives and our industries.”

Solar furnaces, which use an array of moveable mirrors to focus sunlight onto a receiver that reaches high temperatures, could be used at manufacturing sites as an alternative to burning fossil fuels. However, they are currently quite inefficient at converting solar energy to temperatures higher than 1000°C, says Casati.

To improve the efficiency of such devices, Casati and his colleagues have designed a heat-trapping solar receiver with a 300 millimetre layer of quartz around it.

Quartz is a semi-transparent material that allows light energy to pass through it but blocks thermal energy. This means that as the silicon heats up from the concentrated sunlight, the quartz prevents thermal energy leaking back out, trapping the heat and reducing energy loss in the system.

The team tested the modified solar receiver in a facility that simulates sunlight using LEDs. Their initial experiments found that the silicon absorber easily reached 1050°C.

According to heat transfer models, the silicon shield could enable receivers to get to temperatures of up to 1200°C while keeping 70 per cent of the energy input in the system. Without the silicon shield, the energy efficiency drops to just 40 per cent for the same temperature.

While this is just a proof-of-concept device, Casati hopes that it will one day be widely used as a green way of producing the high temperatures needed in manufacturing. “We really need to tackle the challenge of decarbonising these industries, and this could be one of the solutions,” he says.

Journal reference:

Device DOI: 10.1016/j.device.2024.100399

 

Heatwaves seem to be driving severe asthma flare-ups in children

Children are more likely to be hospitalised for asthma complications during a heatwave, a problem that is expected to get worse with climate change

By Sonali Roy

19 May 2024

 

 

 

Hot temperatures can lead to ozone pollution, which irritates the airways of people with asthma

Lopolo/Shutterstock

 

Hot weather appears to be triggering more frequent hospital visits for children with asthma.

Symptoms of the lung condition, such as breathlessness and wheezing, are more commonly associated with cold weather. To better understand the impact of hot temperatures, Morgan Ye at the University of California, San Francisco (UCSF), and her colleagues studied electronic health data from UCSF Benioff Children’s Hospitals.

The data included records on asthma hospitalisations and the patients’ addresses. The researchers used information from PRISM Climate Group at Oregon State University to obtain temperature records at the patients’ homes every day from June to September between 2017 and 2020.

 

The researchers defined heatwaves in 18 different ways. By looking at the range of temperatures that occurred over these periods, they considered it a heatwave if it fell in the top 1 per cent of these temperatures, or the top 2.5 per cent, or the top 5 per cent, and so on.

Presenting their results at the American Thoracic Society conference in San Diego, California, this week, the researchers found that across all of the heatwave definitions, these temperatures were associated with 19 per cent higher odds, on average, of a child with asthma being admitted to hospital, compared with when there wasn’t a heatwave.

While further research is required, hot weather can contribute to smog and ozone pollution, which may inflame or irritate the airways, says Ye.

“As we continue to see global temperatures rise due to human-generated climate change, we can expect a rise in health-related issues as we observe longer, more frequent and severe heatwaves,” she says.

Children are particularly vulnerable to extreme heat, says Stephanie Holm at the UCSF’s Western States Pediatric Environmental Health Specialty Unit. Speaking of the researchers’ approach to defining heatwaves, she says: “The fact that their results were robust to different definitions of extreme heat is powerful.”

 

Solar-powered floating islands could help to regrow coral reefs

A trio of hexagonal islands could generate solar electricity to power a process that accelerates coral growth, with space for a research lab and a garden

By Madeleine Cuff

21 May 2024

 

 

 

Corals growing on a Biorock reef restoration structure in Indonesia

MATTHEW OLDFIELD/SCIENCE PHOTO LIBRARY

 

A cluster of floating, solar-powered islands could be used to support coral reef restoration efforts in coastal waters, a team of researchers has proposed.

It is possible to accelerate the recovery of damaged corals, or the growth of new coral colonies, by pumping an electrical current through seawater. This prompts minerals dissolved in the seawater to crystallise on structures, forming limestone rock that is the perfect habitat for young corals.

 

The approach, known as the Biorock process, has been used on hundreds of coral reefs around the world. But deployment has been limited to reefs close to shore because of the difficulty of running electricity cables out into the deeper ocean.

Lê Thanh Tài at Ho Chi Minh City University of Technology, Vietnam, and his colleagues have designed a system of three interconnected floating islands they say could be used to power the Biorock process at sea, with no need for terrestrial power supplies.

Each island has a distinct function: one would feature a solar array to power the coral restoration efforts; the second would act as a research hub for teams monitoring the reef; and the third would act as a “botanical garden”, with a roof to collect rainwater as a water supply. The islands would be hexagon-shaped, with each side measuring 30 metres, and have a stainless steel frame and a composite outer surface.

The team’s analysis, which hasn’t yet been peer reviewed, suggests the islands could float and provide adequate water and electricity without relying on mainland supplies. Each system would cost around $2 million to build, Lê estimates.

“Our study has demonstrated the feasibility of our artificial islands,” he says. “This highlights the potential for these islands to serve as viable platforms for coral reef restoration efforts.”

The islands would sit in sheltered coastal bays where they are protected from storms. They would transmit electricity to structures on the seabed where the coral would grow.

“There are four anchors per island to prevent the whole system from drifting away without being under control and from being toppled over by large waves,” says Lê, although he says an extreme event such as a tsunami would be likely to cause severe damage.

Alastair Bonnett at Newcastle University, UK, says the design looks sound and has a novel application. “Most artificial islands – and there are a lot in the tropics – are a real engine for destroying coral,” he says. “To see a scheme that is about growing coral is great.”

But floating islands usually only have a lifespan of 50 to 100 years. “If you are having schemes that need replacing every 50 years, that becomes an environmental issue itself,” says Bonnett.

 

Reference:

Research Square DOI: 10.21203/rs.3.rs-4299233