Study reveals Arabia's rainfall was five times more extreme 400 years ago

As the Middle East rapidly urbanizes, wide variability of Late Holocene rains should be considered in flash flood preparedness and future hydroclimate trajectories

University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science

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Brine pools are one of the most extreme environments on Earth, yet despite their high salinity, exotic chemistry, and complete lack of oxygen, these pools are teeming with life and offer a unique record of Earth's rainfall patterns. 

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Credit: OceanXplorer

A new study reconstructing extreme rainfall in Arabia has uncovered that rainfall in the region was five times more extreme just 400 years ago, highlighting the need for preparedness amid growing urbanization.

The findings from the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science-led study suggest that the last 2,000 years were much wetter, with the region’s climate once resembling a vegetated savannah roaming with lions, leopards, and wolves, unlike its present-day hyper-arid desert. The study was published Feb. 21 in the journal Science Advances.

“As major development projects like NEOM in Saudi Arabia continue to reshape the landscape, these findings underscore the critical need for enhanced climate resilience and disaster preparedness to address the growing threat of extreme weather events in the region,” said the study’s lead author Sam Purkis, a professor and chair of the Department of Marine Geosciences at the University of Miami Rosenstiel School.

Using a remotely operated vehicle (ROV) at over a mile depth deployed from the research vessel OceanXplorer, the research team extracted sediment cores from a deep-sea brine pool in the Gulf of Aqaba, an extension of the northern Red Sea. The brine's chemistry preserves undisturbed sediment layers, providing a unique and highly accurate record of Late Holocene rainfall trends. 

They found that the last 2,000 years in Arabia were much wetter, with the region once a vegetated savannah and about 200 years ago, rainfall was double the current amount.

“This is a key record to fill in the history of Middle Eastern climate. What it tells us is that the climate, both the average and the extremes, can change dramatically in this region, and the assumption of long-term climate stability in future development is not a good one.” said Amy Clement, a professor in the Department of Atmospheric Sciences at the University of Miami Rosenstiel School.

The Middle East is considered a climate hotspot, with increasing flash floods from torrential winter rains, interspersed by harsh droughts, in Arabia causing widespread chaos and humanitarian disasters. The variability of Late Holocene rainfall highlights the need for better flash flood and drought preparedness and understanding future hydroclimate trends as the Middle East rapidly urbanizes. The catastrophic flooding across the Arabian Peninsula in the winter of 2024 underscores the urgency of studying the frequency and triggers of such extreme weather events.

“Utilizing the technology on OceanXplorer in combination with multidisciplinary experts in ocean and climate science we can further our understanding of the linkages between ocean systems and long-term weather and climate trends, to help at-risk areas be ready for the future.” said Mattie Rodrigue, science program director at OceanX. 

The study, titled “A 1,600-Year Record of Extreme Rainfall in Northern Arabia,” was published in the journal Science Advances. The study was supported by NEOM Agreement (No: SRA-ENV-2023-001 / AWD-008854) and National Science Foundation Climate and Large-Scale Dynamics Grant (# 2241752).

 

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Journal

Science Advances

DOI

10.1126/sciadv.adq3173 

Method of Research

Observational study

Subject of Research

Not applicable

Article Title

A 1,600-Year Record of Extreme Rainfall in Northern Arabia

Article Publication Date

21-Feb-2025

 

Scented wax melts may not be as safe for indoor air as initially thought, study finds

American Chemical Society

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Researchers monitored the nanoparticles produced from scented wax melts using lab equipment set up inside a model home.

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Credit: Purdue University/Kelsey Lefever

As traditional candles burn, they can contribute to indoor air pollution by emitting volatile compounds and smoke, which may pose inhalation risks. Scented wax melts are often marketed as safer alternatives to candles because they’re flame- and smoke-free. But in a study in ACS’ Environmental Science & Technology Letters, researchers describe how aroma compounds released from the melted wax can react with ozone in indoor air to form potentially toxic particles.

Previous research has shown that scented wax melts emit more airborne scent compounds than traditional candles. The direct heating of the wax maximizes its surface area, thereby releasing more fragrance – such as volatile organic compounds (VOCs) made of hydrocarbons – into the air. Researchers know that these chemicals can react with other compounds in the air to form nanometer-wide particles, which have been linked to negative health effects when inhaled. However, the potential for nanoparticle formation during wax-melt use was unknown. So, Nusrat Jung, Brandon Boor and colleagues set out to investigate this process using wax melts in a full-scale house model that mimicked a typical residential house.

The researchers conducted experiments on 15 commercially available wax melts, both unscented and scented (e.g., lemon, papaya, tangerine and peppermint), in the model house. They first established a baseline of indoor air pollutants and then switched on the wax warmer for about 2 hours. During and after this period, the researchers continuously sampled the air a few yards (meters) away from the wax melts and found airborne nanoparticles, between 1 and 100 nanometers wide, at levels that were comparable to previously reported levels for traditional, combustion-based candles. These particles could pose an inhalation risk because they are small enough to pass through respiratory tissues and enter the bloodstream, say the researchers.

Additionally, using literature data, the team calculated that a person could inhale similar amounts of nanoparticles from wax melts as from traditional candles and gas stoves. Previous studies have found exposure to high levels of nanoparticles in indoor air can be linked to health risks like decreased cognitive function and increased prevalence of childhood asthma.

In the experiments, the main VOCs emitted from the wax melts were terpenes, such as monoterpenes and monoterpenoids. The researchers identified that the airborne terpenes reacted with ozone and formed sticky compounds, which aggregated into nanoscale particles. However, after warming an unscented wax melt, the team observed no terpene emissions or nanoparticle formation, which suggests that these aroma compounds contribute to nanoparticle formation.

The researchers say this study challenges the perception that scented wax melts are a safer alternative to combustion-based candles; however, they emphasize that more toxicology research is needed on the risks of breathing in nanoparticles formed from wax melts.

A deeper analysis by the researchers of how airborne nanoparticles form indoors from volatile scent compounds was published in 2024 in ACS ES&T Air.

The authors acknowledge funding from the National Science Foundation; Purdue University; and the American Society of Heating, Refrigerating, and Air Conditioning Engineers.

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The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, e-books and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

Registered journalists can subscribe to the ACS journalist news portal on EurekAlert! to access embargoed and public science press releases. For media inquiries, contact newsroom@acs.org.

Note: ACS does not conduct research but publishes and publicizes peer-reviewed scientific studies.

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Journal

Environmental Science & Technology Letters

DOI

10.1021/acs.estlett.4c00986 

Article Title

“Flame-Free Candles Are Not Pollution-Free: Scented Wax Melts as a Significant Source of Atmospheric Nanoparticles”

 

Underwater mics and machine learning aid right whale conservation

Cornell University

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ITHACA, N.Y. –Using underwater microphones and machine learning (ML), Cornell University researchers have developed a new method to estimate North Atlantic right whale numbers — offering a potentially safer and more cost-effective way to monitor this critically endangered species.

Their study, published in Endangered Species Research, demonstrates how microphones combined with ML and traditional aerial survey methods can help track right whale populations in Cape Cod Bay, a crucial feeding ground where the whales gather each spring.

To track this endangered species, researchers rely on costly and dangerous surveys by airplanes, or use sound recordings to identify their presence, or absence.

“Using sound recordings to monitor whale populations isn’t new,” said lead author Marissa Garcia of the Cornell Lab of Ornithology’s K. Lisa Yang Center for Conservation Bioacoustics.  “What makes our study unique is that we were able to take those recordings and go beyond getting information on the presence or absence of whales to getting an approximate number of whales in an area.”

The team set out an array of marine autonomous recording units (MARU) across Cape Cod Bay to capture right whale sounds.

Following deployment of the MARUs, the team trained, validated and applied a deep-learning model that could automatically detect right whale sounds with 86% precision.

“By analyzing their distinctive upcall vocalizations, we can detect their presence continuously, day and night,” Garcia said. “This kind of round-the-clock monitoring that results from passive acoustic monitoring just isn’t possible with traditional aerial surveys, which can only happen in daylight hours and in good weather.”

Garcia says there’s still some uncertainty in the counts that the team needs to address in future research, but the team is optimistic that monitoring whale vocalizations holds promise for estimating the abundance of right whales to aid in conservation and management efforts.

Having the ability to expand monitoring efforts across larger areas of the ocean will help scientists better assess the species’ population numbers across the full extent of its range. Garcia said right whales have been traditionally thought of as a conservation challenge in New England, but right whales are found all along the East Coast.

“Using passive acoustic data and deep-learning tools, we can expand the area we can safely monitor and keep track of this critically endangered species,” Garcia said.

The work comes at a critical time for North Atlantic right whales, whose population has declined to fewer than 370 individuals due to ship strikes, fishing gear entanglement and changing ocean conditions affecting their food sources.

For additional information, see this Cornell Chronicle story.

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Journal

Endangered Species Research

DOI

10.3354/esr01384 

Method of Research

Computational simulation/modeling

Subject of Research

Animals

Article Title

Acoustic abundance estimation for Critically Endangered North Atlantic right whales in Cape Cod Bay, Massachusetts, USA

Article Publication Date

21-Feb-2025

Unraveling the mystery of the missing blue whale calves

University of Washington

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A blue whale mother and calf are swimming together in the Gulf of California in Baja, Mexico, one of the warm-water places blue whales spend their winter months.

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Credit: Diane Gendron/Centro Interdisciplinario de Ciencias Marinas - Instituto Politécnico Nacional

Only two blue whale births have ever been recorded in human history, both decades ago. This remains an extraordinary mystery given there used to be hundreds of thousands of blue whales before whaling started — even today blue whales number around 10,000 to 25,000­ — and they give birth every two to three years.

Not only are births very stealthy, but calves are also only rarely sighted — far less than would be expected from their pregnancy rates. Calves closely follow their moms and are sighted as mother-calf pairs, but why are so few detected?

A new University of Washington study, published Feb. 20 in Endangered Species Research, proposes why. Its explanation hints at when and where the unseen births are happening and where blue whale calves spend their earliest months. The findings offer some hope for the health of the population.

Trevor Branch, a UW professor of aquatic and fishery sciences who studies blue whales, set out to unravel this mystery by looking at a range of hypotheses. He proposes that one in particular is the best explanation: It’s mostly because researchers prefer summertime research on feeding congregations of blue whales, but calves are born in fall and winter, and are weaned before they return to feeding areas.

In summer, blue whales migrate to feed in colder regions where krill is plentiful: for example, off California. In winter, when ready to give birth, they return to warmer regions like the Gulf of California and the eastern tropical Pacific. Around seven months after being born, and already at a whopping 52 feet (16 meters) long, the calves are weaned and stop associating with their mothers.

But across various blue whale populations, high pregnancy rates of 33-50% annually seem to contradict the average 3.1% rate of sightings of blue whales involving mother-calf pairs.

When compared with other hypotheses to explain the mystery of why so few calves are observed, such as low fetal survival, low calf survival, low birth rates, or calf separation from mother, Branch discovered that the timing hypothesis best explained observed patterns.

“My conceptual model can explain the mystery of the missing calves: Blue whales produce calves, or give birth, shortly after departing their summer feeding grounds, and wean their calves seven months later, just before they return”, Branch said.

This would explain why researchers – most of whom conduct blue whale field studies in summer months – seldom sight mothers with calves.

Branch compiled data from long-term field studies and combined this with biological information from historical whaling records to come up with this hypothesis, finding higher proportions of calves in winter regions, and lower proportions in summer regions. He is now coordinating a large collaboration to test the idea with field data by month in each region, combined with estimates of the size of calves by month.

One concern about low calf sighting rates was that this might be a warning signal of low birth rates or low survival of calves. Instead, the new hypothesis offers up some hope that higher number of calves could be sighted from field studies concentrated in regions that blue whales travel to in winter and spring.

"This new idea provides an alternative explanation for why some blue whale populations appear to produce very few calves: It's not a failure of calf production, it's because fieldwork in those populations is understandably concentrated in easily accessible summer feeding areas," Branch said.

The research was funded in part by the International Whaling Commission’s Southern Ocean Research Partnership.

 

For more information, contact Trevor Branch at tbranch@uw.edu.  

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Journal

Endangered Species Research

DOI

10.3354/esr01383 

Method of Research

Observational study

Subject of Research

Animals

Article Title

Timing hypothesis explains the mystery of the missing blue whale calves

Article Publication Date

21-Feb-2025

A blue whale mother and calf swimming together in the South Taranaki Bight, New Zealand, a rare summer feeding region with many mother-calf pairs.

Credit

Leigh Torres/Geospatial Ecology of Marine Megafauna Laboratory (GEMM) Lab, Marine Mammal Institute, Oregon State Univers

Aerial footage showing the close association between blue whale mother and calf, in the South Taranaki Bight, New Zealand.

Credit

Leigh Torres/ Geospatial Ecology of Marine Megafauna Laboratory (GEMM) Lab, Marine Mammal Institute, Oregon State University