Explore the latest insights from top science journals in the Muser Press daily roundup (August 31, 2025), featuring impactful research on climate change challenges.
In brief:
When sharks lose their bite
In the scientific journal Frontiers in Marine Science, the HHU research team describes that a more acidic environment weakens the teeth of sharks, causing them to break more easily, which in turn causes the predators to lose their bite.
As more of the greenhouse gas carbon dioxide (CO₂) is released into the atmosphere, more of this gas is also absorbed by the oceans. The consequence: The so-called pH-value of seawater decreases, making it more acidic. The acidity has a potentially corrosive effect on minerals – including those in the tooth material of marine organisms.
Sharks are known for being able to replace their teeth, with new ones growing to replace older ones when they wear down. This is crucial for their survival as they rely on their teeth to catch their prey.
A research team headed by Professor Dr Sebastian Fraune from the Institute of Zoology and Organismic Interactions at HHU has, in collaboration with biologists from the Sealife Oberhausen marine aquarium, examined the impact of ocean acidification on shark teeth. They placed shark teeth in containers of water at different levels of acidity: at the current pH of the oceans and at the expected pH in 2300.
“Shark teeth comprise highly mineralised phosphates, but they are susceptible to corrosion. The more acidic water in the simulated 2300 scenario damaged the shark teeth, including roots and crowns, much more than the water at the current acidity level. Global changes are thus so far-reaching that they can impact the microstructure of shark teeth,” says Maximilian Baum, former HHU student and now a freelance diver, photographer and speaker. He is the lead author of the study.
Corresponding author Professor Fraune: “The teeth are highly sophisticated weapons designed to cut flesh, but not to withstand the acidification of the oceans. Our results show how fragile even nature’s sharpest weapons can be. It is possible that the ability of sharks to replace their teeth on an ongoing basis will not be able to keep up with the changes in their environment.”
Teeth shed naturally by blacktip reef sharks (Carcharhinus melanopterus) kept at Sealife Oberhausen were used for the study. These teeth were divided between separate containers – one holding seawater with a pH of 8.1 (the current level) and the other with a pH of 7.3 (what is expected in 2300) – and incubated for eight weeks. Baum: “This pH corresponds to an almost tenfold increase in acidity compared with today.”
The teeth were then examined under the microscope at the Center for Advanced Imaging at HHU. Fraune: “At a pH-value of 7.3, we observed surface damage such as cracks and holes, increased root corrosion and structural deterioration. In addition, the surface morphology was more irregular, which can weaken the structure of the teeth and make them more susceptible to breaking.”
Timo Haussecker, Aquarium Curator at Sealife Oberhausen and co-author of the study: “As we only examined naturally shed teeth, the study does not take account of any repair processes, which may occur in living organisms. The situation may therefore be more complex in living sharks as they may be able to remineralise damaged teeth, albeit with greater energy expenditure.”
“Even moderate decreases in pH-values can impact more sensitive species with slow tooth replacement cycles or have a cumulative effect over the course of time,” adds Baum. “For sharks, it is certainly of great importance that the pH-value of the oceans remains near the current average of 8.1.”
Maximilian Baum and Professor Fraune conclude: “Our research reminds us that anthropogenic changes can impact entire food webs and ecosystems.”
Journal Reference:
Baum M, Haussecker T, Walenciak O, Köhler S, Bridges CR and Fraune S, ‘Simulated ocean acidification affects shark tooth morphology’, Frontiers in Marine Science 12: 1597592 (2025). DOI: 10.3389/fmars.2025.1597592
Article Source:
Press Release/Material by Heinrich-Heine University Duesseldorf (HHU)
Turbulent flights to continue as warming world shakes skies
New University of Reading research – which builds on a previous study that found turbulence increased as the world warmed over the past 40 years – used 26 of the latest global climate models to study how warming temperatures affect jet streams at typical aircraft cruising altitudes (around 35,000 feet).
Jet streams are the fast-moving air currents that flow around the planet at high altitude. As they change due to climate change, they create stronger wind shear – differences in wind speed at different heights. The new study, published in Journal of the Atmospheric Sciences, found wind shear will increase by 16-27% and the atmosphere will become 10-20% less stable from 2015 to 2100.
Joana de Medeiros, PhD researcher at the University of Reading and lead author, said: “Increased wind shear and reduced stability work together to create favourable conditions for clear-air turbulence – the invisible, sudden jolts that can shake aircraft without warning. Unlike turbulence caused by storms, clear-air turbulence cannot be seen on radar, making it difficult for pilots to avoid.”
Professor Paul Williams, co-author at the University of Reading, said: “Recent years have seen severe turbulence incidents causing serious injuries and, in some tragic cases, fatalities. Pilots may need to keep seatbelt signs on longer and suspend cabin service more often during flights, but airlines will also need new technology to spot turbulence before it hits, protecting passengers as skies become more chaotic.”
The research examined both moderate and high-emission scenarios, with the worst effects occurring for the highest greenhouse gas emissions. Results show the problem will affect both northern and southern hemispheres. Turbulence costs airlines $150-500 million annually in the USA, according to The Research Applications Laboratory.
Read more from the University of Reading’s Turbulence Research Group:
- Aviation turbulence strengthened as the world warmed – study;
- Climate change will bring more turbulence to flights in the Northern Hemisphere – study;
- Holiday flights could carry fewer passengers as world warms – study.
Journal Reference:
de Medeiros, J. and P. D. Williams, ‘Future Trends in Upper-Atmospheric Shear Instability from Climate Change’, Journal of the Atmospheric Sciences (2025). DOI: 10.1175/JAS-D-24-0283.1
Article Source:
Press Release/Material by University of Reading
Changing climate pushed islanders to ‘chase the rain’ across the Pacific 1,000 years ago
Settled islands in Western Polynesia, such as Samoa and Tonga, became drier, while more remote ones in Eastern Polynesia, for example French Polynesia (Tahiti), gradually became wetter and more attractive for colonisation.
This latest study, part of a wider project between Southampton and UEA called PROMS (Pacific Rainfall over Millennial Timescales), examines this shift and its likely impact on migration.
Findings are published in Communications Earth and Environment.
Principal Investigator for PROMS, Professor David Sear comments: “The Pacific Islands today are under threat from changing climate, but we can see from our research that this is not the first time the inhabitants of the region have had to adapt to a changing climate.
“Our research suggests that beginning around 1,000 years ago, people in the region were effectively chasing the rain eastwards as part of adapting to the stress placed on growing populations by a period of drier conditions developing in the western South Pacific.”
The research team collected sediment cores on the islands of Tahiti and Nuku Hiva in Eastern Polynesia to analyse plant waxes – fatty layers left on leaves. World-leading laboratory analysis of these plant waxes reveals how wet or dry the climate was when the leaves grew. The team combined these new records with other records from across Polynesia, in the Pacific.
From this state-of-the-art data, the research team estimated how rainfall had changed across the Pacific during the last 1,500 years. Together with new climate model simulations, the team were able to uncover when and where this climatic shift in rainfall occurred, and what probably caused it.
The most likely cause is that a natural change in the pattern of sea surface temperatures across the Pacific drove an eastward shift of the South Pacific Convergence Zone (SPCZ) between approximately 1,100 and 400 years ago. The SPCZ is one of the biggest features in the global climate system, a region of high rainfall stretching over 7,000 km from Papua New Guinea to beyond the Cook Islands. The climate shift identified in this new study saw the western part of this rain band become progressively drier, and its eastern part wetter.
The researchers believe this long-term drying of western areas could have acted as a ‘push’ for migration, while the increase in rainfall and freshwater availability in the east may have served as a ‘pull’ to settle new islands. It’s possible the climate shift acted as a driver for people, encouraging them to sail progressively east to islands such as the Cooks and Tahiti.
Co-lead author on the paper, Dr Mark Peaple of the University of Southampton says: “The timing and nature of the hydroclimatic change align with the final wave of human settlement into Eastern Polynesia, which began around 1000 years ago.
“Water is essential for people’s survival, for drinking and successful agriculture. If this vital natural resource was running low, it’s logical that over time the population would follow it and colonise in areas with more reliable water security – even if this meant adventurous journeys across the ocean.”
Co-lead author at UEA, Dr Daniel Skinner adds: “Bringing together knowledge from palaeoclimate archives and climate models has given us key insights into how and why a critically understudied region of the world changed over the last 1,500 years.”
Co-Principal Investigator Professor Manoj Joshi, also from UEA, says: “By better understanding how the climate of the South Pacific has been affected by larger-scale climate changes over past millennia, we can build better predictions for how future climate change will affect the region.”
The scientists hope more research and archaeological analysis can further refine the timing and scale of both environmental and societal changes in the South Pacific.
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Fieldwork was supported by Explorer grants from National Geographic Society.
Journal Reference:
Peaple, M., Skinner, D.T., Inglis, G.N. et al., ‘Ocean variability drives a millennial-scale shift in South Pacific hydroclimate’, Communications Earth & Environment 6, 679 (2025). DOI: 10.1038/s43247-025-02676-5
Article Source:
Press Release/Material by University of Southampton
Dinosaur teeth give glimpse of early Earth’s climate
A previously untapped source of data sheds new light on the climate of the early Earth: fossilized dinosaur teeth show that the atmosphere during the Mesozoic era, between 252 and 66 million years ago, contained far more carbon dioxide than it does today.
An international research team at the Universities of Göttingen, Mainz and Bochum made this discovery by analysing oxygen isotopes in tooth enamel. They used a newly developed method that opens up opportunities for research into the Earth’s climate history. In addition, the researchers found that total photosynthesis from plants around the world was twice as high as it is today. This probably contributed to the dynamic climate during the time of the dinosaurs.
The results were published in the journal PNAS.
The research team analysed the enamel of dinosaur teeth found in North America, Africa and Europe dating from the late Jurassic and late Cretaceous periods. Enamel is one of the most stable biological materials. It records different isotopes of oxygen that the dinosaurs inhaled with every breath that they took. The ratio of isotopes in oxygen is affected by changes in atmospheric carbon dioxide and photosynthesis by plants. This correlation allows researchers to draw conclusions about the climate and vegetation during the age of the dinosaurs.
In the late Jurassic period, around 150 million years ago, the air contained around four times as much carbon dioxide as it did before industrialization – that is, before humans started emitting large quantities of greenhouse gases into the atmosphere. And in the late Cretaceous period, around 73 to 66 million years ago, the level was three times as high as today. Individual teeth from two dinosaurs – Tyrannosaurus rex and another known as Kaatedocus siberi which is related to Diplodocus – contained a strikingly unusual composition of oxygen isotopes.
This points to CO₂ spikes that could be linked to major events such as volcanic eruptions – for example, the massive eruptions of the Deccan Traps in what is now India, which happened at the end of the Cretaceous period. The fact that plants on land and in water around the world were carrying out more photosynthesis at that time was probably associated with CO₂ levels and higher average annual temperatures.
This study marks a milestone for paleoclimatology: until now, carbonates in the soil and “marine proxies” were the main tools used to reconstruct the climate of the past. Marine proxies are indicators, such as fossils or chemical signatures in sediments, that help scientists understand environmental conditions in the sea in the past. However, these methods are subject to uncertainty.
By analysing oxygen isotopes in tooth fossils, the researchers have now developed the first method that focuses on vertebrates on land. “Our method gives us a completely new view of the Earth’s past,” explains lead author Dr Dingsu Feng at the University of Göttingen’s Department of Geochemistry. “It opens up the possibility of using fossilized tooth enamel to investigate the composition of the early Earth’s atmosphere and the productivity of plants at that time. This is crucial for understanding long-term climate dynamics.”
Dinosaurs could be the ‘new climate scientists’, according to Feng: “Long ago their teeth recorded the climate for a period of over 150 million years – finally we are getting the message.”
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The study was funded by the German Research Foundation (DFG) and by the VeWA consortium as part of the LOEWE programme of the Hessian Ministry of Science and Research, Arts and Culture.
Journal Reference:
Dingsu Feng, Thomas Tütken, Eva Maria Griebeler, Daniel Herwartz & Andreas Pack, ‘Mesozoic atmospheric CO₂ concentrations reconstructed from dinosaur tooth enamel’, Proceedings of the National Academy of Sciences U.S.A. 122 (33) e2504324122 (2025). DOI: 10.1073/pnas.2504324122
Article Source:
Press Release/Material by University of Göttingen
Featured image credit: Gerd Altmann | Pixabay
