United News of Bangladesh

Scientists say the most extreme climate change scenarios once used in global projections are becoming less realistic, with both the worst and best-case futures now largely ruled out, reflecting how global emissions trends have shifted over time. A new set of seven climate scenarios suggests that while the most catastrophic warming outcomes are now less likely due to the gradual rise of renewable energy, the world is also no longer on track to meet the Paris Agreement’s most ambitious target of limiting warming to 1.5°C above pre-industrial levels. Carbon dioxide emissions from fossil fuels such as coal, oil and gas remain the primary driver of global warming. Although the growing use of cleaner energy sources like solar and wind has reduced the probability of the most extreme warming pathways, scientists say the transition has not been fast enough to prevent significant long-term temperature rise. The updated scenarios replace earlier projections that included both very high-emission futures and highly optimistic pathways. Researchers now say the upper-end projection has been revised downward to about 3.5°C of warming by the end of the century, compared to earlier estimates of around 4.5°C. However, even the most optimistic scenario now exceeds the 1.5°C threshold set in 2015 under the Paris climate accord. Scientists say the planet is currently about 1.3°C warmer than pre-industrial levels and is warming at a rate of roughly 0.1°C every five years. Even small increases, they warn, are intensifying extreme weather, water shortages and biodiversity loss. “There is kind of a narrowing of the futures. It cannot be as bad as we thought, but it cannot be as good as we hoped,” said Johan Rockström of the Potsdam Institute for Climate Impact Research. Researchers say the world is now likely headed toward a “middle” pathway of around 3°C warming by 2100 if current policies continue. Experts also warn that even the best-case scenario would likely see temperatures overshoot 1.5°C for decades before any potential decline, assuming future carbon-removal technologies become viable at scale. “This is just physics,” said climate scientist Bill Hare. “We are losing the ability to limit warming even by two degrees without strong action.” Others stress that exceeding 1.5°C carries serious consequences, particularly for vulnerable nations such as small island states facing rising sea levels. The revision of older high-end scenarios, once widely used in climate research, has also sparked debate. Some scientists argue that extreme coal-heavy projections were never realistic, while others say they were useful as upper-bound possibilities for planning. Despite improvements in renewable energy costs and adoption, scientists caution that emissions are still high enough to lock in significant long-term warming. They also warn that natural climate feedbacks—such as carbon released from oceans, forests and permafrost—could add additional warming beyond human control. “The risks of climate change have not disappeared,” said study author Detlef van Vuuren. “We are still heading towards a future with significant climate impacts that we should avoid.”

Scientists have identified unexpectedly high levels of a little-known silicone-based pollutant in the atmosphere, found across cities, rural areas and forests, raising concerns about its possible impact on human health and the climate. The compounds, known as methylsiloxanes, are widely used in cosmetics, industrial products, transport systems and household items. Researchers say they are now being detected almost everywhere in the air, from densely populated cities to remote natural areas. The study was conducted by researchers from Utrecht University and University of Groningen and published in the journal Atmospheric Chemistry and Physics. Scientists say this form of pollution has received far less attention compared to better-known contaminants such as PFAS and microplastics, even though it may be more widespread in the atmosphere. Researchers previously believed these chemicals mainly entered the air through evaporation from personal care products and industrial materials. However, the new findings show that larger forms of methylsiloxanes are also released from vehicle and ship engines through lubricating oils. The study found that these larger particles are not limited to traffic-heavy zones. They were detected in urban centres, coastal regions, rural areas and even forests, suggesting they are globally distributed. Lead researcher Rupert Holzinger of Utrecht University said the findings show atmospheric levels are higher than expected. According to the study, methylsiloxanes make up between 2 percent and 4.3 percent of total organic aerosols in the air, making them one of the most common synthetic substances found in airborne particles. By comparison, PFAS levels in the atmosphere are more than a thousand times lower. Researchers explained that engine lubricants containing methylsiloxanes can enter combustion chambers during vehicle operation. Because the compounds are highly heat-resistant, they do not fully break down and are released into the air through exhaust emissions. The highest levels were recorded in urban areas, including São Paulo in Brazil, while the lowest were found in forest locations in Lithuania. Samples from rural areas in the Netherlands showed moderate levels. Scientists collected air samples from multiple regions, including Europe, South America and rural locations, to understand how the pollutant spreads across different environments. Researchers warn that people are likely inhaling these compounds continuously, but the long-term health effects remain unknown. Holzinger said estimated daily exposure may already exceed that of other synthetic pollutants such as PFAS and microplastics, calling for urgent research into possible health risks. The study also raises concerns about climate impacts. Methylsiloxanes may affect how aerosols behave in the atmosphere, potentially influencing cloud formation and ice processes. Scientists also found that more than half of the pollution likely comes from vehicle emissions. The chemicals appear to travel long distances in the atmosphere due to their stability, making them more persistent than some related hydrocarbons. Researchers say further studies are needed to understand how far the compounds spread globally and what risks they may pose over time.

Scientists say they have identified a hidden chemical pattern that could help detect life beyond Earth. The new study, published in the journal Nature Astronomy, suggests that scientists may not need to focus only on finding specific molecules on distant planets and moons. Instead, they can look at how those molecules are organized. “We’re showing that life does not only produce molecules,” said Fabian Klenner, an assistant professor of planetary sciences at University of California, Riverside and co-author of the study. “Life also produces an organizational principle that we can see by applying statistics.” Looking beyond individual molecules For years, scientists have searched for signs of life by looking for compounds such as amino acids and fatty acids. But these molecules can also form naturally without any biological activity. They have been found in meteorites and created in laboratories that mimic conditions in space. As a result, simply detecting these chemicals is not enough to confirm the presence of life. The researchers found that amino acids in living organisms are usually more diverse and more evenly distributed than those produced through non-biological processes. Fatty acids showed the opposite pattern. In this case, non-living chemical reactions tended to produce more evenly distributed mixtures than living systems. Statistical clues to life The team said this is the first study to show that signs of life can be identified using statistical analysis alone, without relying on a specific instrument. That means the method could potentially be applied to data already being collected by missions exploring Mars, Europa and Enceladus. “Astrobiology is fundamentally a forensic science,” said Gideon Yoffe, a postdoctoral researcher at the Weizmann Institute of Science and lead author of the study. “We’re trying to infer processes from incomplete clues, often with very limited data collected by missions that are extraordinarily expensive and infrequent,” he said. Borrowing from ecology To develop the method, the researchers adapted a statistical approach commonly used in ecology to measure biodiversity. Ecologists use two key concepts: richness, which counts how many different species are present, and evenness, which measures how evenly they are distributed. The scientists applied the same ideas to chemical data from around 100 existing datasets, including samples from microbes, soils, fossils, meteorites, asteroids and laboratory-made materials. In study after study, biological samples showed clear organizational patterns that distinguished them from non-living chemistry. Ancient fossils still carried the signal The method was also able to detect different levels of preservation in biological materials. “That was genuinely surprising,” Klenner said. “The method captured not only the distinction between life and nonlife, but also degrees of preservation and alteration.” Even heavily degraded samples retained signs of their biological origin. Fossilized dinosaur eggshells included in the study still showed detectable statistical patterns linked to ancient life. A useful tool for future missions The researchers stressed that no single method will be enough to prove the existence of extraterrestrial life. Klenner said any future claim would need multiple independent lines of evidence, interpreted within the geological and chemical context of the environment being studied. Still, the team believes the new statistical approach could become an important tool for future space missions. “Our approach is one more way to assess whether life may have been there,” Klenner said. “And if different techniques all point in the same direction, then that becomes very powerful.” Source: Science Daily

Scientists have proposed a new theory suggesting that the basic laws of the Universe may be closely linked to the existence of life itself. Researchers from Queen Mary University of London say the Universe’s fundamental physical constants appear to fall within a very narrow range that allows liquids such as water and blood to flow properly, making life possible. The study, published in the journal Science Advances in 2023, argues that even a small change in these constants could make liquids either too thick or too thin for living organisms to survive. Scientists explained that life depends heavily on the movement of liquids at microscopic levels. Nutrients must travel through cells, proteins need to fold correctly and molecules constantly move through watery environments inside the body. All of these processes depend on viscosity, the property that determines how easily a liquid flows. According to the researchers, if the fundamental constants of physics changed by only a few percent, water and other biological fluids could behave very differently, possibly preventing complex life from developing. Physicist Kostya Trachenko said the findings show a surprising connection between everyday liquid flow and some of the deepest questions in physics. He noted that if water became as thick as tar, life in its current form might not exist at all. The same would apply to blood and cellular fluids that living organisms rely on. The researchers said even slight changes in constants such as the Planck constant or electron charge could make blood too thick or too thin for the human body to function properly. Scientists have long debated why the Universe’s physical constants appear to be “fine-tuned” for life. Earlier theories mainly focused on stars, galaxies and the formation of heavy elements needed for planets. However, this research shifts attention to biology, suggesting that life may also depend on liquids maintaining very precise flow conditions inside cells. The study adds a new dimension to the long-running scientific debate about why the Universe appears suitable for life. Researchers say the idea remains theoretical, and there is still no widely accepted explanation for why nature’s constants have their current values.Still, scientists believe the findings could help reshape discussions about the connection between physics, biology and the origins of life in the Universe. Source: Science Daily

Scientists have found new evidence that coffee may do more than boost energy, suggesting it can also influence gut bacteria and affect mood, stress levels and brain function. The research, carried out by APC Microbiome Ireland at University College Cork, is among the first to closely examine how coffee interacts with the “gut-brain axis”, the communication system linking the digestive system and the brain. The study was published in *Nature Communications* and supported by the Institute for Scientific Information on Coffee. Researchers say both caffeinated and decaffeinated coffee may help shape the gut microbiome and bring changes in emotional wellbeing.  Study looks at coffee, gut bacteria and mental health The study compared 31 regular coffee drinkers with 31 people who do not drink coffee. Participants underwent psychological tests, recorded diet and caffeine intake, and provided stool and urine samples so scientists could study changes in gut bacteria and mental state. Regular coffee drinkers were defined as people consuming around 3 to 5 cups a day, a level considered moderate and safe by European food safety guidelines. At the beginning of the experiment, coffee drinkers stopped consuming coffee for two weeks. During this period, researchers observed noticeable changes in gut microbial activity and related compounds, separating them from non-coffee drinkers. Mood improvements seen in both decaf and regular coffee After the break, coffee was gradually reintroduced without participants knowing whether they were drinking caffeinated or decaffeinated coffee. Both groups reported improved mood, including lower stress, reduced depression symptoms and less impulsive behaviour. Researchers say this suggests coffee may improve mood even without caffeine. Gut bacteria linked with coffee intake The study also found that certain gut bacteria were more common among coffee drinkers, including ‘Eggertella’ species and ‘Cryptobacterium curtum’. These bacteria are believed to play roles in digestion and protecting against harmful microbes. Higher levels of another group of bacteria, ‘Firmicutes’, were also observed, which earlier research has linked with positive emotional effects in women. Different effects of caffeine and decaf Interestingly, improvements in learning and memory were seen only in those who drank decaffeinated coffee. Researchers suggest that plant compounds like polyphenols, rather than caffeine, may be responsible for these cognitive benefits. Caffeinated coffee, however, showed different advantages. It was linked with reduced anxiety, better focus and increased alertness. It was also associated with lower signs of inflammation. Researchers say coffee interacts with gut and brain Lead researcher Professor John Cryan said growing interest in gut health is helping scientists better understand the connection between digestion and mental wellbeing, though the exact role of coffee had remained unclear until now. He said the findings show that coffee can influence gut microbes and the substances they produce, which may have wider health effects. “Coffee is more than just caffeine. It interacts with our gut microbes, metabolism and even emotional wellbeing,” he said, adding that both regular and decaf coffee may offer different but complementary benefits. Researchers say the findings could help guide future understanding of how diet, especially coffee, may support both digestive and mental health. Source: Science Daily

Scientists in China have identified why people with chronic pain often feel more discomfort at night than during the day. The research, led by Zhang Zhi from the University of Science and Technology of China, was published Friday in the journal Science. Although it has long been known that pain follows a daily pattern—usually milder during active hours and stronger during rest—the exact reason was not clear. Scientists were aware that the brain’s internal clock, called the suprachiasmatic nucleus, controls sleep and hormones, but its role in pain was not fully understood. Using advanced techniques, researchers traced a specific nerve pathway in mice linking this brain clock to the spinal cord. They found that this pathway is influenced by the body’s natural daily rhythm. Since mice are active at night and rest during the day, the pattern is opposite to humans. During their resting period, the brain clock is more active, which increases pain signals. When the mice are active, the brain activity drops, reducing the intensity of pain. The findings help explain why pain sensitivity changes over the course of a day. Researchers say this discovery could help improve pain treatment by timing medications according to the body’s natural biological clock.

Scientists have warned that a newly identified tree species in Australia, nicknamed the “zombie tree,” could disappear within a generation if urgent action is not taken. Researchers say the tree, Rhodamnia zombi, is still alive in some places but cannot grow or reproduce normally because of a fungal disease known as myrtle rust. Professor Rod Fensham, a botanist at the University of Queensland, said the species was first assessed in 2020 before it even had an official name. Since then, about 10 percent of the trees have died, and the remaining ones are unable to produce flowers or fruit due to the disease. Rhodamnia zombi is a small to medium-sized rainforest tree with large dark green leaves, shaggy bark and fuzzy white flowers. It grows in the Burnett region of Queensland. According to researchers, the bright yellow fungal pathogen repeatedly attacks and destroys the tree’s young shoots. As a result, infected trees cannot grow or reproduce properly and eventually die. Myrtle rust was first detected in Australia in 2010 and has since threatened many plant species. Because of this risk, Rhodamnia zombi has been placed on a special list of plants considered potentially critically endangered.Fensham said the 17 species on this “Category X” list could disappear within a generation without intervention, as none appear to have resistance to the disease. However, scientists remain hopeful. Fensham said related species in the Rhodamnia group have shown some resistance to myrtle rust, raising hopes that future generations may survive. Researchers are collecting healthy cuttings from the wild and growing seedlings at protected sites in Lismore and Townsville. If some trees develop resistance, they may eventually be replanted in forests to restore the species. The findings were published in the journal ‘Austral Ecology’. Source: Science daily

Scientists have found possible evidence suggesting that some killer whales may hunt and eat their own species in waters near Russia. The discovery comes after two severed fins of killer whales were found on a remote Russian island. According to a recent study, both fins carried clear tooth marks from other killer whales, raising concerns that some orcas may be attacking members of their own species. Dr. Olga Filatova, an associate professor at the University of Southern Denmark, said she first saw photographs of the fins sent by her long-time collaborator Sergey Fomin. She said the discovery was unexpected. “When he found the first one, it was very surprising,” Filatova told BBC Science Focus, adding that scientists never expected to witness such behaviour in their lifetime. Genetic tests showed the fins belonged to resident killer whales, a population that mainly eats fish and lives in close family groups spanning several generations. Researchers believe the likely attackers were transient killer whales, another group that lives in the same waters but hunts marine mammals such as seals, sea lions and even other whales. Scientifically, the incident could be considered cannibalism because all killer whales belong to a single species, ‘Orcinus orca’. However, Filatova noted that resident and transient killer whales rarely mix, do not interbreed and may not even recognise each other as the same type of animal. Researchers believe the attacks may have occurred during large gatherings when many resident whale families meet for breeding. During these events, young whales can become separated from their family groups, making them easier targets for mammal-hunting orcas. Both fins belonged to young whales. Scientists also noted that predators often remove fins when hunting to reach the flesh underneath. While the findings are based on only two fins, researchers say the evidence could help explain why resident killer whales maintain such strong family bonds, possibly as protection against predators from other killer whale groups.

Scientists say the Moon, Earth’s closest neighbour, is shrinking faster than previously thought, a discovery that could affect future lunar exploration. Research by the National Air and Space Museum’s Center for Earth and Planetary Studies shows that as the Moon’s interior cools, its surface contracts, creating tectonic features such as lobate scarps and small mare ridges (SMRs). The SMRs, which are relatively young and widespread, suggest that the Moon is still geologically active. These features may also indicate new sources of moonquakes, which could influence where astronauts and equipment are placed on future missions. “This work gives us a complete view of recent lunar tectonism, helping understand its interior, thermal history, and potential for moonquakes,” said Cole Nypaver, lead author of the study. The shrinking Moon poses real risks for human exploration. NASA warns that moonquakes caused by surface contraction can originate 20–30 km deep, reach up to magnitude 5.5, and last more than 10 minutes. Such seismic activity will need to be considered when selecting landing sites and designing infrastructure for programs like Artemis, which aims to return humans to the Moon by 2028. Tom Watters, senior scientist emeritus, said the discovery of young ridges in the lunar maria completes a global picture of a dynamic, contracting Moon. Understanding these tectonic changes is critical for the safety of astronauts and the success of future scientific missions. Scientists continue to study the Moon’s internal dynamics to better understand its history and evolution, while providing crucial data for the next wave of lunar exploration. With inputs from BBC.

Horses often whinny to greet companions, call new friends or show excitement during feeding time. Scientists have long wondered how they create this special sound, known as a neigh. A new study has now revealed the secret. Researchers found that a horse’s whinny is actually a mix of both low- and high-pitched sounds produced at the same time. The low tone is created when air passes over vibrating tissues in the voice box, similar to how humans speak or sing. The high-pitched tone, however, had puzzled experts for years. Larger animals usually make deeper sounds because of their bigger vocal systems. But horses appear to break that rule. According to the study published in the journal Current Biology, horses produce the higher pitch by whistling. Scientists used a tiny camera inserted through the animals’ noses to observe the voice box while they whinnied and made softer “nickering” sounds. They also scanned the vocal structures and tested airflow through voice boxes from deceased horses. They discovered that as air vibrates the tissues in the voice box, an area just above tightens and leaves a small gap, allowing a whistle-like sound to escape. Unlike humans, who whistle with their mouths, horses whistle internally through their voice box. Jenifer Nadeau of the University of Connecticut, who was not part of the study, said the finding was surprising and helps explain the unique tone of a neigh. Researchers also noted that while small rodents can whistle this way, horses are the first known large mammals to do so. Alisa Herbst from Rutgers University said the two-tone call shows that a whinny is more complex than previously thought. Study author Elodie Mandel-Briefer of the University of Copenhagen added that the dual tones may help horses express different emotions at once when interacting socially. Scientists are still exploring how this rare vocal ability evolved, as closely related animals like donkeys and zebras cannot produce the same high-pitched sound.