A wobble from Mars could be sign of dark matter

In a new study, MIT physicists propose that if most of the dark matter in the universe is made up of microscopic primordial black holes -- an idea first proposed in the 1970s -- then these gravitational dwarfs should zoom through our solar system at least once per decade. A flyby like this, the researchers predict, would introduce a wobble into Mars' orbit, to a degree that today's technology could actually detect.

Such a detection could lend support to the idea that primordial black holes are a primary source of dark matter throughout the universe.

"Given decades of precision telemetry, scientists know the distance between Earth and Mars to an accuracy of about 10 centimeters," says study author David Kaiser, professor of physics and the Germeshausen Professor of the History of Science at MIT. "We're taking advantage of this highly instrumented region of space to try and look for a small effect. If we see it, that would count as a real reason to keep pursuing this delightful idea that all of dark matter consists of black holes that were spawned in less than a second after the Big Bang and have been streaming around the universe for 14 billion years."

Kaiser and his colleagues report their findings today in the journal Physical Review D. The study's co-authors are lead author Tung Tran '24, who is now a graduate student at Stanford University; Sarah Geller '12, SM '17, PhD '23, who is now a postdoc at the University of California at Santa Cruz; and MIT Pappalardo Fellow Benjamin Lehmann.

Beyond particles

Less than 20 percent of all physical matter is made from visible stuff, from stars and planets, to the kitchen sink. The rest is composed of dark matter, a hypothetical form of matter that is invisible across the entire electromagnetic spectrum yet is thought to pervade the universe and exert a gravitational force large enough to affect the motion of stars and galaxies.

Physicists have erected detectors on Earth to try and spot dark matter and pin down its properties. For the most part, these experiments assume that dark matter exists as a form of exotic particle that might scatter and decay into observable particles as it passes through a given experiment. But so far, such particle-based searches have come up empty.

In recent years, another possibility, first introduced in the 1970s, has regained traction: Rather than taking on a particle form, dark matter could exist as microscopic, primordial black holes that formed in the first moments following the Big Bang. Unlike the astrophysical black holes that form from the collapse of old stars, primordial black holes would have formed from the collapse of dense pockets of gas in the very early universe and would have scattered across the cosmos as the universe expanded and cooled.

These primordial black holes would have collapsed an enormous amount of mass into a tiny space. The majority of these primordial black holes could be as small as a single atom and as heavy as the largest asteroids. It would be conceivable, then, that such tiny giants could exert a gravitational force that could explain at least a portion of dark matter. For the MIT team, this possibility raised an initially frivolous question.

"I think someone asked me what would happen if a primordial black hole passed through a human body," recalls Tung, who did a quick pencil-and-paper calculation to find that if such a black hole zinged within 1 meter of a person, the force of the black hole would push the person 6 meters, or about 20 feet away in a single second. Tung also found that the odds were astronomically unlikely that a primordial black hole would pass anywhere near a person on Earth.

Their interest piqued, the researchers took Tung's calculations a step further, to estimate how a black hole flyby might affect much larger bodies such as the Earth and the moon.

"We extrapolated to see what would happen if a black hole flew by Earth and caused the moon to wobble by a little bit," Tung says. "The numbers we got were not very clear. There are many other dynamics in the solar system that could act as some sort of friction to cause the wobble to dampen out."

Close encounters

To get a clearer picture, the team generated a relatively simple simulation of the solar system that incorporates the orbits and gravitational interactions between all the planets, and some of the largest moons.

"State-of-the-art simulations of the solar system include more than a million objects, each of which has a tiny residual effect," Lehmann notes. "But even modeling two dozen objects in a careful simulation, we could see there was a real effect that we could dig into."

The team worked out the rate at which a primordial black hole should pass through the solar system, based on the amount of dark matter that is estimated to reside in a given region of space and the mass of a passing black hole, which in this case, they assumed to be as massive as the largest asteroids in the solar system, consistent with other astrophysical constraints.

"Primordial black holes do not live in the solar system. Rather, they're streaming through the universe, doing their own thing," says co-author Sarah Geller. "And the probability is, they're going through the inner solar system at some angle once every 10 years or so."

Given this rate, the researchers simulated various asteroid-mass black holes flying through the solar system, from various angles, and at velocities of about 150 miles per second. (The directions and speeds come from other studies of the distribution of dark matter throughout our galaxy.) They zeroed in on those flybys that appeared to be "close encounters," or instances that caused some sort of effect in surrounding objects. They quickly found that any effect in the Earth or the moon was too uncertain to pin to a particular black hole. But Mars seemed to offer a clearer picture.

The researchers found that if a primordial black hole were to pass within a few hundred million miles of Mars, the encounter would set off a "wobble," or a slight deviation in Mars' orbit. Within a few years of such an encounter, Mars' orbit should shift by about a meter -- an incredibly small wobble, given the planet is more than 140 million miles from Earth. And yet, this wobble could be detected by the various high-precision instruments that are monitoring Mars today.

If such a wobble were detected in the next couple of decades, the researchers acknowledge there would still be much work needed to confirm that the push came from a passing black hole rather than a run-of-the-mill asteroid.

"We need as much clarity as we can of the expected backgrounds, such as the typical speeds and distributions of boring space rocks, versus these primordial black holes," Kaiser notes. "Luckily for us, astronomers have been tracking ordinary space rocks for decades as they have flown through our solar system, so we could calculate typical properties of their trajectories and begin to compare them with the very different types of paths and speeds that primordial black holes should follow."

To help with this, the researchers are exploring the possibility of a new collaboration with a group that has extensive expertise simulating many more objects in the solar system.

"We are now working to simulate a huge number of objects, from planets to moons and rocks, and how they're all moving over long time scales," Geller says. "We want to inject close encounter scenarios, and look at their effects with higher precision."

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Critical crops' alternative way to succeed in heat and drought

Scientists have discovered that certain plants can survive stressful, dry conditions by controlling water loss through their leaves without relying on their usual mechanism -- tiny pores known as 'stomata'.

Nonstomatal control of transpiration in maize, sorghum, and proso millet -- all C4 crops which are critical for global food security -- gives these plants an advantage in maintaining a beneficial microclimate for photosynthesis within their leaves.

This allows the plants to absorb carbon dioxide as part of the photosynthesis and growth process, despite raised temperatures and increased atmospheric demand for water without increasing the water expenditure.

Publishing their findings in PNAS, researchers from the University of Birmingham, Australian National University, Canberra, and James Cook University, Cairns, challenge traditional understanding of plant transpiration and photosynthesis under stressful and dry growing conditions -- namely that stomata alone control leaf water loss.

Co-author Dr Diego Márquez, from the University of Birmingham, commented: "This revolutionised our understanding of plant-water relations by showing that nonstomatal control of transpiration limits water loss without compromising carbon gain -- challenging what is typically accepted as an unavoidable trade-off.

"Our findings have significant implications for plant adaptation to climate change and how crops might be grown in arid environments. Understanding this mechanism could open new avenues for improving water-use efficiency in C4 crops, which are vital for global food security."

The study confirms that C4 plants maintain reduced relative humidities in the substomatal cavity, down to 80% under vapour pressure deficit (VPD) stress, reducing water loss and highlighting a critical role of nonstomatal control in water-use efficiency.

This mechanism helps plants sustain photosynthesis by reducing water loss without significantly lowering intercellular CO2 levels for photosynthesis. This is crucial for maintaining growth and ensuring that the crops thrive.

The findings also suggest that nonstomatal control mechanisms may have evolved before the divergence of C3 and C4 photosynthetic pathways, indicating a shared evolutionary trait.

"Our research reframes understanding of water-use efficiency in C4 plants and reveals that this alternative mechanism helps plants continue to grow and capture carbon dioxide, even when atmospheric water demand is high, challenging traditional assumptions about how these plants survive droughts," added Dr Márquez.

Photosynthesis is how plants use light and carbon dioxide to make sugars for growth, using an enzyme called Rubisco. Plants use the carbon dioxide that enters through open stomata to produce sugar, whilst open stomata also let water vapour out.

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Beneath the brushstrokes, van Gogh's sky is alive with real-world physics

Vincent van Gogh's painting "The Starry Night" depicts a swirling blue sky with yellow moon and stars. The sky is an explosion of colors and shapes, each star encapsulated in ripples of yellow, gleaming with light like reflections on water.

Van Gogh's brushstrokes create an illusion of sky movement so convincing it led atmospheric scientists to wonder how closely it aligns with the physics of real skies. While the atmospheric motion in the painting cannot be measured, the brushstrokes can.

In an article published this week in Physics of Fluids, by AIP Publishing, researchers specializing in marine sciences and fluid dynamics in China and France analyzed van Gogh's painting to uncover what they call the hidden turbulence in the painter's depiction of the sky.

"The scale of the paint strokes played a crucial role," author Yongxiang Huang said. "With a high-resolution digital picture, we were able to measure precisely the typical size of the brushstrokes and compare these to the scales expected from turbulence theories."

To reveal hidden turbulence, the authors used brushstrokes in the painting like leaves swirling in a funnel of wind to examine the shape, energy, and scaling of atmospheric characteristics of the otherwise invisible atmosphere. They used the relative brightness, or luminance, of the varying paint colors as a stand-in for the kinetic energy of physical movement.

"It reveals a deep and intuitive understanding of natural phenomena," Huang said. "Van Gogh's precise representation of turbulence might be from studying the movement of clouds and the atmosphere or an innate sense of how to capture the dynamism of the sky."

Their study examined the spatial scale of the painting's 14 main whirling shapes to find out if they align with the cascading energy theory that describes the kinetic energy transfer from large- to small-scale turbulent flows in the atmosphere.

They discovered the overall picture aligns with Kolmogorov's law, which predicts atmospheric movement and scale according to measured inertial energy. Drilling down to the microcosm within the paint strokes themselves, where relative brightness is diffused throughout the canvas, the researchers discovered an alignment with Batchelor's scaling, which describes energy laws in small-scale, passive scalar turbulence following atmospheric movement.

Finding both scalings in one atmospheric system is rare, and it was a big driver for their research.

"Turbulence is believed to be one of the intrinsic properties of high Reynolds flows dominated by inertia, but recently, turbulence-like phenomena have been reported for different types of flow systems at a wide range of spatial scales, with low Reynolds numbers where viscosity is more dominant," Huang said.

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Moderate coffee and caffeine consumption is associated with lower risk of developing multiple cardiometabolic diseases, new study finds

Consuming moderate amounts of coffee and caffeine regularly may offer a protective effect against developing multiple cardiometabolic diseases, including type 2 diabetes, coronary heart disease and stroke, according to new research published in the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism.

Researchers found that regular coffee or caffeine intake, especially at moderate levels, was associated with a lower risk of new-onset cardiometabolic multimorbidity (CM), which refers to the coexistence of at least two cardiometabolic diseases.

The prevalence of individuals with multiple cardiometabolic diseases, or CM, is becoming an increasing public health concern as populations age around the world, notes the study.

Coffee and caffeine consumption could play an important protective role in almost all phases of CM development, researchers found.

“Consuming three cups of coffee, or 200-300 mg caffeine, per day might help to reduce the risk of developing cardiometabolic multimorbidity in individuals without any cardiometabolic disease,” said the study’s lead author Chaofu Ke, M.D., Ph.D., of the Department of Epidemiology and Biostatistics, School of Public Health at Suzhou Medical College of Soochow University, in Suzhou, China.

The study found that compared with non-consumers or consumers of less than 100mg caffeine per day, consumers of moderate amount of coffee (3 drinks per day) or caffeine (200-300 mg per day) had a 48.1% or 40.7% reduced risk for new-onset CM.

Ke and his colleagues based their findings on data from the UK Biobank, a large and detailed longitudinal dietary study with over 500,000 participants aged 37-73 years. The study excluded individuals who had ambiguous information on caffeine intake. The resulting pool of participants included a total of 172,315 individuals who were free of any cardiometabolic diseases at baseline for the analyses of caffeine, and a corresponding 188,091 individuals for the analyses of coffee and tea consumption.

The participants’ cardiometabolic diseases outcomes were identified from self-reported medical conditions, primary care data, linked inpatient hospital data and death registry records linked to the UK Biobank.

Coffee and caffeine intake at all levels were inversely associated with the risk of new-onset CM in participants without cardiometabolic diseases. Those who reported moderate coffee or caffeine intake had the lowest risk, the study found. Moderate coffee or caffeine intake was inversely associated with almost all developmental stages of CM.

“The findings highlight that promoting moderate amounts of coffee or caffeine intake as a dietary habit to healthy people might have far-reaching benefits for the prevention of CM,” Ke said.

Addressing a Research Gap

Numerous epidemiological studies have revealed the protective effects of coffee, tea and caffeine consumption on morbidity of single cardiometabolic diseases. However, the potential effects of these beverages on the development of CM were largely unknown.

The authors reviewed the available research on this topic and found people with single cardiometabolic disease may have a two-fold higher all-cause mortality risk than those free of any cardiometabolic diseases. By contrast, the researchers found individuals with CM may have an almost 4 to 7 times higher risk of all-cause mortality. The researchers also noted that CM may present higher risks of loss of physical function and mental stress than those with single diseases.

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Invisibility cloaks? Wave scattering simulation unlocks potential for advanced metamaterials

A new software package developed by researchers at Macquarie University can accurately model the way waves -- sound, water or light -- are scattered when they meet complex configurations of particles.

This will vastly improve the ability to rapidly design metamaterials -- exciting artificial materials used to amplify, block or deflect waves.

The findings, published in the journal Proceedings of the Royal Society A on 19 June 2024, demonstrated the use of TMATSOLVER -- a multipole-based tool that models interactions between waves and particles of various shapes and properties.

The TMATSOLVER software makes it very easy to simulate arrangements of up to several hundred scatterers, even when they have complex shapes.

Lead author Dr Stuart Hawkins from Macquarie University's Department of Mathematics and Statistics says the software uses the transition matrix (T-matrix) -- a grid of numbers that fully describes how a certain object scatters waves.

"The T-matrix has been used since the 1960s, but we've made a big step forward in accurately computing the T-matrix for particles much larger than the wavelength, and with complex shapes," says Dr Hawkins.

"Using TMATSOLVER, we have been able to model configurations of particles that could previously not be addressed."

Dr Hawkins worked with other mathematicians from the University of Adelaide, as well as the University of Manchester and Imperial College London, both in the UK, and from the University of Augsburg and University of Bonn, both in Germany.

"It was fantastic to work on this project and incorporate the TMATSOLVER software into my research on metamaterials," says Dr Luke Bennetts, a researcher at the University of Adelaide and co-author of the article.

"It meant I could avoid the bottleneck of producing numerical computations to test metamaterial theories and allowed me to easily generalise my test cases to far more complicated geometries."

Applications in metamaterials

The researchers demonstrated the software's capabilities through four example problems in metamaterial design. These problems included arrays of anisotropic particles, high-contrast square particles, and tuneable [JvE1] periodic structures that slow down waves.

Metamaterials are designed to have unique properties not found in nature, letting them interact with electromagnetic, sound or other waves by controlling the size, shape and arrangement of their nanoscale structures.

Examples include super-lenses to view objects at the molecular scale; invisibility cloaks, which refract all visible light; and perfect wave absorption for energy harvesting or noise reduction.

The findings from this research and development of the TMATSOLVER tool will have wide application in accelerating research and development in the growing global market for metamaterials which can be designed for precise wave control.

"We have shown that our software can compute the T-matrix for a very wide range of particles, using the techniques most appropriate for the type of particle," Dr Hawkins says.

"This will enable rapid prototyping and validation of new metamaterial designs."

Professor Lucy Marshall, Executive Dean, Faculty of Science and Engineering at Macquarie University, says the software could accelerate new breakthroughs.

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Microbe dietary preferences influence the effectiveness of carbon sequestration in the deep ocean

The movement of carbon dioxide (CO2) from the surface of the ocean, where it is in active contact with the atmosphere, to the deep ocean, where it can be sequestered away for decades, centuries, or longer, depends on a number of seemingly small processes.

One of these key microscale processes is the dietary preferences of bacteria that feed on organic molecules called lipids, according to a journal article, "Microbial dietary preference and interactions affect the export of lipids to the deep ocean," published in Science.

"In our study, we found incredible variation in what the different microbes preferred to digest. Bacteria seem to have very distinct diet preferences for different lipid molecules. This has real implications for understanding carbon sequestration and the biological carbon pump," said journal article co-author Benjamin Van Mooy, a senior scientist in the Marine Chemistry and Geochemistry Department at the Woods Hole Oceanographic Institution (WHOI). "This study used state-of-the-art methods to link the molecular composition of the sinking biomass with its rates of degradation, which we were able to link to the dietary preferences of bacteria." The biological carbon pump is a process where biomass sinks from the ocean surface to the deep ocean.

About 5 to 30% of surface ocean particulate organic matter is composed of lipids, which are carbon-rich fatty acid biomolecules that microbes use for energy storage and cellular functions. As the organic matter sinks to the deep sea, diverse communities of resident microbes degrade and make use of the lipids, exerting an important control on global CO2 concentrations. Understanding this process is vital to improve our ability to forecast global carbon fluxes in changing ocean regimes. Geographic areas where more lipids reach the deep ocean undegraded could be hotspots for natural carbon sequestration.

"Bacteria isolated from marine particles exhibited distinct dietary preferences, ranging from selective to promiscuous degraders," the article states. "Using synthetic communities composed of isolates with distinct dietary preferences, we showed that lipid degradation is modulated by microbial interactions. A particle export model incorporating these dynamics indicates that metabolic specialization and community dynamics may influence lipid transport efficiency in the ocean's mesopelagic zone." The mesopelagic zone extends about 200-1000 meters below the ocean surface.

"I was thrilled to see how much there is to learn about the functioning of the ocean by combining two technologies- high-end chemical analysis and microscale imaging-that have historically never been used together," said co-author Roman Stocker, professor at the Institute of Environment Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Switzerland, "I believe that work at the interface between the exciting technologies we now have available in microbial oceanography will continue to yield important insights into how microbes shape our oceans, now and into the future."

"Scientists are starting to understand that lipids in the ocean can vary significantly depending on different environments, such as the coast versus the open ocean, and the season," said Van Mooy. "With this information, researchers can start to consider whether there are places in the ocean where lipids sink and are sequestered very efficiently, while there may be other locations where lipids are barely sequestered at all or are very inefficiently sequestered."

"What excites me about this paper is that it shows bacteria are not just eating any type of lipid, but are very specialized and, like us, have specific food preferences," said article co-author Lars Behrendt, associate professor and SciLifeLab fellow at the Science for Life Laboratory, Department of Organismal Biology, Uppsala University, Sweden. "This changes how we think about how microorganisms consume food in their natural environment and how they might help each other or compete for the same resource. It also supports the idea that combinations of bacteria better break down specific compounds, including lipids, or to achieve other desired functions."

In addition to studying specific bacteria species in isolation, the researchers also looked at how dietary preference affects degradation rates by multispecies communities of bacteria, which they stated is ecologically more relevant than species in isolation. The researchers found that simple synthetic co-cultures exhibited different degradation rates and delay times when compared to monocultures. The researchers also noted that the degradation of particulate organic matter in the natural environment is even more complex than what is described in the study.

"Phytoplankton are the main reason the ocean is one of the biggest carbon sinks. These microscopic organisms play a huge role in the world's carbon cycle -- absorbing about as much carbon as all the plants on land combined," said co-author Uria Alcolombri, senior lecturer, Alexander Silberman Institute of Life Sciences, Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Israel. "It's fascinating that we can study tiny microbial processes under the microscope while uncovering the biological factors that regulate this massive 'digestive system' of the ocean."

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Ancient DNA from Rapa Nui (Easter Island) refutes best-selling population collapse theory

Rapa Nui or Te Pito o Te Henua (the navel of the world), also known as Easter Island, is one of the most isolated inhabited places in the world. Located in the Pacific, it lies over 1,900 km east of the closest inhabited Polynesian island and 3,700 km west of South America. Although the island, its inhabitants and their rich culture have been extensively studied by archaeologists, anthropologists and geneticists, two key elements of Rapanui history remain very controversial to this day. One of these is the theory of population collapse through "ecocide" in the 1600s, thought to be the result of overpopulation and resource mismanagement. The other major contention is whether the Polynesian ancestors of the Rapanui interacted with Indigenous Americans before contact with Europeans in 1722.

This week's issue of Nature features a genetic study that sheds light on these two debates related to Rapanui history by examining the genomes of 15 Rapanui individuals who lived between 1670 and 1950. The remains of these 15 individuals are currently hosted at the Musée de l'Homme, in Paris. The new study was carried out by an international team of scientists and was spearheaded by Assistant Professor Víctor Moreno-Mayar from the Globe Institute at the University of Copenhagen (Denmark), and PhD student Bárbara Sousa da Mota and Associate Prof. Anna-Sapfo Malaspinas from the Faculty of Biology and Medicine at the University of Lausanne (Switzerland), in close collaboration with colleagues in Rapa Nui as well as in Austria, France, Chile, Australia and U.S.A.

The collapse that never happened

The story of the Rapanui has often been presented as a warning tale against humanity's over-exploitation of resources. After Polynesians from the west peopled the island by 1250, the landscape on Rapa Nui changed drastically. Towering stone statues -- the moai -- were carved and placed in all corners of the island, while its original forest of millions of palm trees dwindled and, by the 1600s, was all but gone. According to the "ecocide" theory, a population of over 15,000 Rapanui individuals triggered these changes that led to a period of resource scarcity, famine, warfare and even cannibalism culminating in a catastrophic population collapse.

"While it is well established that the environment of Rapa Nui was affected by anthropogenic activity, such as deforestation, we did not know if or how these changes led to a population collapse," comments Anna-Sapfo Malaspinas, Assoc. Professor at the University of Lausanne and group leader at the SIB Swiss Institute of Bioinformatics, Switzerland, last author of the study.

The researchers looked into the genomes of the Ancient Rapanui individuals expecting to find a genetic signature of a population collapse such as a sudden drop in genetic diversity. But surprisingly, the data did not contain any evidence of a population collapse in the 1600s.

"Our genetic analysis shows a stably growing population from the 13th century through to European contact in the 18th century. This stability is critical because it directly contradicts the idea of a dramatic pre-contact population collapse," says Bárbara Sousa da Mota, a researcher at the Faculty of Biology and Medicine at University of Lausanne and first author of the study.

Through their genetic analysis, Moreno-Mayar, Sousa da Mota, Malaspinas and their colleagues have not only provided evidence against the collapse theory, but also stress the resilience of the Rapanui population facing environmental challenges over several centuries until the colonial disruptions that European contact brought after 1722.

Did Polynesians reach the Americas?

Another debate that has tantalized researchers for decades is whether Polynesians ever reached the Americas. Although long-distance maritime navigation using wooden watercraft likely halted after the Rapa Nui forest disappeared, archaeological and genetic evidence from contemporary individuals hints that voyages to the Americas did occur. However, previous studies looking at small amounts of DNA from ancient Polynesians had rejected the hypothesis that transpacific voyages took place. Thus, these findings have put into question whether Polynesians reached the Americas and have suggested that the inferred contact based on present-day genetic data was mediated by European colonial activity after 1722.

By generating high-quality ancient genomes from the 15 Rapanui individuals, the team substantially increased the amount of genomic data from the island and found that about ten percent of the Rapanui gene pool has an Indigenous American origin. But more importantly, they were able to infer both populations met before Europeans arrived in the island and in the Americas.

"We looked into how the Indigenous American DNA was distributed across the Polynesian genetic background of the Rapanui. This distribution is consistent with a contact occurring between the 13th and the 15th centuries, " says first author Víctor Moreno-Mayar, Asst. Professor at the Globe Institute's Section for Geogenetics, University of Copenhagen.

"While our study cannot tell us where this contact occurred, this might mean that the Rapanui ancestors reached the Americas before Christopher Columbus," says Malaspinas.

Altogether, the results from the new study help settle longstanding debates that have led to years of speculation surrounding Rapanui history.

"Personally, I believe the idea of the ecocide is put together as part of a colonial narrative. That is this idea that these supposedly primitive people could not manage their culture or resources, and that almost destroyed them. But the genetic evidence shows the opposite. Although we have to acknowledge that the arrival of humans dramatically changed the ecosystem, there is no evidence of a population collapse before the Europeans arrived on the island. So we can put those ideas to rest now," says Moreno-Mayar.

"Many thought that present-day Rapanui carry Indigenous American genetic ancestry due to European colonial activity. But instead, the data strongly suggests that Rapanui and Indigenous Americans met and admixed centuries before Europeans made it to Rapa Nui or the Americas. We believe this means that Rapanui were capable of even more formidable voyages across the Pacific than previously established, " adds Sousa da Mota.

Future repatriation efforts

Importantly, the scientists held face-to-face discussions with members of the Rapanui community and the "Comision Asesora de Monumentos Nacionales" in Rapa Nui (CAMN). These discussions allowed to steer the research and to define a set of research questions that were equally of high interest to the scientists and the community. For instance, the team was able to show that the populations closest to the ancient Rapanui are indeed those currently living on the island.

"We have seen that museum archives contain mistakes and mislabels. Now that we have established that these 15 individuals were in fact Rapanui we know that they belong back in the island," says Moana Gorman Edmunds, an archaeologist in Rapa Nui and co-author of the study.

Furthermore, when ongoing results were presented to representatives of the Rapanui community, the need to repatriate their ancestors was discussed as a central goal for immediate future efforts.

Read more at Science Daily

Path to prosperity for planet and people shrinking rapidly, scientists warn

Our planet will only remain able to provide even the most basic standard of living for everyone in the future if economic systems and technologies are dramatically transformed and critical resources are more fairly used, managed and shared, a new report shows. The report is co-authored by over sixty leading natural and social scientists from the Earth Commission, led by the UvA's Joyeeta Gupta, as well as Prof. Xuemei Bai and Prof. Diana Liverman. The report was published today in The Lancet Planetary Health.

The new research builds on the 'Safe and Just Earth System Boundaries' published in Nature last year, which found that most of the vital limits within which people and the planet can thrive have been surpassed. The new paper identifies the 'Safe and Just Space' -- within which harm to humans and nature can be minimised while ensuring everyone can be provided for -- and sets out the paths to reach and stay in such a space.

Already shrinking

But future projections to 2050 show that this space will shrink over time, driven by inequality, unless urgent transformations take place. The only way to provide for everyone and ensure societies, businesses and economies thrive without destabilising the planet is to reduce inequalities in how critical Earth system resources, such as freshwater and nutrients, are accessed and used -- alongside economic and technological transformation.

The new work found that inequalities and overconsumption of finite resources by a minority are key drivers of this shrinking. Providing minimum resources for those who don't currently have enough would add much less pressure on the Earth system than that currently caused by the minority who use far greater resources.

Joyeeta Gupta: 'We're beginning to realise the damage that inequality is doing to the Earth. Increasing pollution and poor management of natural resources is causing significant harm to people and nature. The longer we continue to widen the gap between those who have too much and those who don't have enough, the more extreme the consequences for all, as the support systems which underpin our way of life, our markets and our economies begin to collapse.'

A life free from poverty

If the Earth System Boundaries represent the "ceiling," above which Earth systems can no longer remain stable and resilient, and significant damage could be caused to people and nature, the Safe and Just Space represents a "foundation," showing us the minimum the global population needs from the Earth system, in order to live a life free from poverty. The space in between is full of opportunities that we can use to ensure a better future for people and planet.

To reach this space, the paper calls for change in three areas. Firstly, a push for changes to how we run the economy, finding new policies and funding mechanisms that can address inequality whilst reducing pressure on nature and climate. Secondly, more efficient and effective management, sharing and usage of resources at every level of society -- including addressing the excess consumption of some communities which is limiting access to basic resources for those who need them the most. Thirdly, investment in sustainable and affordable technologies, which will be essential to help us use fewer resources and to reopen the Safe and Just Space for all -- particularly where there is little or no space left.

Read more at Science Daily

Climate-change-triggered 2023 mega-landslide caused Earth to vibrate for nine days

A landslide in a remote part of Greenland caused a mega-tsunami that sloshed back and forth across a fjord for nine days, generating vibrations throughout Earth, according to a new study involving UCL researchers.

The study, published in the journal Science, concluded that this movement of water was the cause of a mysterious, global seismic signal that lasted for nine days and puzzled seismologists in September 2023.

The initial event, not observed by human eye, was the collapse of a 1.2km-high mountain peak into the remote Dickson Fjord beneath, causing a backsplash of water 200 metres in the air, with a wave up to 110 metres high. This wave, extending across 10km of fjord, reduced to seven metres within a few minutes, the researchers calculated, and would have fallen to a few centimetres in the days after.

The team used a detailed mathematical model, recreating the angle of the landslide and the uniquely narrow and bendy fjord, to demonstrate how the sloshing of water would have continued for nine days, with little energy able to escape.

The model predicted that the mass of water would have moved back and forth every 90 seconds, matching the recordings of vibrations travelling in the Earth's crust all around the globe.

The landslide, the researchers wrote, was a result of the glacier at the foot of the mountain thinning, becoming unable to hold up the rock-face above it. This was ultimately due to climate change. The landslide and tsunami were the first observed in eastern Greenland.

Co-author Dr Stephen Hicks, of UCL Earth Sciences, said: "When I first saw the seismic signal, I was completely baffled. Even though we know seismometers can record a variety of sources happening on Earth's surface, never before has such a long-lasting, globally travelling seismic wave, containing only a single frequency of oscillation, been recorded. This inspired me to co-lead a large team of scientists to figure out the puzzle.

"Our study of this event amazingly highlights the intricate interconnections between climate change in the atmosphere, destabilisation of glacier ice in the cryosphere, movements of water bodies in the hydrosphere, and Earth's solid crust in the lithosphere.

"This is the first time that water sloshing has been recorded as vibrations through the Earth's crust, travelling the world over and lasting several days."

The mysterious seismic signal -- coming from a vibration through the Earth's crust -- was detected by seismometers all over the globe, from the Arctic to Antarctica. It looked completely different to frequency-rich 'rumbles' and 'pings' from earthquake recordings, as it contained only a single vibration frequency, like a monotonous-sounding hum.

When the study's authors first discovered the signal, they made a note of it as a "USO": unidentified seismic object.

At the same time, news of a large tsunami in a remote northeast Greenland fjord reached authorities and researchers working in the area.

The researchers joined forces in a unique multidisciplinary group involving 68 scientists from 40 institutions in 15 countries, combining seismometer and infrasound data, field measurements, on-the-ground and satellite imagery, and simulations of tsunami waves.

The team also used imagery captured by the Danish military who sailed into the fjord just days after the event to inspect the collapsed mountain-face and glacier front along with the dramatic scars left by the tsunami.

It was this combination of local field data and remote, global-scale observations that allowed the team to solve the puzzle and reconstruct the extraordinary cascading sequence of events.

Lead author Dr Kristian Svennevig, from the Geological Survey of Denmark and Greenland (GEUS), said: "When we set out on this scientific adventure, everybody was puzzled and no one had the faintest idea what caused this signal. All we knew was that it was somehow associated with the landslide. We only managed to solve this enigma through a huge interdisciplinary and international effort."

He added: "As a landslide scientist, an additional interesting aspect of this study is that this is the first-ever landslide and tsunami observed from eastern Greenland, showing how climate change already has major impacts there."

The team estimated that 25 million cubic metres of rock and ice crashed into the fjord (enough to fill 10,000 Olympic-sized swimming pools).

They confirmed the size of the tsunami, one of the largest seen in recent history, using numerical simulations as well as local data and imagery.

Seventy kilometres away from the landslide, four-metre-high tsunami waves damaged a research base at Ella Ø (island) and destroyed cultural and archaeological heritage sites across the fjord system.

The fjord is on a route commonly used by tourist cruise ships visiting the Greenland fjords. Fortunately, no cruise ships were close to Dickson Fjord on the day of the landslide and tsunami, but if they had been, the consequences of a tsunami wave of that magnitude could have been devastating.

Mathematical models recreating the width and depth of the fjord at very high resolution demonstrated how the distinct rhythm of a mass of water moving back and forth matched the seismic signal.

The study concluded that with rapidly accelerating climate change, it will become more important than ever to characterise and monitor regions previously considered stable and provide early warning of these massive landslide and tsunami events.

Co-author Thomas Forbriger, from Karlsruhe Institute of Technology, said: "We wouldn't have discovered or been able to analyse this amazing event without networks of high-fidelity broadband seismic stations around the world, which are the only sensors that can truly capture such a unique signal."

 Read more at Science Daily

How El Nino and mega ocean warming caused the greatest-ever mass extinction

Mega ocean warming El Niño events were key in driving the largest extinction of life on planet Earth some 252 million years ago, according to new research.

The study, published today in Science and co-led by the University of Bristol and China University of Geosciences (Wuhan), has shed new light on why the effects of rapid climate change in the Permian-Triassic warming were so devastating for all forms of life in the sea and on land.

Scientists have long linked this mass extinction to vast volcanic eruptions in what is now Siberia. The resulting carbon dioxide emissions rapidly accelerated climate warming, resulting in widespread stagnation and the collapse of marine and terrestrial ecosystems.

But what caused life on land, including plants and usually resilient insects, to suffer just as badly has remained a source of mystery.

Co-lead author Dr Alexander Farnsworth, Senior Research Associate at the University of Bristol, said: “Climate warming alone cannot drive such devastating extinctions because, as we are seeing today, when the tropics become too hot, species migrate to the cooler, higher latitudes. Our research has revealed that increased greenhouse gases don’t just make the majority of the planet warmer, they also increase weather and climate variability making it even more ‘wild’ and difficult for life to survive.”

The Permian-Triassic catastrophe shows the problem of global warming is not just a matter of it becoming unbearably hot, but also a case of conditions swinging wildly over decades.

“Most life failed to adapt to these conditions, but thankfully a few things survived, without which we wouldn’t be here today. It was nearly, but not quite, the end of the life on Earth,” said co-lead author Professor Yadong Sun at China University of Geosciences, Wuhan.

The scale of Permian-Triassic warming was revealed by studying oxygen isotopes in the fossilised tooth material of tiny extinct swimming organisms called conodonts. By studying the temperature record of conodonts from around the world, the researchers were able to show a remarkable collapse of temperature gradients in the low and mid latitudes.

Dr Farnsworth, who used pioneering climate modelling to evaluate the findings, said: “Essentially, it got too hot everywhere. The changes responsible for the climate patterns identified were profound because there were much more intense and prolonged El Niño events than witnessed today. Species were simply not equipped to adapt or evolve quickly enough.”

In recent years El Niño events have caused major changes in rainfall patterns and temperature. For example, the weather extremes that caused the June 2024 North American heatwave when temperatures were around 15°C hotter than normal. 2023-2024 was also one of the hottest years on record globally due to a strong El Niño in the Pacific, which was further exacerbated by increased human-induced CO2 driving catastrophic drought and fires around the world.

“Fortunately such events so far have only lasted one to two years at a time. During the Permian-Triassic crisis, El Niño persisted for much longer resulting in a decade of widespread drought, followed by years of flooding. Basically, the climate was all over the place and that makes it very hard for any species to adapt,” co-author Paul Wignall, Professor of Palaeoenvironments at the University of Leeds.

The results of the climate modelling also help explain the abundant charcoal found in rock layers of that age.

“Wildfires become very common if you have a drought-prone climate. Earth got stuck in a crisis state where the land was burning and the oceans stagnating. There was nowhere to hide,” added co-author Professor David Bond, a palaeontologist at the University of Hull.

The researchers observed that throughout Earth’s history there have been many volcanic events similar to those in Siberia, and many caused extinctions, but none led to a crisis of the scale of the Permian-Triassic event.

They found Permian-Triassic extinction was so different because these Mega-El Niños created positive feedback on the climate which led to incredibly warm conditions starting in the tropics and then beyond, resulting in the dieback of vegetation. Plants are essential for removing CO2 from the atmosphere, as well as the foundation of the food web, and if they die so does one of the Earth's mechanisms to stop CO2 building up in the atmosphere as a result of continued volcanism.

This also helps explain the conundrum regarding the Permian-Triassic mass extinction whereby the extinction on land occurred tens of thousands of years before extinction in the oceans.

“Whilst the oceans were initially shielded from the temperature rises, the mega-El Nino’s caused temperatures on land to exceed most species thermal tolerances at rates so rapid that they could not adapt in time,” explained Dr Sun.

“Only species that could migrate quickly could survive, and there weren’t many plants or animals that could do that.”

Mass extinctions, although rare, are the heartbeat of the Earth’s natural system resetting life and evolution along different paths.

Read more at Science Daily