5.5 million years ago the Mediterranean dried out, with sobering lessons for humanity today – new research

What would happen if humans dried out the Mediterranean sea, turning it into a giant salt lake? Would its wildlife survive, and if so, how long would it take to recover?

These may seem like wildly theoretical questions, but not for Herman Sörgel, a Bavarian architect who dedicated much of his life to this exact project: building a giant dam across the Strait of Gibraltar, letting the Mediterranean dry up, and colonising the land reclaimed from the sea.

Sörgel organised lectures and documentaries and raised funds until the 1950s for a project which, he believed, would promote cooperation between Africa and Europe, and power both continents through gigantic hydroelectric megaprojects.

What he did not know was that his dream had already come true at the end of the Miocene era, 5.5 million years ago, as a simple result of natural forces.

When the Mediterranean disappeared

Since the 1970s, several generations of marine geologists and geophysicists have confirmed the existence of a one to three kilometre thick layer of salt buried throughout most of the deeper parts of the Mediterranean Sea.

This is almost a million cubic kilometres of salt that testify to a brief period when the Mediterranean was isolated from the rest of the world’s oceans – brief in the geological sense, as the episode lasted about 190,000 years

https://youtu.be/y6GV_tnFta0

The culprit was not, of course, an eccentric German architect, but plate tectonics. The Mediterranean basin, trapped between two continents that today continue to move closer by up to two centimetres every year, was cut off from the Atlantic. Its waters quickly evaporated due to the region’s arid climate, leaving behind vast amounts of salt.

This episode, known as the Messinian salinity crisis (the Messinian being the last period of the Miocene), is the biggest extinction event suffered by the Earth since the meteorite that wiped out the flightless dinosaurs and ended the Mesozoic era 65 million years ago.

As a result, no geoengineering experiments are needed to answer our initial question: how resilient is marine life in the face of an environmental crisis of this magnitude?

The answer has just been published in the journal Science, in a study led by Konstantina Agiadi of the University of Vienna in collaboration with the Spanish National Research Council and 28 other scientists from 25 European institutes.

After gathering all Mediterranean fossil data from between 12 and 3.6 million years ago, the results suggest that native marine life was virtually extinct when the Mediterranean was cut off, and that subsequent recolonisation by Atlantic species gave rise to a Mediterranean fauna more similar to the one we find there today.

Native, extinct and migrant species

By statistically analysing information from more than 750 scientific papers, we were able to document 22,932 presences of a total of 4,897 marine species living in the Mediterranean. Before the crisis, 779 species could be considered endemic species (i.e. documented only in the Mediterranean). Of those, only 86 were still present after the salinity crisis. All the tropical corals that were abundant in the Mediterranean before this cataclysmic environmental change disappeared.

However, some apparently endemic sardine species managed to survive. The sirenian, a sea mammal related to today’s manatees and dugongs (also known as sea cows) also survived.

Because fossil records are limited and fragmented we cannot be certain that these species were all endemic, or that they would not have survived outside the Mediterranean, hence the value of basing our study on statistics from a large number of species. But for those that were endemic, where did they manage to survive, and what refuges did they find to avoid the radical increase in salt levels and temperature?

These questions remain unanswered, but we have been able to establish that changes in populations are the result of replacement by Atlantic species after the Mediterranean’s re-flooding, rather than rapid adaptation to the new hypersaline environment. In other words, life did not have enough time to adapt, and the extinct species were replaced by Atlantic species that migrated into the Mediterranean.

Several iconic species, such as the great white shark and the dolphin, only appeared in the Mediterranean after the crisis. Even more interestingly, the current richness of fauna in the western Mediterranean only came after the re-flooding – previously, the eastern Mediterranean (Ionian and Levantine Seas) had possessed a higher number of different species.

Lessons on mass extinction

The impact of the Mediterranean’s isolation on its fauna and flora was catastrophic, destroying most of its ecosystems. Another significant finding from our research is that it took more than 1.7 million years for species numbers to recover. This slow recovery of the richness of Mediterranean ecosystems provides the first detailed quantification of how wildlife responds to an extinction event of this magnitude.

The Mediterranean’s biodiversity today is very high thanks to the presence of numerous endemic species. Our results suggest that this was also the case six million years ago, but that the vast majority of these endemic species disappeared when it was cut off from the Atlantic.

Perhaps another lesson learned from this study is that, however tempting it may be to believe that geoengineering projects can allow us to maintain our current rate of emissions and ecosystem destruction, the Earth’s geological past will reveal more than any experiment.

When the Mediterranean was reconnected to the Atlantic, it was repopulated by the huge reserve of species in the world’s oceans, yet it still took millions of years for the Mediterranean’s ecosystems to recover in terms of richness. No one knows yet how long it will take for marine life to recover from the kind of global-scale change that is currently underway.

{ https://theconversation.com/europe }

01-09-2024 om 01:22 geschreven door peter  

Being Stranded In Space Could Upend Starliner Astronauts’ Perception of Time

Waiting slows our perception of time.

by Ruth Ogden, Daniel Eduardo Vigo and The Conversation

 

NASA

They arrived in the Boeing Starliner spacecraft — the first test of the spaceship with astronauts. Wilmore and Williams were supposed to stay on the ISS for around eight days and return on the same spacecraft. But there is now debate about the safety of Starliner after it experienced helium leaks and thruster problems on its way to the ISS.

In the coming days, NASA and Boeing may decide to clear Starliner to carry the astronauts back to Earth. This means their stay might not last too much longer. But if officials decide against Starliner, the astronauts face waiting an additional six months in orbit before returning. So how do astronauts cope with a potential six-month wait for a lift home?

Waiting for things is difficult at the best of times. Under normal circumstances, it is frustrating, stressful and anxiety-provoking. But in extreme situations, with high stakes, waiting can be purgatory.

Part of the reason that waiting is difficult is that it distorts our sense of time. Think of the last time you were waiting for a delayed train, test results or a text from a potential new partner. Did it fly by or drag? For most people, time spent waiting crawls at a glacial pace. As a result, delays and periods of anticipation often feel much longer than they actually are.

Waiting slows our perception of time because it changes the amount of time that we spend thinking about time. During normal daily life, we often ignore time, and our brains have a limited capacity. If time isn’t important, we simply don’t think about it, and this helps it to pass quickly.

When we are waiting, our desire to know when the wait is over increases how much we think about time. This “clock watching” can make the minutes and hours feel like they are passing at a snail’s pace. Stress, discomfort and pain exacerbate this effect, meaning that waiting in difficult situations can seem even longer.

Waiting also slows our perception of time because it is what we do and how we feel. Normal life is busy and full of ever-changing activities and interactions. The sudden need to wait halts the flow of life, often leaving us with nothing else to do, thus increasing levels of boredom and frustration.

In general, time filled with activity passes more quickly. We all got a taste of this during COVID lockdowns. When we were stuck inside, unable to see friends and engage in normal daily activities, the loss of routine and distractions caused time to drag for many.

For the astronauts stuck on the ISS, anxiety about when they will return, limited opportunities for activities and fewer opportunities to contact friends and families combine to make their wait to return home feel significantly longer than six months — if it should come to that.

However, as academics who research the effects of time on human psychology and biology, our ongoing work with crew members at research stations in Antarctica aims to shed light on whether waiting in extreme environments is different to waiting during normal daily life.

A year in Antarctica

While being stuck for six months on the ISS may sound like many people’s worst nightmare, it is not uncommon for scientists to spend long periods isolated and confined in extreme environments. Every year, organizations such as the Instituto Antártico Argentino (which uses the Belgrano II Antarctic station), the French Polar Institute and the Italian Antarctic Programme, in cooperation with the European Space Agency (which all use Antarctica’s Concordia station), send crews of people for up to 16 months to conduct research on the frozen continent.

During the March to October polar winter, teams spend six months in near darkness – and from May to August, in complete darkness – facing outside temperatures of up to -60C, wind speeds of 160 km/h (100 mph) and storms which prevent almost all outdoor activity. Limited internet coverage can also prevent constant communication with the outside world.

For the last year, we have researched how life in Antarctica influences people’s experience of time. Each month, we asked crew members how time felt like it was passing in comparison to before their mission. Trapped on base, with limited contact with the outside world, you might expect time to drag. However, our results suggest the opposite may be true.

Analysis of crew members’ experiences indicated that being constantly busy with complex tasks such as scientific research helped the time to pass swiftly, according to 80% of crew responses. Only 3% of responses indicated that time actually dragged, and these reports occurred when nights were long, and there was little to do.

These experiences may provide hope for those stuck on the ISS. Like life in an Antarctic station, these NASA astronauts have busy and mentally demanding lives. These factors may help time to pass quickly.

However, a key factor of their wait may be their ability to tolerate the uncertainty of when they will return. Wilmore and Williams will spend their time in a space equivalent to the inside of a Boeing 747 plane. However, better information about “when” things will happen and “why” delays are being incurred can help people tolerate waiting and reduce its impact on their wellbeing.

• This article was originally published on The Conversation by Ruth Ogden at the Liverpool John Moores University and Daniel Eduardo Vigo at the Pontificia Universidad Católica de Argentina. Read the original article here.

{ https://www.inverse.com/ }

01-09-2024 om 01:00 geschreven door peter  

The Webb Telescope Just Identified 6 Giant Gaseous Planets That Are More Massive Than Jupiter

And these strange worlds may be a lot more common than we thought.

by Kiona Smith

 

STSCI

The James Webb Space Telescope (JWST) peered into a nearby star cluster and found a handful of rogue gas giants — including one with its own disk of dust swirling around it. The results suggests that rogue planets may not only be worlds that got kicked out of their star systems, but worlds that coalesce out of clouds of interstellar gas in the same way stars do — just smaller.

Johns Hopkins University astrophysicist Adam Langeveld and his colleagues published their work in The Astronomical Journal.

Lonely Planets Club

Langeveld and his colleagues surveyed a cluster of stars called NGC 1333, which exists 1,000 light years away in the constellation Perseus, with JWST’s Near Infrared Imager and Slitless Spectrograph (NIRISS) instrument. They found six gas giants — each between five and 10 times more massive than Jupiter — drifting through space on their own, not orbiting a star. One of these lonely worlds even had a disk of dust orbiting it, as if in the process of forming its own little family of planets (or moons). And based on their observations, Langeveld and his colleagues say rogue planets, once thought to be rare flukes of nature, might make up about 10 percent of the objects in the cluster.

We know that stars form when dense clumps of gas and dust in clouds called nebulae collapse under their own gravity, creating enough heat and pressure at their centers to kickstart nuclear fusion. And we know that sometimes, a clump of material can form an object that’s just on the threshold of being able to start burning as a star, but doesn’t have quite enough mass to get there: a brown dwarf. But astronomers weren’t sure whether even smaller objects, like giant gas planets, could form the same way.

The team of astrophysicists used JWST “to search for the faintest members of a young star cluster, seeking to address a fundamental question in astronomy: how light an object can form like a star?” says Johns Hopkins University astrophysicist Ray Jayawardhana, the senior author of the recent paper, in a recent statement. “It turns out the smallest free-floating objects that form like stars overlap in mass with giant exoplanets circling nearby stars.”

The smallest rogue planet Langeveld and his colleagues spotted, a gas giant about 5 times the mass of Jupiter (or 1,600 times the mass of Earth, if you prefer), is an important clue. It sits at the heart of a swirling disk of gas and dust, which looks exactly like the disks that form around newborn stars, where material eventually coalesces into planets. That suggests that the planet probably formed like a star, just from a smaller cloud of gas and dust. And it may be forming its own miniature system, like Jupiter or Saturn with their swarms of moons.

In other words, rogue planets may not always be planets that formed in orbit around a star like our Sun, only to get kicked out of the star system by a close encounter with a sibling planet or a passing star (which may have happened at least once in our own Solar System’s history). Instead, they can apparently spawn all alone, from much smaller clouds of gas than the ones that form stars.

“This is important context for understanding both star and planet formation,” says Langeveld in a recent statement.

What’s Next?

Langeveld and his colleagues hope to learn more about these lonely planets’ atmospheres in their next round of observations with JWST. Once they have that information, they’ll compare the rogue gas giants’ atmospheres to brown dwarfs and to “normal” gas giants that orbit stars. That could offer clues about whether gas giants that coalesce alone in the middle of space contain a different mix of elements than those that form in the disks around newborn stars.

The astronomers also hope to find more objects like the small rogue planet with its own little protoplanetary disk. That could shed light on whether, or how, rogue planets might form their own systems of planets (or moons). Picture all the diverse worlds that orbit the gas giants in our Solar System — Jupiter’s icy moon Europa and volcanic hellworld Io, or Saturn’s Titan with its methane seas — orbiting a version of Jupiter all alone in deep space, unlit by any star, heated only by the tidal pull of their planet.

“The diversity of systems that nature has produced is remarkable and pushes us to refine our models of star and planet formation,” says Jayawardhana.

{https://www.inverse.com/ }

01-09-2024 om 00:42 geschreven door peter  

Microplastics Can Cross the Blood-Brain Barrier, A New Study Suggests — Here’s Why That Matters

Plastic levels in the brain were much higher than in organs surveyed.

by Elana Spivack

 

Kateryna Kon/Science Photo Library/Getty Images

A preprint study — which is a scientific study that has not yet been reviewed by other scientists for publication in a journal — was posted online in May by the National Institutes of Health looking at the amount of microplastics in human brain samples from autopsies. The study found that brains had higher concentrations of microplastics than other organs, and that these autopsy samples also had higher concentrations of microplastics than autopsy samples from a 2016 study. Though this paper is still under review to ensure the methods and findings are trustworthy, the key results of the study exemplify yet another vital organ affected by microplastics.

For the study, the authors examined livers, kidneys, and brains from autopsied cadavers. They found that concentrations of microplastics in the brain samples they examined “ranged from 7 to 30 times the concentrations seen in livers or kidneys.” They also found that brain samples collected and analyzed in 2024 contained significantly higher concentrations of microplastic, with over 3,000 micrograms per gram of human tissue in 2016 and over 4,800 micrograms per gram in 2024. Some samples ranged as high as more than 8,800 micrograms of plastic per gram of brain tissue.

We don’t know yet what effects, if any, microplastics could have on the brain, but this study does confirm that these bits of plastic can cross the blood-brain barrier, which is the protective membrane that helps regulate what molecules enter the brain from circulating blood.

“Based on our observations, we think the brain is pulling in the very smallest nanostructures, like 100 to 200 nanometers in length, whereas some of the larger particles that are a micrometer to five micrometers go into the liver and kidneys,” lead author of the study Matthew Campen, a toxicologist and professor of pharmaceutical sciences at the University of New Mexico in Albuquerque, told CNN.

While it seems like microplastics are omnipresent in today’s society, figuring out how to affect our health is key.

{ https://www.inverse.com/ }

01-09-2024 om 00:32 geschreven door peter  

The Event Horizon Telescope Just Made A Major Breakthrough — Black Holes Can Now Be Seen in ‘Color Vision’

The team that delivered the first-ever image of a black hole is getting more ambitious.

by Doris Elín Urrutia

 

EHT, D. Pesce, A. Chael

“This new ‘color vision’ allows us to tease apart the effects of Einstein’s gravity from the hot gas and magnetic fields that feed the black holes and launch powerful jets that stream over galactic distances,” Sheperd “Shep” Doeleman, astrophysicist and Founding Director of the EHT, said in an announcement published Tuesday.

Two is better than one

Doeleman tells Inverse that supermassive black holes are busy places. Seeing two frequencies would reveal more of its organized chaos. The team has published simulation images to depict how the new frequency changes the view.

“When you have two separate frequencies, you’re able to tease apart different effects around the black hole,” Doeleman says.

Albert Einstein predicted that gravity bends all light, across all wavelengths, in the same way. Right around the black hole’s shadow, where gravity is so strong that not even light can reflect back out, data across both frequencies may look the same.

But farther away from the event horizon, other phenomena like the black hole’s jets of superheated plasma will look differently from one frequency to the next.

Seeing in color

Having two sets of information allows for color. The data from the telescopes is radio, a wavelength of light invisible to human eyes. The single color of existing EHT images are packed with information at 230 GHz. But now that EHT can take observations at 345 GHz, imagery specialists can add a new color to the golden ring. This will be exciting to view not only as a still image, but eventually, as a motion picture.

This composite simulated image from the Event Horizon Telescope shows how the supermassive black hole M87* might look at different radio frequencies of 86 GHz (red), 230 GHz (green), and 345 GHz (blue).

EHT, D. Pesce, A. Chael

Doeleman and other researchers hope the telescopes in the EHT network will be able to take not just two radio wavelengths at the same time, but eventually three.

“The EHT's successful observation at 345 GHz is a major scientific milestone,” Lisa Kewley, Director of the Center for Astrophysics | Harvard & Smithsonian, said in the announcement. “By pushing the limits of resolution, we’re achieving the unprecedented clarity in the imaging of black holes we promised early on, and setting new and higher standards for the capability of ground-based astrophysical research.”

{ https://www.inverse.com/ }

01-09-2024 om 00:22 geschreven door peter