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The influence of ancient Neanderthal DNA on modern daily routines

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Recent research has revealed a link between Neanderthal genetics and the tendency of some modern humans to wake up early. The study traces back to the interbreeding of modern humans and Neanderthals in Eurasia and suggests that genetic variation in Neanderthals influences the circadian rhythms of modern human descendants. Credit: SciTechDaily.com

A new paper has been published in a magazine Genome biology and evolutionAccording to a paper published by Oxford University Press, genetic material from Neanderthal ancestors may have contributed to the tendency of some people today to be “early risers” – the type of people who find it easier to get up early and go to bed. I discovered that there is a possibility that

Human evolution and genetic adaptation

All anatomically modern humans trace their origins to Africa about 300,000 years ago, where environmental factors shaped many of their biological characteristics. About 70,000 years ago, the ancestors of modern Eurasian humans began migrating into Eurasia, where they encountered a variety of new environments, including high latitude regions with large seasonal fluctuations in sunlight and temperature.

But other hominins, such as Neanderthals and Denisovans, lived in Eurasia for more than 400,000 years. These archaic humans diverged from modern humans about 700,000 years ago, and as a result, our ancestors and archaic humans evolved under different environmental conditions. This led to the accumulation of strain-specific genetic variation and phenotypes. When humans came to Eurasia, they interbred with archaic humans from the continent. This created the possibility for humans to acquire genetic variations already adapted to these new environments.

Genes of ancient humans and characteristics of modern humans

Although previous studies have shown that many of the archaic ancestors of modern humans are not beneficial and have been removed by natural selection, some archaic hominin variants that remain in human populations has shown evidence of adaptation. For example, archaic genetic variation is thought to be associated with differences in hemoglobin levels, immune resistance to new pathogens, levels of skin pigmentation, and fat composition among Tibetans at high altitudes.

Changes in patterns and levels of light exposure have biological and behavioral effects that lead to evolutionary adaptations. Scientists have extensively studied the evolution of circadian adaptations in insects, plants, and fish, but humans have been less well studied. The Eurasian environment where Neanderthals and Denisovans lived for hundreds of thousands of years is located at higher latitudes and has more variable daylight hours than where modern humans evolved before leaving Africa. So the researchers investigated whether there was genetic evidence for differences in circadian clocks between Neanderthals and modern humans.

Research methods and findings

The researchers defined a set of 246 circadian genes using a combination of literature searches and expert knowledge. They found hundreds of genetic variations unique to each strain that can affect genes involved in the circadian clock. Using artificial intelligence techniques, they identified 28 circadian genes that contain mutations that could alter splicing in archaic humans and that may be differentially regulated between modern and archaic humans. identified 16 circadian genes.

This indicates that there may be functional differences between the circadian clocks of ancient and modern humans. Eurasian modern humans and Neanderthal ancestors interbred, so some humans may have acquired circadian variation from Neanderthals.

To test this, the researchers studied a large population of hundreds of thousands of people in the UK Biobank and found that introgressed genetic mutations (mutations that passed from Neanderthals to modern humans) could affect wakefulness and sleep. We investigated whether there is a relationship with physical preference for. They discovered a number of introgressed mutants that affected sleep preferences, and most surprisingly, they found that these mutants consistently increased morningness, or the tendency to rise early. This suggests a directional influence on this trait and is consistent with adaptations to high latitudes observed in other animals.

Increased morning time in humans is associated with a shortened circadian clock period. This may be beneficial at high latitudes, as it has been shown that sleep and wakefulness can be coordinated more quickly with external timing cues. Shortening of the circadian period is required to synchronize with the long summer light period at high latitudes in Drosophila, and selection for a shorter circadian period results in the latitudinal period decreasing with increasing latitude in natural Drosophila populations. There is a latitudinal gradient in which the

Therefore, the bias toward morningness in introgressed mutants may indicate selection for shortened circadian periods in populations living at high latitudes. The tendency to be a morning person may have been evolutionarily beneficial to our ancestors who lived in the high latitudes of Europe, and would have been a Neanderthal genetic trait worth preserving.

“By combining ancient times, DNA“After extensive genetic and artificial intelligence research in modern humans, we discovered substantial genetic differences in the circadian systems of Neanderthals and modern humans,” said John, lead author of the paper.・A. Capra said.

“And by analyzing Neanderthal DNA fragments that remain in the genomes of modern humans, we discovered surprising trends, many of which affect the regulation of circadian genes in modern humans. These effects are primarily in the consistent direction of increasing Neanderthal tendencies.” Morning people. This change is consistent with the effects of living at high latitudes on animals’ circadian clocks, which may allow them to adjust more quickly to changing seasonal light patterns.

“Our next steps include applying these analyzes to more diverse modern human populations and investigating the effects of the Neanderthal variants we identified on circadian clocks in model systems. and applying similar analyzes to other potentially adaptive traits.”

Reference: “Archaic Introgression Shaped Human Circadian Traits” by Keila Velazquez-Arcelay, Laura L Colbran, Evonne McArthur, Colin M Brand, David C Rinker, Justin K Siemann, Douglas G McMahon, John A Capra, December 14, 2023 , Genome biology and evolution.
DOI: 10.1093/gbe/evad203

Source: scitechdaily.com

The process of how ancient stars produced elements unattainable by Earth

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Researchers have discovered that ancient stars can produce elements with atomic masses of more than 260, heavier than those found naturally on Earth. This discovery improves our understanding of element formation in stars, particularly through the rapid neutron capture processes (r-processes) that occur in neutron stars. . Credit: SciTechDaily.com

A new study reveals that ancient stars can produce elements heavier than Earth, with atomic masses of more than 260, advancing our understanding of cosmic element formation.

How much do elements weigh? An international team of researchers has found that ancient stars had the ability to produce elements with an atomic mass of more than 260, heavier than any element on the periodic table that occurs naturally on Earth. I discovered that. This discovery deepens our understanding of element formation in stars.

space element factory

We are literally made of star stuff. Stars are elemental factories, where elements are constantly merging or breaking down to create other lighter or heavier elements. When we refer to light or heavy elements, we are talking about their atomic mass. Roughly speaking, atomic mass is based on the number of protons and neutrons in the nucleus. atom of its elements.

The heaviest elements are only known to be produced in neutron stars by rapid neutron capture processes, or r processes. Imagine a single atomic nucleus floating in a soup of neutrons. Suddenly, a bunch of these neutrons attach themselves to the nucleus in a very short time (usually less than a second), causing a change from neutrons to protons inside, and voila! Heavy elements such as gold, platinum, and uranium are formed.

Instability of heavy elements

The heaviest elements are unstable or radioactive and decay over time. One way to do this is through a split called fission.

“If you want to make heavier elements, such as lead or bismuth, you need the R process,” says Ian Roederer, associate professor of physics. north carolina state university and lead author of the study. Mr. Roederer previously attended the University of Michigan.

“We need to add a lot of neutrons very quickly, and the problem is that we need a lot of energy and a lot of neutrons to do that,” Roederer says. “And the best place to find both is at the moment of a person’s birth or death. neutron staror when neutron stars collide and the raw materials for the process are produced.

“We have a general understanding of how the r process works, but the conditions of the process are very extreme,” Roederer says. “We don’t really know how many different sites in the universe generate r-processes, and we don’t know how r-processes end. We also don’t know how many neutrons there are Can you add more? Or how heavy can the elements be? So we looked at the elements produced by nuclear fission in well-studied old stars to find out how heavy these elements are. We decided to see if we could answer some of the questions.”

Identify previously unrecognized patterns

The research team newly investigated the abundance of heavy elements in 42 well-studied stars. milky way. These stars were known to contain heavy elements formed by the r process in earlier generations of stars. By looking more broadly at the amounts of each heavy element found in these stars, rather than individually, as is more common, they identified previously unrecognized patterns.

These patterns indicated that some elements listed near the middle of the periodic table, such as silver and rhodium, were likely remnants of nuclear fission of heavy elements. The research team was able to confirm that the r process can produce atoms with an atomic mass of at least 260 before fission.

“That 260 is interesting because, even in nuclear weapons tests, nothing that heavy has ever been detected in space or in nature on Earth,” Roederer said. “But observing them in space gives us guidance on how to think about models and fission. It also gives us insight into how the rich diversity of elements came about.” may be given.”

For more information on this research, see ‘Incredibly profound’ evidence for nuclear fission throughout the universe.’

Reference: “Elemental abundance patterns in stars show splitting of nuclei heavier than uranium” Ian U. Roederer, Nicole Vassh, Erika M. Holmbeck, Matthew R. Mumpower, Rebecca Surman, John J. Cowan, Timothy C. Beers, Rana Ezzeddine, Anna Froebel, Therese T. Hansen, Vinicius M. Placko, Charlie M. Sakari, December 7, 2023. science.
DOI: 10.1126/science.adf1341

The research was published in the journal Science and was supported in part by the National Science Foundation and the National Aeronautics and Space Administration.

Source: scitechdaily.com

Uncovering the Astonishing Facts about Ancient Bead-Like Fossils

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Paleontologists have determined that a mysterious fruit first discovered in the 1970s is the oldest known frankincense fossil. Scale bar = 2 mm.
Credit: Stephen Manchester

Mysterious fossils discovered in India in the 1970s have been identified as part of the Frankincense family, suggesting a Southern Hemisphere origin and reshaping our understanding of plant evolution. In the early 1970s, paleontologists working on the outskirts of an Indian village discovered tiny bead-like fossils embedded in the gray chert that dotted the surrounding fields. The site was notorious for the discovery of hard-to-identify plant fossils, including the fruits of extinct creatures. The fossils have been named “Enigmocarpon”.

The new fossils proved to be similarly frustratingly unwieldy. More plants were discovered in India in subsequent decades, but scientists were unable to determine which type of plant they belonged to.

A breakthrough in fossil identification: Now, researchers say they have solved the mystery. Stephen Manchester, curator of paleobotany at the Florida Museum of Natural History, used CT scanning technology to create his 3D reconstructions of the original fossil specimens and other specimens collected since then. He showed this to his colleagues and noticed something strange about his five triangular seeds inside.

Before the widespread use of CT scans in paleontology, these small fossils, less than 10 mm in diameter, were particularly difficult to study and identify. “When I showed him the 3-D images, he said, ‘Those aren’t seeds. They’re pyrenes,'” Manchester said with Walter Judd, curator of botany at the Florida Museum. I remembered the conversation. Pyrene is a woody dispersal pod that provides an additional layer of protection to the seeds. Distinguishing between seeds and pyrenes requires close scrutiny, especially when they are the size of a snowflake.

“If we had a specimen that broke in just the right plane, we would have been able to identify it, but we couldn’t identify it with the material we had,” Manchester said. Although they may look like seeds, these woody structures are actually pyrenes, similar to the stones found in peaches and date palms.

Frankincense family connection: Only a few plant groups produce pyrene, and even fewer have fruits containing five seeds arranged in a pentagram. Through a process of elimination, Manchester and Judd determined that the fossils belonged to the frankincense family, an extinct member of the Kansas family. Fossilized trees, leaves, fruits, and flowers of this family have been found elsewhere in India, often sandwiched between thick basalt slabs created by the largest volcanic eruptions in Earth’s history.

Geological background and importance: At that time, India was an island off the southeast coast of Africa. India’s continental plate slowly moved toward Europe and Asia, breaking the seal of a thin layer of Earth’s crust as it passed through Madagascar. The fossils were preserved during a quiet period between eruptions, which makes it the oldest fossil of the Kansidae family ever discovered, and has important implications for the origin of the family. Scientists have a good idea of ​​when this group of plants first evolved, but it’s still unclear where they came from.

Source: scitechdaily.com

Ancient migration revealed in Balkan genome

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An international research team has unraveled the complex genomic history of the Balkans since Roman times, revealing a mix of Anatolian and Slavic influences. The study combines ancient DNA analysis with historical and archaeological data to show how migration and Roman imperial policies have shaped the genetic makeup of the modern-day Balkan population.

Credit: SciTechDaily.com

Interdisciplinary research reveals the genomic history of the Balkans, highlighting the significant impact of Anatolian and Slavic migrations during and after the Roman Empire. This study highlights a shared demographic history across the Balkans.

An interdisciplinary study led by Spain’s Institute of Evolutionary Biology (a joint center between Spain’s National Research Council and Pompeu Fabra University), the University of Belgrade in Serbia, the University of Western Ontario in Canada, and Harvard University in the United States. We reconstruct the genomic history of the Balkans during the first millennium of the Common Era, a time and place of major demographic, cultural, and linguistic changes.

The research team recovered and analyzed whole-genome data from 146 ancient humans excavated primarily in Serbia and Croatia. More than a third of these came from the Roman border area at the huge ruins of Viminacium in Serbia. The data were jointly analyzed. the rest of the Balkans and neighboring areas.

Works published in magazines cellhighlights the cosmopolitanism of the Roman frontier and the long-term effects of migration that accompanied the collapse of Roman rule, including the arrival of Slavic-speaking peoples.archaeological DNA It has become clear that, despite being divided by nation-state boundaries, the populations of the Balkans have been shaped by common demographic processes.

Reconstruction of the amphitheater at the ruins of Viminacium. Credit: Boris Hammer

During the Roman Empire, there was a large influx of people from the east into the Balkans, much of it from the Eastern Mediterranean and even from East Africa.

After Rome occupied the Balkans, this border area became a crossroads that would eventually lead to 26 Roman emperors. Among them was Constantine the Great, who founded the city of Constantinople and moved the capital of his empire to the eastern Balkans.

The researchers’ analysis of ancient DNA shows that people of Anatolian descent made a significant demographic contribution during Roman rule, leaving a long-term genetic imprint on the Balkans. This ancestral migration is very similar to what happened in the megacity of Rome itself, the original core of the empire, in previous studies, but it is noteworthy that this also happened on the periphery of the Roman Empire. .

and so on…

Source: scitechdaily.com

Archaeologists in Mongolia uncover ancient wooden saddle dating back 1,600 years

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New archaeological discoveries in Mongolia show that, despite a fragmentary archaeological record, horse cultures in the eastern Eurasian steppes early adopted framed saddles and stirrups, at least by the turn of the 5th century AD. It shows. His 1,600-year-old saddle, discovered at Urd Ulan Unito, is one of the earliest known examples of a wooden-framed saddle, indicating that it was locally produced and a link to earlier saddle traditions. Both show evidence of a connection. The recent discovery of Khufu Nur suggests that stirrups were also used in the Mongolian steppes at the same time as they first appeared elsewhere in East Asia.

Birch composite frame saddle (top left) from Urud-Ulan-Unit, Mongolia and artist’s restoration. Image credit: P. Lopez Calle.

Horseback riding appears to have been little attempted as a regular mode of transportation until the late 2nd millennium BC or early 1st millennium BC, although some archaeological data suggests that horses were used in Eastern Europe by the early 2nd millennium BC. This suggests that it could have been ridden. Grassland.

Early iconography, written sources, and archaeological finds indicate that in regions of western Eurasia, these first horsemen used simple blankets or soft pads with their legs suspended and separating rider and horse. Basically, I often rode naked.

The Greek writer and soldier Xenophon, writing in the 4th century BC, outlined best practices for cavalry riding, including riding naked, holding the horse only by the upper thighs, letting the lower legs dangle, and holding the mane. I explained the Greek tradition. More security.

Despite their near-ubiquitous use among modern horsemen, neither stirrups nor true saddles appear to have been used by early equestrians.

The earliest direct evidence of mounted horses in the equid family is from mounted cavalrymen in Mesopotamia and the Levant who interbred with donkeys in the third millennium BC.

By the middle of the first millennium BC, at the same time as cavalry was emerging across Eurasia, soft-padded saddles made of leather and stuffed with fur, textiles, and other materials and secured to the horse with a girth strap were being adopted in the Eurasian interior. I did.

These early saddles were sometimes reinforced with wooden or horn supports, and sometimes secured to the horse’s chest or hindquarters with chest straps or clappers.

Throughout Eurasia, by the beginning of the first century AD, simple saddles were adopted for greater safety.

In western Eurasia, Roman military saddles incorporated four large “horns” and grips to increase stability for mounted soldiers. It may also contain hard internal components, but this is debated.

Early semi-structured saddles probably provided greater comfort and safety for rider and horse, and allowed mounted and armored soldiers to handle blunt weapons and swords more directly.

These innovations in saddle stability allowed riders to withstand collisions and ride more heavily armed, allowing heavy cavalry to replace chariots on the battlefield throughout Eurasia by the end of the first millennium BC. It was helpful.

In East Asia, parallel developments were underway towards structured saddles.

Excavations of the tombs of the Xiongnu (c. 200 BC – c. 100 AD), the first steppe empire of Mongolia, have shown that padded saddles are usually supplied with a croupier and/or chest strap to secure the saddle in place. revealed that it had a hard pommel/cantle. Components were also commonly used.

By the 6th century, in East and Central Asia, primitive saddles had been replaced by sophisticated composite frame saddles combined with two metal ribs.

“Ultimately, the technologies that emerged from Mongolia had a domino effect that shaped today’s American horse culture, particularly the tradition of harnesses and stirrups,” said William Taylor, an archaeologist at the University of Colorado Boulder. said.

“But these insights come at a time when Mongolia’s horse culture is beginning to disappear,” added Dr. Jamsranjab Bayarsaikhan, an archaeologist at the Max Planck Institute for the Science of Human History.

“Horses not only influenced the history of the region, but also left a deep mark on the art and worldview of the nomadic Mongolians.”

“However, the age of technology is slowly erasing the culture and use of horses. In the plains of Mongolia, horse-riding pastoralists are increasingly being replaced by motorcyclists.”

In April 2015, Dr. Bayarsaikhan and his colleagues at the National Museum of Mongolia received a report from the police that the Urd Ulan Unit cave burial site in Myangad Sum, Khovd province, had been destroyed by looters.

Police seized some organic material that was well preserved in the cave’s dry environment.

An intact wooden saddle was also recovered from Urd Ulan Unito Cave.

The saddle was made of about six birch pieces held together with wooden nails.

The black trim has red paint marks and contains two leather straps that may have once supported the stirrups.

Archaeologists have not been able to definitively trace where those materials came from. However, birch trees commonly grow in the Altai Mountains of Mongolia, suggesting that local people were not trading saddles, but were making them themselves.

“Since the early days of horseback riding, humans have used pads, the precursor to saddles, to keep horses comfortable after riding,” Dr. Taylor said.

“The combination of a sturdier wooden saddle and stirrup opens up new ranges of what people can do with their horses.”

“One of the things they created was heavy cavalry and fierce fighting on horseback. Think of the jousting of medieval Europe.”

“In the centuries after the Mongol saddle was made, this type of tool quickly spread throughout western Asia and into the early Islamic world.”

“There cavalry was the key to conquering and trading with the Mediterranean region and much of North Africa.”

“But where it all started is less clear. Archaeologists usually think that the birthplace of the first frame saddles and stirrups is modern-day China, and some finds date back to the 5th century AD. It dates back to the 6th century or earlier.

“But our research complicates that picture. It is possible that Mongolia may have been the first to adopt these new technologies, or may actually be the place where the innovations first took place.” This is not the only information that suggests this.”

“Mongolia’s place in its history may have been underestimated for a long time because of the region’s geography.”

“The country’s mountainous regions have some of the lowest population densities on earth, making it difficult to encounter and analyze important archaeological finds.”

“Mongolia is one of the few countries that has preserved horse culture from ancient times to modern times,” said Dr. Bayarsaikhan.

“However, scientific understanding of the origins of this culture is still incomplete.”

team’s findings Published in this month’s magazine ancient.

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Jamsranjaf Bayarsaikhan other. Origins of saddles and horse riding techniques in East Asia: Discoveries from Altai, Mongolia. ancient, published online on December 12, 2023. doi: 10.15184/aqy.2023.172

Source: www.sci.news

Ancient Mayan water systems: A solution to today’s water crisis

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Water lily symbol Mayan vessel

Mayan ships in Guatemala (c. 700-800 AD). It depicts a king wearing a water lily headdress sitting on a throne. Water lilies (Nymphaea ampla) on the surface of the reservoir indicated clean water and symbolized classical Mayan kingship (ca. 250-900 CE).Credit: Provided by the Museum of Fine Arts, Boston

Ancient Mayan reservoirs, which used aquatic plants to filter and purify water, “serve as prototypes for natural, sustainable water systems to address future water demands,” according to a new paper. There is a possibility.”

Lisa Lucero, an anthropology professor at the University of Illinois at Urbana-Champaign, writes from one perspective that the Maya built and maintained reservoirs that they used for more than 1,000 years. Proceedings of the National Academy of Sciences. These reservoirs provided drinking water for thousands to tens of thousands of people in the city during the five-month dry season and prolonged drought each year.

“Many of the major cities in the southern Maya lowlands arose in areas that had excellent agricultural soils but no surface water,” Lucero said. “They compensated by building reservoir systems that started small and increased in size and complexity.”

Innovative water filtration technology

Over time, the Maya built canals, dams, locks, and dog runs to channel, store, and transport water. They used silica sand to filter water, sometimes importing it from far away to large cities like Tikal in what is now northern Guatemala. Sediment cores from one of Tikal’s reservoirs also revealed that zeolite sand was used in its construction. Previous studies have shown that this volcanic sand can filter impurities and disease-causing microorganisms from water. The zeolite is also believed to have been imported from some 30 kilometers away.

“Tikal’s reservoir can store more than 900,000 cubic meters of water,” Lucero wrote. Estimates suggest that up to 80,000 people lived in and around the city during the Late Classic period, approximately 600 to 800 AD. The reservoir kept people and crops hydrated during the dry season, Lucero said.

LIDAR map of Tikal highlighting several reservoirs. Credit: (Image adapted from his Tankersley et al. 2020). LiDAR-derived hillshade image created by Francisco Estrada-Belli of the PAQUNAM LiDAR Initiative. Used with permission. Graphics modified by Bryan Lin.

Mayan royalty derived much of their status from their ability to provide water to their people.

“Clean water and political power were closely linked, as shown by the fact that the largest reservoirs were built near palaces and temples,” Lucero wrote. Kings also performed rituals to gain favor with their ancestors and the rain god Chak.

Aquatic plants of Maya reservoir

A key challenge was to prevent water in reservoirs from becoming stagnant and undrinkable, and for this the Maya likely relied on aquatic plants, many of which still live in the wetlands of Central America. Lucero said. These include cattails, sedges, and reeds. Some of these plants have been identified in sediment cores from Mayan reservoirs.

These plants filtered the water, reducing turbidity and absorbing nitrogen and phosphorus, Lucero said.

“The Maya would have had to dredge every few years… (and) harvest and replenish aquatic plants,” she writes. The nutrient-rich soil and plants extracted from the reservoir could be used to fertilize urban fields and gardens.

Symbolism and practicality of water lilies

The most iconic aquatic plant associated with the ancient Maya is the water lily. water lily ampuraThey only breed in clean water, Lucero said. Its pollen has been found in sediment cores of several Mayan reservoirs. The water lily symbolized “classic Mayan kingship,” Lucero wrote.

“The kings also wore headdresses decorated with flowers, and they are depicted with water lilies in Mayan art,” Lucero said.

“Water lilies are intolerant of acidic conditions, excess calcium, such as limestone, and high concentrations of certain minerals, such as iron and manganese,” she writes.

The Maya built and maintained self-purifying wetland reservoirs that served urban populations for thousands of years. University of Illinois anthropology professor Lisa Lucero writes that the water-related crises they faced hold lessons for today.Credit: Fred Zwicky

To keep the lily pads alive, water managers would have had to line the reservoir with clay, Lucero said. Plant roots require a layer of sediment. Next, water lilies, trees, and shrubs planted near the reservoir covered the water surface, cooling the water and suppressing algae growth.

“The Maya generally did not build their homes near the edges of reservoirs, so pollution seeping through karst terrain would not have been a problem,” Lucero wrote.

Lessons from Mayan Reservoirs for the Modern Age

Lucero said evidence collected from several southern lowland cities shows that Mayan reservoirs were built as wetlands to provide drinking water to people for more than 1,000 years, and that the region was built between 800 and 900 AD. He said the results showed that it only stopped working during the most severe droughts. She points out that current climate trends will require many of the same approaches taken by the Maya, such as the use of aquatic plants to naturally improve and maintain water quality.

“Constructed wetlands have many advantages over traditional wastewater treatment systems,” she writes. “We offer processing techniques that are economical, low technology, low cost and highly energy efficient.”

Constructed wetlands not only provide clean water, but can also be a source of nutrients to feed aquatic animals and replenish agricultural soils, she wrote. “The next step moving forward is to combine our respective expertise and put into practice the lessons embodied in ancient Mayan reservoirs, combined with what is now known about constructed wetlands.” she wrote.

References: “Ancient Maya Reservoirs, Constructed Wetlands, and Future Water Needs” by Lisa J. Lucero, October 9, 2023. Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2306870120

Source: scitechdaily.com

New findings on ancient climate analysis suggest that CO2 is contributing to more warming than previously believed

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A diagram of Earth 65 million years ago, when CO2 levels were much higher than today.

Chris Butler/Science Photo Library

Perhaps the most difficult question in climate science. That is, how much global warming does carbon dioxide cause? A new analysis of 66 million years of Earth’s climate history suggests that the Earth is far more sensitive to greenhouse gases than current climate models predict, which could lead to even warmer temperatures in the long term. This means that there is a possibility of further development.

A key factor determining the impact of our emissions on the planet is how much the planet warms in response to the extra CO2 we pump into the atmosphere. This sensitivity is affected by various feedback loops related to clouds, melting ice sheets, and other influences.

One way to measure this sensitivity is to look at how the climate has changed in the past. Gases trapped in ice cores can only take us back about 800,000 years, so to go even further back in time to look at temperatures and CO2 levels in the atmosphere, researchers used proxies. Masu. For example, the density of pores in plant leaves and the isotope levels in the fossil shells of marine organisms change in response to CO2 levels.

However, discrepancies between different proxies have led to an uncertain view of Earth’s ancient climate. Now, an extensive review by a team of over 80 researchers provides a clearer picture. More accurate representation of ancient CO2 levels. “We now have a much clearer picture of what carbon dioxide levels have been in the past,” he says. Berber Henisch He coordinated the project at Columbia University in New York.

This allows us to understand current CO2 levels in the atmosphere alongside the deep past. This indicates that the last time CO2 levels were as consistently high as they are now was about 14 million years ago, and much earlier than that. previous estimate.

By comparing this new CO2 data with temperature records, “we can learn how sensitive the climate has been to changes in carbon dioxide,” Hoenisch says. Current climate models estimate that doubling his CO2 levels in the atmosphere would result in a warming of 1.5°C to 4.5°C. However, the results suggest that the temperature increase is even larger, between 5°C and 8°C.

However, there is a big caveat. This new insight into the history of Earth’s deep climate covers trends over hundreds of thousands of years, rather than the short timescales of decades or centuries that are relevant to humanity today, and therefore It doesn’t tell you what the temperature is likely to be. “It’s a slow cascading effect that slowly kicks in,” Hoenisch says.

The vast time scales covered in this study also mean that details of climate sensitivity cannot be detected. michael man Researchers at the University of Pennsylvania say climate sensitivities may have been different at other times in Earth’s history compared to today, which is likely why the study yielded higher estimates than those based on more recent periods. I think this explains why I got there.

“The bottom line is that the climate sensitivity estimates from this study probably don’t apply to current anthropogenic warming,” Mann says. “Nonetheless, this study confirms a very close relationship between CO2 and global temperatures, highlighting the continuing threat of fossil fuel combustion.”

topic:

Source: www.newscientist.com