Red-supergiant supernova: Secrets of an earlier Universe

An international research team led by the University of Minnesota Twin Cities has measured the size of a star dating back 2 billion years after the Big Bang, or more than 11 billion years ago. Detailed images show the exploding star cooling and could help scientists learn more about the stars and galaxies present in the early Universe.

The paper is published in Nature, the world's leading peer-reviewed, multidisciplinary science journal.

"This is the first detailed look at a supernova at a much earlier epoch of the Universe's evolution," said Patrick Kelly, a lead author of the paper and an associate professor in the University of Minnesota School of Physics and Astronomy. "It's very exciting because we can learn in detail about an individual star when the Universe was less than a fifth of its current age, and begin to understand if the stars that existed many billions of years ago are different from the ones nearby."

The red supergiant in question was about 500 times larger than the sun, and it's located at redshift three, which is about 60 times farther away than any other supernova observed in this detail.

Using data from the Hubble Space Telescope with follow-up spectroscopy using the University of Minnesota's access to the Large Binocular Telescope, the researchers were able to identify multiple detailed images of the red supergiant because of a phenomenon called gravitational lensing, where mass, such as that in a galaxy, bends light. This magnifies the light emitted from the star.

"The gravitational lens acts as a natural magnifying glass and multiplies Hubble's power by a factor of eight," Kelly said. "Here, we see three images. Even though they can be seen at the same time, they show the supernova as it was at different ages separated by several days. We see the supernova rapidly cooling, which allows us to basically reconstruct what happened and study how the supernova cooled in its first few days with just one set of images. It enables us to see a rerun of a supernova."

The researchers combined this discovery with another one of Kelly's supernova discoveries from 2014 to estimate how many stars were exploding when the Universe was a small fraction of its current age. They found that there were likely many more supernovae than previously thought.

"Core-collapse supernovae mark the deaths of massive, short-lived stars. The number of core-collapse supernovae we detect can be used to understand how many massive stars were formed in galaxies when the Universe was much younger," said Wenlei Chen, first author of the paper and a postdoctoral researcher in the University of Minnesota School of Physics and Astronomy.

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Rats bop to the beat

Accurately moving to a musical beat was thought to be a skill innately unique to humans. However, new research now shows that rats also have this ability. The optimal tempo for nodding along was found to depend on the time constant in the brain (the speed at which our brains can respond to something), which is similar across all species. This means that the ability of our auditory and motor systems to interact and move to music may be more widespread among species than previously thought. This new discovery offers not only further insight into the animal mind, but also into the origins of our own music and dance.

Can you move to the beat, or do you have two left feet? Apparently, how well we can time our movement to music depends somewhat on our innate genetic ability, and this skill was previously thought to be a uniquely human trait. While animals also react to hearing noise, or might make rhythmic sounds, or be trained to respond to music, this isn't the same as the complex neural and motor processes that work together to enable us to naturally recognize the beat in a song, respond to it or even predict it. This is referred to as beat synchronicity.

Only relatively recently, research studies (and home videos) have shown that some animals seem to share our urge to move to the groove. A new paper by a team at the University of Tokyo provides evidence that rats are one of them. "Rats displayed innate -- that is, without any training or prior exposure to music -- beat synchronization most distinctly within 120-140 bpm (beats per minute), to which humans also exhibit the clearest beat synchronization," explained Associate Professor Hirokazu Takahashi from the Graduate School of Information Science and Technology. "The auditory cortex, the region of our brain that processes sound, was also tuned to 120-140 bpm, which we were able to explain using our mathematical model of brain adaptation."

But why play music to rats in the first place? "Music exerts a strong appeal to the brain and has profound effects on emotion and cognition. To utilize music effectively, we need to reveal the neural mechanism underlying this empirical fact," said Takahashi. "I am also a specialist of electrophysiology, which is concerned with electrical activity in the brain, and have been studying the auditory cortex of rats for many years."

The team had two alternate hypotheses: The first was that the optimal music tempo for beat synchronicity would be determined by the time constant of the body. This is different between species and much faster for small animals compared to humans (think of how quickly a rat can scuttle). The second was that the optimal tempo would instead be determined by the time constant of the brain, which is surprisingly similar across species. "After conducting our research with 20 human participants and 10 rats, our results suggest that the optimal tempo for beat synchronization depends on the time constant in the brain," said Takahashi. "This demonstrates that the animal brain can be useful in elucidating the perceptual mechanisms of music."

The rats were fitted with wireless, miniature accelerometers, which could measure the slightest head movements. Human participants also wore accelerometers on headphones. They were then played one-minute excerpts from Mozart's Sonata for Two Pianos in D Major, K. 448, at four different tempos: Seventy-five percent, 100%, 200% and 400% of the original speed. The original tempo is 132 bpm and results showed that the rats' beat synchronicity was clearest within the 120-140 bpm range. The team also found that both rats and humans jerked their heads to the beat in a similar rhythm, and that the level of head jerking decreased the more that the music was sped up.

"To the best of our knowledge, this is the first report on innate beat synchronization in animals that was not achieved through training or musical exposure," said Takahashi. "We also hypothesized that short-term adaptation in the brain was involved in beat tuning in the auditory cortex. We were able to explain this by fitting our neural activity data to a mathematical model of the adaptation. Furthermore, our adaptation model showed that in response to random click sequences, the highest beat prediction performance occurred when the mean interstimulus interval (the time between the end of one stimulus and the start of another) was around 200 milliseconds (one-thousandth of a second). This matched the statistics of internote intervals in classical music, suggesting that the adaptation property in the brain underlies the perception and creation of music."

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A supernova in distant space allows us to understand the origin of the elements in the universe

A supernova is a stellar explosion, which occurs when the lives of some really massive stars come to an end. In this violent epilogue, the star expels the material from its outer layers by means of a shock wave, allowing us to see the various elements it was composed of.

The research team developed a model of the gravitational field of the galaxy that acted as a lens, and that way it was possible to determine that the light from these three images travelled along three different paths, differing in distance by a few days. This accounts for the three colours obtained in the images, because a variation in the colour emitted takes place as the gas in the supernova expands and cools. The higher the temperature is, the bluer the light emitted will be, and as the temperature falls, the light emitted tends towards red. So the blue image is a photograph of the supernova a few hours after the stellar explosion, while the green and red images correspond to 2 and 8 days, respectively, after the explosion.

This information enabled the radius of the star that exploded to be determined; it was a red super-giant with a radius equal to 500 times that of the Sun, and exploded 11.5 billion years ago, long before the Earth was born, specifically at the moment when our Galaxy is thought to have formed. The images of this supernova captured by the Hubble Space Telescope are highly magnified by the gravitational field of a nearby galaxy that acts as a lens and allows us to see much further in distance and in time than all local supernovae in nearby galaxies.

The study of the explosions of these red super-giant stars tallies with the current understanding of how the heavier atomic elements were created inside stars and during supernova explosions: elements forged inside stars are released in these supernova explosions to become the next generation of gas and material from which solar systems and life as we know it are created. Without these explosions, the gas in today's galaxies would only include the hydrogen and helium that formed during the Big Bang and would not support complex life that requires other heavier chemical elements. Moreover, this supernova observed through a gravitational lens demonstrates that an event taking place in the distant Universe can be witnessed several times, so in principle we could focus our instruments in advance to get a detailed view of the eruption of a star turning into a supernova.

From Science Daily

Thirsty wheat needed new water management strategy in ancient China

Research from Washington University in St. Louis shows that a practice of purposeful water management, or irrigation, was adopted in northern China about 4,000 years ago as part of an effort to grow new grains that had been introduced from southwest Asia.

But the story gets more complex from there. Wheat and barley arrived on the scene at about the same time, but early farmers only used water management techniques for wheat. The results, reported Nov. 9 in the journal Antiquity, raise awareness that the dispersal of domesticated crops and the knowledge of best using them can be traced independently across time and space.

"Pioneering farmers who cultivated wheat in this region managed water to meet the higher demand of this newly introduced grain," said Xinyi Liu, an associate professor of archaeology in Arts & Sciences, who collaborated on this study with researchers from several prominent institutions in China and Australia, including Guanghui Dong from Lanzhou University, who led the field expedition on the Loess Plateau. "The water management may have been achieved either by deliberate watering or by strategic planting in soils with higher water retention."

On the other hand, early farmers were able to grow the other new grain, barley, in a rainfed system as if it were just another kind of millet -- the locally domesticated and most commonly grown grain in northern China at the time -- without using any form of irrigation.

Liu published the study with Washington University graduate student Yufeng Sun. Other co-authors include Haiming Li and Petra Vaiglova, former members of Liu's lab group.

Introducing irrigation

Both wheat and barley were domesticated in an area known to archaeologists as the hilly flanks of the Fertile Crescent in southwest Asia, where they originally were grown as winter crops. Traditionally, farmers there sowed their seeds in autumn -- to avoid the summer drought period -- and harvested them in late spring or early summer before the next drought season.

When these Fertile Crescent crops, wheat and barley, were introduced to East Asia about 4,000 years ago, they would have encountered a markedly different climate compared with where they originated.

"Every summer, the East Asian monsoon brings rains from the Pacific Ocean to a region otherwise arid throughout the rest of the year. This environment is perfect for rainfed millet cultivation as these local grains are drought tolerant but need considerable water in the summer growing season," Liu said. "But it is a different story if you try to grow wheat there, not only because it is water demanding, but also the growing cycle doesn't match the rainy season."

Liu and his colleagues wanted to know: Did the farmers who sought to grow the new grains in northern China also introduce new systems of irrigation to support them?

"The introduction of a new irrigation system is something that scholars have speculated about, but now we have the technology to seek direct evidence," Liu said.

Using relatively new techniques, the actual growing conditions of past crops -- including past water and soil conditions during plant growth -- can be measured using the stable carbon and nitrogen isotope compositions of charred plant remains. These methods initially were established in plant science for research concerning environmental conditions of modern-day agriculture and have been subsequently applied to archaeological research.

Previous studies using similar approaches have shed significant light on early crop management in Europe and the Middle East. This research is one of the first attempts to apply it to East Asian monsoon environments with innovative questions.

For this study, the scientists identified more than 35,000 charred seed remains of cereal plants, including wheat, barley and millet, from more than 50 archaeological sites excavated on the Loess Plateau of China spanning a timeframe over eight millennia. Selected plant remains from this collection were radiocarbon dated and isotopically measured.

The results showed major differences between wheat and barley.

Despite the arid local environment, the majority of the wheat samples from all time periods had isotopic values above an optimal watering threshold, indicating that their growth was not limited by water availability.

"We see this in the Qijia culture period, when wheat and barley were just introduced to this region," Liu said. "The isotopic data of wheat show a significant level of water manipulation unambiguously since 4,000 years ago, indicating the new crop was introduced with water management strategies to support it."

Simple ditches can be powerful

This evidence alone does not necessarily imply large-scale irrigation, Liu is quick to point out; instead, wheat crops may have been strategically sown in areas with the best water availability, either close to local springs or in soils with high water retention.

"In those locations, small ditches to diffuse water is sufficient," Liu said. "This explains why there is no archaeological evidence of channels or other irrigation installations in the area until much later."

Barley, on the other hand, appears to have been grown on the dry hills of the Loess Plateau without a special water management approach -- a landscape and cultivation strategy that had been familiar to the Neolithic millet farmers since 8,000 years ago.

This and other evidence suggest to Liu and his collaborators that ancient farmers sought to optimize land use and crop yield by taking advantage of the different water demands of these two crops.

"Our results raise an awareness that the dispersal of domesticated crops and the knowledge of best using them can be traced independently across time and space," Liu said.

"Central to our inquiry is the tension between non-native crops and indigenous farming practices," he said. "When non-native innovations were adopted in another cultural and physical environment, they would have been transformed within the local context. How this happens is an enduring question that is relevant to globalization in the past and present."

This study resonates with other archaeological investigations led by Liu's research group, the Laboratory for the Analysis of Early Food-Webs at Washington University. For example, co-author Sun's previous work with Washington University graduate student Melissa Ritchey demonstrated a similar geographic decoupling of the dispersal of grains and cuisines, such that wheat and barley dispersed into ancient China 4,000 years ago, but the western grinding-and-baking cuisines did not. The eastern movement of these grains involved selections of phenotypic traits adapted to ancient China's cooking tradition of using steaming-and-boiling.

It has been a long time since some scholars assumed the association between the origin of bureaucracy and irrigation, and ancient China had been used as an example of "oriental despotism," according to Liu. The "hydraulic empire" hypothesis speculated that a centralized government structure that maintained power would have been derived from the need for flood control and irrigation.

Read more at Science Daily

No sign of decrease in global CO2 emissions

Global carbon emissions in 2022 remain at record levels -- with no sign of the decrease that is urgently needed to limit warming to 1.5°C, according to the Global Carbon Project science team.

If current emissions levels persist, there is now a 50% chance that global warming of 1.5°C will be exceeded in nine years.

The new report projects total global CO2 emissions of 40.6 billion tonnes (GtCO2) in 2022. This is fuelled by fossil CO2 emissions which are projected to rise 1.0% compared to 2021, reaching 36.6 GtCO2 -- slightly above the 2019 pre-COVID-19 levels[1]. Emissions from land-use change (such as deforestation) are projected to be 3.9 GtCO2 in 2022.

Projected emissions from coal and oil are above their 2021 levels, with oil being the largest contributor to total emissions growth. The growth in oil emissions can be largely explained by the delayed rebound of international aviation following COVID-19 pandemic restrictions.

The 2022 picture among major emitters is mixed: emissions are projected to fall in China (0.9%) and the EU (0.8%), and increase in the USA (1.5%) and India (6%), with a 1.7% rise in the rest of the world combined.

The remaining carbon budget for a 50% likelihood to limit global warming to 1.5°C has reduced to 380 GtCO2 (exceeded after nine years if emissions remain at 2022 levels) and 1230 GtCO2 to limit to 2°C (30 years at 2022 emissions levels).

To reach zero CO2 emissions by 2050 would now require a decrease of about 1.4 GtCO2 each year, comparable to the observed fall in 2020 emissions resulting from COVID-19 lockdowns, highlighting the scale of the action required.

Land and ocean, which absorb and store carbon, continue to take up around half of the CO2 emissions. The ocean and land CO2 sinks are still increasing in response to the atmospheric CO2 increase, although climate change reduced this growth by an estimated 4% (ocean sink) and 17% (land sink) over the 2012-2021 decade.

This year's carbon budget shows that the long-term rate of increasing fossil emissions has slowed. The average rise peaked at +3% per year during the 2000s, while growth in the last decade has been about +0.5% per year.

The research team -- including the University of Exeter, the University of East Anglia (UEA), CICERO and Ludwig-Maximilian-University Munich -- welcomed this slow-down, but said it was "far from the emissions decrease we need."

The findings come as world leaders meet at COP27 in Egypt to discuss the climate crisis.

"This year we see yet another rise in global fossil CO2 emissions, when we need a rapid decline," said Professor Pierre Friedlingstein, of Exeter's Global Systems Institute, who led the study.

"There are some positive signs, but leaders meeting at COP27 will have to take meaningful action if we are to have any chance of limiting global warming close to 1.5°C. The Global Carbon Budget numbers monitor the progress on climate action and right now we are not seeing the action required."

Professor Corinne Le Quéré, Royal Society Research Professor at UEA's School of Environmental Sciences, said: "Our findings reveal turbulence in emissions patterns this year resulting from the pandemic and global energy crises.

"If governments respond by turbo charging clean energy investments and planting, not cutting, trees, global emissions could rapidly start to fall.

"We are at a turning point and must not allow world events to distract us from the urgent and sustained need to cut our emissions to stabilise the global climate and reduce cascading risks."

Land-use changes, especially deforestation, are a significant source of CO2 emissions (about a tenth of the amount from fossil emissions). Indonesia, Brazil and the Democratic Republic of the Congo contribute 58% of global land-use change emissions.

Carbon removal via reforestation or new forests counterbalances half of the deforestation emissions, and the researchers say that stopping deforestation and increasing efforts to restore and expand forests constitutes a large opportunity to reduce emissions and increase removals in forests.

The Global Carbon Budget report projects that atmospheric CO2 concentrations will reach an average of 417.2 parts per million in 2022, more than 50% above pre-industrial levels.

The projection of 40.6 GtCO2 total emissions in 2022 is close to the 40.9 GtCO2 in 2019, which is the highest annual total ever.

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Previously unknown monumental temple discovered near the Tempio Grande in Vulci

An interdisciplinary team headed by archeologists Dr. Mariachiara Franceschini of the University of Freiburg and Paul P. Pasieka of the University of Mainz has discovered a previously unknown Etruscan temple in the ancient city of Vulci, which lies in the Italian region of Latium. The building, which is 45 meters by 35 meters, is situated west of the Tempio Grande, a sacred building which was excavated back in the 1950s. Initial examination of the strata of the foundation of the northeast corner of the temple and the objects they found there, led the researchers to date the construction of the temple towards the end of the sixth or beginning of the fifth century BCE.

"The new temple is roughly the same size and on a similar alignment as the neighboring Tempio Grande, and was built at roughly the same Archaic time," explains Franceschini. "This duplication of monumental buildings in an Etruscan city is rare, and indicates an exceptional finding," adds Pasieka. The team discovered the temple when working on the Vulci Cityscape project, which was launched in 2020 and aimed to research the settlement strategies and urbanistic structures of the city of Vulci. Vulci was one of the twelve cities of the Etruscan federation and in pre-Roman times was one of the most important urban centers in what is now Italy.

New discoveries about city design and development

"We studied the entire northern area of Vulci, that's 22.5 hectares, using geophysical prospecting and Ground Penetrating Radar," explains Pasieka. "We discovered remains from the city's origins that had previously been overlooked in Vulci and are now better able to understand the dynamics of settlement and the road system, besides identifying different functional areas in the city." The researchers were able in 2021 to uncover the first sections of wall, made of solid tuff. "Our knowledge about the appearance and organization of Etruscan cities has been limited until now," says Franceschini. "The intact strata of the temple are offering us insights into more than a thousand years of development of one of the most important Etruscan cities."

Over the coming years the scientists want to study the different phases of use and the precise architectural appearance of the temple in more depth, in order to learn more about the religion of the Etruscans, the social structures in Vulci and what the lives of the city's inhabitants were really like.

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Death of a star reveals midsize black hole lurking in a dwarf galaxy

An intermediate-mass black hole lurking undetected in a dwarf galaxy revealed itself to astronomers when it gobbled up an unlucky star that strayed too close. The shredding of the star, known as a "tidal disruption event" or TDE, produced a flare of radiation that briefly outshone the combined stellar light of the host dwarf galaxy and could help scientists better understand the relationships between black holes and galaxies.

The flare was captured by astronomers with the Young Supernova Experiment (YSE), a survey designed to detect cosmic explosions and transient astrophysical events. An international team led by scientists at UC Santa Cruz, the Niels Bohr Institute at the University of Copenhagen, and Washington State University reported the discovery in a paper published November 10 in Nature Astronomy.

"This discovery has created widespread excitement because we can use tidal disruption events not only to find more intermediate-mass black holes in quiet dwarf galaxies, but also to measure their masses," said coauthor Ryan Foley, an assistant professor of astronomy and astrophysics at UC Santa Cruz who helped plan the YSE survey.

First author Charlotte Angus at the Niels Bohr Institute said the team's findings provide a baseline for future studies of midsize black holes.

"The fact that we were able to capture this midsize black hole whilst it devoured a star offered us a remarkable opportunity to detect what otherwise would have been hidden from us," Angus said. "What is more, we can use the properties of the flare itself to better understand this elusive group of middle-weight black holes, which could account for the majority of black holes in the centers of galaxies."

Supermassive black holes are found at the centers of all massive galaxies, including our own Milky Way. Astronomers conjecture that these massive beasts, with millions or billions of times the mass of the sun, could have grown from smaller "intermediate-mass" black holes with thousands to hundreds of thousands of solar masses.

One theory for how such massive black holes were assembled is that the early universe was rampant with small dwarf galaxies with intermediate-mass black holes. Over time, these dwarf galaxies would have merged or been gobbled up by more massive galaxies, their cores combining each time to build up the mass in the center of the growing galaxy. This merger process would eventually create the supermassive black holes seen today.

"If we can understand the population of intermediate-mass black holes out there -- how many there are and where they are located -- we can help determine if our theories of supermassive black hole formation are correct," said coauthor Enrico Ramirez-Ruiz, professor of astronomy and astrophysics at UCSC and Niels Bohr Professor at the University of Copenhagen.

But do all dwarf galaxies have midsize black holes?

"That's difficult to assert, because detecting intermediate-mass black holes is extremely challenging," Ramirez-Ruiz said.

Classic black hole hunting techniques, which look for actively feeding black holes, are often not sensitive enough to uncover black holes in the centers of dwarf galaxies. As a result, only a minuscule fraction of dwarf galaxies is known to host intermediate-mass black holes. Finding more midsize black holes with tidal disruption events could help to settle the debate about how supermassive black holes form.

"One of the biggest open questions in astronomy is currently how supermassive black holes form," said coauthor Vivienne Baldassare, professor of physics and astronomy at Washington State University.

Data from the Young Supernova Experiment enabled the team to detect the first signs of light as the black hole began to eat the star. Capturing this initial moment was pivotal to unlocking how big the black hole was, because the duration of these events can be used to measure the mass of the central black hole. This method, which until now had only been shown to work well for supermassive black holes, was first proposed by Ramirez-Ruiz and coauthor Brenna Mockler at UC Santa Cruz.

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Evolution of tree roots may have driven mass extinctions

The evolution of tree roots may have triggered a series of mass extinctions that rocked the Earth's oceans during the Devonian Period over 300 million years ago, according to a study led by scientists at IUPUI, along with colleagues in the United Kingdom.

Evidence for this new view of a remarkably volatile period in Earth's pre-history is reported in the Geological Society of America Bulletin. The study was led by Gabriel Filippelli, Chancellor's Professor of Earth Sciences in the School of Science at IUPUI, and Matthew Smart, a Ph.D. student in his lab at the time of the study.

"Our analysis shows that the evolution of tree roots likely flooded past oceans with excess nutrients, causing massive algae growth," Filippelli said. "These rapid and destructive algae blooms would have depleted most of the oceans' oxygen, triggering catastrophic mass extinction events."

The Devonian Period, which occurred 419 million to 358 million years ago, prior to the evolution of life on land, is known for mass extinction events, during which it's estimated nearly 70 percent of all life on Earth perished.

The process outlined in the study -- known scientifically as eutrophication -- is remarkably similar to modern, albeit smaller-scale, phenomenon currently fueling broad "dead zones" in the Great Lakes and the Gulf of Mexico, as excess nutrients from fertilizers and other agricultural runoff trigger massive algae blooms that consume all of the water's oxygen.

The difference is that these past events were likely fueled by tree roots, which pulled nutrients from the land during times of growth, then abruptly dumped them into the Earth's water during times of decay.

The theory is based upon a combination of new and existing evidence, Filippelli said.

Based upon a chemical analysis of stone deposits from ancient lake beds -- whose remnants persist across the globe, including the samples used in the study from sites in Greenland and off the northeast coast of Scotland -- the researchers were able to confirm previously identified cycles of higher and lower levels of phosphorus, a chemical element found in all life on Earth.

They were also able to identify wet and dry cycles based upon signs of "weathering" -- or soil formation -- caused by root growth, with greater weathering indicating wet cycles with more roots and less weathering indicating dry cycles with fewer roots.

Most significantly, the team found the dry cycles coincided with higher levels of phosphorus, suggesting dying roots released their nutrients into the planet's water during these times.

"It's not easy to peer over 370 million years into the past," said Smart. "But rocks have long memories, and there are still places on Earth where you can use chemistry as a microscope to unlock the mysteries of the ancient world."

In light of the phosphorus cycles occurring at the same time as the evolution of the first tree roots -- a feature of Archaeopteris, also the first plant to grow leaves and reach heights of 30 feet -- the researchers were able to pinpoint the decay of tree roots as the prime suspect behind the Devonian Periods extinction events.

Fortunately, Filippelli said, modern trees don't wreak similar destruction since nature has since evolved systems to balance out the impact of rotting wood. The depth of modern soil also retains more nutrients compared to the thin layer of dirt that covered the ancient Earth.

But the dynamics revealed in the study shed light on other newer threats to life in Earth's oceans. The study's authors note that others have made the argument that pollution from fertilizers, manure and other organic wastes, such as sewage, have placed the Earth's oceans on the "edge of anoxia," or a complete lack of oxygen.

"These new insights into the catastrophic results of natural events in the ancient world may serve as a warning about the consequences of similar conditions arising from human activity today," Fillipelli said.

Read more at Science Daily

The world will probably warm beyond the 1. 5-degree limit, but peak warming can be curbed

The world's current climate pledges are insufficient to keep the goal of the 2015 Paris Agreement firmly within grasp. Global warming will likely surpass the 1.5-degree Celsius limit. We are going to overshoot.

But countries can curb time spent in a warmer world by adopting more ambitious climate pledges and decarbonizing faster, according to new research led by scientists at the Department of Energy's Pacific Northwest National Laboratory, the University of Maryland and the U.S. Environmental Protection Agency. Doing so, they warn, is the only way to minimize the overshoot.

While exceeding the 1.5-degree limit appears inevitable, the researchers chart several potential courses in which the overshoot period is shortened, in some cases by decades. The study published today in the journal Nature Climate Change, during the 2022 United Nations Climate Change Conference, also known as COP27, held in Sharm El Sheikh, Egypt.

"Let's face it. We are going to breach the 1.5 degrees limit in the next couple of decades," said corresponding author and PNNL scientist Haewon McJeon. "That means we'll go up to 1.6 or 1.7 degrees or above, and we'll need to bring it back down to 1.5. But how fast we can bring it down is key."

Every second shaved off the overshoot translates to less time courting the most harmful consequences of global warming, from extreme weather to rising sea levels. Forgoing or delaying more ambitious goals could lead to "irreversible and adverse consequences for human and natural systems," said lead author Gokul Iyer, a scientist alongside McJeon at the Joint Global Change Research Institute, a partnership between PNNL and the University of Maryland.

"Moving fast means hitting net-zero pledges sooner, decarbonizing faster, and striking more ambitious emissions targets," said Iyer. "Every little bit helps, and you need a combination of all of it. But our results show that the most important thing is doing it early. Doing it now, really."

During COP26 in 2021, the same research team found that the then updated pledges could substantially increase the chance of limiting warming to 2 degrees Celsius over pre-industrial levels. In their new paper, the authors take an additional step in answering the question of how to move the needle from 2 to 1.5 degrees.

"The 2021 pledges don't add up to anywhere near 1.5 degrees -- we are forced to focus on the overshoot," said PNNL scientist Yang Ou, who co-led the study. "Here, we're trying to provide scientific support to help answer the question: What type of ratcheting mechanism would get us back down and below 1.5 degrees? That's the motivation behind this paper."

The Paths Forward

The authors model scenarios -- 27 emissions pathways in total, each ranging in ambition -- to explore what degree of warming would likely follow which course of action. At a base level, the authors assume that countries will meet their emissions pledges and long-term strategies on schedule.

In more ambitious scenarios, the authors model how much warming is limited when countries decarbonize faster and advance the dates of their net-zero pledges. Their results underscore the significance of "ratcheting near-term ambition," which entails rapid reductions in carbon dioxide emissions from all sectors of the energy system, immediately and through 2030.

If countries uphold their nationally determined contributions through 2030 and follow a two percent minimum decarbonization rate, for example, global carbon dioxide levels would not reach net zero this century.

Taking the most ambitious path outlined, however, could bring net-zero carbon dioxide emissions by 2057. Such a path, the authors write, is marked by "rapid transformations throughout the global energy system" and the scaling up of "low-carbon technologies like renewables, nuclear energy, as well as carbon capture and storage."

"The technologies that help us get to zero emissions include renewables, hydrogen, electric cars, and so on. Of course those are important players," said Iyer. "Another important piece of the puzzle is the technologies that can remove carbon dioxide from the atmosphere, like direct air capture or nature-based solutions."

The most ambitious scenarios outlined in their work are meant to be illustrative of the pathways on offer. But the central takeaway remains clear throughout all modeled scenarios: if 1.5 degrees is to be reattained sooner after we warm past it, more ambitious climate pledges must come.

Read more at Science Daily

New technology creates carbon neutral chemicals out of thin air

It is possible to capture carbon dioxide (CO2) from the surrounding atmosphere and repurpose it into useful chemicals usually made from fossil fuels, according to a study from the University of Surrey.

The technology could allow scientists to both capture CO2 and transform it into useful chemicals such as carbon monoxide and synthetic natural gas in one circular process.

Dr Melis Duyar, Senior Lecturer of Chemical Engineering at the University of Surrey commented:

"Capturing CO2 from the surrounding air and directly converting it into useful products is exactly what we need to approach carbon neutrality in the chemicals sector. This could very well be a milestone in the steps needed for the UK to reach its 2050 net-zero goals.

"We need to get away from our current thinking on how we produce chemicals, as current practices rely on fossil fuels which are not sustainable. With this technology we can supply chemicals with a much lower carbon footprint and look at replacing fossil fuels with carbon dioxide and renewable hydrogen as the building blocks of other important chemicals."

The technology uses patent-pending switchable Dual Function Materials (DFMs), that capture carbon dioxide on their surface and catalyse the conversion of captured CO2 directly into chemicals. The "switchable" nature of the DFMs comes from their ability to produce multiple chemicals depending on the operating conditions or the composition of the added reactant. This makes the technology responsive to variations in demand for chemicals as well as availability of renewable hydrogen as a reactant.

Dr Duyar continued:

"These outcomes are a testament to the research excellence at Surrey, with continuously improving facilities, internal funding schemes and a collaborative culture."

Loukia-Pantzechroula Merkouri, Postgraduate student leading this research at the University of Surrey added:

"Not only does this research demonstrate a viable solution to the production of carbon neutral fuels and chemicals, but it also offers an innovative approach to combat the ever-increasing CO2 emissions contributing to global warming."

Read more at Science Daily