The continuous development and improvement of numerical models for the investigation of the climate system is very expensive and complex. At GEOMAR a new modular system has now been presented, which allows investigations to be carried in a flexible way, with varying levels of complexity. The system, called FOCI (Flexible Ocean and Climate Infrastructure), consists of different components that can be adapted and used, depending on the research question and available computing power.
In their model simulations, climate researchers always have to make compromises. Even with the largest computers available worldwide, they can only reproduce the real world to a limited extent. Depending on the application, simplifications have to be made in the spatial resolution, but also in the physical processes represented by the model. While model experiments over periods of months to a few years can often still be made with high spatial resolution, integrations over centuries to millennia can only be performed at coarser resolution. In the past, models were developed for a specific purpose. Now, GEOMAR Helmholtz Centre for Ocean Research Kiel presented a flexible model kit, called FOCI (Flexible Ocean and Climate Infrastructure). It is based on the Earth system model of the Max Planck Institute for Meteorology in Hamburg and has been modified with the NEMO ocean model, in order to represent small-scale processes in the oceans at higher resolution.
"In FOCI we combine decades of expertise in ocean and climate modelling at GEOMAR. The new system enables the investigation of new questions such as the influence of the stratospheric ozone hole on the circulation in the Southern Ocean or the impact of the Gulf Stream on atmospheric processes," explains Professor Dr. Katja Matthes from the Maritime Meteorology Research Unit at GEOMAR.
"With the new system, we can investigate many different research questions on ar range of time scales," Professor Dr. Arne Biastoch, head of the Ocean Dynamics Research Unit at GEOMAR, points out. "We initially performed a set of standardised basic tests with the FOCI system," the oceanographer continues. "We had to find out whether the model system is capable of reproducing the observed climate and the present ocean circulation. Only if we are confident that the system can successfully simulate the present conditions within limited error bands it can be used to investigate unknown phenomena or for the predictions of future climate conditions." The results, which have been published in the international journal Geoscience Model Development, are very promising. "In particular, our special know-how in operating the ocean model regionally at very high resolution improves the results considerably and reduces, for example, common model errors such as deviations in sea surface temperatures in the Gulf Stream system," says Professor Biastoch. FOCI also enables configurations which were previously impossible at spatial resolutions of up to one kilometre in the ocean.
Read more at Science Daily
Jun 24, 2020
Orb hidden in distant dust is 'infant' Neptune-size planet
Astronomers study stars and planets much younger than the Sun to learn about past events that shaped the Solar System and Earth. Most of these stars are far enough away to make observations challenging, even with the largest telescopes. But now this is changing.
University of Hawai'i at Manoa astronomers are part of an international team that recently discovered an infant planet around a nearby young star. The discovery was reported Wednesday in the international journal Nature.
The planet is about the size of Neptune, but, unlike Neptune, it is much closer to its star, taking only eight and a half days to complete one orbit. It is named "AU Mic b" after its host star, AU Microscopii, or "AU Mic" for short. The planet was discovered using the NASA TESS planet-finding satellite, as it periodically passed in front of AU Mic, blocking a small fraction of its light. The signal was confirmed by observations with another NASA satellite, the Spitzer Space Telescope, and with the NASA Infrared Telescope Facility (IRTF) on Maunakea. The observations on Hawai'i Island used a new instrument called iSHELL that can make very precise measurements of the motion of a star like AU Mic. These measurements revealed a slight wobble of the star, as it moves in response to the gravitational pull of the planet. It confirmed that AU Mic b was a planet and not a companion star, which would cause a much larger motion.
Discovery on Maunakea sets foundation
AU Mic and its planet are about 25 million years young, and in their infancy, astronomically speaking. AU Mic is also the second closest young star to Earth. It is so young that dust and debris left over from its formation still orbit around it. The debris collides and breaks into smaller dust particles, which orbit the star in a thin disk. This disk was detected in 2003 with the UH 88-inch telescope on Maunakea. The newly-discovered planet orbits within a cleared-out region inside the disk.
"This is an exciting discovery, especially as the planet is in one of the most well-known young star systems, and the second-closest to Earth. In addition to the debris disk, there is always the possibility of additional planets around this star. AU Mic could be the gift that keeps on giving," said Michael Bottom, an Assistant Astronomer at the UH Institute for Astronomy.
"Planets, like people, change as they mature. For planets this means that their orbits can move and the compositions of their atmospheres can change. Some planets form hot and cool down, and unlike people, they would become smaller over time. But we need observations to test these ideas and planets like AU Mic b are an exceptional opportunity," said Astronomer Eric Gaidos, a professor in the Department of Earth Sciences at UH M?noa.
Clues to the origin of Earth-like planets
AU Mic is not only much younger than the Sun, it is considerably smaller, dimmer and redder. It is a "red dwarf," the most numerous type of star in the galaxy. The TESS satellite is also discovering Earth-sized and possibly habitable planets around older red dwarfs, and what astronomers learn from AU Mic and AU Mic b can be applied to understand the history of those planets.
"AU Mic b, and any kindred planets that are discovered in the future, will be intensely studied to understand how planets form and evolve. Fortuitously, this star and its planet are on our cosmic doorstep. We do not have to venture very far to see the show," Gaidos explained. He is a co-author on another five forthcoming scientific publications that have used other telescopes, including several on Maunakea, to learn more about AU Mic and its planet.
Read more at Science Daily
University of Hawai'i at Manoa astronomers are part of an international team that recently discovered an infant planet around a nearby young star. The discovery was reported Wednesday in the international journal Nature.
The planet is about the size of Neptune, but, unlike Neptune, it is much closer to its star, taking only eight and a half days to complete one orbit. It is named "AU Mic b" after its host star, AU Microscopii, or "AU Mic" for short. The planet was discovered using the NASA TESS planet-finding satellite, as it periodically passed in front of AU Mic, blocking a small fraction of its light. The signal was confirmed by observations with another NASA satellite, the Spitzer Space Telescope, and with the NASA Infrared Telescope Facility (IRTF) on Maunakea. The observations on Hawai'i Island used a new instrument called iSHELL that can make very precise measurements of the motion of a star like AU Mic. These measurements revealed a slight wobble of the star, as it moves in response to the gravitational pull of the planet. It confirmed that AU Mic b was a planet and not a companion star, which would cause a much larger motion.
Discovery on Maunakea sets foundation
AU Mic and its planet are about 25 million years young, and in their infancy, astronomically speaking. AU Mic is also the second closest young star to Earth. It is so young that dust and debris left over from its formation still orbit around it. The debris collides and breaks into smaller dust particles, which orbit the star in a thin disk. This disk was detected in 2003 with the UH 88-inch telescope on Maunakea. The newly-discovered planet orbits within a cleared-out region inside the disk.
"This is an exciting discovery, especially as the planet is in one of the most well-known young star systems, and the second-closest to Earth. In addition to the debris disk, there is always the possibility of additional planets around this star. AU Mic could be the gift that keeps on giving," said Michael Bottom, an Assistant Astronomer at the UH Institute for Astronomy.
"Planets, like people, change as they mature. For planets this means that their orbits can move and the compositions of their atmospheres can change. Some planets form hot and cool down, and unlike people, they would become smaller over time. But we need observations to test these ideas and planets like AU Mic b are an exceptional opportunity," said Astronomer Eric Gaidos, a professor in the Department of Earth Sciences at UH M?noa.
Clues to the origin of Earth-like planets
AU Mic is not only much younger than the Sun, it is considerably smaller, dimmer and redder. It is a "red dwarf," the most numerous type of star in the galaxy. The TESS satellite is also discovering Earth-sized and possibly habitable planets around older red dwarfs, and what astronomers learn from AU Mic and AU Mic b can be applied to understand the history of those planets.
"AU Mic b, and any kindred planets that are discovered in the future, will be intensely studied to understand how planets form and evolve. Fortuitously, this star and its planet are on our cosmic doorstep. We do not have to venture very far to see the show," Gaidos explained. He is a co-author on another five forthcoming scientific publications that have used other telescopes, including several on Maunakea, to learn more about AU Mic and its planet.
Read more at Science Daily
X-ray scattering enables closer scrutiny of the interior of planets and stars
Recreating extreme conditions in the lab, like those in the interior of planets and stars, is very complex and can only be achieved for fractions of a second. An international research team led by the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) has now presented a new, very precise method of evaluating the behavior of mixtures of different elements under high pressure with the help of X-ray scattering. The results hone previous measurements and reinforce the premise that the matter in planets like Neptune and Uranus can alter dramatically: the hot hydrocarbon mixture in the interior of the ice giants can produce a kind of diamond rain, as the researchers report in Nature Communications.
Neither solid, nor fluid, neither gaseous, nor a plasma: the matter inside planets and stars can take on a particular intermediate state, at a temperature of thousands of degrees, and compressed a thousand times more than our Earth's atmosphere -- experts call it warm dense matter. There is a lot we still don't know about it. Lab experiments are set to change all that but are technically highly complex because this exotic state does not occur naturally on Earth. Which all means that both the crafting and study of artificial warm dense matter is a challenge for investigators and theoreticians alike. "But in the last resort, we have to understand the processes in warm dense matter if we want to model planets," explains Dr. Dominik Kraus, lead author of the study and the mastermind behind the measuring method. "We now have a very promising new approach based on X-ray scattering. Our experiments are delivering important model parameters where, before, we only had massive uncertainty. This will become ever more relevant the more exoplanets we discover."
Diamond showers -- a planetary energy source
At SLAC National Accelerator Laboratory at Stanford University, the researchers studied the structure of the matter in mixtures that are typical for planets, in the case of ice giants, hydrocarbon, employing intense laser light. Standard plastic film served as a substitute for planetary hydrocarbon. An optical high-energy laser converts the plastic into warm dense matter: short, strong laser pulses generate shock waves in the film and compress the plastic to the extreme. "We produce about 1.5 million bars, that is equivalent to the pressure exerted by the weight of some 250 African elephants on the surface of a thumbnail," says Kraus, illustrating the dimensions. What happens is that the laser shock waves also heat up the matter to approximately 5,000 degrees. To evaluate the effect, researchers shoot an extremely powerful X-ray laser at the sample. Depending on how the light is scattered as it passes through the sample, they can draw inferences about the structure of the matter.
The researchers observed that in a state of warm dense matter, what was formerly plastic produces diamonds. The high pressure can split the hydrocarbon into carbon and hydrogen. The carbon atoms that are released compact into diamond structures. In the case of planets like Neptune and Uranus this means that the formation of diamonds in their interior can trigger an additional energy source. The diamonds are heavier than the matter surrounding them and slowly sink to the core of the planet in a kind of diamond rain. In the process, they rub against their surroundings and generate heat -- an important factor for planet models.
X-ray scattering enhances measuring precision
In an earlier experiment, Kraus and his team were the first to prove the possible formation of diamonds in planets using X-ray diffraction in an experimental setting. But the diffraction patterns of X-ray light can only reveal crystalline structures. Using additional detectors, the researchers now also analyzed how the light was scattered by the electrons in the matter. They compared the various scattering components with one another as well as with theoretical simulations. This process enables precise scrutiny of the entire structure of matter. "In the case of the ice giants we now know that the carbon almost exclusively forms diamonds when it separates and does not take on a fluid transitional form," explains Kraus.
The method is not only more sensitive than X-ray diffraction, it can also be used more extensively because it makes fewer technical demands on the light source for the analysis. The international research team is now planning to apply it to hydrogen mixtures similar to those that occur in gaseous planets and to compressed pure hydrogen as found in the interior of small stars. These experiments, which are planned to be conducted, among others, at the Helmholtz International Beamline for Extreme Fields (HIBEF) at the European XFEL, could help researchers to understand the many planets we already know about outside our solar system to ascertain whether life might even be possible on any of them.
Read more at Science Daily
Neither solid, nor fluid, neither gaseous, nor a plasma: the matter inside planets and stars can take on a particular intermediate state, at a temperature of thousands of degrees, and compressed a thousand times more than our Earth's atmosphere -- experts call it warm dense matter. There is a lot we still don't know about it. Lab experiments are set to change all that but are technically highly complex because this exotic state does not occur naturally on Earth. Which all means that both the crafting and study of artificial warm dense matter is a challenge for investigators and theoreticians alike. "But in the last resort, we have to understand the processes in warm dense matter if we want to model planets," explains Dr. Dominik Kraus, lead author of the study and the mastermind behind the measuring method. "We now have a very promising new approach based on X-ray scattering. Our experiments are delivering important model parameters where, before, we only had massive uncertainty. This will become ever more relevant the more exoplanets we discover."
Diamond showers -- a planetary energy source
At SLAC National Accelerator Laboratory at Stanford University, the researchers studied the structure of the matter in mixtures that are typical for planets, in the case of ice giants, hydrocarbon, employing intense laser light. Standard plastic film served as a substitute for planetary hydrocarbon. An optical high-energy laser converts the plastic into warm dense matter: short, strong laser pulses generate shock waves in the film and compress the plastic to the extreme. "We produce about 1.5 million bars, that is equivalent to the pressure exerted by the weight of some 250 African elephants on the surface of a thumbnail," says Kraus, illustrating the dimensions. What happens is that the laser shock waves also heat up the matter to approximately 5,000 degrees. To evaluate the effect, researchers shoot an extremely powerful X-ray laser at the sample. Depending on how the light is scattered as it passes through the sample, they can draw inferences about the structure of the matter.
The researchers observed that in a state of warm dense matter, what was formerly plastic produces diamonds. The high pressure can split the hydrocarbon into carbon and hydrogen. The carbon atoms that are released compact into diamond structures. In the case of planets like Neptune and Uranus this means that the formation of diamonds in their interior can trigger an additional energy source. The diamonds are heavier than the matter surrounding them and slowly sink to the core of the planet in a kind of diamond rain. In the process, they rub against their surroundings and generate heat -- an important factor for planet models.
X-ray scattering enhances measuring precision
In an earlier experiment, Kraus and his team were the first to prove the possible formation of diamonds in planets using X-ray diffraction in an experimental setting. But the diffraction patterns of X-ray light can only reveal crystalline structures. Using additional detectors, the researchers now also analyzed how the light was scattered by the electrons in the matter. They compared the various scattering components with one another as well as with theoretical simulations. This process enables precise scrutiny of the entire structure of matter. "In the case of the ice giants we now know that the carbon almost exclusively forms diamonds when it separates and does not take on a fluid transitional form," explains Kraus.
The method is not only more sensitive than X-ray diffraction, it can also be used more extensively because it makes fewer technical demands on the light source for the analysis. The international research team is now planning to apply it to hydrogen mixtures similar to those that occur in gaseous planets and to compressed pure hydrogen as found in the interior of small stars. These experiments, which are planned to be conducted, among others, at the Helmholtz International Beamline for Extreme Fields (HIBEF) at the European XFEL, could help researchers to understand the many planets we already know about outside our solar system to ascertain whether life might even be possible on any of them.
Read more at Science Daily
Massive prehistoric circle near Stonehenge
What could be one of the largest prehistoric sites in the UK has been discovered near Stonehenge by a consortium of archaeologists led by the University of Bradford.
A massive 2km-wide ring of prehistoric 'shafts' up to 10m across and 5m deep has been discovered around the 'super henge' at Durrington Walls and the famous site at Woodhenge. The structures have been carbon dated to about 2500BC.
Archaeologists believe the circle of shaft marks a boundary around the massive henge at Durrington. It is thought the features, along with an internal post line, could have guided people towards the religious sites and warned others not to cross the boundary.
Prof Vince Gaffney, 50th Anniversary Chair of the School of Archaeological and Forensic Sciences in the Faculty of Life Sciences, said it was extraordinary such a major find had been made so close to Stonehenge.
"The area around Stonehenge is amongst the most studied archaeological landscapes on earth and it is remarkable that the application of new technology can still lead to the discovery of such a massive prehistoric structure which, currently, is significantly larger than any comparative prehistoric monument that we know of in Britain, at least."
"When these pits were first noted it was thought they might be natural features -- solution hollows in the chalk. Only when the larger picture emerged, through the geophysical surveys undertaken as part of the Stonehenge Hidden Landscape Project, could we join the dots and see there was a pattern on a massive scale."
Research on the pits at Durrington was undertaken by a consortium of archaeologists led by the University of Bradford as part of the Stonehenge Hidden Landscape Project (https://lbi-archpro.org/cs/stonehenge/), and with the Ludwig Boltzmann Institute for Archaeological Prospection and Virtual Archaeology, the Universities of Birmingham, St Andrews, Warwick, the University of Wales Trinity Saint Davids, and the Scottish Universities Environmental Research Centre (University of Glasgow).
Researchers have identified up to 20 shafts but estimate there may have been more than 30 originally.
"The size of the shafts and circuit surrounding Durrington Walls is without precedent within the UK. It demonstrates the significance of Durrington Walls Henge, the complexity of the monumental structures within the Stonehenge landscape, and the capacity and desire of Neolithic communities to record their cosmological belief systems in ways, and at a scale, that we had never previously anticipated."
Dr Nick Snashall, National Trust archaeologist for the Stonehenge and Avebury World Heritage Site, said: "As the place where the builders of Stonehenge lived and feasted Durrington Walls is key to unlocking the story of the wider Stonehenge landscape, and this astonishing discovery offers us new insights into the lives and beliefs of our Neolithic ancestors.
"The Hidden Landscapes team have combined cutting-edge, archaeological fieldwork with good old-fashioned detective work to reveal this extraordinary discovery and write a whole new chapter in the story of the Stonehenge landscape."
Read more at Science Daily
A massive 2km-wide ring of prehistoric 'shafts' up to 10m across and 5m deep has been discovered around the 'super henge' at Durrington Walls and the famous site at Woodhenge. The structures have been carbon dated to about 2500BC.
Archaeologists believe the circle of shaft marks a boundary around the massive henge at Durrington. It is thought the features, along with an internal post line, could have guided people towards the religious sites and warned others not to cross the boundary.
Prof Vince Gaffney, 50th Anniversary Chair of the School of Archaeological and Forensic Sciences in the Faculty of Life Sciences, said it was extraordinary such a major find had been made so close to Stonehenge.
"The area around Stonehenge is amongst the most studied archaeological landscapes on earth and it is remarkable that the application of new technology can still lead to the discovery of such a massive prehistoric structure which, currently, is significantly larger than any comparative prehistoric monument that we know of in Britain, at least."
"When these pits were first noted it was thought they might be natural features -- solution hollows in the chalk. Only when the larger picture emerged, through the geophysical surveys undertaken as part of the Stonehenge Hidden Landscape Project, could we join the dots and see there was a pattern on a massive scale."
Research on the pits at Durrington was undertaken by a consortium of archaeologists led by the University of Bradford as part of the Stonehenge Hidden Landscape Project (https://lbi-archpro.org/cs/stonehenge/), and with the Ludwig Boltzmann Institute for Archaeological Prospection and Virtual Archaeology, the Universities of Birmingham, St Andrews, Warwick, the University of Wales Trinity Saint Davids, and the Scottish Universities Environmental Research Centre (University of Glasgow).
Researchers have identified up to 20 shafts but estimate there may have been more than 30 originally.
"The size of the shafts and circuit surrounding Durrington Walls is without precedent within the UK. It demonstrates the significance of Durrington Walls Henge, the complexity of the monumental structures within the Stonehenge landscape, and the capacity and desire of Neolithic communities to record their cosmological belief systems in ways, and at a scale, that we had never previously anticipated."
Dr Nick Snashall, National Trust archaeologist for the Stonehenge and Avebury World Heritage Site, said: "As the place where the builders of Stonehenge lived and feasted Durrington Walls is key to unlocking the story of the wider Stonehenge landscape, and this astonishing discovery offers us new insights into the lives and beliefs of our Neolithic ancestors.
"The Hidden Landscapes team have combined cutting-edge, archaeological fieldwork with good old-fashioned detective work to reveal this extraordinary discovery and write a whole new chapter in the story of the Stonehenge landscape."
Read more at Science Daily
Jun 23, 2020
Ice core research in Antarctica sheds new light on role of sea ice in carbon balance
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past. An international team of scientists with the participation of the University of Bonn has shown that the seasonal growth and destruction of sea ice in a warming world increases the biological productivity of the seas around Antarctica by extracting carbon from the atmosphere and storing it in the deep ocean. This process helps to explain a long-standing question about an apparent 1,900-year pause in CO2 growth during a period known as the Antarctic cold reversal. The research results have now been published in "Nature Geoscience."
Surrounding the remote continent of Antarctica, the Southern Ocean is one of the most important yet poorly understood components of the global carbon cycle. Having captured half of all human-related carbon that has entered the ocean to date, the Southern Ocean is crucial to regulating human-induced CO2. Therefore, understanding the processes that determine its effectiveness as a carbon sink through time are essential to reducing uncertainty in climate projections.
After the Last Ice Age, around 18,000 years ago, the world transitioned naturally into the warm interglacial world we live in today. During this period, CO2 rose rapidly from around 190 ppm to 280 ppm over around 7,000 years. This rise was not steady, and was interrupted by rapid rises and intermittent plateaus, reflecting different processes within the global carbon cycle.
Antarctic Cold Reversal
One period stands out: a 1,900-year plateau of near-constant CO2 levels at 240 ppm starting some 14,600 years ago called the Antarctic Cold Reversal. The cause of this plateau remains unknown, but understanding the processes may be critical for improving projections surrounding climate-carbon feedbacks.
"We found that in sediment cores located in the sea-ice zone of the Southern Ocean biological productivity increased during this critical period, whereas it decreased farther north, outside of the sea-ice zone," says Michael Weber, co-author of the study from the Institute for Geosciences at the University of Bonn. "It was now important to find out how climate records on the Antarctic continent depict this critical time period."
To resolve this question researchers from Keele University, U.K., and the University of New South Wales (UNSW) in Sydney, Australia, travelled to the Patriot Hills Blue Ice Area to obtain new records of marine biomarkers captured in ice cores. Chris Fogwill, lead author of the study from Keele University, says "the cause of this long plateau in global atmospheric CO2 levels may be fundamental to understanding the potential of the Southern Ocean to moderate atmospheric CO2. Whilst recent reductions in emissions due to the Covid-19 pandemic have shown that we can reduce CO2, we need to understand the ways in which CO2 levels have been stabilised by natural processes, as they may be key to the responsible development of geoengineering approaches and remain fundamental to achieving our commitment to the Paris Agreement."
Horizontal ice core analysis
Blue ice areas are created by fierce, high-density katabatic winds that erode the top layer of snow effectively and expose the ice below. As a result, ice flows up to the surface, providing access to ancient ice below. While most Antarctic researchers drill down into the ice to extract samples with a conventional ice core, this team used a different method: horizontal ice core analysis. Chris Turney (UNSW, Sydney) says "Instead of drilling kilometres into the ice, we can simply walk across a blue ice area to travel back through time. This provides the opportunity to sample large volumes of ice necessary for studying new organic biomarkers and DNA that were blown from the Southern Ocean onto Antarctica and preserved in the blue ice."
The results demonstrated a marked increase in the number and diversity of marine organisms across the 1,900 year period of the CO2 plateau, an observation never seen before. The team also conducted climate modelling revealing that this period coincided with the greatest seasonal changes in sea ice extent from summer to winter. Together with the marine cores, these findings provide the first evidence of increased biological productivity record and suggest that processes in the Antarctic Zone of Southern Ocean may have caused the CO2 plateau.
Read more at Science Daily
Surrounding the remote continent of Antarctica, the Southern Ocean is one of the most important yet poorly understood components of the global carbon cycle. Having captured half of all human-related carbon that has entered the ocean to date, the Southern Ocean is crucial to regulating human-induced CO2. Therefore, understanding the processes that determine its effectiveness as a carbon sink through time are essential to reducing uncertainty in climate projections.
After the Last Ice Age, around 18,000 years ago, the world transitioned naturally into the warm interglacial world we live in today. During this period, CO2 rose rapidly from around 190 ppm to 280 ppm over around 7,000 years. This rise was not steady, and was interrupted by rapid rises and intermittent plateaus, reflecting different processes within the global carbon cycle.
Antarctic Cold Reversal
One period stands out: a 1,900-year plateau of near-constant CO2 levels at 240 ppm starting some 14,600 years ago called the Antarctic Cold Reversal. The cause of this plateau remains unknown, but understanding the processes may be critical for improving projections surrounding climate-carbon feedbacks.
"We found that in sediment cores located in the sea-ice zone of the Southern Ocean biological productivity increased during this critical period, whereas it decreased farther north, outside of the sea-ice zone," says Michael Weber, co-author of the study from the Institute for Geosciences at the University of Bonn. "It was now important to find out how climate records on the Antarctic continent depict this critical time period."
To resolve this question researchers from Keele University, U.K., and the University of New South Wales (UNSW) in Sydney, Australia, travelled to the Patriot Hills Blue Ice Area to obtain new records of marine biomarkers captured in ice cores. Chris Fogwill, lead author of the study from Keele University, says "the cause of this long plateau in global atmospheric CO2 levels may be fundamental to understanding the potential of the Southern Ocean to moderate atmospheric CO2. Whilst recent reductions in emissions due to the Covid-19 pandemic have shown that we can reduce CO2, we need to understand the ways in which CO2 levels have been stabilised by natural processes, as they may be key to the responsible development of geoengineering approaches and remain fundamental to achieving our commitment to the Paris Agreement."
Horizontal ice core analysis
Blue ice areas are created by fierce, high-density katabatic winds that erode the top layer of snow effectively and expose the ice below. As a result, ice flows up to the surface, providing access to ancient ice below. While most Antarctic researchers drill down into the ice to extract samples with a conventional ice core, this team used a different method: horizontal ice core analysis. Chris Turney (UNSW, Sydney) says "Instead of drilling kilometres into the ice, we can simply walk across a blue ice area to travel back through time. This provides the opportunity to sample large volumes of ice necessary for studying new organic biomarkers and DNA that were blown from the Southern Ocean onto Antarctica and preserved in the blue ice."
The results demonstrated a marked increase in the number and diversity of marine organisms across the 1,900 year period of the CO2 plateau, an observation never seen before. The team also conducted climate modelling revealing that this period coincided with the greatest seasonal changes in sea ice extent from summer to winter. Together with the marine cores, these findings provide the first evidence of increased biological productivity record and suggest that processes in the Antarctic Zone of Southern Ocean may have caused the CO2 plateau.
Read more at Science Daily
Bread mold avoids infection by mutating its own DNA
Whilst most organisms try to stop their DNA from mutating, scientists from the UK and China have discovered that a common fungus found on bread actively mutates its own DNA as a way of fighting virus-like infections.
All organisms mutate all of the time. You were born with between ten and a hundred new mutations, for example. Many do little harm but, if they hit one of your genes, mutations are much more likely to be harmful than beneficial. If harmful enough they contribute to genetic diseases.
Whilst mutations can enable species to adapt, most mutations are harmful, and so evolutionary biologists have postulated that natural selection will always act to reduce the mutation rate.
While prior data has supported this view, recent work by Professor Laurence Hurst of the Milner Centre for Evolution at the University of Bath (UK) and Sihai Yang, Long Wang and colleagues at Nanjing University (China) have found that Neurospora crassa, a type of bread mould, is a remarkable exception to the rule.
Professor Hurst, Director of the Milner Centre for Evolution at the University of Bath, said: "Many organisms have a problem with transposable elements, otherwise called jumping genes.
"These are virus-like bits of DNA that insert themselves into their host's DNA, copy themselves and keep on inserting -- hence the name jumping genes.
"Organisms have found different ways of combatting this nuisance, many of which try to prevent the transposable elements from expressing their own genes. Neurospora has evolved a different solution: it hits them exceptionally hard with mutations to rapidly degrade them."
The study, published in Genome Biology, found that Neurospora distinguishes jumping genes from its own DNA by detecting two or more copies of the same bit of DNA. The fungus then attacks the jumping genes by mutating them in a process called Repeat-Induced Point mutation (RIP).
To understand how RIP affects the fungus's own DNA, the team sequenced the whole genome from both parents and offspring for many strains of Neurospora to see how many mutations could be found and where they were in the DNA.
Overall, they found that each base pair in the Neurospora genome has about a one in a million chance of mutating every generation; over a hundred times higher than any non-viral life on the planet.
Professor Hurst said: "This was a real surprise to us -- any organism that hits its own genes with that many mutations is likely one that will not persist for very long. It would be like opening up the back of a watch, stabbing at all the cog wheels that look a bit similar and expecting the watch to still function!
"Our findings show that Neurospora has not only a high mutation rate but is also a massive outlier. It appears to use RIP to destroy transposable elements but at a cost, with considerable collateral damage.
Read more at Science Daily
All organisms mutate all of the time. You were born with between ten and a hundred new mutations, for example. Many do little harm but, if they hit one of your genes, mutations are much more likely to be harmful than beneficial. If harmful enough they contribute to genetic diseases.
Whilst mutations can enable species to adapt, most mutations are harmful, and so evolutionary biologists have postulated that natural selection will always act to reduce the mutation rate.
While prior data has supported this view, recent work by Professor Laurence Hurst of the Milner Centre for Evolution at the University of Bath (UK) and Sihai Yang, Long Wang and colleagues at Nanjing University (China) have found that Neurospora crassa, a type of bread mould, is a remarkable exception to the rule.
Professor Hurst, Director of the Milner Centre for Evolution at the University of Bath, said: "Many organisms have a problem with transposable elements, otherwise called jumping genes.
"These are virus-like bits of DNA that insert themselves into their host's DNA, copy themselves and keep on inserting -- hence the name jumping genes.
"Organisms have found different ways of combatting this nuisance, many of which try to prevent the transposable elements from expressing their own genes. Neurospora has evolved a different solution: it hits them exceptionally hard with mutations to rapidly degrade them."
The study, published in Genome Biology, found that Neurospora distinguishes jumping genes from its own DNA by detecting two or more copies of the same bit of DNA. The fungus then attacks the jumping genes by mutating them in a process called Repeat-Induced Point mutation (RIP).
To understand how RIP affects the fungus's own DNA, the team sequenced the whole genome from both parents and offspring for many strains of Neurospora to see how many mutations could be found and where they were in the DNA.
Overall, they found that each base pair in the Neurospora genome has about a one in a million chance of mutating every generation; over a hundred times higher than any non-viral life on the planet.
Professor Hurst said: "This was a real surprise to us -- any organism that hits its own genes with that many mutations is likely one that will not persist for very long. It would be like opening up the back of a watch, stabbing at all the cog wheels that look a bit similar and expecting the watch to still function!
"Our findings show that Neurospora has not only a high mutation rate but is also a massive outlier. It appears to use RIP to destroy transposable elements but at a cost, with considerable collateral damage.
Read more at Science Daily
COVID-19 lockdown reveals human impact on wildlife
In an article published in Nature Ecology & Evolution today (22 June), the leaders of a new global initiative explain how research during this devastating health crisis can inspire innovative strategies for sharing space on this increasingly crowded planet, with benefits for both wildlife and humans.
Many countries around the world went into lockdown to control the spread of Covid-19. Brought about by the most tragic circumstances, this period of unusually reduced human mobility, which the article's authors coined "anthropause," can provide invaluable insights into human-wildlife interactions.
There have been countless posts on social media over the past few months reporting unusual wildlife encounters. Anecdotal observations, especially from metropolitan areas, suggest that nature has responded to lockdown. There not only seem to be more animals than usual, but there are also some surprising visitors: pumas have been spotted prowling the streets of downtown Santiago, Chile, and dolphins recently showed up in untypically calm waters in the harbour of Trieste, Italy.
For other species, the pandemic may have created new challenges. For example, some urban-dwelling animals, like gulls, rats or monkeys, may struggle to make ends meet without access to human food. In more remote areas, reduced human presence may potentially put endangered species, such as rhinos or raptors, at increased risk of poaching or persecution.
The authors emphasise that society's priority must be to tackle the immense human tragedy and hardship caused by Covid-19. But, they argue that we cannot afford to miss the opportunity to chart, for the first time on a truly global scale, the extent to which modern human mobility affects wildlife.
To address this challenge, researchers recently formed the "COVID-19 Bio-Logging Initiative." This international consortium will investigate animals' movements, behaviour and stress levels, before, during and after Covid-19 lockdown, using data collected with nifty animal-attached electronic devices called "bio-loggers."
The article's lead author, Professor Christian Rutz, a biologist at the University of St Andrews, UK, and President of the International Bio-Logging Society, explains: "All over the world, field biologists have fitted animals with miniature tracking devices. These bio-loggers provide a goldmine of information on animal movement and behaviour, which we can now tap to improve our understanding of human-wildlife interactions, with benefits for all."
The team will integrate results from a wide variety of animals, including fish, birds and mammals, in an attempt to build a global picture of lockdown effects.
Dr Francesca Cagnacci, Senior Researcher at the Edmund Mach Foundation in Trento, Italy, and Principal Investigator of the Euromammals research network, says: "The international research community responded quickly to our recent call for collaboration, offering over 200 datasets for analysis. We are very grateful for this support."
So, what do the scientists hope to learn? Dr Matthias-Claudio Loretto, a Marie Sk?odowska-Curie Fellow at the Max Planck Institute of Animal Behavior in Radolfzell, Germany, explains that it will be possible to address previously intractable questions: "We will be able to investigate if the movements of animals in modern landscapes are predominantly affected by built structures, or by the presence of humans. That is a big deal."
These insights will in turn inspire innovative proposals for improving human-wildlife coexistence, according to Professor Martin Wikelski, Director of the Max Planck Institute of Animal Behavior in Radolfzell, Germany. "Nobody is asking for humans to stay in permanent lockdown. But we may discover that relatively minor changes to our lifestyles and transport networks can potentially have significant benefits for both ecosystems and humans."
Read more at Science Daily
Many countries around the world went into lockdown to control the spread of Covid-19. Brought about by the most tragic circumstances, this period of unusually reduced human mobility, which the article's authors coined "anthropause," can provide invaluable insights into human-wildlife interactions.
There have been countless posts on social media over the past few months reporting unusual wildlife encounters. Anecdotal observations, especially from metropolitan areas, suggest that nature has responded to lockdown. There not only seem to be more animals than usual, but there are also some surprising visitors: pumas have been spotted prowling the streets of downtown Santiago, Chile, and dolphins recently showed up in untypically calm waters in the harbour of Trieste, Italy.
For other species, the pandemic may have created new challenges. For example, some urban-dwelling animals, like gulls, rats or monkeys, may struggle to make ends meet without access to human food. In more remote areas, reduced human presence may potentially put endangered species, such as rhinos or raptors, at increased risk of poaching or persecution.
The authors emphasise that society's priority must be to tackle the immense human tragedy and hardship caused by Covid-19. But, they argue that we cannot afford to miss the opportunity to chart, for the first time on a truly global scale, the extent to which modern human mobility affects wildlife.
To address this challenge, researchers recently formed the "COVID-19 Bio-Logging Initiative." This international consortium will investigate animals' movements, behaviour and stress levels, before, during and after Covid-19 lockdown, using data collected with nifty animal-attached electronic devices called "bio-loggers."
The article's lead author, Professor Christian Rutz, a biologist at the University of St Andrews, UK, and President of the International Bio-Logging Society, explains: "All over the world, field biologists have fitted animals with miniature tracking devices. These bio-loggers provide a goldmine of information on animal movement and behaviour, which we can now tap to improve our understanding of human-wildlife interactions, with benefits for all."
The team will integrate results from a wide variety of animals, including fish, birds and mammals, in an attempt to build a global picture of lockdown effects.
Dr Francesca Cagnacci, Senior Researcher at the Edmund Mach Foundation in Trento, Italy, and Principal Investigator of the Euromammals research network, says: "The international research community responded quickly to our recent call for collaboration, offering over 200 datasets for analysis. We are very grateful for this support."
So, what do the scientists hope to learn? Dr Matthias-Claudio Loretto, a Marie Sk?odowska-Curie Fellow at the Max Planck Institute of Animal Behavior in Radolfzell, Germany, explains that it will be possible to address previously intractable questions: "We will be able to investigate if the movements of animals in modern landscapes are predominantly affected by built structures, or by the presence of humans. That is a big deal."
These insights will in turn inspire innovative proposals for improving human-wildlife coexistence, according to Professor Martin Wikelski, Director of the Max Planck Institute of Animal Behavior in Radolfzell, Germany. "Nobody is asking for humans to stay in permanent lockdown. But we may discover that relatively minor changes to our lifestyles and transport networks can potentially have significant benefits for both ecosystems and humans."
Read more at Science Daily
Decline in green energy spending might offset COVID-era emissions benefits
The short-term environmental benefits of the COVID-19 crisis, including declines in carbon emissions and local air pollution, have been documented since the early days of the crisis. This silver lining to the global crisis, however, could be far outweighed by the long-term impacts on clean energy innovation, a new Yale-led study finds.
The economic downturn triggered by the pandemic, researchers say, could have a devastating impact on long-term investment in clean energy.
Under a worst-case -- but realistic -- scenario, they predict an additional 2,500 million metric tons of carbon dioxide -- or the equivalent of nearly 3 trillion pounds of coal burned -- could be emitted, causing 40 more deaths per month, through 2035.
"This global crisis will certainly defer investments in clean energy," said Kenneth Gillingham, an associate professor of environmental and energy economics at the Yale School of Forestry & Environmental Studies (F&ES) and lead author of the paper. "Depending on how policymakers respond, the consequences for human health from this deferred investment could far exceed the short-term environmental benefits that we have seen so far."
Those short-term benefits have been substantial. Consumption for jet fuel and gasoline, for example, declined by 50 and 30 percent, respectively, from early March to June 7, while electricity demand fell by 10 percent. These impacts saved an estimated 200 lives per month since the lockdowns began.
However, there's also been another, subtler outcome: most investment in clean energy technologies has come to a halt.
"Overall clean energy jobs dropped by almost 600,000 by the end of April, as investments in energy efficiency and renewable generation have plummeted," said Marten Ovaere, a postdoctoral researcher at F&ES and co-author of the paper. "If that were to continue it could significantly set back the push toward a clean energy future."
The paper, published in the journal Joule, was coauthored by researchers at MIT Sloan School of Management and Northwestern University.
Drawing on evidence from previous economic shocks, the researchers examine two possible long-term scenarios in the U.S. In the best-case scenario -- in which the threat subsides relatively quickly, the worst projections of human fatalities are avoided, and the economy rebounds -- they say there should be few long-term implications. Most demands for products and services, they predict, "will be deferred rather than destroyed." While record declines in emissions would be temporary, investments in new energy solutions would likely reach pre-pandemic levels.
If there is a persistent, long-term recession, however, the impacts on energy innovation would be significant. While energy use related to travel might remain lower, home energy consumption would increase and commercial building use would stay largely unchanged, particularly if office spaces are used in a similar way (even if more American workers decide to work from home). Also, if the public becomes cautious about using public transportation, many commuters will simply decide to drive instead.
The greater impact, however, would be on the energy innovation sector, the study says. Investment in low-carbon technologies would dry up, the transition to cleaner vehicle fleets would be disrupted, and cash-strapped automakers would abandon new vehicle and energy efficiency technologies.
"For example, there has been a huge amount of investment going into electric vehicles," Gillingham says. "But if companies are just trying to survive, it's much less likely that they can make large investments towards new technologies for the next generation because they don't even know if they're going to make it to the next generation."
In addition, tighter state and local budgets over the next few years will likely deflate much of the investment in clean-energy options.
Even if green energy investments stall for just a single year, the authors calculate, it would outweigh any emissions reductions that occurred from March to June.
However, while the uncertainty of this crisis poses potentially enormous threats, it also presents an opportunity, Gillingham says. If federal governments produce large stimulus packages to strengthen the economy, even modest investments in clean energy technologies would pay long-term dividends.
"Including a green component in those stimulus packages would be an investment in the future, but it also has short-term benefits," he says. "We looked back at analyses of the clean energy investments that were part of the American Recovery and Reinvestment Act of 2009 -- which promoted new energy infrastructure, smart meters, and other new technologies -- and it made a big difference.
Read more at Science Daily
The economic downturn triggered by the pandemic, researchers say, could have a devastating impact on long-term investment in clean energy.
Under a worst-case -- but realistic -- scenario, they predict an additional 2,500 million metric tons of carbon dioxide -- or the equivalent of nearly 3 trillion pounds of coal burned -- could be emitted, causing 40 more deaths per month, through 2035.
"This global crisis will certainly defer investments in clean energy," said Kenneth Gillingham, an associate professor of environmental and energy economics at the Yale School of Forestry & Environmental Studies (F&ES) and lead author of the paper. "Depending on how policymakers respond, the consequences for human health from this deferred investment could far exceed the short-term environmental benefits that we have seen so far."
Those short-term benefits have been substantial. Consumption for jet fuel and gasoline, for example, declined by 50 and 30 percent, respectively, from early March to June 7, while electricity demand fell by 10 percent. These impacts saved an estimated 200 lives per month since the lockdowns began.
However, there's also been another, subtler outcome: most investment in clean energy technologies has come to a halt.
"Overall clean energy jobs dropped by almost 600,000 by the end of April, as investments in energy efficiency and renewable generation have plummeted," said Marten Ovaere, a postdoctoral researcher at F&ES and co-author of the paper. "If that were to continue it could significantly set back the push toward a clean energy future."
The paper, published in the journal Joule, was coauthored by researchers at MIT Sloan School of Management and Northwestern University.
Drawing on evidence from previous economic shocks, the researchers examine two possible long-term scenarios in the U.S. In the best-case scenario -- in which the threat subsides relatively quickly, the worst projections of human fatalities are avoided, and the economy rebounds -- they say there should be few long-term implications. Most demands for products and services, they predict, "will be deferred rather than destroyed." While record declines in emissions would be temporary, investments in new energy solutions would likely reach pre-pandemic levels.
If there is a persistent, long-term recession, however, the impacts on energy innovation would be significant. While energy use related to travel might remain lower, home energy consumption would increase and commercial building use would stay largely unchanged, particularly if office spaces are used in a similar way (even if more American workers decide to work from home). Also, if the public becomes cautious about using public transportation, many commuters will simply decide to drive instead.
The greater impact, however, would be on the energy innovation sector, the study says. Investment in low-carbon technologies would dry up, the transition to cleaner vehicle fleets would be disrupted, and cash-strapped automakers would abandon new vehicle and energy efficiency technologies.
"For example, there has been a huge amount of investment going into electric vehicles," Gillingham says. "But if companies are just trying to survive, it's much less likely that they can make large investments towards new technologies for the next generation because they don't even know if they're going to make it to the next generation."
In addition, tighter state and local budgets over the next few years will likely deflate much of the investment in clean-energy options.
Even if green energy investments stall for just a single year, the authors calculate, it would outweigh any emissions reductions that occurred from March to June.
However, while the uncertainty of this crisis poses potentially enormous threats, it also presents an opportunity, Gillingham says. If federal governments produce large stimulus packages to strengthen the economy, even modest investments in clean energy technologies would pay long-term dividends.
"Including a green component in those stimulus packages would be an investment in the future, but it also has short-term benefits," he says. "We looked back at analyses of the clean energy investments that were part of the American Recovery and Reinvestment Act of 2009 -- which promoted new energy infrastructure, smart meters, and other new technologies -- and it made a big difference.
Read more at Science Daily
Jun 22, 2020
300-million-year-old fish resembles a sturgeon but took a different evolutionary path
Sturgeon, a long-lived, bottom-dwelling fish, are often described as "living fossils," owing to the fact that their form has remained relatively constant, despite hundreds of millions of years of evolution.
In a new study in the Zoological Journal of the Linnean Society, researchers led by Jack Stack, a 2019 University of Pennsylvania graduate, and paleobiologist Lauren Sallan of Penn's School of Arts & Sciences, closely examine the ancient fish species Tanyrhinichthys mcallisteri, which lived around 300 million years ago in an estuary environment in what is today New Mexico. Although they find the fish to be highly similar to sturgeons in its features, including its protruding snout, they show that these characteristics evolved in a distinct evolutionary path from those species that gave rise to modern sturgeons.
The find indicates that, although ancient, the features that enabled Tanyrhinichthys to thrive in its environment arose multiple times in different fish lineages, a burst of innovation that was not previously fully appreciated for fish in this time period.
"Sturgeon are considered a 'primitive' species, but what we're showing is that the sturgeon lifestyle is something that's been selected for in certain conditions and has evolved over and over again," says Sallan, senior author on the work.
"Fish are very good at finding solutions to ecological problems," says Stack, first author on the study, who worked on the research as a Penn undergraduate and is now a graduate student at Michigan State University. "This shows the degree of both innovation and convergence that's possible in fishes. Once their numbers got up large enough, they started producing brand new morphologies that we now see have evolved numerous times through the history of fishes, under similar ecological conditions. "
The first fossil of Tanyrhinichthys was found in 1984 in a fossil-rich area called the Kinney Brick Quarry, about a half hour east of Albuquerque. The first paleontologist to describe the species was Michael Gottfried, a Michigan State faculty member who now serves as Stack's advisor for his master's degree.
"The specimen looks like someone found a fish and just pulled on the front of its skull," Stack says. Many modern fish species, from the swordfish to the sailfish, have protuberant snouts that extend out in front of them, often aiding in their ability to lunge at prey. But this characteristic is much rarer in ancient fishes. In the 1980s when Gottfried described the initial specimen, he posited that the fish resembled a pike, an ambush predator with a longer snout.
During the last decade, however, several more specimens of Tanyrhinichthys have been found in the same quarry. "Those finds were an impetus for this project, now that we had better information on this enigmatic and strange fish," Stack says.
At the time that Tanyrhinichthys roamed the waters, Earth's continents were joined in the massive supercontinent called Pangea, surrounded by a single large ocean. But it was an ice age as well, with ice at both poles. Just before this period, the fossil record showed that ray-finned fishes, which now dominate the oceans, were exploding in diversity. Yet 300 million years ago, "it was like someone hit the pause button," Sallan says. "There's an expectation that there would be more diversity, but not much has been found, likely owing to the fact that there just hasn't been enough work on this time period, especially in the United States, and particularly in the Western United States."
Aiming to fill in some of these gaps by further characterizing Tanyrhinichthys, Stack, Sallan, and colleagues closely examined the specimens in detail and studied other species that dated to this time period. "This sounds really simple, but it's obviously difficult in execution," Stack notes, as fossils are compressed flat when they are preserved. The researchers inferred a three-dimensional anatomy using the forms of modern fishes to guide them.
What they noticed cast doubt on the conception of Tanyrhinichthys as resembling a pike. While a pike has an elongated snout with its jaws at the end of it, allowing it to rush its prey head-on, Tanyrhinichthys has an elongated snout with its jaws at the bottom.
"The whole form of this fish is similar to other bottom dwellers," Stack says. Sallan also noticed canal-like structures on its snout concentrated in the top of its head, suggestive of the locations where sensory organs would attach. "These would have detected vibrations to allow the fish to consume its prey," says Sallan.
The researchers noted that many of the species that dwelled in similar environments possessed longer snouts, which Sallan called "like an antenna for your face."
"This also makes sense because it was an estuary environment," Sallan says, "with large rivers feeding into it, churning up the water, and making it murky. Rather than using your eyesight, you have to use these other sensory organs to detect prey."
Despite this, other features of the different ancient fishes' morphology were so different from Tanyrhinichthys that they do not appear to have shared a lineage with one another, nor do modern sturgeon descend from Tanyrhinichthys. Instead the long snouts appear to be an example of convergent evolution, or many different lineages all arriving at the same innovation to adapt well to their environment.
Read more at Science Daily
In a new study in the Zoological Journal of the Linnean Society, researchers led by Jack Stack, a 2019 University of Pennsylvania graduate, and paleobiologist Lauren Sallan of Penn's School of Arts & Sciences, closely examine the ancient fish species Tanyrhinichthys mcallisteri, which lived around 300 million years ago in an estuary environment in what is today New Mexico. Although they find the fish to be highly similar to sturgeons in its features, including its protruding snout, they show that these characteristics evolved in a distinct evolutionary path from those species that gave rise to modern sturgeons.
The find indicates that, although ancient, the features that enabled Tanyrhinichthys to thrive in its environment arose multiple times in different fish lineages, a burst of innovation that was not previously fully appreciated for fish in this time period.
"Sturgeon are considered a 'primitive' species, but what we're showing is that the sturgeon lifestyle is something that's been selected for in certain conditions and has evolved over and over again," says Sallan, senior author on the work.
"Fish are very good at finding solutions to ecological problems," says Stack, first author on the study, who worked on the research as a Penn undergraduate and is now a graduate student at Michigan State University. "This shows the degree of both innovation and convergence that's possible in fishes. Once their numbers got up large enough, they started producing brand new morphologies that we now see have evolved numerous times through the history of fishes, under similar ecological conditions. "
The first fossil of Tanyrhinichthys was found in 1984 in a fossil-rich area called the Kinney Brick Quarry, about a half hour east of Albuquerque. The first paleontologist to describe the species was Michael Gottfried, a Michigan State faculty member who now serves as Stack's advisor for his master's degree.
"The specimen looks like someone found a fish and just pulled on the front of its skull," Stack says. Many modern fish species, from the swordfish to the sailfish, have protuberant snouts that extend out in front of them, often aiding in their ability to lunge at prey. But this characteristic is much rarer in ancient fishes. In the 1980s when Gottfried described the initial specimen, he posited that the fish resembled a pike, an ambush predator with a longer snout.
During the last decade, however, several more specimens of Tanyrhinichthys have been found in the same quarry. "Those finds were an impetus for this project, now that we had better information on this enigmatic and strange fish," Stack says.
At the time that Tanyrhinichthys roamed the waters, Earth's continents were joined in the massive supercontinent called Pangea, surrounded by a single large ocean. But it was an ice age as well, with ice at both poles. Just before this period, the fossil record showed that ray-finned fishes, which now dominate the oceans, were exploding in diversity. Yet 300 million years ago, "it was like someone hit the pause button," Sallan says. "There's an expectation that there would be more diversity, but not much has been found, likely owing to the fact that there just hasn't been enough work on this time period, especially in the United States, and particularly in the Western United States."
Aiming to fill in some of these gaps by further characterizing Tanyrhinichthys, Stack, Sallan, and colleagues closely examined the specimens in detail and studied other species that dated to this time period. "This sounds really simple, but it's obviously difficult in execution," Stack notes, as fossils are compressed flat when they are preserved. The researchers inferred a three-dimensional anatomy using the forms of modern fishes to guide them.
What they noticed cast doubt on the conception of Tanyrhinichthys as resembling a pike. While a pike has an elongated snout with its jaws at the end of it, allowing it to rush its prey head-on, Tanyrhinichthys has an elongated snout with its jaws at the bottom.
"The whole form of this fish is similar to other bottom dwellers," Stack says. Sallan also noticed canal-like structures on its snout concentrated in the top of its head, suggestive of the locations where sensory organs would attach. "These would have detected vibrations to allow the fish to consume its prey," says Sallan.
The researchers noted that many of the species that dwelled in similar environments possessed longer snouts, which Sallan called "like an antenna for your face."
"This also makes sense because it was an estuary environment," Sallan says, "with large rivers feeding into it, churning up the water, and making it murky. Rather than using your eyesight, you have to use these other sensory organs to detect prey."
Despite this, other features of the different ancient fishes' morphology were so different from Tanyrhinichthys that they do not appear to have shared a lineage with one another, nor do modern sturgeon descend from Tanyrhinichthys. Instead the long snouts appear to be an example of convergent evolution, or many different lineages all arriving at the same innovation to adapt well to their environment.
Read more at Science Daily
New research hints at the presence of unconventional galaxies containing 2 black holes
A Clemson University scientist has joined forces with an international team of astronomers to identify periodic gamma-ray emissions from 11 active galaxies, paving the way for future studies of unconventional galaxies that might harbor two supermassive black holes at their centers.
Among astronomers, it has long been well-established that most galaxies host a black hole at their center. But galaxies hosting a pair of black holes has remained theoretical.
The results of the team's research appeared in The Astrophysical Journal on June 19, 2020 in a paper titled "Systematic search for gamma-ray periodicity in active galactic nuclei detected by the Fermi Large Area Telescope."
"In general, supermassive black holes are characterized by masses of more than a million masses of that of our sun," said Pablo Peñil, lead author of the study and a Ph.D. student at Universidad Complutense de Madrid in Spain. "Some of these supermassive black holes, known as active galactic nuclei (AGN) have been found to accelerate particles to near the speed of light in collimated beams called jets. The emission from these jets is detected throughout the entire electromagnetic spectrum, but most of their energy is released in the form of gamma rays."
Gamma rays, which are the most extreme form of light, are detected by the Large Area Telescope onboard NASA's Fermi Gamma-ray Space Telescope. AGN are characterized by abrupt and unpredictable variations in brightness.
"Identifying regular patterns in their gamma-ray emission is like looking at the stormy sea and searching for the tiny regular set of waves caused by, say, the passage of a small boat," Peñil said. "It becomes very challenging very quickly."
The team accomplished the first difficult step of identifying a large number of galaxies that emits periodically over years and is trying to address the question of what is producing that periodic behavior in these AGN. Several of the potential explanations are fascinating.
"The next step will be the preparation of observational campaigns with other telescopes to closely follow up on these galaxies and hopefully unravel the reasons behind these compelling observations," said co-author Marco Ajello, an associate professor in the College of Science's department of physics and astronomy at Clemson University. "We have a few possibilities in mind -- from lighthouse effects produced by the jets to modulations in the flow of matter to the black hole -- but one very interesting solution would be that periodicity is produced by a pair of supermassive black holes rotating around each other. Understanding the relation of these black holes with their environment will be essential for a complete picture of galaxy formation."
Thanks to a decade of Fermi-LAT observations, the team was able to identify the repetition of gamma-ray signals over cycles of a few years. On average, these emissions repeated about every two years.
"Our study represents the most complete work to date on the search for periodicity in gamma rays, a study that will be instrumental in deriving insights about the origin of this peculiar behavior," said co-author Alberto Domínguez, Peñil's Ph.D. supervisor in Madrid and also a former postdoctoral researcher in Ajello's group at Clemson. "We have used nine years of continuous LAT all-sky observations. Among the more than two thousand AGN analyzed, only about a dozen stand out for this intriguing cyclical emission."
Enlarging the limited sample of periodic emitters constitutes an important leap forward for understanding the underlying physical processes in these galaxies.
Read more at Science Daily
Among astronomers, it has long been well-established that most galaxies host a black hole at their center. But galaxies hosting a pair of black holes has remained theoretical.
The results of the team's research appeared in The Astrophysical Journal on June 19, 2020 in a paper titled "Systematic search for gamma-ray periodicity in active galactic nuclei detected by the Fermi Large Area Telescope."
"In general, supermassive black holes are characterized by masses of more than a million masses of that of our sun," said Pablo Peñil, lead author of the study and a Ph.D. student at Universidad Complutense de Madrid in Spain. "Some of these supermassive black holes, known as active galactic nuclei (AGN) have been found to accelerate particles to near the speed of light in collimated beams called jets. The emission from these jets is detected throughout the entire electromagnetic spectrum, but most of their energy is released in the form of gamma rays."
Gamma rays, which are the most extreme form of light, are detected by the Large Area Telescope onboard NASA's Fermi Gamma-ray Space Telescope. AGN are characterized by abrupt and unpredictable variations in brightness.
"Identifying regular patterns in their gamma-ray emission is like looking at the stormy sea and searching for the tiny regular set of waves caused by, say, the passage of a small boat," Peñil said. "It becomes very challenging very quickly."
The team accomplished the first difficult step of identifying a large number of galaxies that emits periodically over years and is trying to address the question of what is producing that periodic behavior in these AGN. Several of the potential explanations are fascinating.
"The next step will be the preparation of observational campaigns with other telescopes to closely follow up on these galaxies and hopefully unravel the reasons behind these compelling observations," said co-author Marco Ajello, an associate professor in the College of Science's department of physics and astronomy at Clemson University. "We have a few possibilities in mind -- from lighthouse effects produced by the jets to modulations in the flow of matter to the black hole -- but one very interesting solution would be that periodicity is produced by a pair of supermassive black holes rotating around each other. Understanding the relation of these black holes with their environment will be essential for a complete picture of galaxy formation."
Thanks to a decade of Fermi-LAT observations, the team was able to identify the repetition of gamma-ray signals over cycles of a few years. On average, these emissions repeated about every two years.
"Our study represents the most complete work to date on the search for periodicity in gamma rays, a study that will be instrumental in deriving insights about the origin of this peculiar behavior," said co-author Alberto Domínguez, Peñil's Ph.D. supervisor in Madrid and also a former postdoctoral researcher in Ajello's group at Clemson. "We have used nine years of continuous LAT all-sky observations. Among the more than two thousand AGN analyzed, only about a dozen stand out for this intriguing cyclical emission."
Enlarging the limited sample of periodic emitters constitutes an important leap forward for understanding the underlying physical processes in these galaxies.
Read more at Science Daily
Evidence supports 'hot start' scenario and early ocean formation on Pluto
The accretion of new material during Pluto's formation may have generated enough heat to create a liquid ocean that has persisted beneath an icy crust to the present day, despite the dwarf planet's orbit far from the sun in the cold outer reaches of the solar system.
This "hot start" scenario, presented in a paper published June 22 in Nature Geoscience, contrasts with the traditional view of Pluto's origins as a ball of frozen ice and rock in which radioactive decay could have eventually generated enough heat to melt the ice and form a subsurface ocean.
"For a long time people have thought about the thermal evolution of Pluto and the ability of an ocean to survive to the present day," said coauthor Francis Nimmo, professor of Earth and planetary sciences at UC Santa Cruz. "Now that we have images of Pluto's surface from NASA's New Horizons mission, we can compare what we see with the predictions of different thermal evolution models."
Because water expands when it freezes and contracts when it melts, the hot-start and cold-start scenarios have different implications for the tectonics and resulting surface features of Pluto, explained first author and UCSC graduate student Carver Bierson.
"If it started cold and the ice melted internally, Pluto would have contracted and we should see compression features on its surface, whereas if it started hot it should have expanded as the ocean froze and we should see extension features on the surface," Bierson said. "We see lots of evidence of expansion, but we don't see any evidence of compression, so the observations are more consistent with Pluto starting with a liquid ocean."
The thermal and tectonic evolution of a cold-start Pluto is actually a bit complicated, because after an initial period of gradual melting the subsurface ocean would begin to refreeze. So compression of the surface would occur early on, followed by more recent extension. With a hot start, extension would occur throughout Pluto's history.
"The oldest surface features on Pluto are harder to figure out, but it looks like there was both ancient and modern extension of the surface," Nimmo said.
The next question was whether enough energy was available to give Pluto a hot start. The two main energy sources would be heat released by the decay of radioactive elements in the rock and gravitational energy released as new material bombarded the surface of the growing protoplanet.
Bierson's calculations showed that if all of the gravitational energy was retained as heat, it would inevitably create an initial liquid ocean. In practice, however, much of that energy would radiate away from the surface, especially if the accretion of new material occurred slowly.
"How Pluto was put together in the first place matters a lot for its thermal evolution," Nimmo said. "If it builds up too slowly, the hot material at the surface radiates energy into space, but if it builds up fast enough the heat gets trapped inside."
The researchers calculated that if Pluto formed over a period of less that 30,000 years, then it would have started out hot. If, instead, accretion took place over a few million years, a hot start would only be possible if large impactors buried their energy deep beneath the surface.
The new findings imply that other large Kuiper belt objects probably also started out hot and could have had early oceans. These oceans could persist to the present day in the largest objects, such as the dwarf planets Eris and Makemake.
"Even in this cold environment so far from the sun, all these worlds might have formed fast and hot, with liquid oceans," Bierson said.
Read more at Science Daily
This "hot start" scenario, presented in a paper published June 22 in Nature Geoscience, contrasts with the traditional view of Pluto's origins as a ball of frozen ice and rock in which radioactive decay could have eventually generated enough heat to melt the ice and form a subsurface ocean.
"For a long time people have thought about the thermal evolution of Pluto and the ability of an ocean to survive to the present day," said coauthor Francis Nimmo, professor of Earth and planetary sciences at UC Santa Cruz. "Now that we have images of Pluto's surface from NASA's New Horizons mission, we can compare what we see with the predictions of different thermal evolution models."
Because water expands when it freezes and contracts when it melts, the hot-start and cold-start scenarios have different implications for the tectonics and resulting surface features of Pluto, explained first author and UCSC graduate student Carver Bierson.
"If it started cold and the ice melted internally, Pluto would have contracted and we should see compression features on its surface, whereas if it started hot it should have expanded as the ocean froze and we should see extension features on the surface," Bierson said. "We see lots of evidence of expansion, but we don't see any evidence of compression, so the observations are more consistent with Pluto starting with a liquid ocean."
The thermal and tectonic evolution of a cold-start Pluto is actually a bit complicated, because after an initial period of gradual melting the subsurface ocean would begin to refreeze. So compression of the surface would occur early on, followed by more recent extension. With a hot start, extension would occur throughout Pluto's history.
"The oldest surface features on Pluto are harder to figure out, but it looks like there was both ancient and modern extension of the surface," Nimmo said.
The next question was whether enough energy was available to give Pluto a hot start. The two main energy sources would be heat released by the decay of radioactive elements in the rock and gravitational energy released as new material bombarded the surface of the growing protoplanet.
Bierson's calculations showed that if all of the gravitational energy was retained as heat, it would inevitably create an initial liquid ocean. In practice, however, much of that energy would radiate away from the surface, especially if the accretion of new material occurred slowly.
"How Pluto was put together in the first place matters a lot for its thermal evolution," Nimmo said. "If it builds up too slowly, the hot material at the surface radiates energy into space, but if it builds up fast enough the heat gets trapped inside."
The researchers calculated that if Pluto formed over a period of less that 30,000 years, then it would have started out hot. If, instead, accretion took place over a few million years, a hot start would only be possible if large impactors buried their energy deep beneath the surface.
The new findings imply that other large Kuiper belt objects probably also started out hot and could have had early oceans. These oceans could persist to the present day in the largest objects, such as the dwarf planets Eris and Makemake.
"Even in this cold environment so far from the sun, all these worlds might have formed fast and hot, with liquid oceans," Bierson said.
Read more at Science Daily
First dinosaur eggs were soft like a turtle's
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| Soft turtle eggshells |
"The assumption has always been that the ancestral dinosaur egg was hard-shelled," said lead author Mark Norell, chair and Macaulay Curator in the Museum's Division of Paleontology. "Over the last 20 years, we've found dinosaur eggs around the world. But for the most part, they only represent three groups -- theropod dinosaurs, which includes modern birds, advanced hadrosaurs like the duck-bill dinosaurs, and advanced sauropods, the long-necked dinosaurs. At the same time, we've found thousands of skeletal remains of ceratopsian dinosaurs, but almost none of their eggs. So why weren't their eggs preserved? My guess -- and what we ended up proving through this study -- is that they were soft-shelled."
Amniotes -- the group that includes birds, mammals, and reptiles -- produce eggs with an inner membrane or "amnion" that helps to prevent the embryo from drying out. Some amniotes, such as many turtles, lizards, and snakes, lay soft-shelled eggs, whereas others, such as birds, lay eggs with hard, heavily calcified shells. The evolution of these calcified eggs, which offer increased protection against environmental stress, represents a milestone in the history of the amniotes, as it likely contributed to reproductive success and so the spread and diversification of this group. Soft-shelled eggs rarely preserve in the fossil record, which makes it difficult to study the transition from soft to hard shells. Because modern crocodilians and birds, which are living dinosaur, lay hard-shelled eggs, this eggshell type has been inferred for all non-avian dinosaurs.
The researchers studied embryo-containing fossil eggs belonging to two species of dinosaur: Protoceratops, a sheep-sized plant-eating dinosaur that lived in what is now Mongolia between about 75 and 71 million years ago, and Mussaurus, a long-necked, plant-eating dinosaur that grew to 20 feet in length and lived between 227 and 208.5 million years ago in what is now Argentina. The exceptionally preserved Protoceratops specimen includes a clutch of at least 12 eggs and embryos, six of which preserve nearly complete skeletons. Associated with most of these embryos -- which have their backbones and limbs flexed -- consistent with the position the animals would assume while growing inside of the egg -- is a diffuse black-and-white egg-shaped halo that obscures some of the skeleton. In contrast, two potentially hatched Protoceratops newborns in the specimen are largely free of the mineral halos. When they took a closer look at these halos with a petrographic microscope and chemically characterized the egg samples with high-resolution in situ Raman microspectroscopy, the researchers found chemically altered residues of the proteinaceous eggshell membrane that makes up the innermost eggshell layer of all modern archosaur eggshells. The same was true for the Mussaurus specimen. And when they compared the molecular biomineralization signature of the dinosaur eggs with eggshell data from other animals, including lizards, crocodiles, birds, and turtles, they determined that the Protoceratops and Mussaurus eggs were indeed non-biomineralized -- and, therefore, leathery and soft.
"It's an exceptional claim, so we need exceptional data," said study author and Yale graduate student Jasmina Wiemann. "We had to come up with a brand-new proxy to be sure that what we were seeing was how the eggs were in life, and not just a result of some strange fossilization effect. We now have a new method that can be applied to all other sorts of questions, as well as unambiguous evidence that complements the morphological and histological case for soft-shelled eggs in these animals."
With data on the chemical composition and mechanical properties of eggshells from 112 other extinct and living relatives, the researchers then constructed a "supertree" to track the evolution of the eggshell structure and properties through time, finding that hard-shelled, calcified eggs evolved independently at least three times in dinosaurs, and probably developed from an ancestrally soft-shelled type.
"From an evolutionary perspective, this makes much more sense than previous hypotheses, since we've known for a while that the ancestral egg of all amniotes was soft," said study author and Yale graduate student Matteo Fabbri. "From our study, we can also now say that the earliest archosaurs -- the group that includes dinosaurs, crocodiles, and pterosaurs -- had soft eggs. Up to this point, people just got stuck using the extant archosaurs -- crocodiles and birds -- to understand dinosaurs."
Because soft eggshells are more sensitive to water loss and offer little protection against mechanical stressors, such as a brooding parent, the researchers propose that they were probably buried in moist soil or sand and then incubated with heat from decomposing plant matter, similar to some reptile eggs today.
Read more at Science Daily
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