среда, 30 января 2019 г.

A landscape unseen in over 40,000 years

Glacial retreat in the Canadian Arctic has uncovered landscapes that haven’t been ice-free in more than 40,000 years and the region may be experiencing its warmest century in 115,000 years, new University of Colorado Boulder research finds.











A landscape unseen in over 40,000 years
Credit: University of Colorado at Boulder

The study, published this week in the journal Nature Communications, uses radiocarbon dating to determine the ages of plants collected at the edges of 30 ice caps on Baffin Island, west of Greenland. The island has experienced significant summertime warming in recent decades.


“The Arctic is currently warming two to three times faster than the rest of the globe, so naturally, glaciers and ice caps are going to react faster,” said Simon Pendleton, lead author and a doctoral researcher in CU Boulder’s Institute of Arctic and Alpine Research (INSTAAR).


Baffin is the world’s fifth largest island, dominated by deeply incised fjords separated by high-elevation, low-relief plateaus. The thin, cold plateau ice acts as a kind of natural cold storage, preserving ancient moss and lichens in their original growth position for millennia.


“We travel to the retreating ice margins, sample newly exposed plants preserved on these ancient landscapes and carbon date the plants to get a sense of when the ice last advanced over that location,” Pendleton said. “Because dead plants are efficiently removed from the landscape, the radiocarbon age of rooted plants define the last time summers were as warm, on average, as those of the past century”


In August, the researchers collected 48 plant samples from 30 different Baffin ice caps, encompassing a range of elevations and exposures. They also sampled quartz from each site in order to further establish the age and ice cover history of the landscape.


Once the samples were processed and radiocarbon dated back in labs at the Institute of Arctic and Alpine Research (INSTAAR) at CU Boulder and the University of California Irvine, the researchers found that these ancient plants at all 30 ice caps have likely been continuously covered by ice for at least the past 40,000 years.


“Unlike biology, which has spent the past three billion years developing schemes to avoid being impacted by climate change, glaciers have no strategy for survival,” said Gifford Miller, senior author of the research and a professor of geological sciences at CU Boulder. “They’re well behaved, responding directly to summer temperature. If summers warm, they immediately recede; if summers cool, they advance. This makes them one of the most reliable proxies for changes in summer temperature.”


When compared against temperature data reconstructed from Baffin and Greenland ice cores, the findings suggest that modern temperatures represent the warmest century for the region in 115,000 years and that Baffin could be completely ice-free within the next few centuries.


“You’d normally expect to see different plant ages in different topographical conditions,” Pendleton said. “A high elevation location might hold onto its ice longer, for example. But the magnitude of warming is so high that everything is melting everywhere now.”


“We haven’t seen anything as pronounced as this before,” Pendleton said.


Author: Trent Knoss | Source: University of Colorado at Boulder [Janaury 25, 2019]



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Climate change reshaping how heat moves around globe

The Earth’s atmosphere and oceans play important roles in moving heat from one part of the world to another, and new research is illuminating how those patterns are changing in the face of climate change.











Climate change reshaping how heat moves around globe
Gentoo penguins stand on a rock near station Bernardo O’Higgins, Antarctica
[Credit:Natacha Pisarenko/AP]

“The greenhouse effect and carbon dioxide aren’t the only issues to consider as the planet grows warmer — they are just one part of the equation. The way that the atmosphere and oceans move heat around is changing, too, and this could have significant effects on temperatures around the world,” said Zhengyu Liu, co-lead author of the study and professor of climate dynamics in the Department of Geography at The Ohio State University.
Liu and Chengfei He, a graduate student in Ohio State’s atmospheric science program, analyzed model simulations to illustrate how heat is expected to be transferred by the oceans and atmosphere in the near future. The researchers compared the models with historical temperature data from the oceans themselves to paint a clearer picture of how climate change is shifting and will continue to shift these patterns in this century. Their study appears online in the journal Nature Climate Change.


Without heat transfer, the world’s hottest spots would be sizzling and the coolest spots would be even more frigid. Conditions in both hot and cold climates are affected by the movement of heat from the equator toward the poles in the atmosphere and oceans, He said.


As scientists look for a better understanding of all the factors contributing to climate change — and for ways to ameliorate the problem — these heat-transfer patterns are important to watch, He said.


This is the first study to examine current changes in heat transfer and to conclude that warming temperatures are driving increased heat transfer in the atmosphere, which is compensated by a reduced heat transfer in the ocean. Additionally, the researchers concluded that the excess oceanic heat is trapped in the Southern Ocean around the Antarctic.


“The ocean stores a lot of heat and in the last 50 years that has increased. And we can correlate that directly with increases in atmospheric carbon dioxide caused by human activity,” Liu said. “Most studies like this have looked at future changes, hundreds of years from now. We examined the near-term differences of a warming climate.”


For now, that heat is not re-entering the atmosphere, but at some point it may. If that were to happen, changes in heat transfer could contribute to significant shifts in normal temperatures worldwide, he said.


“For instance, if we didn’t have heat transfer, Ohio would be 20 or 30 degrees colder than we are right now,” Liu said. “Therefore, it is important to predict how the heat transfer will be changed in the future.”


Author: Misti Crane | Source: Ohio State University [January 28, 2019]



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Humans colonized diverse environments in Southeast Asia and Oceania during the...

Investigations into what it means to be human have often focused on attempts to uncover the earliest material traces of ‘art’, ‘language’, or technological ‘complexity’. More recently, however, scholars have begun to argue that more attention should be paid to the ecological uniqueness of our species. A new study, published in Archaeological Research in Asia, reviews the palaeoecological information associated with hominin dispersals into Southeast Asia and Oceania throughout the Pleistocene (1.25 Ma to 12 ka).











Humans colonized diverse environments in Southeast Asia and Oceania during the Pleistocene
Despite previous notions of tropical forests as “green deserts” not suitable for human habitation it is now clear that
human occupation and modification of these habitats occurred as far back as 45,000 years ago. As our species
expanded into these settings beyond Africa, they burnt vegetation to maintain resources patches and practiced
specialized, sustainable hunting of select animals such as primates [Credit: Patrick Roberts]

Our species’ ability to specialize in the exploitation of diverse and ‘extreme’ settings in this part of the world stands in stark contrast to the ecological adaptations of other hominin taxa, and reaffirms the utility of exploring the environmental adaptations of Homo sapiens as an avenue for understanding what it means to be human.
The paper, published by scientists from the Max Planck Institute for the Science of Human History focuses on hominin movements across the supposed ‘Movius Line’ a boundary previously argued to separate populations with different cultural and cognitive capacities.


While such divisions and assumptions are now clearly outdated, the authors argue that focus on this part of the world may, instead, be used to study the different patterns of colonization of diverse tropical and maritime habitats by different members of our ancestral line.











Humans colonized diverse environments in Southeast Asia and Oceania during the Pleistocene
Lowland Palawan, the Philippines — Southeast Asia offers a particularly exciting region in regard of early hominin
movements across the supposed “Movius Line” a boundary previously argued to separate populations. Records
from the region can be linked to a variety of hominins throughout the Pleistocene, including Homo erectus,
Homo floresiensis (or “the Hobbit”), and Homo sapiens [Credit: Noel Amano]

As Noel Amano, co-author on the study states, ‘analysis of biogeochemical records, animal assemblages, and fossil plant records associated with hominin arrival can be used to reconstruct the degree to which novel or specialized adaptations were required at a given place and time’.
Southeast Asia offers a particularly exciting region in this regard as such records can be linked to a variety of hominins throughout the Pleistocene, including Homo erectus, Homo floresiensis (or ‘the Hobbit’), and Homo sapiens.


As Patrick Roberts, lead author of the study states the accumulated evidence shows, ‘While earlier members of our genus appear to have followed riverine and lacustrine corridors, Homo sapiens specialized in adaptations to tropical rainforests, faunally depauperate island settings, montane environments, and deep-water marine habitats.’











Humans colonized diverse environments in Southeast Asia and Oceania during the Pleistocene
Cagayan, Northern Luzon, the Philippines — Southeast Asia offers a particularly exciting region in regard of early
hominin movements across the supposed “Movius Line” a boundary previously argued to separate populations.
Records from the region can be linked to a variety of hominins throughout the Pleistocene, including
Homo erectus, Homo floresiensis (or “the Hobbit”), and Homo sapiens [Credit: Noel Amano]

The authors hope that, in future, the growth of new methods and records for determining past hominin ecologies will enable similar comparisons to be undertaken in different parts of the world, further testing the unique capacities of our species during its global expansion.


Source: Max Planck Institute for the Science of Human History [January 28, 2019]



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Long-necked dinosaurs rotated their forefeet to the side

Long-necked dinosaurs (sauropods) could orient their forefeet both forward and sideways. The orientation of their feet depended on the speed and centre of mass of the animals. An international team of researchers investigated numerous dinosaur footprints in Morocco at the foot of the Atlas Mountains using state-of-the-art methods. By comparing them with other sauropods tracks, the scientists determined how the long-necked animals moved forward. The results have now been published in the Journal of Vertebrate Paleontology.











Long-necked dinosaurs rotated their forefeet to the side
Well preserved footprints of the find site in Morocco with clearly visible claw impressions
[Credit: The Society of Vertebrate Paleontology]

“Long-necked dinosaurs” (sauropods) were among the most successful herbivores of the Mesozoic Era — the age of the dinosaurs. Characteristic for this group were a barrel-shaped body on columnar legs as well as an extremely long neck, which ended in a relatively small head. Long-necked dinosaurs existed from about 210 to 66 million years ago — they thus had been able to assert themselves on earth for a very long period. Also their gigantism, with which they far surpassed other dinosaurs, points at their success.
Sauropods included the largest land animals in Earth history, some over 30 metres long and up to 70 tonnes in weight. “However, it is still unclear how exactly these giants moved,” says Jens Lallensack, paleontologist at the Institute of Geosciences and Meteorology at the University of Bonn in Germany. The limb joints were partly cartilaginous and therefore not fossilised, allowing only limited conclusions about the range of movement.


Detective work with 3D computer analyses


The missing pieces of the puzzle, however, can be reconstructed with the help of fossil footprints of the giants. An international team of researchers from Japan, Morocco and Germany, led by the University of Bonn, has now investigated an unique track site in Morocco at the foot of the Atlas Mountains. The site consists of a surface of 54 x 6 metres which was vertically positioned during mountain formation and shows hundreds of individual footprints, some of which overlap.











Long-necked dinosaurs rotated their forefeet to the side
This is the complete surface of the track site in Morocco, which is 54 meters in length and contains hundreds
of footprints [Credit: © The Society of Vertebrate Paleontology]

A part of these footprints could be assigned to a total of nine trackways (sequences of individual footprints). “Working out individual tracks from this jumbled mess of footprints was detective work and only possible through the analysis of high-resolution 3D models on the computer,” says Dr. Oliver Wings of the Zentralmagazin Naturwissenschaftlicher Sammlungen der Martin-Luther-Universität Halle-Wittenberg in Germany.
The researchers were amazed by the results: the trackways are extremely narrow — the right and left footprints are almost in line. Also, the forefoot impressions are not directed forwards, as is typical for sauropod tracks, but point to the side, and sometimes even obliquely backwards. Even more: The animals were able to switch between both orientations as needed.











Long-necked dinosaurs rotated their forefeet to the side
The front part of the track site in Morocco with the two longest trackways. Above: 3-D model as depth color image,
below: Interpretation of the footprints [Credit: The Society of Vertebrate Paleontology]

“People are able to turn their palms downwards by crossing the ulna and radius,” says Dr. Michael Buchwitz of the Museum für Naturkunde Magdeburg. However, this complicated movement is limited to mammals and chameleons in today’s terrestrial vertebrates. It was not possible in other animals, including dinosaurs. Sauropods must therefore have found another way of turning the forefoot forwards.


How can the rotation of the forefoot be explained?


How can the rotation of the forefoot in the sauropod tracks be explained? The key probably lies in the mighty cartilage layers, which allowed great flexibility in the joints, especially in the shoulder. But why were the hands rotated outwards at all?


“Outwardly facing hands with opposing palms were the original condition in the bipedal ancestors of the sauropods,” explains Shinobu Ishigaki of the Okayama University of Science, Japan. The question should therefore be why most sauropods turned their forefeet forwards — an anatomically difficult movement to implement.











Long-necked dinosaurs rotated their forefeet to the side
Life reconstruction of the trackmaker, an early sauropod dinosaur
[Credit: Darius Nau]

A statistical analysis of sauropod tracks from all over the world could provide important clues: Apparently the animals tended to have outwardly directed forefeet when the foreleg was not used for active locomotion but only for carrying body weight.
Thus the forefeet were often rotated further outwards when the animal moved slowly and the centre of mass of the body was far back. Only if the hands were also used for the forward drive, a forefoot directed to the front was advantageous.


The analysis furthermore showed that the outer rotation of the forefeet was limited to smaller individuals, whereas in larger animals they were mostly directed forward. The large animals apparently could no longer rotate their forefeet sideways. “This loss of mobility was probably a direct result of their gigantism,” says Lallensack.


Author: Jens Lallensack | Source: University of Bonn [January 29, 2019]



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Researchers address challenges of curating ancient biomolecules

University of Oklahoma researchers, led by Courtney Hofman and Rita Austin, in collaboration with the Smithsonian National Museum of Natural History, are addressing the challenges of curating ancient biomolecules and working toward the development and dissemination of best practices. In a recent paper published in the Proceedings of the National Academy of Sciences, Hofman and her collaborators suggest museums play a critical role among stakeholders in ancient biomolecules research and should be responsive to these concerns.











Researchers address challenges of curating ancient biomolecules
Hofman co-directs the Laboratories for Molecular Anthropology and Microbiome
on the OU Research Campus [Credit: University of Oklahoma]

“Ancient biomolecules research has been transformed by new methods, but more dialogue is needed between researchers and museum collections, as historical curation practices can influence biomolecular preservation in unexpected ways,” said Hofman, assistant professor in the Department of Anthropology, OU College of Arts and Sciences, and co-director of the Laboratories for Molecular Anthropology and Microbiome Research. “Biomolecular techniques offer new avenues to understand the past, and curating for biomolecules can increase their research applicability and continuing relevance.”
Biomolecular research has sparked a methodological revolution in the field of anthropology, and museums are now faced with the challenge of conserving and evaluating materials for these new methods. Anthropological collections are important for science and society, due in no small part to their potential applications for biomolecular research. Museums everywhere face challenges to balance the scientific interests, descendant concerns and the need to preserve collections for future generations.
“As centralized places housing biomolecules, disseminating knowledge to the public and connecting stakeholders (including descendant communities), the voice and role of museums is imperative for establishing best practices and standards for molecular research on collections to ensure ethical scientific investigations of museum materials, and support sustainable collaborations,” said Austin, OU graduate student. “Active discussion and consultation with stakeholders continue to be critical for preserving collections and developing innovative research partnerships.”


Source: University of Oklahoma [January 29, 2019]



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Ancient Mongolian skull is the earliest modern human yet found in the region

A much debated ancient human skull from Mongolia has been dated and genetically analysed, showing that it is the earliest modern human yet found in the region, according to new research from the University of Oxford. Radiocarbon dating and DNA analysis have revealed that the only Pleistocene hominin fossil discovered in Mongolia, initially called Mongolanthropus, is in reality a modern human who lived approximately 34 – 35 thousand years ago.











Ancient Mongolian skull is the earliest modern human yet found in the region
Salkhit skullcap [Credit: © Maud Dahlem, Muséum de Toulouse (France)]

The skullcap, found in the Salkhit Valley northeast Mongolia is, to date, the only Pleistocene hominin fossil found in the country.


The skullcap is mostly complete and includes the brow ridges and nasal bones. The presence of archaic or ancient features have led in the past to the specimen being linked with uncharacterized archaic hominin species, such as Homo erectus and Neanderthals. Previous research suggested ages for the specimen ranging from the Early Middle Pleistocene to the terminal Late Pleistocene.


The Oxford team re-dated the specimen to 34,950 – 33,900 years ago. This is around 8,000 years older than the initial radiocarbon dates obtained on the same specimen.


To make this discovery, the Oxford team employed a new optimised technique for radiocarbon dating of heavily contaminated bones. This method relies on extracting just one of the amino acids from the collagen present in the bone. The amino acid hydroxyproline (HYP), which accounts for 13% of the carbon in mammalian collagen, was targeted by the researchers. Dating this amino acid allows for the drastic improvement in the removal of modern contaminants from the specimens.


The new and reliable radiocarbon date obtained for the specimen shows that this individual dates to the same period as the Early Upper Palaeolithic stone tool industry in Mongolia, which is usually associated with modern humans. The age is later than the earliest evidence for anatomically modern humans in greater Eurasia, which could be in excess of 100,000 years in China according to some researchers.











Ancient Mongolian skull is the earliest modern human yet found in the region
View of the find spot in the Salkhit Valley, Mongolia [Credit: © Institute of History
and Archaeology & Academy of Sciences (Mongolia)]

This new result also suggests that there was still a significant amount of unremoved contamination in the sample during the original radiocarbon measurements. Additional analyses performed in collaboration with scientists at the University of Pisa (Italy) confirmed that the sample was heavily contaminated by the resin that had been used to cast the specimen after its discovery.


“The research we have conducted shows again the great benefits of developing improved chemical methods for dating prehistoric material that has been contaminated, either in the site after burial, or in the museum or laboratory for conservation purposes.” said Dr Thibaut Devièse first author on the new paper and leading the method developments in compound specific analysis at the University of Oxford. “Robust sample pretreatment is crucial in order to build reliable chronologies in archaeology.”


DNA analyses were also performed on the hominin bones by Professor Svante Pääbo’s team at the Max-Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Diyendo Massiliani and colleagues reconstructed the complete mitochondrial genome of the specimen. It falls within a group of modern human mtDNAs (haplogroup N) that is widespread in Eurasia today, confirming the view of some researchers that the cranium is indeed a modern human. Further nuclear DNA work is underway to shed further light on the genetics of the cranium.


‘This enigmatic cranium has puzzled researchers for some time”, said Professor Tom Higham, who leads the PalaeoChron research group at the University of Oxford. “A combination of cutting edge science, including radiocarbon dating and genetics, has now shown that this is the remain of a modern human, and the results fit perfectly within the archaeological record of Mongolia which link moderns to the Early Upper Palaeolithic industry in this part of the world.’


The research has been published in the journal Nature Communications.


Source: University of Oxford [January 30, 2019]



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Extreme Science: Launching Sounding Rockets from The Arctic

This winter, our scientists and engineers traveled to the

world’s northernmost civilian town to launch rockets equipped with cutting-edge

scientific instruments.


image

This is the beginning of a 14-month-long campaign to study a particular

region of Earth’s magnetic field — which means launching near the poles. What’s

it like to launch a science rocket in these extreme conditions?


image

Our planet is protected by a natural magnetic field that

deflects most of the particles that flow out from the Sun — the solar wind —

away from our atmosphere. But near the north and south poles, two oddities in

Earth’s magnetic field funnel these solar particles directly into our

atmosphere. These regions are the polar cusps, and it turns out they’re the

ideal spot for studying how our atmosphere interacts with space.


image

The scientists of the Grand Challenge Initiative — Cusp are

using sounding rockets to do their research. Sounding

rockets are suborbital rockets that launch to a few hundred miles in altitude,

spending a few minutes in space before falling back to Earth. That means

sounding rockets can carry sensitive instruments above our atmosphere to study

the Sun, other stars and even distant galaxies.


They also fly directly through some of the most interesting

regions of Earth’s atmosphere, and that’s what scientists are taking advantage

of for their Grand Challenge experiments.


image

One of the ideal rocket ranges for cusp science is in

Ny-Ålesund, Svalbard, off the coast of Norway and within the Arctic circle.

Because of its far northward position, each morning Svalbard passes directly

under Earth’s magnetic cusp.


But launching in this extreme, remote environment puts another

set of challenges on the mission teams. These launches need to happen during

the winter, when Svalbard experiences 24/7 darkness because of Earth’s axial

tilt. The launch teams can go months without seeing the Sun.


image

Like for all rocket launches, the science teams have to wait

for the right weather conditions to launch. Because they’re studying upper

atmospheric processes, some of these teams also have to wait for other science

conditions, like active auroras. Auroras are created when charged particles

collide with Earth’s atmosphere — often triggered by solar storms or changes in

the solar wind — and they’re related to many of the upper-atmospheric processes

that scientists want to study near the magnetic cusp.


image

But even before launch, the extreme conditions make

launching rockets a tricky business — it’s so cold that the rockets must be

encased in styrofoam before launch to protect them from the low temperatures

and potential precipitation.


image

When all is finally ready, an alarm sounds throughout the

town of Ny-Ålesund to alert residents to the impending launch. And then it’s

up, up and away! This photo shows the launch of the twin VISIONS-2 sounding rockets on Dec.

7, 2018 from Ny-Ålesund.


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These rockets are designed to break up during flight — so

after launch comes clean-up. The launch teams track where debris lands so that

they can retrieve the pieces later.


image

The

next launch of the Grand Challenge Initiative is AZURE, launching from Andøya

Space Center in Norway in April 2019.


 For even more about what it’s like to launch science rockets

in extreme conditions, check out one scientist’s notes from the field: https://go.nasa.gov/2QzyjR4


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For updates on the Grand Challenge Initiative and other

sounding rocket flights, visit nasa.gov/soundingrockets or follow along with NASA Wallops and NASA

heliophysics on Twitter and Facebook.


@NASA_Wallops | NASA’s Wallops Flight Facility | @NASASun | NASA Sun Science


Roman Barracks Columns and Corner Interval Tower, Chesters Roman Fort, Hadrian’s...

Roman Barracks Columns and Corner Interval Tower, Chesters Roman Fort, Hadrian’s Wall, Northumberland, 27.1.19.











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2019 January 30 Wide Field View of Great American Eclipse Image…


2019 January 30


Wide Field View of Great American Eclipse
Image Credit & Copyright: Nicolas Lefaudeux


Explanation: Only in the fleeting darkness of a total solar eclipse is the light of the solar corona easily visible. Normally overwhelmed by the bright solar disk, the expansive corona, the sun’s outer atmosphere, is an alluring sight. But the subtle details and extreme ranges in the corona’s brightness, although discernible to the eye, are notoriously difficult to photograph. Pictured here, however, using over 120 images and meticulous digital processing, is a detailed wide-angle image of the Sun’s corona taken during the Great American Eclipse in 2017 August. Clearly visible are intricate layers and glowing caustics of an ever changing mixture of hot gas and magnetic fields. Hundreds of stars as faint as 11th magnitude are visible behind the Moon and Sun, with Mars appearing in red on the far right. The next total eclipse of the Sun will occur on July 2 and be visible during sunset from a thin swath across Chile and Argentina.


∞ Source: apod.nasa.gov/apod/ap190130.html


South Gatehouse and Interval Tower, Chesters Roman Fort, Hadrian’s Wall,...


South Gatehouse and Interval Tower, Chesters Roman Fort, Hadrian’s Wall, Northumberland, 27.1.19.











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The West Gate of Chesters Roman Fort, Hadrian’s Wall, Northumberland, 27.1.19.This...











The West Gate of Chesters Roman Fort, Hadrian’s Wall, Northumberland, 27.1.19.


This site shows the remains of the gate post holes and a round oven. It was overlaid by a further building in the medieval period at one end.


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