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The latest Research, Reviews, News and information about Geology / Earth Science from around the web. GEOLOGY INFO
The relic of King Albert I of Belgium, bought at an auction by VTM journalist Reinout Goddyn: blood-stained tree leaves collected by people living near the forest at the foot of the rocks of Marche-les-Dames. The DNA analysis has confirmed that the blood really belonged to the monarch. Credit: Copyright KU Leuven - Maarten Larmuseau
The relic of King Albert I of Belgium, bought at an auction by VTM journalist Reinout Goddyn: blood-stained tree leaves collected by people living near the forest at the foot of the rocks of Marche-les-Dames. The DNA analysis has confirmed that the blood really belonged to the monarch. Credit: Copyright KU Leuven - Maarten Larmuseau
The death of King Albert I of Belgium in 1934 -- officially a climbing accident -- still fuels speculation. Forensic geneticist Maarten Larmuseau and his colleagues at KU Leuven (University of Leuven, Belgium), have now compared DNA from blood found on the scene in 1934 to that of two distant relatives. Their analysis confirms that the blood really is that of Albert I. This conclusion is at odds with several conspiracy theories about the king's death.

On 17 February 1934, King Albert I -- the third King of the Belgians -- died after a fall from the rocks in Marche-les-Dames, in the Ardennes region of Belgium near Namur. Albert I was popular and world famous due to his role during the First World War. The fact that there were no witnesses to his death soon fuelled speculations about the king's 'real' cause of death.

Conspiracy theories are circulating to this very day, ranging from a political murder to a crime of passion: the king is said to have been murdered elsewhere, his dead body allegedly never was in Marche-les-Dames, or his fall is believed to have been staged only later. Evidence for these theories, however, has never been found.

After the death of Albert I, Marche-les-Dames virtually became a place of pilgrimage, and relics turned up with the king's trails of blood, said to have been collected during the night of 17 to 18 February by people living in the neighbourhood.

VTM journalist Reinout Goddyn, who works for the Flemish television programme Royalty, bought one of these relics: blood-stained tree leaves. He wanted to know if this could really be the blood of Albert I, given the conspiracy theories. In 2014, UGent Professor Dieter Deforce had already confirmed that the blood was definitely human.

Forensic geneticist Maarten Larmuseau and his colleagues from KU Leuven (University of Leuven, Belgium) continued the investigation and found two living relatives of Albert I: "King Simeon II of Saxe-Coburg and Gotha, the last tsar and former prime minister of Bulgaria who is related to Albert I on his father's side, and Anna Maria Freifrau von Haxthausen, a German baroness who is related to Albert I on her mother's side, were willing to cooperate. They gave up DNA samples that we compared with the DNA of the trails of blood. We found that the blood is indeed that of Albert I."

This confirmation has historical importance. "80 years after the fact, everyone involved has passed away, and most material is gone; we will probably never be able to dismiss all speculations concerning this 'cold case'. This study was one of the last possibilities to gather additional data. The authenticity of the trails of blood confirms the official account of the death of Albert I. The story that the dead body of the king has never been in Marche-les-Dames or was only placed there at night has now become very improbable. Furthermore, the results show that conducting a perfect legal investigation at the time was impossible right from the start, because souvenir hunters had disturbed the scene."

This type of genetic family-tree research confronts researchers with quite a few ethical questions, adds bioethicist Pascal Borry from the KU Leuven Interfaculty Centre for Biomedical Ethics and Law: "We have to take into account the consequences of this study for living relatives. After all, in addition to the actual identification, a genetic profile can reveal quite a bit of sensitive information, in the context of a kinship analysis or in terms of hereditary conditions. This particular case concerns someone who's deceased and has obviously never given permission for a genetic profile."

"We only focused on the identification of the trails of blood and deliberately avoided deducing unexpected results from the DNA," Larmuseau continues. "The latter was the most difficult aspect of this study. We also want to protect the privacy of everyone involved and of living relatives, and avoid commercialization of the genetic information, following international guidelines for biomedical research. Therefore, the genetic profiles have not been published, but they were double-checked by independent experts. The DNA samples of our study have been destroyed. What is left of the relic will be entrusted to an institution for cultural heritage or a scientific institution."
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Source:
The above post is reprinted from materials provided by KU Leuven. Note: Materials may be edited for content and length.

Reference:
Maarten H.D. Larmuseau, Bram Bekaert, Maarten Baumers, Tom Wenseleers, Pieter Deforce, Pascal Borry, and Ronny Decorte. Biohistorical materials and contemporary privacy concerns -- The forensic case of King Albert I. Forensic Science International: Genetics, 2016 DOI: 10.1016/j.fsigen.2016.07.008
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The Chao volcano in northern Chile with a lava coulée approx. 14.5 km long (centre of picture). The composition of the lava matches that of deposits of adjacent supervolcanic calderas. Chao erupted about 75,000 years ago, but zircon crystals in the lava were already forming in a subterranean magma reservoir for nearly three million years. Credit: Landsat 8, U.S. Geological Survey
The Chao volcano in northern Chile with a lava coulée approx. 14.5 km long (centre of picture). The composition of the lava matches that of deposits of adjacent supervolcanic calderas. Chao erupted about 75,000 years ago, but zircon crystals in the lava were already forming in a subterranean magma reservoir for nearly three million years. Credit: Landsat 8, U.S. Geological Survey
Geoscientists from Heidelberg University have discovered accumulations of magma in the Andes sufficient to have set off a super-eruption but which, in fact, did not. Such eruptions, which expel enormous quantities of magma, are the largest volcanic events on earth. Together with colleagues from the USA, researchers from the Institute of Earth Sciences discovered that magma volumes of supervolcanic proportions have been continuously accumulating in the Altiplano-Puna region since the last super-eruption nearly 2.9 million years ago. These magmas, however, did not reach the surface to trigger a catastrophic eruption but instead slowly cooled at depth and hardened into plutonic rock. The results of the research were published in the journal Geology.

"A supervolcanic eruption spews out more than 1,000 cubic kilometres of magma, which accumulated over time in reservoirs close the earth's surface," explains Prof. Dr Axel Schmitt of the Institute of Earth Sciences. "In turn, these reservoirs are fed from deeper layers in the earth's crust and the underlying mantle. During an eruption, the overlying rock layers collapse into the empty magma chamber and form depressions, known as calderas, of up to 100 kilometres in diameter." Axel Schmitt indicates that there have been at least seven super-eruptions in the Altiplano-Puna region within the last ten million years, the most recent one about 2.9 million years ago. What remains unclear is why no further major eruptions have occurred since then and whether the region can now be considered inactive for such events.

Using samples from five comparatively small lava domes in northern Chile and southeast Bolivia, the Heidelberg researchers and their American colleagues investigated the most recent eruptions whose chemical composition matches the supervolcanic magmas from the region. They determined the age of very small zircon crystals from these lava flows with the aid of a high-spatial-resolution mass spectrometer. "The mineral zircon forms almost exclusively in magmas, so its age revealss when those magmas were present under the volcano," explains Axel Schmitt. "The astonishing result was that the ages of the zircons measured from all five of the smaller volcanoes extended continuously from the time of the eruption 75,000 years ago back to the last supervolcanic eruption."

Prof. Schmitt reports that model calculations demonstrated that zircon formation is only possible over such protracted durations if the inflow of magma amounted to approx. one cubic kilometre over 1,000 years, which is unusually high for a relatively small volcano. "This means that over a long period of time a magma volume of supervolcanic proportions must have accumulated under the five lava domes, which then solidified into plutonic rock at depth." The volcanologist explains that the lack of a major volcanic eruption does not necessarily indicate that magmatic activity has come to a complete halt. Perhaps the rise in magma from deeper regions merely slowed during the last 2.9 million years, forming an enormous body of rock known as a pluton.

"However, our results also show that a relatively small increase in the long-term magma recharge from about one to five cubic kilometres in 1,000 years would recreate conditions favouring a catastrophic supervolcanic eruption. A new super-eruption in the Altiplano-Puna region would be possible, but only after a long lead time," explains Prof. Schmitt.

Researchers from Oregon State University and the University of California in Los Angeles also contributed to the research.
***
Source:
The above post is reprinted from materials provided by Heidelberg University.

Reference:
Casey R. Tierney, Axel K. Schmitt, Oscar M. Lovera, Shanaka L. de Silva. Voluminous plutonism during volcanic quiescence revealed by thermochemical modeling of zircon. Geology, 2016; 44 (8): 683 DOI: 10.1130/G37968.1
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Schematic diagram of a subduction zone with sediments structure. Credit: C. Kersten GEOMAR
Schematic diagram of a subduction zone with sediments structure. Credit: C. Kersten GEOMAR
Where a tectonic plate dives under another, in the so-called subduction zones at ocean margins, many strong earthquakes occur. Especially the earthquakes at shallow depths often cause tsunamis. How exactly are such earthquakes initiated? Which rock composition favours a break in the earth's interior that can lead to such natural disasters? Scientists at GEOMAR Helmholtz Centre for Ocean Research Kiel and the University of Utrecht (NL) published a study in the scientific journal Nature Geoscience which points to earthquake nucleation in calcareous sediments.

The effects of earthquakes are often severe and highly visible. They can destroy homes, induce slope failures and trigger tsunamis. The main cause for earthquakes are the stresses that occur in the Earth's interior, when two tectonic plates pass each other and interlock during this process. But even the worst earthquake starts with a very small first crack in the rock from which a large fracture can develop. So far it was assumed that initial cracks for earthquakes mainly occur in clay-rich sediments. Scientists at GEOMAR Helmholtz Centre for Ocean Research Kiel and the University of Utrecht (NL) were now able to prove that under certain conditions calcareous sediments are the most likely candidates for the first breakage of an earthquake. The study is published today in the international journal Nature Geoscience.

For their investigations the scientists used samples obtained during two expeditions in 2011 and 2012 with the US drillship JOIDES RESOLUTION off the coast of Costa Rica. There the Pacific Cocos plate is subducted beneath the Caribbean plate. In the past this has repeatedly led to severe earthquakes in this region. "The aim of the Costa Rica Seismogenesis Project (CRISP) was to obtain information about the structure of the subducting and the overriding plate using drill cores" Dr. Michael Stipp from GEOMAR, initiator and second author of the current research study, explains.

During subduction the Cocos Plate carries its overlying sediments downwards, which are thus sandwiched between the plates. "Off the coast of Costa Rica, the seismogenic zone that is the zone where earthquakes are generated along the plate boundary, starts already in an exceptionally shallow depth of about five to six kilometres. This is right in these subducted sediments," Robert Kurzawski states, PhD student at GEOMAR and first author of the study.

However, the sediments usually show variable compositions. Off the coast of Costa Rica and in most subduction zones in the tropical and subtropical area both clayey and calcareous sediment layers are found. Due to the drill cores obtained from JOIDES RESOLUTION the scientist could investigate samples exactly from these sediment layers. In the "Rock Mechanics Laboratory" of the University of Utrecht they brought the samples to conditions that prevail at depth, where shallow earthquakes occur. "These conditions include an increased pressure, temperatures of about 100 degrees Celsius and finally shear movements," Dr. Stipp explains.

Since the clay sediments are considered mechanically weak, it was assumed that the first cracks would be formed in these when the subsurface stresses are large enough. In the experiments, it became clear that the clay-rich sediments from Costa Rica in contrast to the calcareous sediments react less sensitive to changes in stress, temperature and especially pore pressure. The calcareous sediments, however, change their frictional properties significantly during the increase in temperature and pore pressure. "Exactly at the conditions which are expected for shallow earthquakes the chalks suddenly got unstable and weaker than the clayey material. With these properties the calcareous sediments form the predetermined breaking point in the rock sequence, " Robert Kurzawski explains.

These results are particular interesting, because calcareous sediments are typical and widespread especially for tropical and subtropical oceans and thus occur at many subduction zones around the Pacific, but also in the Caribbean and Mediterranean Sea. "Of course we still do not know all the processes that can trigger earthquakes. But we have demonstrated by this study that material properties cannot simply be extrapolated from surface conditions to those at greater depth. Therefore, further drilling, especially in the framework of the International Ocean Discovery Program (IODP), is required to learn more about the earthquake processes at depth, " Michael Stipp concludes.
***
Source:
The above post is reprinted from materials provided by Helmholtz Centre for Ocean Research Kiel (GEOMAR).

Reference:
Kurzawski, R. M., M. Stipp, A. R. Niemeijer, C. J. Spiers, J. H. Behrmann. Earthquake nu-cleation in weak subducted carbonates. Nature Geoscience, 2016 DOI: 10.1038/ngeo2774
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Metatarsal (a) and (b) surface rendered models show medullary spongy bone infill and clear focalized cortical destruction near the periosteal margin; also evident on external cortical margin directly abutting malignant neoplasm is the characteristic hair on end bone reaction in (b). Credit: Edward Odes (Wits)
Metatarsal (a) and (b) surface rendered models show medullary spongy bone infill and clear focalized cortical destruction near the periosteal margin; also evident on external cortical margin directly abutting malignant neoplasm is the characteristic hair on end bone reaction in (b). Credit: Edward Odes (Wits)
An international team of researchers led by scientists from the University of the Witwatersrand's Evolutionary Studies Institute and the South African Centre for Excellence in PalaeoSciences today announced in two papers, published in the South African Journal of Science, the discovery of the most ancient evidence for cancer and bony tumors yet described in the human fossil record.

The discovery of a foot bone dated to approximately 1.7 million years ago from the site of Swartkrans with definitive evidence of malignant cancer, pushes the oldest date for this disease back from recent times into deep prehistory. Although the exact species to which the foot bone belongs is unknown, it is clearly that of a hominin, or bipedal human relative.

In an accompanying paper appearing in the same journal, a collaborating team of scientists identify the oldest tumor ever found in the human fossil record, a benign neoplasm found in the vertebrae of the well-known Australopithecus sediba child, Karabo from the site of Malapa, and dated to almost two million years in age. The oldest previously demonstrated possible hominin tumor was found in the rib of a Neanderthal and dated to around 120,000 years old.

Edward Odes, a Wits doctoral candidate and lead author of the cancer paper, and co-author on the tumor paper, notes "Modern medicine tends to assume that cancers and tumors in humans are diseases caused by modern lifestyles and environments. Our studies show the origins of these diseases occurred in our ancient relatives millions of years before modern industrial societies existed."

The cancer in a foot bone, a metatarsal, was identified as an osteosarcoma, an aggressive form of cancer which usually affects younger individuals in modern humans, and, if untreated typically results in early death. "Due to its preservation, we don't know whether the single cancerous foot bone belongs to an adult or child, nor whether the cancer caused the death of this individual, but we can tell this would have affected the individuals' ability to walk or run," says Dr Bernhard Zipfel, a Wits scientist and an expert on the foot and locomotion of early human relatives. "In short, it would have been painful."

Lead author of the tumor paper and co-author of the cancer paper, Dr Patrick Randolph-Quinney of Wits University and the University of Central Lancashire in the UK, suggests "The presence of a benign tumor in Australopithecus sediba is fascinating not only because it is found in the back, an extremely rare place for such a disease to manifest in modern humans, but also because it is found in a child. This, in fact, is the first evidence of such a disease in a young individual in the whole of the fossil human record."

Prof. Lee Berger, an author on both papers and leader of the Malapa project where the fossil vertebra was found adds "not only has there been an assumption that these sorts of cancers and tumors are diseases of modernity, which these fossils clearly demonstrate they are not, but that we as modern humans exhibit them as a consequence of living longer, yet this rare tumor is found in a young child. The history of these types of tumors and cancers is clearly more complex than previously thought."

Both incidents of disease were diagnosed using state of the art imaging technologies including those at the European Synchrotron Research Facility in Grenoble, France, medical CT at the Charlotte Maxeke Hospital in Johannesburg, and the micro-CT facility at the Nuclear Energy Corporation of South Africa at Pelindaba.

"Researchers in South Africa are at the forefront of using various X-Ray modalities to discover new and interesting facts about ancient human relatives," notes Dr Jacqueline Smilg, a radiologist based at Charlotte Maxeke Hospital, who is an author on both papers and was involved in the clinical diagnoses. "This is another good example of how the modern clinical sciences and the science of palaeoanthropology are working together in South Africa and with international collaborators to advance our understanding of diseases in both the past and the present."

Source:
The above post is reprinted from materials provided by University of the Witwatersrand. 

References:
  • Lee R. Berger, Paul Tafforeau, Tanya Augustine, Edward J. Odes, Steven E. Churchill, Jacqueline S. Smilg, Marc R. Meyer, Maryna Steyn, Scott A. Williams, Patrick S. Randolph-Quinney. Osteogenic tumour in Australopithecus sediba: Earliest hominin evidence for neoplastic disease. South African Journal of Science, 2016; Volume 112 (Number 7/8) DOI: 10.17159/sajs.2016/20150470
  • Lee R. Berger, Ryan D. Franklin, Jakobus W. Hoffman, Frikkie de Beer, Tanya N. Augustine, Bernhard Zipfel, Jacqueline S. Smilg, Zach Throckmorton, Maryna Steyn, Patrick S. Randolph-Quinney, Edward J. Odes. Earliest hominin cancer: 1.7-million-year-old osteosarcoma from Swartkrans Cave, South Africa. South African Journal of Science, 2016; Volume 112 (Number 7/8) DOI: 10.17159/sajs.2016/20150471
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In a new study from the U.S. Department of Energy's Argonne National Laboratory and the University of Illinois at Chicago, researchers have found a way to convert carbon dioxide into a usable energy source by using sunlight. Credit: © Romolo Tavani / Fotolia
In a new study from the U.S. Department of Energy's Argonne National Laboratory and the University of Illinois at Chicago, researchers have found a way to convert carbon dioxide into a usable energy source by using sunlight. Credit: © Romolo Tavani / Fotolia
As scientists and policymakers around the world try to combat the increasing rate of climate change, they have focused on the chief culprit: carbon dioxide.

Produced by the burning of fossil fuels in power plants and car engines, carbon dioxide continues to accumulate in the atmosphere, warming the planet. But trees and other plants do slowly capture carbon dioxide from the atmosphere, converting it to sugars that store energy.

In a new study from the U.S. Department of Energy's Argonne National Laboratory and the University of Illinois at Chicago, researchers have found a similar way to convert carbon dioxide into a usable energy source using sunlight.

One of the chief challenges of sequestering carbon dioxide is that it is relatively chemically unreactive. "On its own, it is quite difficult to convert carbon dioxide into something else," said Argonne chemist Larry Curtiss, an author of the study.

To make carbon dioxide into something that could be a usable fuel, Curtiss and his colleagues needed to find a catalyst -- a particular compound that could make carbon dioxide react more readily. When converting carbon dioxide from the atmosphere into a sugar, plants use an organic catalyst called an enzyme; the researchers used a metal compound called tungsten diselenide, which they fashioned into nanosized flakes to maximize the surface area and to expose its reactive edges.

While plants use their catalysts to make sugar, the Argonne researchers used theirs to convert carbon dioxide to carbon monoxide. Although carbon monoxide is also a greenhouse gas, it is much more reactive than carbon dioxide and scientists already have ways of converting carbon monoxide into usable fuel, such as methanol. "Making fuel from carbon monoxide means travelling 'downhill' energetically, while trying to create it directly from carbon dioxide means needing to go 'uphill,'" said Argonne physicist Peter Zapol, another author of the study.

Although the reaction to transform carbon dioxide into carbon monoxide is different from anything found in nature, it requires the same basic inputs as photosynthesis. "In photosynthesis, trees need energy from light, water and carbon dioxide in order to make their fuel; in our experiment, the ingredients are the same, but the product is different," said Curtiss.

The setup for the reaction is sufficiently similar to nature that the research team was able to construct an "artificial leaf" that could complete the entire three-step reaction pathway. In the first step, incoming photons -- packets of light -- are converted to pairs of negatively-charged electrons and corresponding positively-charged "holes" that then separate from each other. In the second step, the holes react with water molecules, creating protons and oxygen molecules. Finally, the protons, electrons and carbon dioxide all react together to create carbon monoxide and water.

"We burn so many different kinds of hydrocarbons -- like coal, oil or gasoline -- that finding an economical way to make chemical fuels more reusable with the help of sunlight might have a big impact," Zapol said.

Towards this goal, the study also showed that the reaction occurs with minimal lost energy -- the reaction is very efficient. "The less efficient a reaction is, the higher the energy cost to recycle carbon dioxide, so having an efficient reaction is crucial," Zapol said.

According to Curtiss, the tungsten diselenide catalyst is also quite durable, lasting for more than 100 hours -- a high bar for catalysts to meet.

The study, "Nanostructured transition metal dichalcogenide electrocatalysts for CO2 reduction in ionic liquid," is published in Science. Much of the experimental work was performed at the University of Illinois at Chicago, while the computational work was performed at Argonne.

Source:
The above post is reprinted from materials provided by Argonne National Laboratory.

Reference:
M. Asadi, K. Kim, C. Liu, A. V. Addepalli, P. Abbasi, P. Yasaei, P. Phillips, A. Behranginia, J. M. Cerrato, R. Haasch, P. Zapol, B. Kumar, R. F. Klie, J. Abiade, L. A. Curtiss, A. Salehi-Khojin. Nanostructured transition metal dichalcogenide electrocatalysts for CO2 reduction in ionic liquid. Science, 2016; 353 (6298): 467 DOI: 10.1126/science.aaf4767
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Simulated sunlight powers a solar cell that converts atmospheric carbon dioxide directly into syngas. Credit: University of Illinois at Chicago/Jenny Fontaine
Simulated sunlight powers a solar cell that converts atmospheric carbon dioxide directly into syngas. Credit: University of Illinois at Chicago/Jenny Fontaine
Researchers at the University of Illinois at Chicago have engineered a potentially game-changing solar cell that cheaply and efficiently converts atmospheric carbon dioxide directly into usable hydrocarbon fuel, using only sunlight for energy.

The finding is reported in the July 29 issue of Science and was funded by the National Science Foundation and the U.S. Department of Energy. A provisional patent application has been filed.

Unlike conventional solar cells, which convert sunlight into electricity that must be stored in heavy batteries, the new device essentially does the work of plants, converting atmospheric carbon dioxide into fuel, solving two crucial problems at once. A solar farm of such "artificial leaves" could remove significant amounts of carbon from the atmosphere and produce energy-dense fuel efficiently.

"The new solar cell is not photovoltaic -- it's photosynthetic," says Amin Salehi-Khojin, assistant professor of mechanical and industrial engineering at UIC and senior author on the study.

"Instead of producing energy in an unsustainable one-way route from fossil fuels to greenhouse gas, we can now reverse the process and recycle atmospheric carbon into fuel using sunlight," he said.

While plants produce fuel in the form of sugar, the artificial leaf delivers syngas, or synthesis gas, a mixture of hydrogen gas and carbon monoxide. Syngas can be burned directly, or converted into diesel or other hydrocarbon fuels.

The ability to turn CO2 into fuel at a cost comparable to a gallon of gasoline would render fossil fuels obsolete.

Chemical reactions that convert CO2 into burnable forms of carbon are called reduction reactions, the opposite of oxidation or combustion. Engineers have been exploring different catalysts to drive CO2 reduction, but so far such reactions have been inefficient and rely on expensive precious metals such as silver, Salehi-Khojin said.

"What we needed was a new family of chemicals with extraordinary properties," he said.

Salehi-Khojin and his coworkers focused on a family of nano-structured compounds called transition metal dichalcogenides -- or TMDCs -- as catalysts, pairing them with an unconventional ionic liquid as the electrolyte inside a two-compartment, three-electrode electrochemical cell.

The best of several catalysts they studied turned out to be nanoflake tungsten diselenide.

"The new catalyst is more active; more able to break carbon dioxide's chemical bonds," said UIC postdoctoral researcher Mohammad Asadi, first author on the Science paper.

In fact, he said, the new catalyst is 1,000 times faster than noble-metal catalysts -- and about 20 times cheaper.

Other researchers have used TMDC catalysts to produce hydrogen by other means, but not by reduction of CO2. The catalyst couldn't survive the reaction.

"The active sites of the catalyst get poisoned and oxidized," Salehi-Khojin said. The breakthrough, he said, was to use an ionic fluid called ethyl-methyl-imidazolium tetrafluoroborate, mixed 50-50 with water.

"The combination of water and the ionic liquid makes a co-catalyst that preserves the catalyst's active sites under the harsh reduction reaction conditions," Salehi-Khojin said.

The UIC artificial leaf consists of two silicon triple-junction photovoltaic cells of 18 square centimeters to harvest light; the tungsten diselenide and ionic liquid co-catalyst system on the cathode side; and cobalt oxide in potassium phosphate electrolyte on the anode side.

When light of 100 watts per square meter -- about the average intensity reaching Earth's surface -- energizes the cell, hydrogen and carbon monoxide gas bubble up from the cathode, while free oxygen and hydrogen ions are produced at the anode.

"The hydrogen ions diffuse through a membrane to the cathode side, to participate in the carbon dioxide reduction reaction," said Asadi.

The technology should be adaptable not only to large-scale use, like solar farms, but also to small-scale applications, Salehi-Khojin said. In the future, he said, it may prove useful on Mars, whose atmosphere is mostly carbon dioxide, if the planet is also found to have water.

"This work has benefitted from the significant history of NSF support for basic research that feeds directly into valuable technologies and engineering achievements," said NSF program director Robert McCabe.

"The results nicely meld experimental and computational studies to obtain new insight into the unique electronic properties of transition metal dichalcogenides," McCabe said. "The research team has combined this mechanistic insight with some clever electrochemical engineering to make significant progress in one of the grand-challenge areas of catalysis as related to energy conversion and the environment."

Source:
The above post is reprinted from materials provided by University of Illinois at Chicago.

Reference:
Mohammad Asadi et al. Nanostructured transition metal dichalcogenide electrocatalysts for CO2 reduction in ionic liquid. Science, July 2016 DOI: 10.1126/science.aaf4767
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Rope making tool from mammoth ivory from Hohle Fels Cave in southwestern Germany, ca. 40,000 years old. Credit: Copyright University of Tübingen
Rope making tool from mammoth ivory from Hohle Fels Cave in southwestern Germany, ca. 40,000 years old. Credit: Copyright University of Tübingen
Prof. Nicholas Conard and members of his team, present the discovery of a tool used to make rope in today‘s edition of the journal: Archäologische Ausgrabungen Baden-Württemberg.

Rope and twine are critical components in the technology of mobile hunters and gatherers. In exceptional cases impressions of string have been found in fired clay and on rare occasions string was depicted in the contexts of Ice Age art, but on the whole almost nothing is known about string, rope and textiles form the Paleolithic.

A key discovery by Conard’s team in Hohle Fels Cave in southwestern Germany and experimental research and testing by Dr. Veerle Rots and her team form the University of Liège is rewriting the history of rope.

The find is a carefully carved and beautifully preserved piece of mammoth ivory 20.4 cm in length with four holes between 7 and 9 mm in diameter. Each of the holes is lined with deep, and precisely cut spiral incisions. The new find demonstrates that these elaborate carvings are technological features of rope-making equipment rather than just decoration.

Similar finds in the past have usually been interpreted as shaft-straighteners, decorated artworks or even musical instruments. Thanks to the exceptional preservation of the find and rigorous testing by the team in Liège, the researchers have demonstrated that the tool was used for making rope out of plant fibers available near Hohle Fels. “This tool answers the question of how rope was made in the Paleolithic”, says Veerle Rots, “a question that has puzzled scientists for decades.”

Excavators found the rope-making tool in archaeological horizon Va near the base of the Aurignacian deposits of the site. Like the famous female figurines and the flutes recovered from the Hohle Fels, the rope-making tool dates to about 40,000 years ago, the time when modern humans arrived in Europe. The discovery underlines the importance of fiber technology and the importance of rope and string for mobile hunters and gatherers trying to cope with challenges of life in the Ice Age.

Prof. Conard’s team has excavated at Hohle Fels over each of the last 20 years, and it is this long-term commitment that has over and over again paid off, to make Hohle Fels one of the best known Paleolithic sites worldwide. Hohle Fels and neighboring sites from the Ach and Lone Valleys have been nominated for UNESCO World Cultural Heritage status. The excavations at Hohle Fels near Schelklingen in the Ach Valley are funded by the HeidelbergCement AG, the Ministry of Science of Baden-Württemberg and the Heidelberger Academie of Sciences.

The rope-making tool will be on exhibit at the Urgeschichtliches Museum in Blaubeuren starting Saturday, July 23rd . (www.urmu.de)
***

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The above post is reprinted from materials provided by Universitaet Tübingen.
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Plastic pollution is now recognized as a global problem, representing a threat to marine biodiversity. In particular, this surface drift acts as a means of transport for the viruses and bacteria that the spread across the oceans. Credit: © IRD / Y. Bettarel
Plastic pollution is now recognized as a global problem, representing a threat to marine biodiversity. In particular, this surface drift acts as a means of transport for the viruses and bacteria that the spread across the oceans. Credit: © IRD / Y. Bettarel
Plastic "continents" are not static. Based on the oceanic circulation modelling work conducted in the Pacific, the IRD and CNRS researchers have recently shown that there are exit currents for these areas of the sea where these piles of waste build up. This means that they are not caught in a never-ending whirlpool in the middle of the ocean, as had been previously thought. Although inappropriate given the actual estimated concentrations, this term highlights the awareness of the impact of human activity on the oceans.

A huge waste vortex in each ocean

Due to the winds on the surface of the oceans and the rotation of Earth (via the Coriolis force), huge vortexes, called "oceanic gyres," are formed in each of the five major basins: North and South Pacific, North and South Atlantic, and the Indian Ocean. These huge whirlpools slowly gather in their wake all the plastic objects and waste floating on the surface of the water, accumulating year after year.

This pollution is now recognized as a global problem, representing a threat to marine biodiversity. In particular, this surface drift acts as a means of transport for the viruses and bacteria that the spread across the oceans.

"Exit doors"exist

Nevertheless, these plastic "continents," as they incorrectly christened, are not, in fact, static. The IRD and CNRS researchers have recently revealed the existence of "exit doors" leading away from these large surface current convergence zones. The scientists started by studying the oceanic circulation in the Pacific modelled with a much finer spatial resolution than that of the models generally used for this type of study (those typically used for climate research). They simulated the trajectories of several million particles, with currents defined on networks of 1/32° to 1/4° (meaning a range from a few kilometres to thirty or forty kilometres). The results obtained highlight currents, several hundred kilometres wide, which escape from the heart of the subtropical gyre and head eastwards instead. In addition to these currents there are physical processes such as the effects of the wind and waves, not taken into account in the models, which can also alter the trajectory and the transit time of the particles and waste.

Bound for South American coastlines

In the Pacific, the waste may not necessarily be trapped in the centre of the oceanic gyre and may be removed in the direction of the American coasts. Furthermore, these results are backed up by the work of the IRD's Chilean partners. They have observed an increase in the amount of waste collected on their coastlines.

More detailed observations, modelling and analyses are required to gain a better understanding of the ocean surface currents that regulate the slow routing of plastic waste on the surface of the seas and, in the medium-term, implement strategies for collecting and recycling all of this waste.
***

Source:
The above post is reprinted from materials provided by Institut de Recherche pour le Développement (IRD).

Reference:
Christophe Maes, Bruno Blanke, Elodie Martinez. Origin and fate of surface drift in the oceanic convergence zones of the eastern Pacific. Geophysical Research Letters, 2016; 43 (7): 3398 DOI: 10.1002/2016GL068217
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Schematic diagram of the atmosphere. Credit: Graphics: C. Kersten, GEOMAR
Schematic diagram of the atmosphere. Credit: Graphics: C. Kersten, GEOMAR
Water plays a major role for our planet not only in its liquid form at the surface. In the atmosphere too, it considerably affects our lives as well as weather and climate. Clouds and rainfall are one example. Water vapor, the gaseous form of water, also plays a prominent role on Earth. It is the most important greenhouse gas in the atmosphere, without it the Earth would be a frozen planet. For climate variations, water vapor is particularly important in the stratosphere at altitudes between 15 and 50 kilometers. How much of the gas actually reaches the stratosphere mainly depends on the temperature at the transition between the lowest atmospheric layer, the troposphere, and the overlying stratosphere. This boundary layer is called the tropopause.

Now scientists of the GEOMAR Helmholtz Centre for Ocean Research Kiel, together with a colleague from Bergen (Norway), were able to demonstrate for the first time that natural fluctuations in water temperatures of the Pacific -- which occur on decadal timescales -- are directly related to the temperature of the tropical tropopause. "It has long been thought that human influences already affected the tropopause. However, it seems that natural variability is still the dominating factor," says Dr. Wuke Wang from GEOMAR, lead author of the study just published in the international journal Scientific Reports.

For their study, the researchers used observations for the period 1979-2013 and also climate models. "We were thus able to extend the study period to nearly 150 years. The model allows us to easily look at both human and natural influences and to separate their impacts from each other," explains Prof. Dr. Katja Matthes, climate researcher at GEOMAR and co-author of the study.

A well-known climatic phenomenon is the so-called Pacific Decadal Oscillation (PDO). "This natural variation with decadal timescale leads to anomalously high or low water temperatures of the Pacific," explained Dr. Wang. The PDO influences the climate and ecosystems in the Pacific region and also the global mean temperature of the Earth.

The model simulations show that the fluctuations in water temperatures also affect the wind systems over the tropical and subtropical Pacific. This in turn also alters the air transport between the lower and upper layers of the troposphere, ultimately regulating the temperatures at the boundary to the stratosphere. "We were now able to demonstrate these relationships for the first time," said Dr. Wang.

Thus, the current study contradicts earlier hypotheses about the temperature variability of the tropical tropopause. As early as in the late 20th century, scientists had seen a cooling trend there which began in the 1970s. They traced this observation back to anthropogenic causes, in particular the increase in greenhouse gases. "However, this assumption was based on a rather patchy data base and simplified climate models. Our study shows that the cooling of the tropical tropopause does not have to be a one-way street but could also be part of a natural fluctuation which extends over several decades," Professor Matthes emphasized.

This knowledge is also of paramount importance for the general climate research. The temperature of the tropopause decides on the input of water vapor into the stratosphere: The higher the water vapor content in the stratosphere, the higher the increase in surface temperatures. Anthropogenic climate change also has an effect on the temperature of the tropopause, and this effect could become more evident in the coming decades. "Only if we can clearly distinguish natural variability from anthropogenic influences, we can make reliable forecasts for the future development of our climate," Prof. Matthes summarizes.
***

Source:
The above post is reprinted from materials provided by Helmholtz Centre for Ocean Research Kiel (GEOMAR).

Reference:
Wuke Wang, Katja Matthes, Nour-Eddine Omrani, Mojib Latif. Decadal variability of tropical tropopause temperature and its relationship to the Pacific Decadal Oscillation. Scientific Reports, 2016; 6: 29537 DOI: 10.1038/srep29537
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Brandon VanderBeek, a doctoral student at the University of Oregon, led a study that investigated interactions of the Earth's mantle and tectonic plates off the coast of Washington state. Credit: University of Oregon
Brandon VanderBeek, a doctoral student at the University of Oregon, led a study that investigated interactions of the Earth's mantle and tectonic plates off the coast of Washington state. Credit: University of Oregon
Deep down below us is a tug of war moving at less than the speed of growing fingernails. Keeping your balance is not a concern, but how the movement happens has been debated among geologists.

New findings from under the Pacific Northwest Coast by University of Oregon and University of Washington scientists now suggest a solution to a mystery that surfaced when the theory of plate tectonics arose: Do the plates move the mantle, or does the mantle move the plates.

The separation of tectonic plates, the researchers proposed in a paper online ahead of print in the journal Nature Geoscience, is not simply dictating the flow of the gooey, lubricating molten material of the mantle. The mantle, they argue, is actually fighting back, flowing in a manner that drives a reorientation of the direction of the plates.

The new idea is based on seismic imaging of the Endeavor segment of the Juan de Fuca Plate in the Pacific Ocean off Washington and on data from previous research on similar ridges in the mid-Pacific and mid-Atlantic oceans.

"Comparing seismic measurements of the present mantle flow direction to the recent movements of tectonic plates, we find that the mantle is flowing in a direction that is ahead of recent changes in plate motion," said UO doctoral student Brandon P. VanderBeek, the paper's lead author. "This contradicts the traditional view that plates move the mantle."

While the new conclusion is based on a fraction of such sites under the world's oceans, a consistent pattern was present, VanderBeek said. At the three sites, the mantle's flow is rotated clockwise or counterclockwise rather than in the directions of the separating plates. The mantle's flow, the researchers concluded, may be responsible for past and possibly current changes in plate motion.

The research -- funded through National Science Foundation grants to the two institutions -- also explored how the supply of magma varies under mid-ocean ridge volcanoes. The researchers conducted a seismic experiment to see how seismic waves moved through the shallow mantle below the Endeavor segment.

They found that the middle of the volcanic segment, where the seafloor is shallowest and the inferred volcanic activity greatest, the underlying mantle magma reservoir is relatively small. The ends, however, are much deeper with larger volumes of mantle magma pooling below them because there are no easy routes for it to travel through the material above it.

Traditional thinking had said there would be less magma under the deep ends of such segments, known as discontinuities.

"We found the opposite," VanderBeek said. "The biggest volumes of magma that we believe we have found are located beneath the deepest portions of the ridges, at the segment ends. Under the shallow centers, there is much less melt, about half as much, at this particular ridge that we investigated.

"Our idea is that the ultimate control on where you have magma beneath these mountain ranges is where you can and cannot take it out," he said. "At the ends, we think, the plate rips apart much more diffusely, so you are not creating pathways for magma to move, build mountains and allow for an eruption."
***

Source:
The above post is reprinted from materials provided by University of Oregon.

Reference:
Brandon P. VanderBeek, Douglas R. Toomey, Emilie E. E. Hooft, William S. D. Wilcock. Segmentation of mid-ocean ridges attributed to oblique mantle divergence. Nature Geoscience, 2016; DOI: 10.1038/ngeo2745
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Illustration showing size comparison of Australian marsupials including new extinct species of carnivorous marsupial, Whollydooleya tomnpatrichorum, from New Riversleigh fossil site in Queensland. Credit: Illustration: Karen Black/UNSW
Illustration showing size comparison of Australian marsupials including new extinct species of carnivorous marsupial, Whollydooleya tomnpatrichorum, from New Riversleigh fossil site in Queensland. Credit: Illustration: Karen Black/UNSW
A new species of extinct flesh-eating marsupial that terrorised Australia's drying forests about 5 million years ago has been identified from a fossil discovered in remote northwestern Queensland.

The hypercarnivore, which is thought to have weighed about 20 to 25 kilograms, is a distant and much bigger cousin of Australia's largest living, flesh-eating marsupial, the Tasmanian Devil, which weighs in at about 10 kilogram.

Named Whollydooleya tomnpatrichorum, it is the first creature to be formally identified from a range of strange new animals whose remains have been found in a recently discovered fossil site in Queensland dubbed 'New Riversleigh'.

A description of the new marsupial, based on its fossil molar tooth, is published in the Memoirs of Museum Victoria.

"W. tomnpatrichorum had very powerful teeth capable of killing and slicing up the largest animals of its day," says study lead author UNSW Professor Mike Archer.

The late Miocene period between about 12 and 5 million years ago, when Australia began to dry out and the megafauna began to evolve, is one of the most mysterious and least well-understood periods in the continent's past. Fossils of land animals from this period are extremely rare, because of the increasing aridity.

"Fortunately, in 2012, we discovered a whole new fossil field that lies beyond the internationally famous Riversleigh World Heritage Area fossil deposits in north-western Queensland," says Professor Archer.

"This exciting new area - New Riversleigh - was detected by remote sensing using satellite data."

With the help of ARC funding and a grant from the National Geographic Society, Professor Archer and his colleagues began to systematically explore New Riversleigh in 2013.

The new species' highly distinctive molar was one of the first fossil teeth obtained from a particularly fossil-rich site in the area which was discovered by team member Phil Creaser and named Whollydooley Hill in honour of his partner and Riversleigh volunteer Genevieve Dooley.

"New Riversleigh is producing the remains of a bevy of strange new small to medium-sized creatures, with Whollydooleya tomnpatrichorum, the first one to be described," says Professor Archer.

"These new discoveries are starting to fill in a large hole in our understanding about how Australia's land animals transformed from being small denizens of its ancient wet forests to huge survivors on the second most arid continent on Earth."

Team member UNSW Professor Suzanne Hand says medium to large-sized Australian Late Miocene animals have previously been known from fossil deposits in the Northern Territory, such as at Alcoota.

"But those deposits give almost no information about the small to medium-sized mammals that existed at the same time, which generally provide more clues about the nature of prehistoric environments and climates," Professor Hand says.

Team member and UNSW postdoctoral researcher in palaeontology, Dr Karen Black, adds: "The small to medium-size mammals from the New Riversleigh deposits will reveal a great deal about how Australia's inland environments and animals changed between 12 and 5 million years ago - a critical time when increasing dryness ultimately led to the Ice Ages of the Pleistocene."

The Whollydooley Site deposit provides other exciting clues about how the environment was changing. For example, it contains the first signs of wind-blown sand grains, which are absent from the older Riversleigh World Heritage deposits.

And the teeth of the other animals in this deposit are unusual for Riversleigh, because they are more worn down. This suggests that the foods animals were eating in the late Miocene were perhaps tougher, more drought-resistant plants, and there was more abrasive dust in the environment.

"Although Whollydooleya terrorized the drying forests around 5 million years ago, its own days were numbered," says Archer.

"While it was at least distantly related to living and recently living carnivorous marsupials such as Devils, Thylacines and Quolls, it appears to have represented a distinctive subgroup of hypercarnivores that did not survive into the modern world.

"Climate change can be a merciless eliminator of the mightiest of mammals," he says.
***

Source:
The above post is reprinted from materials provided by University of New South Wales.

Reference:
Archer, M.; Christmas, O.; Hand, S.J.; Black, K.H.; Creaser, P.; Godthelp, H.; Graham, I.; Cohen, D.; Arena, D.A.; Anderson, C.; Soares, G.; Machin, N.; Beck, R.M.D.; Wilson, L.A.B.; Myers, T.J.; Gillespie, A.K.; Khoo, B., and Travouillon, K.J. Earliest known record of a hypercarnivorous dasyurid (Marsupialia), from newly discovered carbonates beyond the Riversleigh World Heritage Area, north Queensland. Memoirs of Museum Victoria, July 2016
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Paleoparadoxia (left: Desmostylia, Paenungulata) and Ambulocetus (right: Cetacea, Cetartiodactyla) in two different ways of reconstructions -- top: terrestrial/semi-aquatic; bottom: obligate aquatic. Credit: Fujiwara
Paleoparadoxia (left: Desmostylia, Paenungulata) and Ambulocetus (right: Cetacea, Cetartiodactyla) in two different ways of reconstructions -- top: terrestrial/semi-aquatic; bottom: obligate aquatic. Credit: Fujiwara
Despite the extensive fossil record of mammals, it is often difficult to use fossil data to reconstruct the lifestyles and habitats of extinct species. The fact that some species spent all or part of their time underwater, respectively similar to modern-day whales and seals, further complicates this.

Konami Ando and Shin-chi Fujiwara, researchers at Nagoya University, addressed this by developing a new index for predicting if a species lived its entire life in the water. The index is based on how the ribs must be relatively strong for an animal to walk or crawl over land, but not for it to swim. After establishing the index via measurements of living terrestrial, semiaquatic, and exclusively aquatic species, Ando and Fujiwara used it to predict that some extinct species could not have supported themselves on land.

Although mammals originally evolved as terrestrial organisms, cladistics shows that some returned to aquatic lives, and that this sometimes occurred independently. Examples include whales, dolphins, and manatees, which never leave the water, and seals and hippopotamuses, which split time between land and water. Studies of fossils of extinct species also suggest some species spent all or some of their time in the water. However, inability to use fossil records alone to determine a species' lifestyle has made this hard to confirm.

In their study, reported in the Journal of Anatomy, Ando and Fujiwara analyzed rib cages and their resistance to vertical compression in a range of mammalian species. This important factor represents an animal's ability to support its body weight against gravity while walking or crawling; a trait aquatic organisms do not need. The researchers investigated 26 modern-day terrestrial, semiaquatic, and exclusively aquatic species, including the killer whale, polar bear, dugong, giraffe, and hippopotamus. They used their data to establish an index for differentiating between groups with different habitats. They then applied the index to four extinct mammalian species, all of which had retained their four limbs but showed signs of having been partially or completely aquatic, to shed light on their potential lifestyles.

"We selected mammals with different habitats from a range of taxa and analyzed fossils for which the bones in the thoracic region were well-preserved," Fujiwara says. "We focused on the fracture loads of ribs. We found the sum of the fracture loads of all true ribs directly connected to the sternum divided by the body weight effectively separated the extant species groups by habitat. Exclusively aquatic species were clearly differentiated."

After establishing that the index could correctly classify living species with known habitats and lifestyles, the researchers applied it to extinct groups: Ambulocetus, an early ancestor of whales, and three desmostylian species, which are the keens of elephants and sea cows. This was to confirm or reject earlier hypotheses about these groups' lifestyles, which were based on other morphological findings.

"Our index lets us conclude that Ambulocetus and two desmostylians (Paleoparadoxia and Neoparadoxia) could not have supported themselves on land; they were exclusively aquatic," Ando says. "But the findings were inconclusive for the third desmostylian (Desmostylus). We may need to perform additional studies on the intermediate group of semiaquatic species, include a bone density variable in our model, or improve our data on the body mass of extinct species to refine the index."

The new index should help in both reconstructing the lifestyles and habitats of extinct mammals and clarifying anatomical changes associated with mammals shifting to a life partly or exclusively in the water.
***

Source:
The above post is reprinted from materials provided by Nagoya University.

Reference:
Konami Ando, Shin-ichi Fujiwara. Farewell to life on land - thoracic strength as a new indicator to determine paleoecology in secondary aquatic mammals. Journal of Anatomy, 2016; DOI: 10.1111/joa.12518

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Ilopango lake and San Vicente volcano, Salvador. Credit: Carlos Rodriguez Mata // flickr
Ilopango lake and San Vicente volcano, Salvador.
Credit: Carlos Rodriguez Mata // flickr
The build-up of magma six kilometres below El Salvador's Ilopango caldera means the capital city of San Salvador may be at risk from future eruptions, University of Bristol researchers have found.

A caldera is a large cauldron-like volcanic depression or crater, formed by the collapse of an emptied magma chamber. The depression often originates from very big explosive eruptions. In Guatemala and El Salvador, caldera volcanoes straddle tectonic fault zones along the Central American Volcanic Arc (CAVA). The CAVA is 1,500 kilometres long, stretching from Guatemala to Panama.

The team, from the Volcanology research group at Bristol's School of Earth Sciences and the Ministry of the Environment and Natural Resources in El Salvador, studied the density distribution beneath the Ilopango caldera and the role tectonic stresses -- caused by the movement of tectonic plates along fault lines -- have on the build-up of magma at depth. Their study is published in the journal Nature Communications.

The Ilopango caldera is an eight km by 11 kilometre volcanic collapse structure of the El Salvador Fault Zone. The collapsed caldera was the result of at least five large eruptions over the past 80,000 years.

The last of these occurred about 1,500 years ago and produced enough volcanic ash to form a 15 centimetre thick layer across the entire UK. This catastrophic eruption destroyed practically everything within a 100 kilometre radius, including a well-developed native Mayan population, and significantly disturbed the Mayan populations as far as 200 kilometres away.

The most recent eruptions occurred in 1879-1880 and were on a much smaller scale than the previous one.

Project leader and co-author Dr Joachim Gottsmann said: "Most earthquakes take place along the edges of tectonic plates, where many volcanoes are also located. There is therefore a link between the breaking of rocks, which causes faults and earthquakes and the movement of magma from depth to the surface, to feed a volcanic eruption. The link between large tectonic fault zones and volcanism is, however, not very well understood."

Existing studies show that magma accumulation before a large caldera-forming eruption, as well as the caldera collapse itself, may be controlled by fault structures.

"However, it is unclear to what extent regional tectonic stresses influence magma accumulation between large caldera-forming eruptions.," co-author Professor Katharine Cashman said.

Lead author Jennifer Saxby, whose research towards a MSc in Volcanology contributed to the study, said: "Addressing this question is important not only for understanding controls on the development of magmatic systems, but also for forecasting probable locations of future eruptive activity from caldera-forming volcanoes."

The team discovered that the current tectonic stress field promotes the accumulation of magma and hydrothermal fluids at shallow (< 6km) depth beneath Ilopango. The magma contains a considerable amount of gas, which indicates the system is charged to possibly feed the next eruption.

Dr Gottsmann said: "Our results indicate that localised extension along the fault zone controls the accumulation, ascent and eruption of magma at Ilopango. This fault-controlled magma accumulation and movement limits potential vent locations for future eruptions at the caldera in its central, western and northern part -- an area that now forms part of the metropolitan area of San Salvador, which is home to 2 million people. As a consequence, there is a significant level of risk to San Salvador from future eruptions of Ilopango."
***

Source:
The above post is reprinted from materials provided by University of Bristol.

Reference:
J. Saxby, J. Gottsmann, K. Cashman, E. Gutiérrez. Magma storage in a strike-slip caldera. Nature Communications, 2016; 7: 12295 DOI: 10.1038/ncomms12295
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Climate Change. Credit: Jacob Braun / flickr
Climate Change. Credit: Jacob Braun / flickr
There is some consolation in how the fossil fuel-induced climatic changes we increasingly experience through droughts and storm surges are playing out. It could have happened sooner, and therefore already have been much worse.

Luckily, the natural atmosphere already contained carbon dioxide, enough that the human-induced changes were relatively small, for a long time. Had these concentrations been even slightly lower, the effects of the emission of harmful greenhouse gases would have been felt much earlier, at a time when humankind was not yet ready or knowledgeable enough to face up to mitigation efforts. This silver lining approach is taken by David Archer of the University of Chicago in the US, in a scenario exercise in Springer's journal Climatic Change.

The concentration of carbon dioxide molecules in the atmosphere is measured as parts per million of dry air, or ppm. In the climatic past and earlier glacial periods, this level fluctuated between 180 ppm and 260 ppm. Measurements taken of Antarctic sheet ice show that the concentration of naturally occurring carbon dioxide in the atmosphere was already 278 ppm in the 1750s before industrialization started in earnest.

"If the initial atmospheric carbon dioxide concentration were half its actual value, we would currently be experiencing the climate expected for the year 2050," says Archer, setting out one possible scenario. "If there were only one-tenth as much carbon dioxide in the atmosphere initially, the climate forcing we are experiencing today would have already happened, in the year 1900."

Archer therefore describes the climatic changes currently being experienced on Earth as "moderate," thanks to the blanketing effect that naturally occurring carbon dioxide in the atmosphere has had. This has given scientists the time to piece together an understanding of Earth's climate system and the effects of fossil fuel emissions.

The first ideas about radiative balance and the greenhouse effect date back to 1827, while predictions about climatic sensitivity due to carbon dioxide were made by 1896. It was, however, only after the advent of the computer that a modern understanding emerged of how fossil fuel use would impact the climate. This understanding was able to mature to the extent of public warnings about it by the 1970s.

"If the natural concentration had been a factor of two or more lower, the climate impacts of fossil fuel carbon dioxide release would have occurred about 50 or more years sooner, making it much more challenging for the developing human society to scientifically understand the phenomenon of humanmade climate change in time to prevent it," he says. "To the extent that a thorough scientific understanding is also a requisite for making a decision to abandon fossil fuels, the outlook for humanity would have been considerably darker in this altered world than it has turned out in actuality."
***

Source:
The above post is reprinted from materials provided by Springer.

Reference:
David Archer. Near miss: the importance of the natural atmospheric CO2 concentration to human historical evolution. Climatic Change, 2016; DOI: 10.1007/s10584-016-1725-y
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Solar Power. Credit: Liam / flickr
Solar Power. Credit: Liam / flickr
As climate change garners more attention around the world, scientists at the University of Virginia and Cornell University have made critical advances in understanding the physical properties of an emerging class of solar cells that have the potential to dramatically lower the cost of solar energy.

Solar cells remain a focal point of scientific investigation because the sun offers the most abundant source of energy on earth. The concern, however, with conventional solar cells made from silicon is their cost. Even with recent improvements, they still require a significant amount of electricity and industrial processing to be manufactured.

In 2009, energy researchers turned their attention to a class of materials called "metal halide perovskites," or MHPs. They are sprayed on like paint onto solid objects, says Joshua Choi, an assistant professor of chemical engineering at the University of Virginia. As the solution dries, the MHPs crystallize into a thin film that can be used to capture energy in a solar cell.

Within just a few years, MHP solar cells have been crafted whose performance rivals conventional silicon solar cells. This is the fastest recorded improvement in history for any photovoltaic material and it has been verified by the National Renewable Energy Laboratory in Golden, Colorado.

The challenge is that these existing MHP solar cells are no larger than a human fingernail.

"To be really technologically relevant," Choi said, "we need to be able to scale up this process while maintaining or even improving the efficiency of the solar cell. To do that, we need to understand how this material crystallizes and grows from solution into a thin film."

Collaborating with scientists from Cornell University's High Energy Synchrotron Source, which receives funding from the National Science Foundation, Choi and his team monitored in real time the growth of MHP crystals at the atomic level by exposing them to high intensity X-rays.

The scientists will present their findings at the 66th meeting of the American Crystallographic Association, held July 22-26 in Denver, Colorado.

By adding different chemicals to the solution, they were able to control how fast the MHP crystals formed and what direction they grew on a surface. The specific orientation of the MHP crystals on a surface affected how well a solar cell performed, Choi said.

Moreover, this research provides this nascent field with the kinds of insights about MHP crystal formation that scientists will need as they determine how to manufacture the larger MHP solar cells that could reduce the price of solar energy.

But there's more to MHP solar cells than just their potential to cut costs.

"MHP solar cells can be used in flexible, lightweight materials," Choi said. The ultimate goal would be to make manufacturing MHP solar cells as easy as printing newspapers, generating rolls of thin solar cell material that could be easily applied to houses, cars, or anywhere else they were needed.

One significant drawback with many current MHP solar cells is that they contain lead. Researchers are working on identifying viable alternative compositions that are not toxic.

Choi and his research are funded by NASA, which is examining the potential for MHPs to be used in high temperature solar cells that could be installed in solar probes deployed in space. Elsewhere, MHPs have already been used in lasers, photo detectors, transistors and light emitting diodes (LEDs).

Still, it is the solar cell that arguably offers MHPs the best chance to address pressing global problems.

"To mitigate the impact of climate change and also to ensure the energy security of the United States and the world, it is very important to come up with renewable energy sources rather than just be relying on fossil fuel-based energy," Choi said.
***

Source:
The above post is reprinted from materials provided by American Institute of Physics (AIP).
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