New study favors cold, icy early Mars

June 17, 2015

This is a conceptual rendition of the competing warm and cold scenarios for early Mars. Credit: Robin D. Wordsworth

The high seas of Mars may never have existed, according to a new study that looks at two opposite climate scenarios of early Mars and suggests that a cold and icy planet billions of years ago better explains water drainage and erosion features seen on the planet today.
For decades, researchers have debated the climate history of Mars and how the planet’s early climate led to the many water-carved channels seen today. The idea that 3 to 4 billion years ago Mars was once warm, wet and Earth-like with a northern sea — conditions that could have led to life — is generally more popular than that of a frigid, icy planet where water is locked in ice most of the time and life would be hard put to evolve.

To see which early Mars better explains the modern features of the planet, researcher Robin Wordsworth of the Harvard Paulson School of Engineering and Applied Sciences and his colleagues used a 3-dimensional atmospheric circulation model to compare a water cycle on Mars under different scenarios 3 to 4 billion years ago, during what’s called the late Noachian and early Hesperian periods. One scenario looked at Mars as a warm and wet planet with an average global temperature of 10 degrees Celsius (50 degrees Fahrenheit) and the other as a cold and icy world with an average global temperature of minus 48 degrees Celsius (minus 54 degrees Fahrenheit).

The study’s authors found that the cold scenario was more likely to have occurred than the warm scenario, based on what is known about the history of the Sun and the tilt of Mars’s axis 3 to 4 billion years ago. The cold model also did a better job explaining the water erosion features that have been left behind on the Martian surface, and which have puzzled and intrigued scientists since they were first discovered by the Viking orbiters in the 1970s.

A paper presenting the results has been accepted for publication in AGU’s Journal of Geophysical Research – Planets.

The colder scenario was more straightforward to model, Wordsworth explained, because Mars only gets 43 percent of the solar energy of Earth, and early Mars was lit by a younger Sun believed to have been 25 percent dimmer than it is today. That makes it very likely early Mars was cold and icy, he said.

An extreme tilt of the Martian axis would have pointed the planet’s poles at the Sun and driven polar ice to the equator, where water drainage and erosion features are seen today. More importantly, under a thicker atmosphere that likely existed under the colder scenario, highland regions at the equator get colder and northern low-lying regions get warmer – the so-called ‘icy highlands effect’ that is responsible for making the peaks of mountains snow-covered on Earth today. Despite a number of warming factors – including a thicker atmosphere filled with climate-warming carbon dioxide — Mars still would have been quite cold, Wordsworth added.

Creating a warm/wet Mars took more work, Wordsworth said. Previous studies have shown that even when the effects of climate-warming clouds, dust and carbon dioxide are taken into account, climate models still don’t show early Mars developing any warm and wet periods, he said.

But the conditions on early Mars may have been different than scientists’ thought, Wordsworth said. The study’s authors added to their model different climate effects to force Mars into a warmer, wet state.

Even then, however, the warm/wet early Mars does not explain the patchwork of Martian water erosion features and valley networks observed on the planet today, and why these features tend to be concentrated near the planet’s equator, Wordsworth said.

Under the warm/wet model, rainfall rates varied a lot with longitude and latitude. The warm/wet model predicts that on early Mars rain was greatest in an area called Arabia and around the Hellas basin, including in the west and southeast areas of the basin, where few water drainage features are found today. At the same time, several regions with many water-carved valleys, such as Margaritifer Sinus, received one-tenth to one-twentieth as much rain as Arabia and the Hellas basin under the warm/wet scenario.

In the warm/wet scenario, mountains also created rain shadows, like those that wring water from clouds to create deserts on Earth. On Mars, the bulge of Tharsis would have caused more rain to fall on the windward western side of the volcanic plateau, where few water features are seen today. To the east, downwind of the bulge, drier air would flow over Margaritifer Sinus, causing less rain to fall there – a situation that doesn’t match the drainage features observed there.

The cold/icy scenario isn’t perfect but it’s a better fit to the observations in general, Wordsworth said. While this scenario accumulates frozen water closer to the drainage features observed today on Mars, something had to have melted the ice which carved the valleys, he said. In this scenario, the climate is cool most of the time, and short-lived events like meteor impacts and volcanic eruptions likely caused the necessary melting, he said.

“I’m still trying to keep an open mind about this,” said Wordsworth. “There is lots of work to be done. But our results show that the cold/icy scenario matches the surface distribution of erosion features more closely. This strongly suggests that early Mars was generally cold, and water was supplied to the highland regions as snow, not as rain.”

Proving that a cold climate on early Mars led to the features seen on the planet today is a “big question”, said Bethany Ehlmann, a planetary scientist at California Institute of Technology and NASA’s Jet Propulsion Laboratory in Pasadena, California, who was not involved in the new study.

The new paper answers part of that question by showing that locations with snow accumulation in the cold and icy scenario roughly correspond to valley network locations seen today, she said. Further, the model of the cold and icy early Mars shows that some melting of ice would occur, she said.

“We know from rover- and orbiter-based data that there were lakes on ancient Mars,” she said. “Key questions are: how long did they persist? Were they episodic or persistent? And does the feeder valley network demand rain or is snow and ice melt sufficient?”

The 3-D climate modeling used in the new study begins to address these questions with a new level of sophistication by investigating how specific locations might have accumulated rain or snow, she said.

Reference:
Robin D. Wordsworth, Laura Kerber, Raymond T. Pierrehumbert, Francois Forget, James W. Head. Comparison of “warm and wet” and “cold and icy” scenarios for early Mars in a 3D climate model. DOI: 10.1002/2015JE004787

Note : The above story is based on materials provided by American Geophysical Union.

Why big dinosaurs steered clear of the tropics

June 16, 2015

212 million years ago in what is now northern New Mexico, the landscape was dry and hot with common wildfires. Early dinosaurs such as the carnivorous dinosaur in background were small and rare, whereas other reptiles such as the long-snouted phytosaurs and armored aetosaurs were quite common. Credit: Victor Leshyk

For more than 30 million years after dinosaurs first appeared, they remained inexplicably rare near the equator, where only a few small-bodied meat-eating dinosaurs eked out a living. The age-long absence of big plant-eaters at low latitudes is one of the great, unanswered questions about the rise of the dinosaurs.
And now the mystery has a solution, according to an international team of scientists who pieced together a remarkably detailed picture of the climate and ecology more than 200 million years ago at Ghost Ranch in northern New Mexico, a site rich with fossils from the Late Triassic Period.

The new findings show that the tropical climate swung wildly with extremes of drought and intense heat. Wildfires swept the landscape during arid regimes and continually reshaped the vegetation available for plant-eating animals.

“Our data suggest it was not a fun place,” says study co-author Randall Irmis, curator of paleontology at the Natural History Museum of Utah and assistant professor at the University of Utah. “It was a time of climate extremes that went back and forth unpredictably and large, warm-blooded dinosaurian herbivores weren’t able to exist nearer to the equator — there was not enough dependable plant food.”

The study, led by geochemist Jessica Whiteside, lecturer at the University of Southampton, is the first to provide a detailed look at the climate and ecology during the emergence of the dinosaurs. The results are important, also, for understanding human-caused climate change. Atmospheric carbon dioxide levels during the Late Triassic were four to six times current levels. “If we continue along our present course, similar conditions in a high-CO2 world may develop, and suppress low-latitude ecosystems,” Irmis says.

The other authors are Sofie Lindström, Ian Glasspool, Morgan Schaller, Maria Dunlavey, Sterling Nesbitt, Nathan Smith and Alan Turner. They report the findings today in the Proceedings of the National Academy of Sciences.

Table of Contents

Reconstructing the deep past

The earliest known dinosaur fossils, found in Argentina, date from around 230 million years ago. Within 15 million years, multitudes of species with different diets and body sizes had evolved and were abundant beyond the tropical latitudes. In the tropics, the only dinosaurs present were small carnivores. This pattern persisted for 30 million years after the first dinosaurs appeared.

In the new study, the authors focused on Chinle Formation rocks, which were deposited by rivers and streams between 205 and 215 million years ago at Ghost Ranch (better known to many outside of paleontology as the place where artist Georgia O’Keeffe lived and painted for much of her career). The multi-colored rocks of the Chinle Formation are a common sight on the Colorado Plateau at places such as the Painted Desert at Petrified Forest National Park in Arizona. During the Late Triassic, North America and other land masses of the world were bound together in the supercontinent Pangea. The Ghost Ranch site stood close to the equator at roughly the same latitude as present-day southern India.

The researchers reconstructed the deep past by analyzing several kinds of data: fossils, charcoal left by ancient wildfires, and stable isotopes from organic matter and carbonate nodules that formed in ancient soils. “Each dataset complements the others, and they all point towards similar conditions,” Whiteside says. “I think this is one of the major strengths of our study.”

Fossilized bones, pollen grains and fern spores revealed the types of animals and plants living at different times, marked by layers of sediment. Dinosaurs remained rare among the fossils, accounting for less than 15 percent of vertebrate animal remains. They were outnumbered in diversity, abundance and body size by the reptiles known as Pseudosuchian archosaurs, the lineage that gave rise to crocodiles and alligators.

The sparse dinosaurs consisted mostly of small, carnivorous theropods. Big, long-necked dinosaurs, or sauropodomorphs — already the dominant plant-eaters at higher latitudes — did not exist at the study site or any other low-latitude site in Triassic Pangaea, as far as the fossil record shows.

Abrupt changes in climate left a record in the shifting abundance of different types of pollen and fern spores between sediment layers. Fossilized organic matter from decaying plants provided another window on climate shifts. Changes in the ratio of stable isotopes of carbon in the organic matter bookmarked times when plant productivity declined during extended droughts.

Drought and fire

Wildfire burn temperatures varied drastically, the researchers found, consistent with a fluctuating environment in which the amount of combustible plant matter rose and fell over time. The researchers estimated the intensity of wildfires using bits of charcoal recovered in the sediment layers. The amount of light reflected from the fossil charcoal under a light microscope relates directly to the burn temperature of the wood. The overall picture, the authors say, is that of a climate punctuated by extreme shifts in precipitation in which plant die-offs fueled hotter fires, which in turn killed more plants, damaged soils and increased erosion.

Atmospheric carbon dioxide levels, calculated from stable isotope analyses of soil carbonate and preserved organic matter, rose from about 1,200 parts per million at the base of the section, to about 2,400 parts per million near the top. At these high CO2 concentrations, climate models predict more frequent and more extreme weather fluctuations consistent with the fossil and charcoal evidence.

Continuing shifts between extremes of dry and wet likely prevented the establishment of dinosaur-dominated communities found in the fossil record at higher-latitudes across South America, Europe and southern Africa, where aridity and temperatures were less extreme and humidity was consistently higher. Resource-limited conditions could not support a diverse community of fast-growing, warm-blooded, large dinosaurs, which require a productive and stable environment to thrive.

“The conditions would have been something similar to the arid western United States today, although there would have been trees and smaller plants near streams and rivers and forests during humid times,” says Whiteside. “The fluctuating and harsh climate with widespread wild fires meant that only small two-legged carnivorous dinosaurs, such as Coelophysis, could survive.”

Reference:
Jessica H. Whiteside, Sofie Lindström, Randall B. Irmis, Ian J. Glasspool, Morgan F. Schaller, Maria Dunlavey, Sterling J. Nesbitt, Nathan D. Smith, and Alan H. Turner. Extreme ecosystem instability suppressed tropical dinosaur dominance for 30 million years. PNAS, 2015 DOI: 10.1073/pnas.1505252112

Note: The above post is reprinted from materials provided by University of Utah.

Cave study reveals 3000 years of climate variation

June 16, 2015

Roaring Cave in Scotland. A study of its limestone has produced a unique 3000-year-long record of climatic variations that may have influenced historical events including the fall of the Roman Empire and the Viking Age of expansion. Credit: Courtesy of UNSW

Research on limestone formations in a remote Scottish cave has produced a unique 3000-year-long record of climatic variations that may have influenced historical events including the fall of the Roman Empire and the Viking Age of expansion.
The UNSW-led study of five stalagmites in Roaring Cave north of Ullapool in north-west Scotland is the first to use a compilation of cave measurements to track changes in a climate phenomenon called the North Atlantic Oscillation.

“Our results also provide the longest annual record of this important phenomenon, which has a big impact on the climate in Europe,” says study leader, UNSW Professor Andy Baker.

“It confirms that the during the Medieval Warm Period between 1080 and 1430 the oscillation index was in an unusually prolonged positive phase, which brings increased rain to Scotland and drier conditions in the western Mediterranean,” says Professor Baker, of the UNSW Connected Waters Initiative Research Centre.

“Our results also reveal there was another persistent positive phase between 290 and 550, which coincides with the decline of Rome and a period of intensified human migration in southern Europe during the Dark Ages.

“This was followed by a persistent negative phase between 600 and 900 which may have provided warm and dry conditions in north-western Europe that made it suitable for westward expansion by the Vikings, although the precise timing of this event is contested.”

The study is published in the journal Scientific Reports.

The North Atlantic Oscillation climate index measures the air pressure difference between Iceland and the Azores islands off the Portuguese coast, and is a record of the strength of the westerly winds in the North Atlantic.

Roaring Cave, or Uamh an Tartair, in north-west Scotland, is a shallow cave beneath a blanket of peat that has accumulated during the past 4000 years.

Rainfall levels in this region closely correspond with the strength of the oscillation index in winter, with higher precipitation when it is positive. And the upward rate of growth of stalagmites in the cave is very sensitive to rainfall – the more water in the peat, the more slowly the stalagmites grow.

“We painstakingly measured the thickness of each annual growth ring in five stalagmites taken from the cave, including one that provides a continuous annual record spanning more than 1800 years,” says Professor Baker.

By overlapping the five stalagmites they obtained a proxy record of the climate at the cave during a 3000-year period from about 1000 BC to 2000 AD.

“Our research provides a climate context for some of the big human migration events in Europe and allows us to start building hypotheses about the impact of environment on societal change,” says Professor Baker.

The team includes researcher from UNSW, the University of Lausanne in Switzerland and the University of Arizona in the US.

Reference:
Andy Baker, John C. Hellstrom, Bryce F. J. Kelly, Gregoire Mariethoz, Valerie Trouet. A composite annual-resolution stalagmite record of North Atlantic climate over the last three millennia. Scientific Reports, 2015; 5: 10307 DOI: 10.1038/srep10307

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

Mount Everest, moved three centimetres due to Nepal earthquake

June 16, 2015

Everest Base Camp shown on April 26, 2015, a day after an avalanche triggered by an earthquake caused the death of 18 people Credit: AFP Photo/Roberto Schmidt

The world’s tallest peak, Mount Everest, moved three centimetres (1.2 inches) to the southwest because of the Nepal earthquake that devastated the country in April, Chinese state media reported Tuesday.
The 7.8-magnitude quake reversed the gradual northeasterly course of the mountain, according to a report in the state-run China Daily, citing the National Administration of Surveying, Mapping and Geoinformation.

Before the quake, Everest had moved 40 centimetres to the northeast over the past decade at a speed of four centimetres a year, the report said. The mountain also rose three centimetres over the same time period.

The earthquake caused an avalanche on Everest, killing 18 people and leaving its climbing base camp in ruins. It prompted authorities in both China and Nepal to cancel all climbs for this year.

The mountain straddles the border between the two countries.

Two earthquakes, on April 25 and May 12, killed more than 8,700 people in Nepal, triggered landslides and destroyed half a million homes, leaving thousands without shelter just weeks ahead of monsoon rains.

The second quake, which had a magnitude of 7.3, did not move the mountain, China Daily said.

Note : The above story is based on materials provided by AFP.

New Study: Origins of Red Sea’s mysterious ‘cannon earthquakes’ revealed

June 16, 2015

Annotated view of the Nile and Red Sea, with a dust storm Credit: NASA

For many generations, Bedouin people living in the Abu Dabbab area on the Egyptian Red Sea coast have heard distinct noises—like the rumbling of a quarry blast or cannon shot—accompanying small earthquakes in the region. Now, a new study published in the Bulletin of the Seismological Society of America offers an explanation for this uniquely noisy seismic event.
Seismic activity in the area of the Egyptian seaside resort Abu Dabbab may be caused by an active fault that lays below a 10-kilometer thick block of old, now rigid igneous rock. The surface of the block slides along the active parts of the fault, lubricated by fluids from the Red Sea that have penetrated the crust, according to Sami El Khrepy of King Saud University in Riyadh, Saudi Arabia and colleagues.

The researchers think this large and rigid block of igneous crust acts as a sort of broadcaster, allowing the full sounds of seismic movement to rise through the rock with little weakening of the acoustic signal. The high-frequency sounds of earthquakes can then be heard by humans at the surface.

Earlier studies had suggested that the Abu Dabbab earthquakes were caused by magma rising through the crust, but the new report “found that a volcanic origin of the seismicity is unlikely, and the area is not expected to be subjected to volcanic hazard,” said El Khrepy.

Earthquake swarms are frequent in this area of the northern Red Sea near Abu Dabbab, but most of the earthquakes are weak, ranging in magnitude from 0.3 to 3.5. The largest well-documented earthquakes, measuring magnitude 6.1 and magnitude 5.1, occurred in 1955 and 1984, respectively.

El Khrepy and colleagues decided to take a closer look at the structure of the Abu Dabbab crust, to determine the origin of this seismicity. To peer into the crust, they combined data from local earthquake monitoring with a new set of local and regional earthquake data collected by the National Seismic Network of Egypt (ENSN), which was completed in 2002. They then applied a technique called seismic tomography, which uses data on the speed of seismic waves traveling through different rock types to develop a 3-D map of some of the subsurface geological features in the area.

“This study is the first detailed look at the seismic tomography in this region of Abu Dabbab’s cannon earthquakes,” said El Khrepy, “It was not possible to do this work without ENSN deployment.”

The researchers determined that the earthquakes at Abu Dabbab extend in a line from the coast into the Red Sea, “and the seismicity pattern is arc-shaped in depth, confined to the dome-like structure of the rigid igneous body that formed during the Precambrian era” above an active fault, El Khrepy said.

The strike-slip and thrust movements of the fault may drive water from the Red Sea in between the fault and the surface of the igneous block, allowing the two to slip past each other, the scientists suggest.

“Based on the new results and also the historical data,” El Khrepy concluded, “we report that the confined seismicity in this zone is of tectonic, and not volcanic, origin.”

Reference:
I. Koulakov, S. El Khrepy, N. Al-Arifi, P. Kuznetsov, E. Kasatkina. Structural cause of a missed eruption in the Harrat Lunayyir basaltic field (Saudi Arabia) in 2009. Geology, 2015; 43 (5): 395 DOI: 10.1130/G36271.1

Note : The above story is based on materials provided by Seismological Society of America.

Understanding the softness in Earth’s lithosphere

June 16, 2015

This figure shows a photo-micrograph of a thin section of a rock from the lithosphere, on which records of seismic waves are superimposed. Regions with different colors show minerals with different orientations.

Yale researchers have proposed a new model to explain the drop in elastic stiffness in the middle of the Earth’s continental lithosphere.
Lithosphere is the stiff layer of rock that lies atop the slow-motion convection of Earth’s solid, yet ductile, interior. It is the “plate” of plate tectonics, the system of interlocking fragments that explains earthquakes, volcanoes, and even the long-term variation of carbon dioxide in the atmosphere.

A softening in the middle of the continental lithosphere was discovered when seismologists studied the structure of the United States. This same softening was observed in other continents as well, at a depth of 80 to 150 km. Researchers found the phenomenon puzzling, because softening detected by seismology is usually linked to softening that occurs over millions of years (also known as geologic time). If that were the case, the continental lithosphere would have a weak layer in it, and it would be difficult to explain the continents’ long-term stability.

Yale geophysicists Shun-ichiro Karato, Tolulope Olugboji (a former Yale student, now at the University of Maryland), and Jeffrey Park may have found the answer.

In a study published June 15 in the journal Nature Geoscience, they present a new model to describe the phenomenon. They say the softening is a natural consequence of the way rocks deform as temperatures rise below the melting point. The key is that this softening occurs in a second or less (the seismic time scale), rather than over millions of years.

Rocks are composed of strong mineral crystals separated by grain boundaries, where atoms are disordered and weaker. As temperature increases, the mineral grains remain strong, but grain boundaries weaken and allow sliding to occur. As a consequence of this sliding, the overall stiffness of a rock is reduced at the seismic time scale, but not the geological time scale.

“Our model is consistent with a stable continent, because the weakness of grain-boundary sliding is limited to deformation of the lithosphere in approximately one second, not its long-term deformation,” Karato said.

Reference:
Mechanisms and geologic significance of the mid-lithosphere discontinuity in the continents, DOI: 10.1038/ngeo2462

Note : The above story is based on materials provided by Yale University.

Accelerated warming of continental shelf off northeast coast of U.S.

June 16, 2015

A new study shows that water temperatures in this continental shelf region have been trending upward, with unprecedented warming occurring over the last 13 years. The research is based upon temperature data from the waters off the northeast coast of the U.S. that were collected in collaborative effort between scientists and the operators of the container ship Oleander, which routinely travels between Bermuda and New Jersey (green line). The mean surface circulation in the northwestern North Atlantic is shown. Credit: Forsyth, et al

A couple of unexplained large scale changes in the waters off the northeast coast of the U.S. have oceanographers perplexed: an accelerated rate of sea level rise compared to most other parts of the world; and the disturbing signs of collapsing fisheries in the region.
A new study by physical oceanographers at Woods Hole Oceanographic Institution (WHOI), published in the Journal of Geophysical Research, shows that water temperatures in this continental shelf region have been trending upward, with unprecedented warming occurring over the last 13 years. The study also suggests a connection between sea level anomalies and water temperature along the continental shelf.

“The warming rate since 2002 is 15 times faster than from the previous 100 years,” says co-author Glen Gawarkiewicz, a WHOI senior scientist. “There’s just been this incredible acceleration to the warming, and we don’t know if its decadal variability, or if this trend will continue.”

The scientists compared their findings with a study of surface waters using data collected by Nantucket Light ship, and other light ships up and down the East Coast between 1880 and 2004, previously analyzed by Steve Lentz of WHOI and Kipp Shearman of Oregon State University. The new study shows that recent accelerated warming is not confined to the surface waters, but extends throughout the water column.

“Others have reported on the temperature increase in this region,” says Gawarkiewicz’s colleague, WHOI assistant scientist Magdalena Andres, “but they’ve been confined to looking at the surface temperatures from satellites or buoys.” And Gawarkiewicz and Andres wanted to understand how deep the warming went.

The research is based upon a rare collection of temperature data from the waters off the northeast coast of the U.S. that were collected in collaborative effort between scientists and the operators of the container ship Oleander, which routinely travels between Bermuda and New Jersey. The effort, which began in the late 1970s with funding from NOAA/NMFS, involved launching bathythermographs along the ship’s track to collect temperature data approximately 14 times each year. Later the program was funded through the National Science Foundation and the University of Rhode Island and Stony Brook University. The bulk of the prior analysis has been on velocity data also collected by the Oleander.

“The Oleander data is special, because it goes through the whole water column on the shelf. And if you’re a fish living on the bottom, you care more about that,” says Andres. “It was this trove of shelf temperature data that we could use to help us address these questions.”

That’s where Jacob Forsyth, lead author of the study, came into the picture. In 2014, Forsyth had just begun an 11-week summer student fellowship at WHOI, with Andres and Gawarkiewicz as his co-advisors. “On a lark, we had Jacob look at the data, not knowing if it would pan out,” says Andres. “But it was a super data set, and Jacob did a great job analyzing the data,” she added.

A physics and economics major at Bowdoin College, Forsyth had taken just one college oceanography course but had a passion for the ocean and for science. Early into his fellowship, Forsyth found himself at WHOI immersed in the academic literature, quality controlling nearly 40 years’ worth of data, and teaching himself MatLab to begin looking at this database no one had really assembled before.

The bulk of the data were collected by volunteer observers who rode the Oleander from New Jersey to Bermuda at monthly intervals deploying the bathythermographs, a probe that is dropped from a ship to measure the temperature as it falls through the water. Two very small wires transmit the temperature data to the ship where it is recorded for later analysis. Because water temperature can vary by layer, it was important to obtain information on the temperature structure of the ocean to depths of up to 700 meters. More recently an automated data collection system has been used which was developed by Dave Fratantoni, formerly of WHOI.

The researchers looked at the temperatures for a given year and averaged them across the shelf, to get a temperature index for the year. Their work showed that temperature has been steadily increasing, and most recently, it’s been getting warmer, faster. Superimposed on that, they found a lot of year-to-year variability.

Andres says, “what’s controlling the trends may be different than what’s controlling the year to year changes.” She notes, “There are two questions: What are the mechanisms for the slow, sustained warming? And what is it for the inter-annual variability? Those don’t have to be the same thing.”

What the researchers did determine is that the slow, sustained warming is not just due to warming of the atmosphere, but that it’s something related to dynamics of the shelf break, where the shallow continental shelf abuts the deeper continental slope.

“The warming more recently seems to be at the edge of the continental shelf, which would indicate there might be a Gulf Stream role or a slope water role in the warming,” says Gawarkiewicz, “and that’s different than if it was all from the atmosphere over the last 12 years, because that would be uniform and near the surface.” Investigating the exact cause is among their next steps.

In addition to analyzing the warming trend, Forsyth, who will enter the MIT-WHOI Joint Program in Oceanography this summer, used the data to search for a relationship between sea levels and temperatures. He found, in fact, there is a very strong relationship between the two, where sea level anomalies may serve as a predictor of shelf temperature. Forsyth determined the lag between the two indicators was approximately two years — enough time to give environmental monitors a chance to respond.

The researchers underscore the importance of a long, continuous set of measurements, and that they are hard to come by due to the limitations of funding. The Oleander program and the newly installed Pioneer Array, a part of a larger NSF-funded network of observatories in the Atlantic and Pacific called the Ocean Observatories Initiative, which is positioned along the shelf break, will collect continuous measurements, so critical in understanding the dynamics of the region. Because it’s a productive fishing ground, the warming at lower depths can have a big impact on the distribution and abundance of fish in the area.

Reference:
Jacob Samuel Tse Forsyth, Magdalena Andres, Glen G. Gawarkiewicz. Recent accelerated warming of the continental shelf off New Jersey: Observations from the CMVOleander expendable bathythermograph line. Journal of Geophysical Research: Oceans, 2015; 120 (3): 2370 DOI: 10.1002/2014JC010516

Note: The above post is reprinted from materials provided by Woods Hole Oceanographic Institution.

Sarychev Volcano Eruption snapped from Space, June 12, 2009

June 15, 2015

A fortuitous orbit of the International Space Station allowed the astronauts this striking view of Sarychev Volcano (Kuril Islands, northeast of Japan) in an early stage of eruption on June 12, 2009. Sarychev Peak is one of the most active volcanoes in the Kuril Island chain, and it is located on the northwestern end of Matua Island.

Fossils explain how life coped during snowball Earth

June 15, 2015

A close-up of one of wart-like bumps on the putative fossilized red algae. Credit: Cohen et al

Researchers have discovered what they think are fossils of a unique red algae species that lived about 650 million years ago during a brief respite between some of the most extreme ice ages the world has ever known. The fossils could speak to how life coped in the aptly named Cryogenian period, when glaciers held most of Earth in a frozen grip.
“The reason we were looking at these samples in the first place is that they come from a really interesting time period in Earth’s history, right between two major global glaciations called Snowball Earth events,” said Phoebe Cohen, the study’s lead author and an assistant professor of geosciences at Williams College, in Williamstown, Mass. “We want to understand how these glaciations affected the evolution of life.”

Learning how life on our planet changed under the extreme conditions of back-to-back Snowball Earths—separated by just 10 million years, a relatively short gap in geological time—should shed light on how extraterrestrial life deals with the vicissitudes of nature.

“We are fundamentally interested in the co-evolution between our planet and the life that inhabits it,” said Cohen. “We want to know: What can this teach us about how life might evolve on other planets?”

The new study appeared in the March issue of the journal Palaios and was funded by grants from the NASA Astrobiology Institute element and the Exobiology & Evolutionary Biology element of the NASA Astrobiology Program.

Table of Contents

Identifying what once was

The fossils, uncovered within layered rocks in southwestern Mongolia, consist of thin, flat sheets with bumpy protuberances on one side. “These samples look like weird scraps of stiff slime with tiny warts on them,” said Cohen.

The fossil sheets are only between 50 and 350 micrometers, or millionths of a meter, in thickness. (For comparison, a human hair is about 100 micrometers in girth.) Tiny, round bumps as tall as 230 or so micrometers rise and here from the sheets, whose undersides are featurelessly smooth.

The tops of the bumps have a small depression in them, much like the warts that grow on human skin caused by viruses. Ridges of material, meanwhile, skirt the bumps and intersect or split in places, forming structures that look like flaps.

Compared to most organism remains, both before and after the emergence of these warty sheets, these fossils have a superficial resemblance to “biofilms.” These films are composed of bacteria that join together and secrete a gooey, protective substance. The fossils also bear a resemblance to groups of microbes, such as amoebas, that similarly link up to form so-called slime molds.

A scanning elecgtron microscope image of a sample of the top surface fossilized warty sheets, with evident bumps and ridges. Credit: Cohen et al

But the best match given all of the fossils’ features is red algae. This group of creatures includes many seaweeds and other types of marine plants.

A telltale identifier is the bumps, which Cohen and her colleagues think served as reproductive structures. “They are similar in a lot of ways to reproductive structures in modern red algal groups,” said Cohen.

The function of the ridges on the wart-like mounds, however, remains a conundrum.

“We aren’t sure what they are,” said Cohen, “but the fact that they don’t have a modern comparison, frankly, is not surprising to me at all.”

As Cohen pointed out, the organisms preserved as warty sheets have been extinct for hundreds of millions of years. “So much evolution has happened within the red algae since then,” Cohen said. “Some things stay the same, or similar, like reproductive structures, but other things, like these ridges, may have once had a function that we don’t yet understand.”

One theory is that the ridges provided some sort of structural support to the organism, “like corrugated cardboard,” Cohen said. Even so, any strong claims about the ridges’ ultimate purpose are difficult to make given the small amount of fossil material to work with and a limited knowledge of the environment where the wart-shaped microbes went about their daily lives.

An eon of red algae?

Notably, the new red algae fossils—if that is indeed what they are—fill a gap in the fossil record documenting the rise of this marine plant group. The oldest known sample of red algae goes back about a billion years. Fossils reckoned to belong to the same lineage then do not appear again until about 600 million years, well after the glaciers of the second Snowball Earth had receded.

Neither the red algae fossils from a billion years ago, nor those from shortly after the Cryogenian period’s end, possess the ridge and flaplike structures of the newfound fossils. “In this case, we’re seeing a new morphology show up in between these two Snowball Earth events,” said Cohen.

The “why” remains unknown, but future finds could provide clues.

“New fossils always give us more information about how groups of organisms evolved, and potentially why as well,” said Cohen. “So adding more fossils to the record of red algae helps us get a better picture of how this major group of algae evolved, and in what context.”

Life’s steadfastness

Red algae as a branch in the tree of life seems to have weathered the storm of two globe-spanning glaciations. “We know red algae are around before the first Snowball Earth event, in between the two, and after,” said Cohen. “In my opinion, that’s an impressive feat, and it makes predictions about what these events were like.”

For instance, in order for life like algae to have survived, water must have remained unfrozen in at least some pockets on the planet. Overall, Cohen is encouraged by what the findings show of the resiliency of life in a broader, astrobiological perspective. “Once life gets going, it seems pretty hard to extinguish,” said Cohen “You can freeze it, throw giant meteors at it, change the air it has to breath, and it keeps on evolving and adapting and expanding.”

“Hopefully, what is true for life on Earth will also be true for life elsewhere,” Cohen added, “and that persistence will increase the likelihood of us identifying life elsewhere in the Universe.”

Note : The above story is based on materials provided by Astrobio.net
This story is republished courtesy of NASA’s Astrobiology Magazine. Explore the Earth and beyond at www.astrobio.net .

Three-horned dinos had self-sharpening teeth

June 15, 2015

In “Jurassic World,” kids visiting the Gentle Giants Petting Zoo get to ride on and feed a triceratops. Turns out that’s not such a good idea: University of Florida researchers recently learned that the three-horned dinos had self-sharpening teeth.

The discovery came about when UF mechanical engineer Greg Sawyer got a call from a paleontologist, who said that no matter how much he polished triceratops teeth before putting them under a microscope, he couldn’t get them flat. Sawyer and his then-doctoral student Brandon Krick found that alternating layers of tissue in the teeth interacted to make them sharper rather than duller as they wore. That might have given triceratops and its relatives an advantage – because they could chew tougher plants than their competition, they had more food sources and territory available. The adaptation isn’t just impressive for a prehistoric creature: It’s more sophisticated than any surface humans have created, Sawyer says. The discovery could revolutionize how we design things that wear down, from shoes to tires.So if you ever get a chance to ride a Jurassic World gyrosphere through a herd of triceratops, you’ll definitely want to keep your hands inside the vehicle. They may be plant-eaters, but their teeth mean business.

Note : The above story is based on materials provided by University of Florida.

Brain of ancient sea creature reconstructed by undergraduate researcher

June 14, 2015

The world’s first study into the brain anatomy of an ichthyosaur, a marine reptile that lived at the same time as the dinosaurs, has shed light on how the reptilian brain adapted to life in the oceans. The work, led by University of Bristol undergraduate Ryan Marek, is out this week in the journal Palaeontology.

With strong ties to Mary Anning, the renowned nineteenth century fossil collector, ichthyosaurs are ingrained within the history of palaeontological research, having first been discovered over 200 years ago. Despite this, research into these ancient marine reptiles is difficult as their fossilised remains are usually found compressed and flattened, making studies of skull function and brain anatomy near impossible.

However, one specimen from the Bath Royal Literary and Scientific Institute, originally found locally at a site now lost to science in Strawberry Bank, Somerset, is almost complete, and is preserved spectacularly in three dimensions.

Ryan Marek, lead author on the paper said: “The fossil is incredible – its skull is in a good enough condition to use the latest visualisation techniques, allowing us to carry out work that’s never been done on ichthyosaurs before.”

Ichthyosaurs were a group of marine reptiles closely related to plesiosaurs and pliosaurs, all of which are found on various British coastlines on a semi-regular basis. They superficially resemble dolphins, however ichthyosaurs have much larger eyes, used to see when diving to depths of up to 600 metres, and longer, thinner snouts.

Using CT scanning and digital visualisation software, the researchers were able to fully restore the skull of the ichthyosaur, which was assigned to the species Hauffiopteryx typicus that lived 180 million years ago. Then, by infilling the cavity in the skull which the brain used to occupy, the researchers, for the first time ever, were able to study the brain anatomy of an ichthyosaur.

The study found enlarged optic lobes, which correspond to the specimen’s huge eyes and allows it to see when diving to deeper waters. The ichthyosaur also had an enlarged cerebellum, the part of the brain responsible for motor control, enabling it to be a highly mobile, visual predator. Unexpectedly, the olfactory region, the area responsible for processing smell, is enlarged.

Co-author Professor Mike Benton said: “These results both confirm previous hypotheses on ichthyosaur sensory biology and also offer new insights into how these marine reptiles interacted with their environments – perhaps the creatures relied more on their sense of smell than we previously thought.”

Not only does the study break new ground on ichthyosaur brain anatomy, it also provides scientists with more information on other aspects of ichthyosaur skull anatomy, previously difficult to study due to the flattened nature of many ichthyosaur skull fossils.

Another co-author, Benjamin Moon said: “Identifying these features allows us to better understand the evolutionary relationships of ichthyosaurs, and how the group evolved, and this study will hopefully encourage others to research other ichthyosaur specimens with the latest techniques.”

Reference:
“The skull and endocranium of a Lower Jurassic ichthyosaur based on digital reconstructions.” Palaeontology. DOI: 10.1111/pala.12174

Note : The above story is based on materials provided by University of Bristol.

Researchers Use Prehistoric Amber to Test Glass Theory

June 14, 2015

20-million-year-old Dominican fossil amber

Along the way, the investigation sheds light on the long-held urban myth of the fluidity of stained glass.

In some circles, no matter how much experimentation and research is done that gives a definitive answer to the contrary, some urban myths continue to live.
Even in the scientific community some urban legends never seem to go away. One of those involves whether glass flows over time, using the example of stained-glass windows in medieval cathedrals as an example where the glass pieces appear thicker at the bottom. The thinking is the glass flowed downward over centuries.

A pair of Texas Tech University professors and a doctoral student, however, recently used prehistoric amber to test theories of glasses and concurrently provided new information to dispel that myth. Their findings were highlighted by the National Science Foundation (NSF), which funded the research.

The study by Greg McKenna, Horn Professor and the John R. Bradford Chair in the Department of Chemical Engineering, Sindee Simon, Horn Professor and chemical engineering department chair; and Jing Zhao, a chemical engineering doctoral student, tested the thermal, mechanical and flow properties of 20 million-year-old Dominican amber glass.

What they found was the density of the amber after 20 million years of aging is just roughly 2 percent more than the same amber that had been heated past its glass transition temperature and then rapidly cooled, a process referred to as thermal rejuvenation. In the first heating, they determined the fictive temperature of the amber to be about 44 degrees Celsius lower than the glass transition temperature, an important piece of their study.

McKenna and his colleagues showed the molecular mobility of the amber in the temperature window between the fictive temperature and the glass transition temperature does not diverge as suggested by classical glass theory. In addition, McKenna commented the extremely long time to get a 2 percent density change in the amber at a temperature only 110 degrees Celsius below the glass transition temperature shows that the glass in windows that are 900-1,200 years old and multiple hundreds of degrees Celsius below the glass transition would certainly not have noticeably changed in that time frame, thus dispelling the myth of glass flowing far below its glass transition temperature.

“It’s a cute story,” McKenna said. “If you do the calculations you can show that it’s really not true. But it makes it exciting to show that the time scale involved in this process is way too long for cathedral glass to be flowing.”

Table of Contents

Necessary time

The impetus for the experiment began, McKenna said, after Zhao carried out experiments for her doctorate qualifying exam where a polyvinyl acetate polymer was aged 22 days at about 14 degrees Celsius below the glass temperature. That’s a long time in the life of a graduate or doctoral student but not long enough to answer fundamental questions regarding glass transition temperature.

McKenna said for common window glass, the glass transition temperature is more than 1,000 degrees Celsius, while for many polymer glasses it is about 100 degrees Celsius. Even in high-performance polymers it may be below 250 degrees Celsius. McKenna said it is important to understand that range of temperatures and the glass theories that he and his colleagues were testing form the current basis for making long-term predictions about materials such as polymeric adhesives or polymer resin-based composites that are used in products such as passenger jet airplanes.

McKenna, Simon and Zhao, however, wanted to take the experiment beyond the 220 days, so McKenna was able to find a reliable source for Dominican amber through the Dead Bug in Amber Club, and Zhao “took the amber and ran with it,” McKenna said.

Through heating the material and cooling it either rapidly or gradually, the researchers discovered that, in the course of 20 million years, the reduction in glass transition temperature to fictive temperature was only about 45 degrees, a relatively slow change considering the age of the material.

“For us, that window is important because previously, it was only about 15 degrees in 22 days,” McKenna said. “To go from 22 days to 20 million years and only get an extra 30 degrees, it shows how slow things move in glass forming materials once they are below the glass transition temperature. Then we were able to establish with the amber in that window that the paradigm of diverging time scales above absolute zero didn’t seem to be true, and that’s what we were looking to test.

“By working between fictive temperature and the glass transition temperature we’re able to say the upper-bound behavior is not close to the extrapolated models.”

The myth lives

McKenna points to a 1995 comment in the journal Science on the nature of glass by Phillip Anderson, who won the Nobel Prize in Physics in 1977, as a reason why research continues in this area. Anderson said, “The deepest and most interesting unsolved problem in solid state theory is probably the theory of the nature of glass and the glass transition.”

McKenna said many theories arising from the research tend to be those of the behavior of glass above the glass transition temperature when the material is in equilibrium. The problem, he said, is that below glass transition temperature, the material falls out of equilibrium.

“It is these really long time scales that are needed to get it back into equilibrium,” McKenna said. “Scientists want to know if, below the glass transition, is the behavior as predicted by theory? And we’ve found there is a whole class of theory that does not agree with what has been found. And, in my opinion, that class of theory should be abandoned because it is incorrect and you will never be able to correctly predict below glass transition behavior using such theories. New theories are being developed in laboratories, and the amber data are good enough that we can actually discriminate among these theories.”

McKenna said a group of scientists at the University of Wisconsin has developed a way to create 10 million-year-old glass in 10 minutes through a method called physical vapor deposition, and this may provide researchers a way to conduct more thorough examinations of glass dynamics. McKenna also is planning to test theories using metallic glass.

The ultimate goal is to make long-term predictions on the behavior of materials in the glassy state and how those materials can be used. Examples range from the new Airbus A-380 or the Boeing 787 Dreamliner place that make broad use of composite materials that are made with glassy organic resins and polymers that will age over the lifespan of the aircraft.

“Understanding that aging will also affect our understanding and ability to predict when they will break,” McKenna said. “We think it’s important. For example, I was just at a workshop last year at the NSF where scientists from universities and industry got together to look at lifetime issues. The reality is there’s a whole group of people who say the same thing, that we don’t know enough about the behavior of these materials in the glassy state to make reliable long-term predictions.”

Note : The above story is based on materials provided by Texas Tech University.

Answering the mystery of turquoise provenance

June 14, 2015

This is a turquoise sample from Cananea, Sonora, Mexico. Credit: Wikipedia; CC BY 2.0

Turquoise has had cultural significance for Native American peoples in the southwestern United States and Mexico for more than a millennium, and turquoise artifacts have been recovered from archaeological sites hundreds of kilometers distant from known sources of the mineral. Evidence for pre-Hispanic turquoise mining has been recognized across much of the southwestern United States and northern Mexico, including as far north as Leadville, Colorado, and as far south as Zacatecas.

Detailed archaeological studies of ancient turquoise mines are rare, and little is known about the timing of their exploitation or the cultural identities of the miners In this study, Alyson M. Thibodeau and colleagues show that many geological sources of turquoise in the southwestern U.S. and northern Mexico can be distinguished from each other through the measurement of lead and strontium isotopic ratios. These isotopic analyses thus provide a new way to investigate the mining and movement of this mineral in prehistory.

Reference:
Isotopic evidence for the provenance of turquoise in the southwestern United States
A.M. Thibodeau et al., Dickinson College, Carlisle, Pennsylvania, USA. Published online ahead of print on 3 June 2015; DOI: 10.1130/B31135.1

Note : The above story is based on materials provided by Geological Society of America.

Raptor tracker: Hot on the trail of Velociraptor relative

June 13, 2015

This is an illustration representing raptor tracks. Credit: Illustration by Scott Persons and Lida Xing

In this summer’s much anticipated blockbuster Jurassic World, actor Chris Pratt joins forces with a pack of swift and lethal velociraptors. ‘Velociraptor belongs to a group of predatory dinosaurs called the deinonychosaurs, or simply the ‘raptors’,’ says University of Alberta paleontologist Scott Persons. ‘Raptors are characterized by particularly nasty feet. Their big toes each bore an enlarged and wickedly hooked talon, which makes raptors well suited for Hollywood fight scenes.’

Persons and University of Alberta alumnus Lida Xing are part of the research team that has just documented a rich fossil footprint site in central China, which contains the tracks of several kinds of dinosaurs, including raptors. From these tracks, the team has gained new insights into raptor locomotion. The raptor track research was published this month in the scientific journal PaleoWorld.

‘The enlarged raptorial claw was a killing tool. To keep it sharp, raptors normally held it in a raised position,’ Persons explains. ‘That way, the claw stayed sharp. Otherwise, it would have become dulled as it dug into the ground when the dinosaur walked. Modern cats retract their claws while walking or running for the same purpose.’

This unique foot posture makes the tracks of raptors easy to identify. ‘Most other carnivorous dinosaur tracks show three forward-pointing toes, like a bird. But a raptor footprint usually only records two complete toes and sometimes just the base of a third — although we have discovered that there are exceptions,’ Persons notes, referring to one of the study’s new findings.

In a small percentage of the raptor tracks, an impression of the usually raised big-toe claw was found. The claw’s thin edge left a long and narrow gouge that does not have the splay of a typical toe print. ‘It’s unclear why the raptors occasionally lowered their killing claws into the ground,’ Persons says. ‘One hypothesis is that, because the tracks were left in the soft mud of a lake shore, the raptors might have needed a little extra traction. So, although the hooked claw was primarily a weapon, it could also be deployed like a big cleat.’

Note : The above story is based on materials provided by University of Alberta.

New Grand Canyon age research focuses on western Grand Canyon

June 13, 2015

Figure 2 from Darling and Whipple: Photographs taken from Twin Point overlook by Rich Rudow. (A) View to the southeast, showing the Shivwitz Plateau escarpment above the Sanup Plateau. (B) View to the south, showing the Sanup Plateau in the foreground and the Hualapai Plateau in the background. Surprise and Spencer canyons are prominent recesses in the plateau. Credit: Photographs taken from Twin Point overlook by Rich Rudow; Geosphere, 10 June 2015.

The age of the Grand Canyon (USA) has been studied for years, with recent technological advances facilitating new attempts to determine when erosion of this iconic canyon began. The result is sometimes conflicting ages based on different types of data; most data support the notion that the canyon began to erode to its current form about six million years ago. Then even newer, “high-tech,” data became available and questions were again raised about whether the western end of the canyon could be older.
Two numbers are used as general time markers for these alternate hypotheses. The first suggests that the canyon may have started incising 17 million years ago. The second suggests that the canyon may have looked largely as it does today 70 million years ago. The time contrast between these hypotheses is striking, and any accurate concept of the canyon would have to be consistent with all observations.

Other researchers have studied the Grand Wash Fault, which truncates the western Grand Canyon. The fault runs north to south, nearly perpendicular to the Canyon. The fault slides in such a way that the west side of the fracture moves down relative to the east side, leaving a cliff face called the Grand Wash Cliffs. This slip, called “normal slip,” has led to the opening of a valley called the Grand Wash trough along the east end of Lake Meade. Erosion of hillslopes and canyons in the Grand Wash Cliffs is driven by the fault movement exposing the rock at the surface. These hillslopes and canyons are similar to the Colorado River’s tributaries in Grand Canyon, except hills and side streams are all steeper in Grand Canyon.

This comparison is useful because the Grand Wash fault has been studied extensively, and other scientists have shown that the fault completed most of its sliding between 18 and 12 million years ago. The rocks and climate in both regions are similar, so the difference in landform shape is most likely due to when the landforms started eroding.

In this new article for Geosphere, Andrew Darling and Kelin Whipple focus on the western Grand Canyon, west of the Hurricane fault. Their data show that the Grand Canyon must be younger than the fault slip that occurred 18 to 12 million years ago. Comparing their data to other datasets suggests that the notion that the canyon starting eroding around six million years ago is still the best scientific idea for the age of the Grand Canyon.

Reference:
Geomorphic constraints on the age of the western Grand CanyonAndrew Darling and Kelin Whipple, Arizona State University, Tempe, Arizona, USA. Published online on 10 June 2015; DOI: 10.1130/GES01131.1.

Note : The above story is based on materials provided by Geological Society of America.

New research initiative at Stanford to comprehensively study the use of natural gas

June 13, 2015

The Natural Gas Initiative will expand Stanford’s research on energy and the environment by focusing additional resources on the growing importance of natural gas. Credit: Courtesy of Stanford University

In the transition to a low-carbon energy system, how can society use increasing supplies of natural gas to minimize greenhouse gas emissions, improve air quality, boost economies and strengthen energy security? Stanford University’s new Natural Gas Initiative will work to answer that question, as well as myriad scientific, technological and policy questions that underlie it.

The new program will expand Stanford’s research on energy and the environment by focusing additional resources on the growing importance of natural gas. U.S. production has risen almost 50 percent in the past 10 years, and global demand for gas is anticipated to outpace all other fossil fuels. More than 35 professors and research staff from a dozen Stanford academic departments have already affiliated with the Natural Gas Initiative.

‘If developed in a responsible manner, natural gas can be the critical transition fuel that reduces the environmental impacts of fossil fuels and keeps us on a path toward a decarbonized energy future,’ said Mark Zoback, a professor of geophysics and NGI’s director.

‘When electric power plants burn natural gas instead of coal, that reduces emissions of carbon dioxide and other pollutants, which are rising in many countries,’ Zoback said. ‘If done properly, domestic gas development can also improve energy security and boost economic growth elsewhere, as it has in North America.’

U.S. emissions of CO2 have declined to the level of the mid-1990s. Compared with burning coal, natural gas emits about half the carbon dioxide and substantially less soot, mercury and sulfur. Natural gas has also revitalized several domestic industries and reduced the U.S. trade imbalance. Idle natural gas import terminals are being retooled to export liquefied natural gas to Asia and Europe, which is looking to lessen its dependence on Russia for natural gas.

However, the technologies that have released the new supplies — hydraulic fracturing and horizontal drilling — have also unleashed anxieties about contaminated drinking water, induced earthquakes and lenient regulation. At times directly affecting residential neighborhoods, the large-scale industrial process has strained many U.S. communities. The increased use of natural gas has angered opponents of fossil fuels and heightened concerns about methane leaks throughout the U.S. natural gas production and pipeline system.

‘Natural gas must be developed with safeguards to reduce impacts on water, air quality, land, nearby communities and ecosystems,’ Zoback said. ‘While we have to meet both short-term energy and economic needs, we also need to meet society’s long-term environmental goals.’

Table of Contents

Initial research projects funded

The Natural Gas Initiative has begun funding early stage, exploratory research, following a ‘seed grant’ model used by Stanford’s Precourt Institute for Energy, one of NGI’s hosting organizations. The program will fund interdisciplinary research in six key areas: resource development, uses, environmental impacts and climate change, global markets and finance, policy and regulatory reform, and geopolitical impacts.

‘The growth of natural gas is happening, and that presents both opportunities and challenges,’ said Pamela Matson, dean of Stanford’s School of Earth, Energy & Environmental Sciences, which is NGI’s other hosting organization. ‘Stanford can bring our expertise — in engineering, geophysics, water resources, environmental science, economics, policy and law — to address the issues.’

In one of the first research projects NGI is funding, Robert Jackson, professor of environmental Earth system science, and Adam Brandt, assistant professor of energy resources engineering, are starting to develop a more accurate, faster and less expensive method for detecting leaks of methane — a very potent greenhouse gas and the primary component of natural gas — at well pads and gas processing stations. At a natural gas field in Utah thought to have particularly high methane leakage, the investigators will couple helicopter-based infrared imaging with aircraft and ground-based estimates of methane leaks to develop software to recognize plumes. Jackson, a member of the Earth System Science Department, has mapped thousands of natural gas leaks across city streets in Boston and Washington, and published the first studies of hydraulic fracturing’s impact on drinking water. Brandt, in Energy Resources Engineering, led a national study last year on methane leaks in the U.S. natural gas system.

NGI’s other four inaugural research projects are:

To aid government decision-making, John Weyant and Hillard Huntington of the Management Science & Engineering Department and Michael Wara of Stanford Law School are designing a robust structure for evaluating the opportunities, economics and environmental impacts of exporting U.S. natural gas to Europe and Asia.
Chemical Engineering’s Thomas Jaramillo is experimenting with electrochemically converting natural gas into higher-value products, like methanol. Such fuels could lower greenhouse gas emissions from transportation compared with gasoline and diesel fuel.
Eric Shaqfeh of the Chemical Engineering and Mechanical Engineering departments and Gianluca Iaccarino of Mechanical Engineering are making a computational tool for inventing new, benign fluids for use in hydraulic fracturing.
Eric Dunham of the Geophysics Department is developing methods for three-dimensional imaging of complex fracture networks in order to identify the location of constrictions or regions of partial closure.
‘Making the most of our natural gas resources and making sure they provide the environmental benefits we seek will require much more than technology,’ said Sally Benson, director of the Precourt Institute for Energy and a professor in energy resources engineering. ‘Good policies, international engagement and a rich dialogue with key stakeholders will be critical for success.’

Additional leadership

Bradley Ritts will be NGI’s managing director. Ritts, most recently with Chevron Asia Pacific Exploration & Production Co., earned a doctorate in geological and environmental sciences at Stanford. Previously the Robert R. Shrock Professor of Sedimentary Geology at Indiana University, Ritts is a National Science Foundation CAREER grant recipient, and an expert on oil and gas exploration. Tisha Schuller, who earned a bachelor’s degree in Earth systems from Stanford, will be a strategic advisor. Schuller was president of the Colorado Oil & Gas Association when that state’s energy companies and the Environmental Defense Fund worked with state regulators to enact the first rules in the United States to reduce methane emissions and volatile gases.

Initial funding for NGI was provided by Stanford’s School of Earth, Energy & Environmental Sciences; the Precourt Institute for Energy; the Office of the Dean of Research; and the President’s Office. Zoback, Ritts and Schuller are in the process of building out NGI’s corporate affiliates program. Support will also come from individual donors, non-governmental organizations and foundations.

Note : The above story is based on materials provided by Stanford University.

Stone tools from Jordan point to dawn of division of labor

June 13, 2015

Two stone tool points were made using a prismatic blade technique (left and center), and a bone point or needle (right). Credit: Photo by Aaron Stutz, Emory University.

Thousands of stone tools from the early Upper Paleolithic, unearthed from a cave in Jordan, reveal clues about how humans may have started organizing into more complex social groups by planning tasks and specializing in different technical skills.
The Journal of Human Evolution published a study of the artifacts from Mughr el-Hamamah, or Cave of the Doves, led by Emory University anthropologists Liv Nilsson Stutz and Aaron Jonas Stutz.

“We have achieved remarkably accurate estimates of 40,000 to 45,000 years ago for the earliest Upper Paleolithic stone tools in the Near East,” Aaron Stutz says. “Our findings confirm that the Upper Paleolithic began in the region no later than 42,000 years ago, and likely at least 44,600 years ago.”

The rich array of artifacts shows a mix of techniques for making points, blades, scrapers and cutting flakes. “These toolmakers appear to have achieved a division of labor that may have been part of an emerging pattern of more organized social structures,” Stutz says.

The theory that greater social division of labor was important at this prehistoric juncture was first put forward by anthropologists Steven Kuhn and Mary Stiner.

“Our work really seems to support that idea,” Stutz says. “The finds from Mughr el-Hamamah give us a new window onto a transitional time, on the cusp of modern human cultural behaviors, bridging the Middle and Upper Paleolithic.”

This pivotal time also marked the ebbing of Neanderthals as a last wave of anatomically modern humans spread out from Africa and into the Near East. This region, also known as the Levant, comprises the eastern Mediterranean at the crossroads of western Asia and northeast Africa. As the final surge of modern humans passed through the Levant, they would likely have encountered human populations that arrived earlier, and they may also have interbred with Neanderthals.

“Our find sits right in the Levantine corridor, midway between the Dead Sea and the Sea of Galilee, where each generation expanding into Eurasia would have foraged for food and made campsites,” Stutz says. “We don’t know if these toolmakers were mainly Neanderthals or anatomically modern humans, but recent evidence from other studies now raises the possibility that they were a mix of different populations. What we see at the Mughr el-Hamamah site is that individuals were starting to live, work and form families in larger, more culturally structured social networks.”

Mughr el-Hamamah is located in a limestone outcrop 240 feet above sea level. It overlooks the Jordan Valley, opposite the Nablus Mountains in the West Bank. The Stutzes, a husband-and-wife team, led excavations of the cave in 2010, funded by a grant from the National Science Foundation.

The relatively undisturbed Upper Paleolithic layer included fireplaces stacked atop one another that yielded chunks of well-preserved charcoal from hearths associated with the tools. Co-authors Jeff Pigati of the U.S. Geological Survey and Jim Wilson of Aeon Laboratories derived radiocarbon dates for the charcoal specimens, using advanced techniques that minimized the chances of contamination.

The cave is about 30-feet deep with an entrance about 20-feet wide. “We can speculate that several families shared the space and worked alongside one another,” Aaron Stutz says. “We found burned animal bones, so they were likely roasting meat, and perhaps boiling plants in hides suspended over their fires as they sat nearby making tools. From the mouth of the cave, they would have had a commanding view of what was likely wetlands and open-vegetation terrain. They could see approaching visitors and deer and gazelle wandering in the distance. If their kids were playing outside, they might also be watching for leopards or other predators.”

Toolmaking was a major activity of the group, as evidenced by their prolific output. Co-author John Shea, an anthropologist from Stony Brook University and an expert flint knapper himself, is continuing to analyze the thousands of implements they left behind.

Many discoveries of Near Eastern tool assemblages dating prior to the early Upper Paleolithic show that humans focused on just one technology. The tools tend to look similar and likely served many uses – the Stone Age version of a Swiss Army Knife. “It takes a good bit of cleverness to be able to devise a tool that helps you cover lots of different situations,” Stutz says. “And it makes sense in a context where you don’t necessarily know what you’re going to need your piece of flint for that day.”

The group of toolmakers at Mughr el-Hamamah, however, used different technologies to get different tools. “They were investing in the kinds of activities that require maintaining relationships and group planning,” Stutz says. “They were gearing up for a clearly defined division of labor, including firewood gathering, plant gathering, hunting and food foraging.”

They produced large quantities of blades for knives, and for hafting onto spears, using a prismatic blade technique that yields long, narrow points that are nearly identical. “This standardization minimizes waste of the rock while maximizing the end product,” Stutz says. “It’s the conceptual forerunner to assembly-line production.”

Through this method, the toolmakers could have efficiently produced the armature for multiple hunters going out on a lengthy foray, increasing the chances for finding and striking a target, he says.

“It would have been socially advantageous for individuals to give blades that they made to others, to entice them to stay together as a group,” he adds. “That kind of reciprocity builds relationships. And the stronger the connectivity of your social networks, the greater chance of increasing the number of calories and the quality of nutrients for the group.”

Artifacts from the cave also included scraping tools, made on thick blades for hafting onto a handle and likely used for working wood and animal hides.

Other tools continued to be crafted with what is known as the Levallois technique, which was more often used to make the multi-use flakes and triangular points so common in earlier periods.

Even more surprising, Shea’s analysis identified hundreds of basic flakes made from the oldest, easiest Stone Age technology of striking a rock that the toolmaker balances on a stone anvil. These tiny, sharp flakes may have served almost like disposable cutlery – handy implements that could be grabbed for a variety of purposes and tossed aside when no longer needed, Stutz says.

It is not yet known if the few fragments of human bones found at Mughr el-Hamamah have left enough intact fragments of DNA for any genetic analysis. But the diverse tool technologies, in use throughout the occupation period of the cave, support the theory of hunter-gatherer populations starting to band together in larger, more interconnected social networks.

As humans began to dominate the landscape, the researchers theorize, they reached a population density threshold for living in larger groups and gained access to a range of technologies. That process may have helped tip the balance for the rise of modern human culture and the disappearance of the Neanderthals.

“Our findings positively show that the cultural changes associated with Neanderthal extinction in the Near East and wider western Eurasia really are more complex than many leading researchers have assumed,” Stutz says. “Instead of looking for a smoking-gun technology or climatic fluctuation or volcanic eruption, it’s clear we need to look at interconnected behavioral, population and ecological processes. That approach might reveal more clearly the similarities, as well as differences, between our mainly African, and slightly Neanderthal, biological inheritance.”

Reference:
Early Upper Paleolithic chronology in the Levant: new ABOx-SC accelerator mass spectrometry results from the Mughr el-Hamamah Site, Jordan. DOI:10.1016/j.jhevol.2015.04.008

Note: The above story is based on materials provided by Emory Health Sciences. The original article was written by Carol Clark.

Fossil from 20-foot shark found near Fort Worth

June 12, 2015

Paleontologists literally stumbled upon fossils just outside Fort Worth that were vertebrae of a monster shark that trolled the shallow seas that covered Texas a hundred millennia ago.

A group of college students was searching for fossils in 2009 during a paleontology trip to the Duck Creek Formation, hoping to bring home some pieces to display.

Walking along a section of the formation with exposed limestone, Joseph Frederickson’s wife, Janessa Doucette-Frederickson, tripped over a boulder and noticed a fossil.

“We dig it out and realize it was a unique fossil,” Joseph Frederickson told the Fort Worth Star-Telegram. “None of us had seen anything of this size before – we ended up digging up three total fossils.”

The fossils are vertebrae that belonged to a shark at least 20 feet long, dating from 100 million to 105 million years ago. In comparison, present-day great white sharks average 15 feet long.

The Duck Creek Formation, home to Cretaceous Period fossils, is just west of Fort Worth and extends all the way to Oklahoma. Frederickson and his wife are now graduate students at the University of Oklahoma.

Last week, the couple and their colleague Scott Schaefer published their findings, “A Gigantic Shark From the Lower Cretaceous Duck Creek Formation of Texas,” in the scientific journal PLOS One.

While the paleontologists were studying the vertebrae, they learned of other large shark fossils found in Kansas dating from the same period. That shark would have been 27 feet long.

“They would have been living alongside each other,” Frederickson said. “The impressive thing about this is that we have this gigantic shark – over 20 feet – that’s as large as the largest documented great white.”

The finding changes the way people view sharks of that era.

“We didn’t even know there were sharks this large that could have been dominant predators,” Frederickson said. ” … These sharks kind of paved the way for other gigantic species.”

Scientists previously thought that Cretaceous sharks were really small.

“Now we know that they weren’t,” he said.

Frederickson, now a doctoral student in ecology and evolutionary biology at OU, is moving the study forward by looking into the ontogeny of the shark – how it developed.

“Was it quick? Or did it live 100 years and do it really slowly?”

Note : The above story is based on materials provided by Fort Worth Star-Telegram, Distributed by Tribune Content Agency, LLC..

Reactivating fault slip with fluid injection

June 12, 2015

Seismogram being recorded by a seismograph at the Weston Observatory in Massachusetts, USA. Credit: Wikipedia

Water injected into an inactive fault can cause aseismic slip along the fault — movement without detectable earthquakes — that may then indirectly lead to micro-earthquakes. That’s the result from a controlled experiment by Yves Guglielmi and colleagues, who observed these events in real time after injecting fluid into a natural fault near an underground experimental facility in southeastern France.

Researchers are intensely interested in this type of induced seismicity, especially with a rise in earthquakes caused by injections of wastewater from gas and oil exploration. The experiment by Guglielmi and colleagues offers a better look at how friction in fluid-filled faults contributes to slip along the fault. In this case, the injected water caused very slow, four-micrometers-per-second aseismic creep on the fault before transitioning to a faster, 10-micrometers-per-second seismic slip and a series of tiny earthquakes. As Francois Cornet notes in a related Perspective article, experiments like this could guide monitoring at injection sites by potentially keeping the injection flow rate at a level that maintains aseismic slip rather than triggering earthquakes.

Reference:
“Seismicity triggered by fluid injection-induced aseismic slip,” by Y. Guglielmi; P. Henry at University of Aix-Marseille in Aix-en-Provence, France; Y. Guglielmi; P. Henry at CNRS in Aix-en-Provence, France; Y. Guglielmi; P. Henry at Institut de recherche pour le développement (IRD) in Aix-en-Provence, France; F. Cappa at University of Nice Sophia-Antipolis in Sophia-Antipolis, France; F. Cappa at CNRS in Sophia-Antipolis, France; F. Cappa at Institut de recherche pour le développement (IRD) in Sophia-Antipolis, France; F. Cappa at Côte d’Azur Observatory in Sophia-Antipolis, France; F. Cappa; J.-P. Avouac at California Institute of Technology in Pasadena, CA; D. Elsworth at Pennsylvania State University in University Park, PA; J.-P. Avouac at University of Cambridge in Cambridge, UK. DOI: 10.1126/science.aab0476

Note : The above story is based on materials provided by American Association for the Advancement of Science.

Fluid injection causes ground to creep before quakes

June 11, 2015

Researchers injected water into a geological fault in France to understand how fluids affect seismic activity. Credit: Yves Guglielmi/Institut Pythéas

Injecting water into a geological fault causes the rock to move harmlessly for a short time before it slips enough to produce an earthquake, a study shows. The discovery suggests that energy companies might be able to control the start of the earthquakes that they sometimes trigger as they inject fluids into the ground during oil, gas or geothermal exploration.
To test how fluid injections affect seismic activity, geologists squirted water 282 metres deep into rocks at an underground laboratory in southeastern France. They measured, more carefully than ever before, exactly how the ground shifted as the fluid coursed through it.

For the first several minutes, the ground moved quietly, with no earthquakes. “Only after a while do you see some seismicity occurring,” says team leader Yves Guglielmi, a geologist at the University of Aix-Marseille in France, whose findings are published in Science.

Pumping fluid into the ground can trigger earthquakes by unclamping the stresses that hold the sides of a geological fault together. The extra fluid relieves those stresses and allows the rock to shift.

Researchers have understood the basics of this phenomenon since the late 1960s and early 1970s, when the US Geological Survey counted the earthquakes set off as operators injected fluids down an industrial well. But Guglielmi’s team went further by carefully controlling and measuring the whole process from start to finish.

Slip and slide

The researchers developed a cylindrical probe that can record precisely how a fault moves in all three dimensions, while monitoring fluid pressure. They lowered the instrument into a borehole that penetrates a fault in limestone rocks at the Low-Noise Underground Laboratory in Rustrel, France.

Over a half an hour, the scientists injected a total of 950 litres of water into the fault, at rates comparable to industrial injections. During the first part of the test injection, the rocks crept along without generating any earthquakes. Then they began to move faster, and small earthquakes began to break out. By the time the researchers turned off the water, one rock face in the fault had moved a little more than 1 millimetre past the other. “The experiment is quite tiny,” says Guglielmi.

If operators of commercial wells can monitor their equipment as carefully as the research team did, they might be able to control how much the ground slips by adjusting the rate of fluid injection, says François Cornet, a geophysicist at the University of Strasbourg in France. In 2009, a geothermal project in Basel, Switzerland, was shut down because of the risk of triggering earthquakes. In Oklahoma, oil and gas operators are facing a huge public backlash because of a rash of small earthquakes that have been rattling the region, almost certainly linked to wells that inject waste water deep into the underlying rocks.

Cornet warns that the discovery applies to only one particular hole, and that it might not hold up in areas with different geology. Still, in 1993, he and his colleagues injected large amounts of water down a geothermal well in northeastern France, and measured what could have been the same sort of non-earthquake slip as pressure built up along the fault.

Guglielmi says that his team has already run tests at a second borehole drilled into shale, with similar results.

Note : The above story is based on materials provided by Nature. The original article was written by Alexandra Witze.

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Reactivating fault slip with fluid injection

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Slip and slide

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