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Geoengineering report: Scientists urge more research on climate intervention

Deep cuts in greenhouse gas emissions, while necessary, may not happen soon enough to stave off climate catastrophe. So, in addition, the world may need to resort to so-called geoengineering approaches that aim to deliberately control the planet’s climate.

That’s according to a National Research Council committee that today released a pair of sweeping reports on climate intervention techniques.

The University of Michigan’s Joyce Penner, who is the Ralph J. Cicerone Distinguished University Professor of Atmospheric Science, served on the committee. Penner studies how clouds affect climate.

The reports consider the two main ways humans could attempt to steer the Earth’s system: We could try to take carbon dioxide out of the atmosphere. Or we could try to reflect more sunlight back into space. The committee examined the socioeconomic and environmental impacts as well as the costs and technological readiness of approaches in each category.

The researchers said that certain CO2-removal tactics could have a place in a broader climate change response plan. But the sunlight reflecting technologies, on the other hand, are too risky at this point. They underscored how important it is for humans to limit the levels of CO2 they put into the atmosphere in the first place, and they called for more research into all climate intervention approaches.

“I, for one, am concerned with the continuing rise in CO2 concentrations without clear efforts to reduce emissions,” Penner said. “The widespread impacts from these increases are readily apparent, and the cost of climate change impacts is likely to be high.

“We may need to employ some of these climate interventions techniques to avoid a catastrophe such as the loss of the Antarctic ice sheets, or even to remain below levels of climate change that are considered dangerous in the political arena.”

Techniques to remove CO2 include restoring forests and adopting low-till farming — both of which trap carbon in plants and soils. Oceans could be seeded with iron to promote growth of CO2-consuming organisms. And carbon could be be sucked directly out of the air and injected underground.

Methods to reflect sunlight include pumping sulfuric compounds into the stratosphere to, in essence, simulate a volcanic eruption; and spraying sea water mist or other finer-than-usual particles over the ocean. Smaller particles lead to brighter clouds, Penner said.

While the committee said that some of the CO2 removal strategies including “carbon capture and sequestration” have potential to be part of a viable plan to curb climate change, it noted that only prototype sequestration systems exist today. Much development would have to occur before it could be ready for broad use.

The scientists caution against dumping iron in the oceans, as the technical and environmental risks currently outweigh the benefits. Similarly, they warned against sunlight-reflecting approaches, also known as “albedo modification.”

These efforts might be able to reduce the Earth’s temperature in just a few years, and they’re relatively cheap when compared to transitioning to a carbon-free economy. But they’d have to be kept up indefinitely and could have numerous negative secondary effects on ozone, weather and human health.

Even in its opposition to sunlight reflecting tactics, the committee still recommended more research into them, as it urged more study of all climate intervention possibilities. Penner was struck by this call to action.

“U.S. agencies may have been reluctant to fund this area because of the sense of what we call ‘moral hazard’ — that if you start down the road of doing this research you may end up relying on this or condoning this as a way of saving the planet from the cost of decreasing CO2 emissions,” Penner said. “But we’ve stated that decreasing emissions must go hand in hand with any climate intervention efforts.”

Penner says the recommendation is a sign of the climate problem’s urgency.

“We need to develop the knowledge base to allow informed decisions before these dangerous effects are upon us,” she said.

The study was sponsored by the National Academy of Sciences, U.S. intelligence community, National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, and U.S. Department of Energy. The National Academy of Sciences is a private, independent nonprofit institution that provides science, technology and health policy advice under a congressional charter granted to NAS in 1863. The National Research Council is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering.

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

Analysis of recent earthquake sequence reveals geologic fault, epicenters in Irving and West Dallas

Locations of seismographic instruments as of January 30, 2015 together with revised earthquake locations (dark red).

Initial results from SMU’s seismology team reveal that the recent series of earthquakes occurring near the site of the old Texas Stadium were relatively shallow and concentrated along a narrow two mile line that indicates a fault extending from Irving into West Dallas.

SMU and the United States Geological Survey (USGS) on Friday shared an interim report with the mayors of Dallas and Irving spelling out preliminary information gleaned after SMU’s installation in January of more than 20 portable earthquake monitors around the earthquake sites.

“This is a first step, but an important one, in investigating the cause of the earthquakes,” said SMU seismologist Brian Stump.  “Now that we know the fault’s location and depth, we can begin studying how this fault moves – both the amount and direction of motion.”

“Then we can move on to what might have triggered it – examining factors both natural and manmade,” said SMU seismologist Heather DeShon. “Sometimes what triggers an earthquake can be very small, so all of these factors have to be considered when looking for that trigger.”

The earthquakes have occurred in the granite “basement,” below the layers of sedimentary rock that make up the large geological formation known as the Fort Worth Basin, at depths between 4.5 and 7 kilometers, according to the report.  It is not unusual for earthquakes to occur at different levels on a fault. Those depths are considered relatively close to the surface in earthquake terms, however, which helps explain why people as far away as Plano feel even smaller magnitude 2 earthquakes in the area.

The USGS initially mapped the earthquake locations as being spread out in a roughly circular area centered on the old Texas Stadium site, developing those locations from data collected by distant seismic monitors ranging from the closest at about 40 miles away to as far as 900 miles away. But once SMU installed more than 20 monitors in the immediate area – supplied by the USGS and the academic consortium IRIS – the enhanced data they were able to retrieve shows the January 2015 earthquakes actually have occurred along a line from Irving to West Dallas, running north-by-northeast from TX Highway 114 to Walnut Hill Road along the Trinity River.

That line indicates the approximate location of a subsurface fault.

This initial mapping of the fault provides important information for municipal hazard assessment in Irving and Dallas, Stump said, allowing city officials to know which parts of their cities might experience the worst shaking if the fault remains active. As has been the case with other earthquake sequences in North Texas since 2008, this latest bout of seismic activity appears to be diminishing over time. But SMU scientists stress that there is no way to predict when the series will end, or what the largest magnitude will be.

The earthquakes in the Irving area began in April 2014.  SMU scientists had just installed the first of its local monitors in the city of Irving on Jan. 5, 2015 when the area recorded its two largest earthquakes – 3.5 and 3.6 magnitude events – on Jan. 6 During January members of the SMU seismology team installed more than 20 seismographs in the affected area, including twelve short-term units that had to be removed from the field to collect their data.  There will be 11 temporary seismographs running as part of the Irving network moving forward.

The report notes the presence of two wells drilled for shale gas (only one was put into production, last producing in 2012) near the earthquake epicenters and the location of a wastewater injection well approximately eight miles to the northwest. Production and disposal activities in this region are generally confined to the sedimentary layers above the “basement” layers where regional earthquakes have occurred.

“Scientific questions about the nature of events in North Texas have heightened local and national concerns about the impact of activities related to shale gas production on geological infrastructure and subsurface infrastructure,” the report reads.  SMU scientists continue to explore all possible natural and anthropogenic (due to human activity) causes for the Irving earthquakes and do not have a conclusion at this time.”

The next steps of the Irving study are already underway.

Video:

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

Earthquake activity linked to injection wells may vary by region

The Williston Basin in north central U.S. produced fewer earthquakes caused by wastewater injection than in Texas, suggesting the link between seismicity and production activities may vary by region, according to a new study published in the journal Seismological Research Letters (SRL).

Ongoing since 1950s, petroleum and gas production in the Williston Basin, underlying parts of Montana, North Dakota, South Dakota and Saskatchewan in Canada, changed in recent years to include hydraulic fracturing and horizontal drilling. Scientists from University of Texas at Austin took advantage of new monitoring data to explore the connection between seismicity and petroleum production near the Bakken Formation, an area of historically low seismicity, but with a recent history of increased hydraulic fracturing and wastewater disposal.

“I’m looking at the relationship between seismicity and industry activity across different geographical areas,” said Cliff Frohlich, lead-author of the study and associate director of the Institute for Geophysics at University of Texas at Austin, who previously conducted similar studies, including one of the Barnett Shale near Fort Worth, Texas.

Frohlich and his colleagues analyzed data recorded by the EarthScope USArray, a National Science Foundation-funded network of temporary broadband seismometers, during September 2008 and May 2011, and from IHS, Inc., a private company that compiles information about petroleum operations from state regulatory sources. The authors identified nine regional earthquakes in the Williston Basin, comprising an area of approximately 100,000 square kilometers. Three of the nine earthquakes occurred near active injection wells, suggesting a connection to the disposal of wastewater.

Using a similar method, Frohlich’s previous study of the Barnett Shale region in Texas found significantly greater induced seismicity — 55 earthquakes within a 5,000 square kilometer region near Fort Worth.

“Why are earthquakes triggered in some areas and not in others? It’s an important question for regulators and the scientific community. Some answers are emerging,” said Frohlich, who cites differences in geology, orientation of pre-existing faults, local fault strength, injection practices and the timing and duration of oil and gas production as factors that might influence seismicity.

“Before we implement severe regulations or schemes to manage injection activity in a particular region, we need to do the homework — survey the relationship between seismicity and injection activity there to determine what’s warranted,” said Frohlich.

The study, “Analysis of Transportable Array (USArray) Data Shows Earthquakes are Scarce Near Injections Wells in the Williston Basin, 2008-2011,” will be published online February 11, 2015 and in the March/April print edition of SRL. In addition to Frohlich, co-authors include Jacob I. Walter and Julia F. W. Gate of University of Texas at Austin. The Seismological Society of America publishes the journal SRL.

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

Floods created home of Europe’s biggest waterfall

A downstream view of the Joumlkulsa Fjoumlllum river in the Joumlkulsa rgljuafur canyon in Iceland. New research from the University of Edinburgh shows that the canyon was formed in a matter of days by extreme floods. Credit: Edwin Baynes

A massive canyon that is home to Europe’s most powerful waterfall was created in a matter of days by extreme flooding, new research reveals.

The Jökulsárgljúfur canyon in Iceland, which is 28 km long and 100 metres deep in places, was formed by a series of distinct floods that occurred thousands of years apart, a study shows.

Scientists analysed rocks along a 5km stretch of the canyon — which contains the Jökulsá á Fjöllum river and the mighty Dettifoss waterfall — to create a timeline of how the landscape was created.

They used geochemical analysis to determine how long rocks on the canyon walls had been exposed to the elements. This helped the team pinpoint how the position and shape of the landscape had changed over time.

Researchers connected major shifts in the landscape to a series of extreme floods, which took place 9,000, 5,000 and 2,000 years ago. The floods were caused by volcanic activity under glaciers, and each was powerful enough to tear up bedrock. They formed the canyon’s 100-metre walls and pushed three waterfalls, including Dettifoss, back upstream by as much as 2km during each flood.

Scientists from the University of Edinburgh, who carried out the study, say the findings demonstrate the long-term impact that extreme flood events can have on landscapes. The floods were triggered by eruptions from volcanoes beneath Vatnajökull, the largest ice cap in Iceland. One of these volcanoes, Bárdarbunga, has been active since August 2014.

Edwin Baynes, of the University of Edinburgh’s School of GeoSciences, who led the study, said: “We think of natural environments as being formed over thousands of years, but sometimes they are shaped very suddenly. This insight into one of Iceland’s magnificent landscapes helps us better understand these processes, and illustrates their legacy.”

Reference:
Edwin R. C. Baynes, Mikaël Attal, Samuel Niedermann, Linda A. Kirstein, Andrew J. Dugmore, and Mark Naylor. Erosion during extreme flood events dominates Holocene canyon evolution in northeast Iceland. PNAS, February 9, 2015 DOI: 10.1073/pnas.1415443112

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

Geologists unlock mysteries of the planet’s inner core

A research team from the University of Illinois and colleagues in China found earth’s inner core has an inner core of its own, with crystals aligned in a different direction. Credit: Lachina Publishing Services

Seismic waves are helping scientists to plumb the world’s deepest mystery: the planet’s inner core.

Thanks to a novel application of earthquake-reading technology, a research team at the University of Illinois and colleagues at Nanjing University in China have found that the Earth’s inner core has an inner core of its own, which has surprising properties that could reveal information about our planet.
Led by Xiaodong Song, a professor of geology at the U. of I., and visiting postdoctoral researcher Tao Wang, the team published its work in the journal Nature Geoscience on Feb. 9.

“Even though the inner core is small — smaller than the moon — it has some really interesting features,” said Song. “It may tell us about how our planet formed, its history, and other dynamic processes of the Earth. It shapes our understanding of what’s going on deep inside the Earth.”

Researchers use seismic waves from earthquakes to scan below the planet’s surface, much like doctors use ultrasound to see inside patients. The team used a technology that gathers data not from the initial shock of an earthquake, but from the waves that resonate in the earthquake’s aftermath. The earthquake is like a hammer striking a bell; much like a listener hears the clear tone that resonates after the bell strike, seismic sensors collect a coherent signal in the earthquake’s coda.

“It turns out the coherent signal enhanced by the technology is clearer than the ring itself,” said Song. “The basic idea of the method has been around for a while, and people have used it for other kinds of studies near the surface. But we are looking all the way through the center of the Earth.”

Looking through the core revealed a surprise at the center of the planet — though not of the type envisioned by novelist Jules Verne.

The inner core, once thought to be a solid ball of iron, has some complex structural properties. The team found a distinct inner-inner core, about half the diameter of the whole inner core. The iron crystals in the outer layer of the inner core are aligned directionally, north-south. However, in the inner-inner core, the iron crystals point roughly east-west.

Not only are the iron crystals in the inner-inner core aligned differently, they behave differently from their counterparts in the outer-inner core. This means that the inner-inner core could be made of a different type of crystal, or a different phase.

“The fact that we have two regions that are distinctly different may tell us something about how the inner core has been evolving,” Song said. “For example, over the history of the Earth, the inner core might have had a very dramatic change in its deformation regime. It might hold the key to how the planet has evolved. We are right in the center — literally, the center of the Earth.”

Reference:
Xiaodong Song et al. Equatorial anisotropy in the inner part of Earth’s inner core from autocorrelation of earthquake coda. Nature Geoscience, Feb 9, 2015, Doi:10.1038/ngeo2354

Note : The above story is based on materials provided by University of Illinois at Urbana-Champaign.

Amber fossil links earliest grasses, dinosaurs and fungus used to produce LSD

Oldest grass fossil This grass spikelet from the middle Cretaceous is about 100 million years old, preserved in amber as the earliest fossil ever found of the evolution of grass, and covered on its tip by the parasite ergot. (Photo courtesy of Oregon State University)

A perfectly preserved amber fossil from Myanmar has been found that provides evidence of the earliest grass specimen ever discovered – about 100 million years old – and even then it was topped by a fungus similar to ergot, which for eons has been intertwined with animals and humans.

Ergot has played roles as a medicine, a toxin, and a hallucinogen; been implicated in everything from disease epidemics to the Salem witch trials; and more recently provided the hallucinogenic drug LSD.

Apparently both ergot and the grasses that now form most of the diet for the human race evolved together.

And if they already seemed a little scary, imagine a huge sauropod dinosaur that just ate a large portion of this psychotropic fungus, which in other animal species can cause anything from hallucinations to delirium, gangrene, convulsions or the staggers. The fungus, the grasses it lived on and dinosaurs that ate grass co-existed for millions of years.

The findings and analysis of this remarkable fossil were just published online in the journal Palaeodiversity, by researchers from Oregon State University, the USDA Agricultural Research Service and Germany.

“It seems like ergot has been involved with animals and humans almost forever, and now we know that this fungus literally dates back to the earliest evolution of grasses,” said George Poinar, Jr., an internationally recognized expert on the life forms found in amber and a faculty member in the OSU College of Science.

“This is an important discovery that helps us understand the timeline of grass development, which now forms the basis of the human food supply in such crops as corn, rice or wheat,” Poinar said. “But it also shows that this parasitic fungus may have been around almost as long as the grasses themselves, as both a toxin and natural hallucinogen.

“There’s no doubt in my mind that it would have been eaten by sauropod dinosaurs, although we can’t know what exact effect it had on them.”

Amber begins as a tree sap that can flow around small plant and animal forms and permanently preserve them, as it fossilizes into a semi-precious stone. Poinar is a world leader in examining such specimens and using them to learn more about prehistoric ecosystems.

The fungus in this grass specimen, which is now extinct, was named Palaeoclaviceps parasiticus. It’s very similar to the fungus Claviceps, commonly known as ergot. The fossil, taken from amber mines in Myanmar, dates 97-110 million years ago to the early-to-mid Cretaceous, when the land was still dominated by dinosaurs and conifers, but the earliest flowering plants, grasses and small mammals were beginning to evolve. The fossil shows a grass floret tipped by the dark fungus.

Much later in evolution, grasses would become a powerful life form on Earth, creating vast prairies, nourishing herds of animals, and eventually providing for the domestication of range animals and the cultivation of many food crops. The rise of crop agriculture changed the entire development of the human race, and it’s now estimated that grasses compose about 20 percent of global vegetation.

Researchers also noted in their report that “few fungi have had a greater historical impact on society than ergot.”

Some grasses have natural defense mechanisms, and ergot may be one of them, helping to repel herbivores. It’s bitter and not a preferred food to livestock, and it’s still a problem in cereal and grass seed production, as well as pastures and grazing land.

In animal and human history, the fungus has been known to cause delirium, irrational behavior, convulsions, severe pain, gangrenous limbs and death. In cattle it causes a disease called the “Paspalum staggers.” In the Middle Ages it sometimes killed thousands of people during epidemics when ergot-infected rye bread was more common. It’s been used as a medicine to induce abortion or speed labor in pregnant women, and one researcher – whose findings have been disputed – suggested it may have played a role in the Salem witch trials.

More than 1,000 compounds have been extracted or derived from it, some of them valuable drugs. They also included, in the mid-1900s, the powerful psychedelic compound lysergic acid diethylamide, or LSD, that is still being studied and has been widely used as an illegal recreational drug.

Ergot is strange. And a very, very old fossil now makes clear that it’s been around about as long as grass itself.

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

Understanding the copper heart of volcanoes

The Island of Stromboli, Shot 2004 Sep 28 Photo Copyright © Steven W. Dengler.

The link between volcanism and the formation of copper ore has been discovered by researchers from the University of Bristol. Their findings, published today in Nature Geoscience, could have far-reaching implications for the search for new copper deposits.
With global demand for copper high (the average UK house contains about 200kg of the metal, mostly in electric cables and transformers) and current reserves relatively limited, finding new reserves is a priority.

The researchers, led by Professor Jon Blundy of Bristol’s School of Earth Sciences, studied giant porphyry copper deposits of the variety that host 75 per cent of the world’s copper reserves.

Copper forms in association with volcanoes such as those around the Pacific Ring of Fire but the nature of this association has never been entirely clear.  Copper ore is predominantly in the form of copper-iron sulphides so an enduring problem has been how to simultaneously create enrichments in both copper and sulphur.  Volcanoes rich in copper tend to be poor in sulphur and vice versa.

To resolve this copper-sulphur paradox, the Bristol team, working in collaboration with BHP Billiton, the world’s largest mining company, drew on observations of modern arc volcanoes, including several in Chile, source of most of the world’s copper, to postulate a two-step process for porphyry copper formation.

They proposed that first, salt-rich fluids, or brines, separate from large magma bodies and become trapped in the crust at a depth of a few kilometres.  These brines have the ability to concentrate copper from the magma from which they separate.  At a later stage, sulphur-rich gases ascend from deeper in the same volcanic system.  When they meet the trapped, copper-rich brines they react explosively to form sulphide ores and hydrogen chloride gas.

To demonstrate their idea, the researchers simulated the process of copper ore formation in their laboratory using high temperature and pressure apparatus.  They were able to replicate many of the features of natural porphyry copper deposits in a capsule measuring just a few millimetres in length.

Lead author Professor Jon Blundy of the University of Bristol said: “This is a remarkable result with far-reaching implications for how we go about searching for new copper deposits.”

Finding the link between volcanism and ore formation means that even recently active volcanoes may be targeted as copper mines of the future.  Professor Blundy and colleagues speculate that copper deposits are forming beneath many active volcanoes today, including the Soufrière Hills volcano on the tiny Caribbean island of Montserrat that has been erupting since 1995.  “Despite its potential for copper deposit formation it is unlikely to be ready for mining for a few centuries yet,” said Professor Blundy.

Reference:
Generation of porphyry copper deposits by gas-brine reaction in volcanic arcs, J. Blundy, J. Mavrogenes, B. Tattitch, S. Sparks and A. Gilmer, Nature Geoscience, 2015: DOI: 10.1038/ngeo2351

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

Swimming reptiles make their mark in the Early Triassic

This image shows a swim traceway from Capitol Reef National Park. Credit: Tracy J. Thomson and Mary L. Droser, Geology, 5 Feb. 2015.

Vertebrate tracks provide valuable information about animal behavior and environments. Swim tracks are a unique type of vertebrate track because they are produced underwater by buoyant trackmakers, and specific factors are required for their production and subsequent preservation. Early Triassic deposits contain the highest number of fossil swim track occurrences worldwide compared to other epochs, and this number becomes even greater when epoch duration and rock outcrop area are taken into account.

This spike in swim track occurrences suggests that during the Early Triassic, factors promoting swim track production and preservation were more common than at any other time. Coincidentally, the Early Triassic period follows the largest mass extinction event in Earth’s history, and the fossil record indicates that a prolonged period of delayed recovery persisted throughout this time period.

During this recovery interval, sediment mixing by animals living within the substrate was minimal, especially in particularly stressful environments such as marine deltas. The general lack of sediment mixing during the Early Triassic was the most important contributing factor to the widespread production of firm-ground substrates ideal for recording and preserving subaqueous trace fossils like swim tracks.

Reference:
T. J. Thomson, M. L. Droser. Swimming reptiles make their mark in the Early Triassic: Delayed ecologic recovery increased the preservation potential of vertebrate swim tracks. Geology, 2015; DOI: 10.1130/G36332.1

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

Reduced rainfall in the northern tropics linked to industrial emissions, research suggests

Abundant stalagmites, stalactites and columns in Yok Balum Cave, Belize. Dr. Harriet Ridley is visible in the centre of the photo, and Dr. Keith Prufer is visible to the right. Credit: Dr. James Baldini, Durham University

Scientists have produced a rainfall record strongly suggesting that man-made industrial emissions have contributed to less rainfall in the northern tropics.
The research team, led by experts at Durham University, UK, reconstructed rainfall patterns stretching back more than 450 years by analysing the chemical composition of a stalagmite recovered from a cave in Belize, Central America.

They identified a substantial drying trend from 1850 onwards, coinciding with a steady rise in sulphate aerosols in the atmosphere as a result of burning fossil fuels to drive the industrial boom in Europe and North America.

Importantly they also identified nine short-lived drier spells in the northern tropics since 1550 following very large volcanic eruptions in the Northern Hemisphere that produced similar emissions as those produced by burning fossil fuels.

This provided very strong evidence that any injection of sulphate aerosols into the upper atmosphere could lead to shifts in rainfall patterns, the researchers said.

Writing in the journal Nature Geoscience the researchers said that sulphate aerosols moderated temperatures in the Northern Hemisphere by reflecting the Sun’s radiation.

As a result the Intertropical Convergence Zone (ITCZ) – a tropical rainfall belt near the equator – shifted towards the warmer Southern Hemisphere leading to dryer conditions in the northern tropics.

The findings confirm previously published observations using 20th Century historical data and computer modelling, the researchers said.

Lead author Dr Harriet Ridley, from the Department of Earth Sciences at Durham University, said: “The research presents strong evidence that industrial sulphate emissions have shifted this important rainfall belt, particularly over the last 100 years.

“Although warming due to man-made carbon dioxide emissions has been of global importance, the shifting of rain belts due to aerosol emissions is locally critical, as many regions of the world depend on this seasonal rainfall for agriculture.

“The role of sulphate aerosols in repositioning the ITCZ was previously identified using computer modelling, but until now no suitable climate record existed to support those ideas.

“Our research allows us to make more accurate predictions about future climate trends and it appears that regional sulphate aerosol production is an essential factor to include in these predictions.”

The researchers said their interpretations were made possible because of the quality of the stalagmite sample they obtained from the Yok Balum cave in Belize, which is located at the northernmost extent of the modern day ITCZ and is sensitive to changes in its position.

By analysing the isotope values of the stalagmite – where more negative values equal wet conditions and less negative values equal dry conditions – they were able to reconstruct rainfall.

Co-author Dr James Baldini, of the Department of Earth Sciences, at Durham University, said: “The stalagmite was composed entirely of mineral aragonite, and subtle changes in the chemistry of the mineral were linked to rainfall variability. The stalagmite grew remarkably quickly and was easily dated.

“The fact that tropical drying follows both Northern Hemisphere volcanic and industrial sulphate injections is critical. It essentially rules out the possibility that the climate shifts were caused by a previously unknown natural climate cycle or increasing atmospheric carbon dioxide concentrations.”

The Durham-led research team also included researchers from the University of New Mexico, Pennsylvania State University, SUNY Stony Brook, Northern Arizona University, ETH Zurich, and the Potsdam Institute for Climate Impact Research.

The work was funded by the European Research Council, the National Science Foundation of the United States, the Alphawood Foundation and the Schweizer National Fund, Sinergia.

Reference:
Aerosol forcing of the position of the intertropical convergence zone since AD 1550, Ridley, HE, et al, Nature Geoscience, DOI: 10:1038/NGEO2353

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

New ionoscopiform fish found from the Middle Triassic of Guizhou, China

Fig.2 Paratype (IVPP V 19972) and reconstruction of Panxianichthys imparilis (Image by XU Guanghui)

The Ionoscopiformes are a fossil fish lineage of halecomorphs known only from the Mesozoic marine deposits. Because of their close relationships with the Amiiformes, the Ionoscopiformes are phylogenetically important in investigating the early evolution and biogeography of the Halecomorphi, but fossil evidence of early ionoscopiforms was scarce. Robustichthys recently reported from the Middle Triassic Luoping Biota, eastern Yunnan, China, represents the oldest and only known ionoscopiform in the Triassic.

In a paper published in the latest issue of Vertebrata PalAsiatica, Dr. XU Guanghui, Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences, and his colleague reported the discovery of a new ionoscopiform, Panxianichthys imparilis, on the basis of two well preserved specimens from the Middle Triassicof the Guanling Formation exposed in Xinmin of Panxian County, western Guizhou, China. Although Panxianichthys is slightly younger than Robustichthys, it is significantly older than other members of this group from the Late Jurassic of Europe, and Early Cretaceous of North and South America.

Fig.1 Holotype of Panxianichthys imparilis (IVPP V 19971) (Image by XU Guanghui)

Panxianichthys possesses an important synapomorphy of the Ionoscopiformes: a sensory canal in the maxilla, but retains some primitive characters unknown in other ionoscopiforms. It is distinguished from other members of this order by a combination of features.

Phylogenetic analysis indicates that Panxianichthys is the most primitive ionoscopiform fish, and provides new insight on the early evolution of this clade. The new finding extends the geographical distribution of early ionoscopiforms from eastern Yunnan into western Guizhou, demonstrating a wider distribution than previously appreciated for this group. The successive discoveries of Robustichthys and Panxianichthys from China indicate that the early diversification of the Ionoscopiformes is more rapid than previously thought.

This research was mainly supported by the National Natural Science Foundation of China, and the State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences).

Reference:
“Panxianichthys imparilis gen. et sp. nov., a new ionoscopiform (Halecomorphi) from the Middle Triassic of Guizhou, China”: www.ivpp.cas.cn/cbw/gjzdwxb/xb… 0121394053090016.pdf

Note : The above story is based on materials provided by Chinese Academy of Sciences.

Drilling reveals fault rock architecture in New Zealand’s central alpine fault

Figure 1 is a Location map. (A) Key tectonic elements of the Pacific-Australian plate boundary, including the Alpine fault through the continental South Island of New Zealand. Topography is after Sandwell and Smith (1997). White box illustrates location of B. (B) More detailed map of the Alpine fault (red line), illustrating locations mentioned in the text. Orange lines are roads; gray lines are topographic contours. (C) Composite schematic section through a typical Alpine fault oblique thrust segment, illustrating the sequence of fault rocks exposed in the hanging wall, modified after Norris and Cooper (2007). Outcrops at Stoney Creek, Hare Mare Creek/Waikukupa River, and Havelock Creek are particularly characteristic. DFDP–Deep Fault Drilling Project. Credit: V. Toy et al., and Lithosphere

Rocks within plate boundary scale fault zones become fragmented and altered over the earthquake cycle. They both record and influence the earthquake process. In this new open-access study published in Lithosphere on 4 Feb., Virginia Toy and colleagues document fault rocks surrounding New Zealand’s active Alpine Fault, which has very high probability of generating a magnitude 8 or greater earthquake in the near future.

Descriptions already suggest that the complex fault rock sequence results from slip at varying rates during multiple past earthquakes, and even sometimes during aseismic slip. They also characterize this fault before rupture; Toy and colleagues anticipate that repeat observations after the next event will provide a previously undescribed link between changes in fault rocks and the ground shaking response. They write that in the future this sort of data might allow realistic ground shaking predictions based on observations of other “dormant” faults.

Reference:
Fault rock lithologies and architecture of the central Alpine Fault, New Zealand, revealed by DFDP-1 drilling
V.G. Toy et al., University of Otago, Dunedin, New Zealand. Published online ahead of print on 4 Feb. 2015; http://dx.doi.org/10.1130/L395.1. This article is OPEN ACCESS.

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

Giant rodent used incisors like tusks

Artist’s impression of Josephoartigasia monesi. Credit: James Gurney

The largest rodent ever to have lived may have used its front teeth just like an elephant uses its tusks, a new study led by scientists at the University of York and The Hull York Medical School (HYMS) has found.
Josephoartigasia monesi, a rodent closely related to guinea pigs, lived in South America approximately 3 million years ago.  It is the largest fossil rodent ever found, with an estimated body mass of 1000 kg and was similar in size to a buffalo.

Dr Philip Cox, of the Centre for Anatomical and Human Sciences, a joint research centre of the University’s Department of Archaeology and HYMS, used computer modelling to estimate how powerful the bite of Josephoartigasia could be.

He found that, although the bite forces were very large – around 1400 N, similar to that of a tiger – the incisors would have been able to withstand almost three times that force, based on earlier estimates by co-authors, Dr Andres Rinderknecht, of  The Museo Nacional de Historia Natural, Montevideo, and Dr Ernesto Blanco, of Facultad de Ciencias, Instituto de Fısica, Montevideo, who first described the fossil in 2008.

Dr Cox said: “We concluded that Josephoartigasia must have used its incisors for activities other than biting, such as digging in the ground for food, or defending itself from predators. This is very similar to how a modern day elephant uses its tusks.”

The research, which is published in the Journal of Anatomy, involved CT scanning the Josephoartigasia monesi specimen and making a virtual reconstruction of its skull. This was then subjected to finite element analysis, an engineering technique that predicts stress and strain in a complex geometric object.

Reference:
Philip G. Cox, Andrés Rinderknecht, R. Ernesto Blanco. Predicting bite force and cranial biomechanics in the largest fossil rodent using finite element analysis. Journal of Anatomy, 2015; DOI: 10.1111/joa.12282

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

Ice ages made Earth’s ocean crust thicker

Melting glaciers lead to higher sea levels and a thinner oceanic crust. Credit: Duane Miller/Getty

The Earth’s ice ages have left their mark on the thickness of the planet’s oceanic crust, scientists have discovered. During glacial periods, when sea levels are low, the magma that spreads out from mid-ocean ridges to form virgin crust wells up thick and fast. But the production of new crust is stunted in warmer times when sea levels are high, such as they are today.
“We know that volcanism has an effect on climate. What we’re seeing is that climate cycles are also affecting ocean volcanism,” says Richard Katz, a geophysicist at the University of Oxford, UK, and one of the authors of the study, which is reported today in Science.

The researchers say that they have spotted the effect in chains of hillocks under the sea between Australia and the Antarctic. The reason, Katz explains, is that higher sea levels exert a greater pressure on Earth’s mantle below the ocean floor. This seems to slow the transport of molten rock and gas from the mantle up to mid-ocean ridges, where it erupts.

Periodic variations in Earth’s axial tilt and orbit around the Sun have driven the planet’s succession of ice ages and warm periods over the past two million years. During an ice age, more water is trapped on land; as a result, sea levels are more than 100 metres lower than in warm periods. And that can thicken the oceanic crust by around 800 metres (on the order of 10%), Katz says.

Anthropogenic climate change will not impose much extra variation on this pattern. Today’s sea levels are already high, geologically speaking. And scientists will have to hang around for quite a while to spot the effects of modern sea-level rise in the oceanic crust: because magma creeps slowly up from Earth’s interior to the surface, the lag between a change in sea level and the peak crustal thickness response might be about 50,000 years.

A tale of high seas

Scientists knew that changes in the pressure of ice sheets affect what happens in Earth’s upper mantle below land masses. For example, the disappearance of ice is thought to have strongly increased mantle melting and volcanism beneath Iceland. But many geologists were doubtful about whether sea-level variations alone could produce similar effects beneath ridge zones in the deep ocean.

Yet Katz and his colleagues calculated that sea-level variation should sometimes have a discernible effect on the thickness of oceanic crust spreading from ridge zones. The effect is complicated: it depends on the level of the sea, the rate at which this level rises or falls, the rate at which magma upwells from the mantle, and the rate at which oceanic crust spreads sideways from mid-ocean ridges.

The team then backed up its hypothesis by examining two areas of a mid-oceanic ridge between Australia and the Antarctic, which had been surveyed in 2011 and 2013 by the Korean icebreaker  Araon. There, the sea floor is lined by elongated chains of hills around 200 metres high. (The change in oceanic crust thickness needed to produce the hills is up to about 800 metres, says Katz; much of the crust is submerged into the mantle, rather as the bulk of a floating iceberg sits under water).

The hills have been formed by a mixture of seismic activity, sedimentation, volcanoes and sea-floor spreading. But the researchers say that in the geological fabric there seems to be a distinct pattern of crustal-thickness variations that are synchronized with 23,000-, 41,000- and 100,000-year glacial cycles known as Milankovitch cycles.

“This is a fascinating discovery and an important key to understanding the creation of oceanic crust,” says Ken Macdonald, a geologist at the University of California, Santa Barbara, who was not involved in the study.

“It’s very convincing, because they actually work through the physics,” says Carl Wunsch, an oceanographer at the Massachusetts Institute of Technology in Cambridge.

A second paper, published today in Geophysical Research Letters, comes to similar conclusions. Maya Tolstoy, a geophysicist at Columbia University in New York, found that volcanic activity along the East Pacific Rise, an ocean ridge off the coast of Mexico, ebbs and flows in regular cycles. Among other shorter cycles, she found on the fast-spreading sea floor in that region a 100,000-year pattern strikingly in synch with the most prominent of Earth’s natural glacial cycles.

Conceivably, examining variations in crust thickness might provide new insights into past glacial cycles and help scientists to better narrow down sea-level change in the deep past, says Wunsch. Meanwhile, a high-resolution topography survey carried out last summer across the Juan de Fuca ridge off the coast of Oregon and Washington offers an opportunity to test the team’s hypothesis further.  “We’re going to look at that data very soon,” says Katz.

Reference:
Nature doi:10.1038/nature.2015.16856

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

15-million-year-old mollusk protein found

A 15-million year old fossil gastropod, Ecphora, from the Calvert Cliffs of southern Maryland is depicted. The golden brown color arises from the original shell-binding proteins and pigments preserved in the mineralized shell. Credit: John Nance

A team of Carnegie scientists have found “beautifully preserved” 15 million-year-old thin protein sheets in fossil shells from southern Maryland. Their findings are published in the inaugural issue of Geochemical Perspectives Letters.
The team–John Nance, John Armstrong, George Cody, Marilyn Fogel, and Robert Hazen–collected samples from Calvert Cliffs, along the shoreline of the Chesapeake Bay, a popular fossil collecting area. They found fossilized shells of a snail-like mollusk called Ecphora that lived in the mid-Miocene era–between 8 and 18 million years ago.

Ecphora is known for an unusual reddish-brown shell color, making it one of the most distinctive North American mollusks of its era. This coloration is preserved in fossilized remains, unlike the fossilized shells of many other fossilized mollusks from the Calvert Cliffs region, which have turned chalky white over the millions of years since they housed living creatures.

Shells are made from crystalline compounds of calcium carbonate interleaved with an organic matrix of proteins and sugars proteins and sugars. These proteins are called shell-binding proteins by scientists, because they help hold the components of the shell together.They also contain pigments, such as those responsible for the reddish-brown appearance of the Ecphora shell. These pigments can bind to proteins to form a pigment-protein complex.

The fact that the coloration of fossilized Ecphora shells is so well preserved suggested to the research team that shell proteins bound to these pigments in a complex might also be preserved. They were amazed to find that the shells, once dissolved in dilute acid, released intact thin sheets of shell proteins more than a centimeter across. Chemical analysis including spectroscopy and electron microscopy of these sheets revealed that they are indeed shell proteins that were preserved for up to 15 million years.

“These are some of the oldest and best-preserved examples of a protein ever observed in a fossil shell,” Hazen said.

Remarkably, the proteins share characteristics with modern mollusk shell proteins. They both produce thin, flexible sheets of residue that’s the same color as the original shell after being dissolved in acid. Of the 11 amino acids found in the resulting residue, aspartate and glutamate are prominent, which is typical of modern shell proteins. Further study of these proteins could be used for genetic analysis to trace the evolution of mollusks through the ages, as well as potentially to learn about the ecology of the Chesapeake Bay during the era in which Ecphora thrived.

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

Getting to the bottom of tectonic plates

Recent earthquakes (yellow) and volcanoes (red) of the world plotted against tectonic plate boundaries.

CProfessors Tim Stern and Martha Savage and Drs Simon Lamb and Rupert Sutherland from Victoria’s School of Geography, Environment and Earth Sciences—along with scientists from GNS Science and universities in the United States and Japan—developed new methods to get the most detailed images yet of the base of the tectonic plate beneath Wellington.

A paper on the team’s finding, entitled A seismic reflection image for the base of a tectonic plate, has been published in the February 5, 2015 edition of the prestigious international scientific journal, Nature.

The team recorded reflected seismic waves from an array of controlled underground dynamite explosions across the southern part of the North Island, which gave the scientists an image of the bottom of the Pacific Plate, 100 kilometres beneath the Earth’s surface. The recordings were many times higher resolution than what has been previously achieved, and showed that Earth’s tectonic plates are gliding on a distinct layer of ‘soft’ rock, only 10 kilometres thick and weak enough to allow the plates to shift many centimetres per year.

“The idea that Earth’s surface consists of a mosaic of moving plates is a well-established scientific paradigm, but it had never been clear about what actually moves the plates around,” says Professor Stern. “To work this out requires an understanding of what happens at the bottom of a tectonic plate. It’s been difficult to obtain the necessary detailed images at such great depths using the usual method of recording natural earthquake waves.

Cartoon showing the oceanic lithosphere of the Pacific plate subducting beneath the continental Australian plate. The blown up piece shows what we interpret to the be a ~ 10 km thick channel at the base of the plate where melts have ponded, and high strain rates have focused and localised the melt into a thin layer. This channel is likely to be of low viscosity and weak, and effectively allows the plates to slide unhindered by any convective connection to the viscous mantle beneath. Credit: Tim Stern

“But by generating our own seismic waves using higher frequency dynamite shots we were able to see how they became modified as they passed through different layers in the earth. This, along with some new techniques in seismic reflection processing, allowed us to obtain the most detailed image yet of an oceanic tectonic plate.”

Professor Stern says the thinner layer beneath the plate appears to contain pockets of molten rock that make it easier for the plates to slide on. “This means that the plates can be pushed and pulled around without strong resistance at the base. A weak slippery base also explains why tectonic plates can sometimes abruptly change the direction in which they’re slipping. It’s a bit like a ski sliding on snow.

“Understanding this boundary between the base of cold, rigid tectonic plates and the underlying hot, convecting mantle underneath is central to our knowledge of plate tectonics and the very formation and evolution of our planet.”

Professor Stern says being recognised by such an internationally-respected scientific journal indicates the significance of the team’s discovery. “This study also demonstrates the long-standing ability of New Zealand’s geoscience community to leverage international funds—in this case from Japan and the United States—into New Zealand for the purposes of making fundamental discoveries about how the earth works.”

Reference:
“A seismic reflection image for the base of a tectonic plate.” Nature 518, 85–88 (05 February 2015) DOI: 10.1038/nature14146

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

Randomness of megathrust earthquakes implied by rapid stress recovery after the Japan earthquake

Pre-Tohoku earthquake (from December 2003 until the occurrence of the mega-thrust event) b-values resolved along the subduction interface: high b-values in the low-stress normal-faulting outer-rise area; low and very low b-values along the highly-stressed megathrust, high b-values in the magma source region at depth (reflecting dehydration and partial melting below the volcanic front). Star: 2011 M9 epicenter, white contours: Tohoku-oki earthquake slip model (Yagi and Fukahata, 2011) indicating the M9 highest slip area (previously locked, highly stressed asperity, reflected by very low b-values); triangles: volcanoes. Inset: Cross-sectional view at 40°N, as indicated, showing the relation between b-values and the tectonic processes at the subduction zone. Credit: Image courtesy of University of Tsukuba

Associate Professor Bogdan Enescu, Faculty of Life and Environmental Sciences, University of Tsukuba, collaborated with colleagues at the Swiss Federal Institute of Technology in Zurich (ETH Zurich), to show that the stress recovery following the 2011 M9.0 Tohoku-oki earthquake has been significantly faster than previously anticipated; specifically, the stress-state at the plate interface returned within just a few years to levels observed before the megathrust event. In addition, since there is no observable spatial difference in the stress state along the megathrust zone, it is difficult to predict the location and extent of future large ruptures.

Constraining the recurrence of megathrust earthquakes is genuinely important for hazard assessment and mitigation. The prevailing approach to model such events worldwide relies on the segmentation of the subduction zone and quasi-periodic recurrence due to constant tectonic loading. The researchers analyzed earthquakes recorded along a 1,000-km-long section of the subducting Pacific Plate beneath Japan since 1998 to map the relative frequency of small to large earthquakes (the so-called “b-value” parameter — which on average is close to 1.0), in both space and time. Evidence from laboratory experiments, numerical modeling and natural seismicity indicates that the b-value is negatively correlated with the differential stress. The present analysis reveals that the spatial distribution of b-values reflects well the tectonic processes accompanying plate motion. However, there is no evidence of distinct earthquake-generation regions along the megathrust, associated with the so-called “characteristic earthquakes.”

Nevertheless, the authors show that parts of the plate interface that ruptured during the 2011 Tohoku-oki earthquake were highly stressed in the years leading up to the earthquake, as expressed by mapped, very low regional b-values. Although the stress was largely released during the 2011 rupture, thus leading to an increase in b-values immediately after the megathrust event, the stress levels (i.e., b-values) quickly recovered to pre-megaquake levels within just a few years. This suggests that the megathrust zone is likely ready for large earthquakes any time with a low but on average constant probability.

The study concludes that large earthquakes may not have a characteristic location, size or recurrence interval, and might therefore occur more randomly distributed in time. The authors bring also strong evidence that the size distribution of earthquakes is sensitive to stress variations and its careful monitoring can improve the seismic hazard assessment of the megathrust zone.

Reference:
Thessa Tormann, Bogdan Enescu, Jochen Woessner, Stefan Wiemer. Randomness of megathrust earthquakes implied by rapid stress recovery after the Japan earthquake. Nature Geoscience, 2015; 8 (2): 152 DOI: 10.1038/ngeo2343

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

Seafloor volcano pulses may alter climate

Magma from undersea eruptions congealed into forms known as pillow basalts on the Juan De Fuca Ridge, off the U.S. Pacific Northwest. A new study shows such eruptions wax and wane on regular schedules. Credit: Deborah Kelley/University of Washington

Vast ranges of volcanoes hidden under the oceans are presumed by scientists to be the gentle giants of the planet, oozing lava at slow, steady rates along mid-ocean ridges. But a new study shows that they flare up on strikingly regular cycles, ranging from two weeks to 100,000 years — and, that they erupt almost exclusively during the first six months of each year. The pulses — apparently tied to short- and long-term changes in earth’s orbit, and to sea levels–may help trigger natural climate swings.
Scientists have already speculated that volcanic cycles on land emitting large amounts of carbon dioxide might influence climate; but up to now there was no evidence from submarine volcanoes. The findings suggest that models of earth’s natural climate dynamics, and by extension human-influenced climate change, may have to be adjusted. The study appears this week in the journal Geophysical Research Letters.

“People have ignored seafloor volcanoes on the idea that their influence is small — but that’s because they are assumed to be in a steady state, which they’re not,” said the study’s author, marine geophysicist Maya Tolstoy of Columbia University’s Lamont-Doherty Earth Observatory. “They respond to both very large forces, and to very small ones, and that tells us that we need to look at them much more closely.” A related study by a separate team this week in the journal Science bolsters Tolstoy’s case by showing similar long-term patterns of submarine volcanism in an Antarctic region Tolstoy did not study.

Volcanically active mid-ocean ridges crisscross earth’s seafloors like stitching on a baseball, stretching some 37,000 miles. They are the growing edges of giant tectonic plates; as lavas push out, they form new areas of seafloor, which comprise some 80 percent of the planet’s crust. Conventional wisdom holds that they erupt at a fairly constant rate–but Tolstoy finds that the ridges are actually now in a languid phase. Even at that, they produce maybe eight times more lava annually than land volcanoes. Due to the chemistry of their magmas, the carbon dioxide they are thought to emit is currently about the same as, or perhaps a little less than, from land volcanoes — about 88 million metric tons a year. But were the undersea chains to stir even a little bit more, their CO2 output would shoot up, says Tolstoy.

Alternating ridges and valleys formed by volcanism near the East Pacific Rise, a mid-ocean ridge in the Pacific Ocean. Such formations indicate ancient highs and lows of volcanic activity. (Haymon et al., NOAA-OE, WHOI)

Some scientists think volcanoes may act in concert with Milankovitch cycles–repeating changes in the shape of earth’s solar orbit, and the tilt and direction of its axis — to produce suddenly seesawing hot and cold periods. The major one is a 100,000-year cycle in which the planet’s orbit around the sun changes from more or less an annual circle into an ellipse that annually brings it closer or farther from the sun. Recent ice ages seem to build up through most of the cycle; but then things suddenly warm back up near the orbit’s peak eccentricity. The causes are not clear.

Enter volcanoes. Researchers have suggested that as icecaps build on land, pressure on underlying volcanoes also builds, and eruptions are suppressed. But when warming somehow starts and the ice begins melting, pressure lets up, and eruptions surge. They belch CO2 that produces more warming, which melts more ice, which creates a self-feeding effect that tips the planet suddenly into a warm period. A 2009 paper from Harvard University says that land volcanoes worldwide indeed surged six to eight times over background levels during the most recent deglaciation, 12,000 to 7,000 years ago. The corollary would be that undersea volcanoes do the opposite: as earth cools, sea levels may drop 100 meters, because so much water gets locked into ice. This relieves pressure on submarine volcanoes, and they erupt more. At some point, could the increased CO2 from undersea eruptions start the warming that melts the ice covering volcanoes on land?

That has been a mystery, partly because undersea eruptions are almost impossible to observe. However, Tolstoy and other researchers recently have been able to closely monitor 10 submarine eruption sites using sensitive new seismic instruments. They have also produced new high-resolution maps showing outlines of past lava flows. Tolstoy analyzed some 25 years of seismic data from ridges in the Pacific, Atlantic and Arctic oceans, plus maps showing past activity in the south Pacific.

The long-term eruption data, spread over more than 700,000 years, showed that during the coldest times, when sea levels are low, undersea volcanism surges, producing visible bands of hills. When things warm up and sea levels rise to levels similar to the present, lava erupts more slowly, creating bands of lower topography. Tolstoy attributes this not only to the varying sea level, but to closely related changes in earth’s orbit. When the orbit is more elliptical, Earth gets squeezed and unsqueezed by the sun’s gravitational pull at a rapidly varying rate as it spins daily — a process that she thinks tends to massage undersea magma upward, and help open the tectonic cracks that let it out. When the orbit is fairly (though not completely) circular, as it is now, the squeezing/unsqueezing effect is minimized, and there are fewer eruptions.

The idea that remote gravitational forces influence volcanism is mirrored by the short-term data, says Tolstoy. She says the seismic data suggest that today, undersea volcanoes pulse to life mainly during periods that come every two weeks. That is the schedule upon which combined gravity from the moon and sun cause ocean tides to reach their lowest points, thus subtly relieving pressure on volcanoes below. Seismic signals interpreted as eruptions followed fortnightly low tides at eight out of nine study sites. Furthermore, Tolstoy found that all known modern eruptions occur from January through June. January is the month when Earth is closest to the sun, July when it is farthest — a period similar to the squeezing/unsqueezing effect Tolstoy sees in longer-term cycles. “If you look at the present-day eruptions, volcanoes respond even to much smaller forces than the ones that might drive climate,” she said.

Daniel Fornari, a senior scientist at Woods Hole Oceanographic Institution not involved in the research, called the study “a very important contribution.” He said it was unclear whether the contemporary seismic measurements signal actual lava flows or just seafloor rumbles and cracking. But, he said, the study “clearly could have important implications for better quantifying and characterizing our assessment of climate variations over decadal to tens to hundreds of thousands of years cycles.”

Edward Baker, a senior ocean scientist at the National Oceanic and Atmospheric Administration, said, “The most interesting takeaway from this paper is that it provides further evidence that the solid Earth, and the air and water all operate as a single system.”

The research for this paper was funded in large part by the U.S. National Science Foundation.

Note: The above story is based on materials provided by The Earth Institute at Columbia University.

Tracking glaciers with accelerators

Tracking glaciers with accelerators. Credit: Photo by Rodrigo A. SEPÚLVEDA SCHULZ

Geologists once thought that, until about 18,000 years ago, a mammoth glacier covered the top two-thirds of Ireland. Recently, however, they found evidence that it wasn’t just the top two-thirds: The Irish glacier was much larger, completely engulfing the country and extending far offshore.
They learned this with the help of a particle accelerator.

Glaciers are always on the move, advancing or retreating as fast as 30 meters a day or as slow as half a meter a year. During the most recent ice age, huge glaciers spread over much of Earth’s northern climes, extending all the way from the northern tip of Greenland to Cape Cod and across to Chicago, which was buried under a kilometer of ice. It was the same in Europe, with parts of the British Isles, Germany, Poland and Russia all hidden beneath an enormous ice sheet.

“For the last 2.5 million years of Earth’s history, we’ve had this pattern of alternating ice ages and interglacials,” says Fred Phillips, a professor in New Mexico Tech’s Department of Earth and Environmental Science who, among other things, is an expert at dating the movements of glaciers.

“Trying to understand these cycles — to understand geographical distribution of climate fluctuations and trying to pin down the chronology — has preoccupied scientists for 200 years now.”

Over the past 30 years, scientists have begun to use particle accelerators to help them track how these glaciers move.

The process begins with a globetrotting geologist and some huge rocks. As a glacier recedes, it will sometimes pluck a boulder from its depths and push it into daylight. While trapped beneath the ice, the boulder is shielded from the barrage of cosmic rays that continuously assaults Earth’s surface. But as soon as the boulder is exposed, cosmic rays begin to interact with the atoms inside the rock, rapidly producing rare isotopes called cosmogenic nuclides, such as helium-3, neon-21 or beryllium-10.

To determine just how long ago the boulder was forced to the surface, geologists like Phillips use a hammer and chisel — or, sometimes, rock saws and small explosive devices — to remove a chunk of rock about the size of a grapefruit. They bring that sample back to the lab, grind it up and extract one specific mineral, such as quartz, that produces cosmogenic nuclides at a known rate.

1. Geologists in Antarctica use a hammer and chisel to sample the upper few centimeters of a boulder for cosmogenic nuclide dating.

2. Bethan Davies samples a boulder for cosmogenic nuclide dating in Greenland. Courtesy of: David Roberts and Bethan Davies, www. AntarcticGlaciers .org

After isolating one particular nuclide from that mineral, they send a beam of cesium ions at the sample. That adds an extra electron to atoms within the sample, forming negative elemental or molecular ions. These ions are sent into an accelerator beam and smashed through a thin foil or gas, which strips them of electrons and destroys any remaining molecules. Finally, the ions are sent into a detector that counts the ratio of unstable to stable atoms, revealing the amount of cosmogenic nuclides. The more cosmogenic nuclides in the sample, the more time has elapsed since the glacier ejected the boulder.

The original idea for this type of geological dating came from none other than Raymond Davis Jr., the Brookhaven National Laboratory nuclear chemist who won a Nobel Prize for detecting neutrinos streaming from the sun. Davis came up with the idea working in collaboration with Oliver Schaeffer, an expert in the environmental production of background radioactivity.

Although the duo correctly set forth the basic experimental concept for using cosmogenic nuclides to date rock samples in the mid-1950s, it took nearly 30 years for detector technologies to catch up with their ideas. Once possible, the technique took off. “Since the mid-1980s, there have been thousands of scientific papers published on glacial chronologies and other geological dating using this method,” Phillips says.

Today, Phillips says, significant effort is being made to understand the rise and fall of the West Antarctic Ice Sheet.

“This is important because it looks like now this ice sheet is in a state of slow collapse, which could raise sea level by about 5 meters,” he says. “Understanding what controls the extent of that ice is critically important.”

By understanding the past, researchers like Phillips might better understand what’s to come.

Note : The above story is based on materials provided by Department of Energy, Office of Science.

Methane seepage from Arctic seabed occurring for millions of years

Illustration of the ocean floor offshore West-Svalbard, including the Vestnesa Ridge. Credit: Andreia Plaza Faverola/CAGE

Natural seepage of methane offshore the Arctic archipelago Svalbard has been occurring periodically for at least 2,7 million years. Major events of methane emissions happened at least twice during this period, according to a new study.

We worry about greenhouse gas methane. It´s lifetime in the atmosphere is much shorter than CO2´s, but the impact of methane on climate change is over 20 times greater than CO2 over a 100-year period.
60 percent of the methane in the atmosphere comes from emissions from human activities. But methane is a natural gas, gigatonnes of it trapped under the ocean floor in the Arctic.

And it is leaking. And has been leaking for the longer time than the humans have roamed the Earth.

” Our planet is leaking methane gas all the time. If you go snorkeling in the Caribbean you can see bubbles raising from the ocean floor at 25 meters depth. We studied this type of release, only in a much deeper, colder and darker environment. And found out that it has been going on, periodically, for as far back as 2,7 million years.” says Andreia Plaza Faverola the primary author behind a new paper in Geophysical Research Letters.

She is talking about Vestnesa Ridge in Fram Strait, a thousand meters under the surface of the Arctic Ocean, offshore West-Svalbard. Here, enormous, 800 meters high gas flares rise from the seabed. That’s the size of the tallest manmade structure in the world — Burj Khalifa in Dubai.

“Half of Vestnesa Ridge is showing very active seepage of methane. The other half is not. But there are obvious pockmarks on the inactive half, cavities and dents in the ocean floor, that we recognized as old seepage features. So we were wondering what activates, or deactivates, the seepage in this area.,” says Plaza Faverola.

Why 2,7 million years?

She, and a team of marine geophysicists from CAGE, used the P-Cable technology, to figure it out. It is a seismic instrument that is towed behind a research vessel. It recorded the sediments beneath these pockmarks. P-Cable renders images that look like layers of a cake and enables scientists to visualize deep sediments in 3D.

” We know from other studies in the region that the sediments we are looking at in our seismic data are at least 2.7 million years old. This is the period of increase of glaciations in the Northern Hemisphere, which influenced the sediment. The P-Cable helped us to see features in this sediment, associated with gas release in the past. ”

“These features can be buried pinnacles, or cavities, that form what we call gas chimneys in the seismic data. Gas chimneys appear like vertical disturbances in the layers of our sedimentary cake. This enabled us to reconstruct the evolution of gas expulsion from this area, for at least 2,7 million years.” says Andreia Plaza Faverola.

The seismic signal penetrated into 400 to 500 meters of sediment to map this timescale.

How is the methane released?

By using this method, scientists were able to identify two major events of gas emission throughout this time period: One 1,8 million years ago, the other 200,000 years ago.

This means that there is something that activated and deactivated the emissions several times. Plaza Faverola´s paper gives a plausible explanation: It is the movement of the tectonic plates that influences the gas release. Vestnesa is not like California though, riddled with earthquakes because of the moving plates. The ridge is on a so-called passive margin. But as it turns out, it doesn´t take a huge tectonic shift to release the methane stored under the ocean floor.

“Even though Vestnesa Ridge is on a passive margin, it is between two oceanic ridges that are slowly spreading. These spreading ridges resulted in separation of Svalbard from Greenland and opening of the Fram Strait. The spreading influences the passive margin of West-Svalbard, and even small mechanical collapse in the sediment can trigger seepage.” says Faverola.

Where does the methane come from? The methane is stored as gas hydrates, chunks of frozen gas and water, up to hundreds of meters under the seabed. Vestnesa hosts a large gas hydrate system. There is some concern that global warming of the oceans may melt this icy gas and release it into the atmosphere. That is not very likely in this area, according to Andreia Plaza Faverola.

” This is a deep water gas hydrate system, which means that it is in permanently cold waters and under a lot of pressure. This pressure keeps the hydrates stable and the whole system is not vulnerable to global temperature changes. But under the stable hydrates there is gas that is not frozen. The amount of this gas may increase if hydrates melt at the base of this stability zone, or if gas from deeper in the sediments arrives into the system. This could increase the pressure in this part of the system, and the free gas may escape the seafloor through chimneys. Hydrates would still remain stable in this scenario[IS8] .”

Historical methane peaks coincide with increase in temperature

Throughout Earth´s history there have been several short periods of significant increase in temperature. And these periods often coincide with peaks of methane in the atmosphere, as recorded in ice cores. Scientists such as Plaza Faverola are still debating about the cause of this methane release in the past.

” One hypotheses is that massive gas release from geological sources, such as volcanos or ocean sediments may have influenced global climate. What we know is that there is a lot of methane released at present time from the ocean floor. What we need to find out is if it reaches the atmosphere, or if it ever did.”

Historical events of methane release, such as the ones in the Vestnesa Ridge, provide crucial information that can be used in future climate modeling. Knowing if these events repeat, and identifying what makes them happen, may help us to better predict the potential influence of methane from the oceans on future climate.

Video:

Reference:
A. Plaza-Faverola, S. Bünz, J. E. Johnson, S. Chand, J. Knies, J. Mienert, P. Franek. Role of tectonic stress in seepage evolution along the gas hydrate-charged Vestnesa Ridge, Fram Strait. Geophysical Research Letters, 2015; DOI: 10.1002/2014GL062474

Note : The above story is based on materials provided by University of Tromso (Universitetet i Tromsø – UiT).

Evidence from warm past confirms recent IPCC estimates of climate sensitivity

A composite image of the Western hemisphere of the Earth. Credit: NASA

New evidence showing the level of atmospheric CO2 millions of years ago supports recent climate change predications from the Intergovernmental Panel on Climate Change (IPCC).

A multinational research team, led by scientists at the University of Southampton, has analysed new records showing the CO2 content of the Earth’s atmosphere between 2.3 to 3.3 million years ago, over the Pliocene.

During the Pliocene, the Earth was around 2ºC warmer than it is today and atmospheric CO2 levels were around 350-400 parts per million (ppm), similar to the levels reached in recent years.

By studying the relationship between CO2 levels and climate change during a warmer period in Earth’s history, the scientists have been able to estimate how the climate will respond to increasing levels of carbon dioxide, a parameter known as ‘climate sensitivity’.

The findings, which have been published in Nature, also show how climate sensitivity can vary over the long term.

“Today the Earth is still adjusting to the recent rapid rise of CO2 caused by human activities, whereas the longer-term Pliocene records document the full response of CO2-related warming,” says Southampton’s Dr Gavin Foster, co-author of the study.

“Our estimates of climate sensitivity lie well within the range of 1.5 to 4.5ºC increase per CO2 doubling summarised in the latest IPCC report. This suggests that the research community has a sound understanding of what the climate will be like as we move toward a Pliocene-like warmer future caused by human greenhouse gas emissions.”

Lead author of the study, Dr Miguel Martínez-Botí, also from Southampton said: “Our new records also reveal an important change at around 2.8 million years ago, when levels rapidly dropped to values of about 280 ppm, similar to those seen before the industrial revolution. This caused a dramatic global cooling that initiated the ice-age cycles that have dominated Earth’s climate ever since.”

The research team also assessed whether climate sensitivity was different in warmer times, like the Pliocene, than in colder times, like the glacial cycles of the last 800,000 years.

Professor Eelco Rohling of The Australian National University in Canberra says: “We find that climate change in response to CO2 change in the warmer period was around half that of the colder period. We determine that this difference is driven by the growth and retreat of large continental ice sheets that are present in the cold ice-age climates; these ice sheets reflect a lot of sunlight and their growth consequently amplifies the impact of CO2 changes.”

Professor Richard Pancost from the University of Bristol Cabot Institute, added: “When we account for the influence of the ice sheets, we confirm that the Earth’s climate changed with a similar sensitivity to overall forcing during both warmer and colder climates.”

Reference:
M. A. Martínez-Botí, G. L. Foster, T. B. Chalk, E. J. Rohling, P. F. Sexton, D. J. Lunt, R. D. Pancost, M. P. S. Badger, D. N. Schmidt. Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records. Nature, 2015; 518 (7537): 49 DOI: 10.1038/nature14145

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

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