This is an artist’s impression of Zhenyuanlong suni. Credit: Chuang Zhao
A newly identified species of feathered dinosaur is the largest ever discovered to have a well-preserved set of bird-like wings, research suggests.
Palaeontologists working in China unearthed the fossil remains of the winged dinosaur — a close cousin of Velociraptor, which was made famous by the Jurassic Park films.
Researchers say its wings — which are very short compared with other dinosaurs in the same family — consisted of multiple layers of large feathers. They found that the species’ feathers were complex structures made up of fine branches stemming from a central shaft.
Although larger feathered dinosaurs have been identified before, none have possessed such complex wings made up of quill pen-like feathers, the team says. Scientists have known for some time that many species of dinosaur had feathers, but most of these were covered with simple filaments that looked more like hair than modern bird feathers.
This latest discovery suggests that winged dinosaurs with larger and more complex feathers were more diverse than previously thought.
The species belonged to a family of feathered carnivores that was widespread during the Cretaceous Period, and lived around 125 million years ago, the team says.
The near-complete skeleton of the animal — which is remarkably well preserved — was studied by scientists from the University of Edinburgh and the Chinese Academy of Geological Sciences. The fossil reveals dense feathers covered the dinosaur’s wings and tail.
The newly discovered species — named Zhenyuanlong suni — grew to more than five feet in length. Despite having bird-like wings, it probably could not fly, at least not using the same type of powerful muscle-driven flight as modern birds, researchers say.
It is unclear what function the short wings served. The species may have evolved from ancestors that could fly and used its wings solely for display purposes, in a similar way to how peacocks use their colourful tails, researchers say.
The study is published in the journal Scientific Reports. The research was supported by Natural Science Foundation of China, the European Commission, and the US National Science Foundation.
Dr Steve Brusatte, of the University of Edinburgh’s School of GeoSciences, who co-authored the study, said: “This new dinosaur is one of the closest cousins of Velociraptor, but it looks just like a bird. It’s a dinosaur with huge wings made up of quill pen feathers, just like an eagle or a vulture. The movies have it wrong — this is what Velociraptor would have looked like too.”
Professor Junchang Lü, of the Institute of Geology, Chinese Academy of Geological Sciences, who led the study, said: “The western part of Liaoning Province in China is one of the most famous places in the world for finding dinosaurs. The first feathered dinosaurs were found here and now our discovery of Zhenyuanlong indicates that there is an even higher diversity of feathered dinosaurs than we thought. It’s amazing that new feathered dinosaurs are still being found.”
Reference:
Junchang Lü, Stephen L. Brusatte. A large, short-armed, winged dromaeosaurid (Dinosauria: Theropoda) from the Early Cretaceous of China and its implications for feather evolution. Scientific Reports, 2015; 5: 11775 DOI: 10.1038/srep11775
The Cambrian explosion about 540 million years ago was when all the major living groups (phyla) of animal life appeared. Did a rise in oceanic trace elements initiate this event? Credit: Wikia, CC BY-SA
When Charles Darwin published his theory of evolution by natural selection in 1859, the world hadn’t even heard of plate tectonics. The notion that continents drifted on molten rock currents deep in the Earth’s mantle was unimaginable.
So it would have come as a shock to Darwin to think the movement of the Earth’s continental plates could have been a major driver of evolutionary change in all life.
In our research, published this month in Gondwana Research, we suggest that the regular collision of tectonic plates over the past 700 million years has been a prime driver of evolutionary change on Earth.
We used laser technology housed in the Earth Science laboratories at the University of Tasmania to analyse more than 4,000 pyrite grains from seafloor mudstone samples collected from around the globe.
This enabled us to determine how concentrations of trace elements in the oceans have varied over the 700 million years. Trace elements included copper, zinc, phosphorus, cobalt and selenium, which are necessary for nearly all life – from marine phytoplankton through to humans – to function.
The most surprising finding was that there were certain periods in Earth’s history when nutrient trace elements were highly enriched in the oceans, and other periods when levels of these critical trace elements were very low.
The nutrient-rich periods promoted rapid plankton growth in the short term, and this appears to correlate with periods of increased evolutionary change. An example of this is the rapid rise in trace elements preceding the Ediacaran (635 to 542 million years ago) and Cambrian (541 to 485 mya) periods, a time when multicellular animal life took off in a big way.
The Cambrian explosion, around 540 million years ago, is when most major groups of living animals appeared. This corresponds to a time when essential trace elements were peaking in the oceans, thus nutrient levels were very high.
The nutrient-poor periods caused depletion of plankton and promoted a slow-down in rates of diversification and ultimately could have played a role in three major mass extinction events. These occurred at the end of the Ordovician, Devonian and Triassic periods.
Although several possible explanations are given for these extinctions events, depletion in oceanic trace elements might be another plausible factor. Work is currently underway demonstrating that these events are tied to rapid declines in certain essential trace elements, particularly selenium.
Plate tectonics and nutrient cycles
Nutrients in the oceans ultimately come from weathering and erosion of rocks on thecontinents. Weathering breaks down the minerals in the rocks and releases thenutrient trace elements, which nourish life. Thus when weathering and erosion rates increase for extended periods, more nutrients are supplied to the oceans.
In the long term of geological history, erosion rates rise dramatically duringmountain building events caused by the gradual collision of tectonic plates.
Geologists have known since the 1960s that collisions of tectonic plates lead to the formation of huge mountain ranges. The Himalayas were formed when India, drifting northwards after splitting off from the supercontinent of Gondwana, slammed into Asia and pushed up the Tibetan Plateau. These collisions are called called orogenic events and their timing through Earth’s history is now well established.
Continued erosion eventually depletes the surface of nutrients, causing a drop in the ocean’s nutrients. This might have led to extinction events in the seas.
This is the first time nutrient trace element curves have been developed that demonstrate the relationship between tectonic collisions and the generation of cycles of nutrients.
While the link between these nutrient cycles as drivers of evolution and factors in mass extinction events remains to be proven, it really makes us think about evolution in a broad sense. Plate tectonics and evolution both operate on the same time scale of millions of years, and it seems logical that they could be causally related.
The relationship between increased nutrients in the oceans with bursts of evolutionary change are clearly correlated for the early part of the cycles, but less clear is the correlation with the evolution of advanced land animals.
Life out of the oceans
The origin of the first land animals, tetrapods about 370 million years ago, corresponds with a decrease in oceanic nutrients and a series of mass extinction events in the oceans. This could explain why certain sarcopterygian fishes with robust limbs left the seas when they did in order to leave the nutrient-poor ocean and make out on land.
But the first appearance of dinosaurs and mammals in the early Triassic, about 225 million years ago, has no correlation with trace element abundance.
Perhaps the cycles pertain mainly to biodiversity in the oceans. There is certainly a close correlation with the drop in nutrients and some global oceanic mass extinctions. These events are being tested and explored further in further research on selenium, to be released soon.
Note: The above post is reprinted from materials provided by The Conversation. This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives).
Mud volcano or mud dome refers to formations created by geo-exuded slurries (usually including water) and gases. There are several geological processes that may cause the formation of mud volcanoes. Mud volcanoes are not true (igneous) volcanoes as they produce no lava. The earth continuously exudes a mud-like substance, which may sometimes be referred to as a “mud volcano”. Mud volcanoes may range in size from merely 1 or 2 meters high and 1 or 2 meters wide, to 700 meters high and 10 kilometers wide. Smaller mud exudations are sometimes referred to as mud-pots. The largest mud volcano, Indonesia’s Lusi, is 10 kilometres (6 mi) in diameter.
The mud produced by mud volcanoes is most typically formed as hot water, which has been heated deep below the earth’s surface, begins to mix and blend with subterranean mineral deposits, thus creating the mud slurry exudate. This material is then forced upwards through a geological fault or fissure due to local subterranean pressure imbalances. Mud volcanoes are associated with subduction zones and about 1100 have been identified on or near land. The temperature of any given active mud volcano generally remains fairly steady and is much lower than the typical temperatures found in igneous volcanoes. Mud volcano temperatures can range from near 100 °C (212 °F) to occasionally 2 °C (36 °F), some being used as popular “mud baths.”
About 86% of the gas released from these structures is methane, with much less carbon dioxide and nitrogen emitted. Ejected materials are most often a slurry of fine solids suspended in water that may contain a mixture of salt, acids and various hydrocarbons.
Possible mud volcanoes have been identified on Mars.
What causes a mud volcano? “Details”
A mud volcano may be the result of a piercement structure created by a pressurized mud diapir that breaches the Earth’s surface or ocean bottom. Their temperatures may be as low as the freezing point of the ejected materials, particularly when venting is associated with the creation of hydrocarbon clathrate hydrate deposits. Mud volcanoes are often associated with petroleum deposits and tectonic subduction zones and orogenic belts; hydrocarbon gases are often erupted. They are also often associated with lava volcanoes; in the case of such close proximity, mud volcanoes emit incombustible gases including helium, whereas lone mud volcanoes are more likely to emit methane.
Approximately 1,100 mud volcanoes have been identified on land and in shallow water. It has been estimated that well over 10,000 may exist on continental slopes and abyssal plains.
Features
Gryphon: steep-sided cone shorter than 3 meters that extrudes mud
Mud cone: high cone shorter than 10 meters that extrudes mud and rock fragments
Scoria cone: cone formed by heating of mud deposits during fires
Salse: water-dominated pools with gas seeps
Spring: water-dominated outlets smaller than 0.5 metres
Mud shield
Emissions
Most liquid and solid material is released during eruptions, but seeps occur during dormant periods.
The mud is rich in halite (rock salt).
First-order estimates of mud volcano emissions have been made (1 Tg = 1 million metric tonnes).
2002: L.I. Dimitrov estimated that 10.2–12.6 Tg/yr of methane is released from onshore and shallow offshore mud volcanoes.
2002: Etiope and Klusman estimated at least 1–2 and as much as 10–20 Tg/yr of methane may be emitted from onshore mud volcanoes.
2003: Etiope, in an estimate based on 120 mud volcanoes: “The emission results to be conservatively between 5 and 9 Tg/yr, that is 3–6% of the natural methane sources officially considered in the atmospheric methane budget. The total geologic source, including MVs (this work), seepage from seafloor (Kvenvolden et al., 2001), microseepage in hydrocarbon-prone areas and geothermal sources (Etiope and Klusman, 2002), would amount to 35–45 Tg/yr.”
2003: analysis by Milkov et al. suggests that the global gas flux may be as high as 33 Tg/yr (15.9 Tg/yr during quiescent periods plus 17.1 Tg/yr during eruptions). Six teragrams per year of greenhouse gases are from onshore and shallow offshore mud volcanoes. Deep-water sources may emit 27 Tg/yr. Total may be 9% of fossil CH4 missing in the modern atmospheric CH4 budget, and 12% in the preindustrial budget.
2003: Alexei Milkov estimated approximately 30.5 Tg/yr of gases (mainly methane and CO2) may escape from mud volcanoes to the atmosphere and the ocean.
2003: Achim J. Kopf estimated 1.97×1011 to 1.23×1014 m³ of methane is released by all mud volcanoes per year, of which 4.66×107 to 3.28×1011 m³ is from surface volcanoes. That converts to 141–88,000 Tg/yr from all mud volcanoes, of which 0.033–235 Tg is from surface volcanoes.
Where Are the Mud Volcanoes?
Europe
Asia
Lusi (Indonesia)
Central Asia
Azerbaijan
Iran
India
Pakistan
Philippines
Other Asian locations
China has a number of mud volcanoes in Xinjiang province.
Some active mud volcanoes are in Oesilo (Oecusse District, East Timor). Arthur Wichmann reports a mud volcano in Bibiluto (Viqueque District), which erupted between 1856 and 1879.
There are mud volcanoes at the Minn Buu Township, Magway division in Myanmar (Burma).
There are two active mud volcanoes in South Taiwan and several inactive ones. The Wushan Mud Volcanoes (烏山頂泥火山 in Chinese) are in the Yanchao District of Kaohsiung City. There are active mud volcanoes in Wandan township of Pingtung county.
There are mud volcanoes on the island of Pulau Tiga, off the western coast of the Malaysian state of Sabah on Borneo.
A drilling accident offshore of Brunei on Borneo in 1979 caused a mud volcano which took 20 relief wells and nearly 30 years to halt.
Tiny fossilised eggs, like the one shown above, discovered in Thailand have been found to contain the remains of a 125 million year old lizard embryo related to modern Komodo dragons and slow worms. Unlike almost all living lizards, however, this ancient species, which has yet to be named, laid hard shelled eggs
Tiny fossil eggs long thought to harbour the embryos of dinosaurs or primitive birds, in fact contained unhatched baby lizards—the oldest ever found, scientists said Wednesday.
The eggs, roughly the size of a one-euro coin or sparrow egg, are about 125 million years old, and were discovered in Thailand in 2003.
They have hard shells, unusual for lizards, and initial examinations concluded they must have been laid by a small carnivorous dinosaur or early type of bird.
Not satisfied, an international team of scientists decided to look inside the fossil eggs using the powerful European Synchrotron Radiation Facility (ESRF) in Grenoble, France.
High-resolution, ultra-bright X-rays allowed them to observe the finest details of the minute bones inside the six knob-covered shells, and recreate the skeletons in 3D.
They found features of a “hitherto unknown lizard”, including a long and slender skull ending in a pointed snout, and a “quadrate”—a jaw articulation bone found in the lizard family.
“These embryos were neither dinosaurs, nor birds, but lizards from a group called anguimorph,” the ESRF said in a statement.
The group includes komodo dragons and mosasaurs, a type of extinct marine reptile.
“The discovery of anguimorphs in hard-shelled eggs comes as a considerable surprise,” said the statement—and recast the evolution of lizard reproduction.
“So far, only geckos were known to lay hard-shell eggs.”
The study was published in the journal PLOS ONE.
Video
Note: The above post is reprinted from materials provided by AFP.
Yellow cake uranium, a solid form of uranium oxide produced from uranium ore. Credit: Nuclear Regulatory Commission
EXTRACTIVE metallurgists from Murdoch University have discovered the dissolution mechanism for a mineral previously considered to be unrecoverable and discarded as waste.
Brannerite (UTi2O6) is the most common refractory uranium mineral and accounts for up to 15 per cent of uranium currently unrecovered in extraction, translating into tens of millions of lost dollars for industry.
However, Dr Aleks Nikoloski and PhD candidate Rorie Gilligan have discovered how brannerite can be extracted relatively easily, all thanks to a counter-intuitive approach.
“The traditional wisdom in extractive metallurgy is that if you use more aggressive corrosive conditions, say by increasing the acid concentration, minerals will dissolve allowing the metal to come out, but it’s not the case with brannerite because of its chemical properties,” Dr Nikoloski says.
“While it can be extracted with high temperatures, high free acid concentrations and long leaching times, the process isn’t efficient or economical.
“By gaining an understanding of the chemical processes of brannerite, we have found a dissolution mechanism that supports effective extraction under relatively mild conditions.”
This discovery is the result of a thorough literature review by Mr Gilligan and several years of testing in the lab by a team lead by Dr Nikoloski.
Historical research acts as good springboard
“In doing my literature review, I found a number of largely forgotten studies from the 1950s and ‘60s looking at brannerite extraction,” Mr Gilligan says.
“We took these as a starting point and applied more current knowledge.
“We started by considering how brannerite behaves in the standard sulphuric acid/iron sulfate media and then looked at how it behaved when we introduced other substances, such as phosphates and fluoride, which are known to occur in natural deposits.
“There was no research into how these interacted with brannerite, so by taking a step-by-step approach we were able to better understand the mineral’s chemical processes.”
When Mr Gilligan applied this knowledge to extraction, the results prompted Dr Nikoloski to request that the samples be re-examined.
“I wanted to ensure we were using brannerite,” Dr Nikoloski says.
“At first I couldn’t believe the results. We were getting an extraction rate of 80 to 90 per cent for a mineral that was supposed to be refractory.”
Mr Gilligan says the amount of uranium that will be recovered from brannerite will depend on the geological composition of each ore deposit.
Brannerite is found in significant concentrations in deposits in Mount Isa, Queensland and Crocker Well in South Australia.
This view of Henry’s Lake in Utah’s Uinta Mountains shows several ways water on land reaches the atmosphere: It evaporates from lake waters, streams and soils and also is transpired or “exhaled” by trees and other plants. Such evaporation – as well as from the ocean – helps form clouds in the sky. In a new study in the journal Science, University of Utah researchers determined how much of the rain and snowmelt that falls on the land moves to the atmosphere from plant transpiration and evaporation from soil and surface waters. Credit: Stephen Good/University of Utah
More than a quarter of the rain and snow that falls on continents reaches the oceans as runoff. Now a new study helps show where the rest goes: two-thirds of the remaining water is released by plants, more than a quarter lands on leaves and evaporates and what’s left evaporates from soil and from lakes, rivers and streams.
“The question is, when rain falls on the landscape, where does it go?” says University of Utah geochemist Gabe Bowen, senior author of the study published today in the journal Science. “The water on the continents sustains all plant life, all agriculture, humans, aquatic ecosystems. But the breakdown – how much is used for those things – has always been unclear.”
“Some previous estimates suggested that more water was used by plants than we find here,” he adds. “It means either that plants are less productive globally than we thought, or plants are more efficient at using water than we assumed.”
University of Utah hydrologist Stephen Good, the study’s first author, says, “We’ve broken down the different possible pathways that water takes as it moves from rainfall [and snowfall] through soils, plants and rivers. Here we’ve found the proportions of water that returns to the atmosphere though plants, soils and open water.”
The study used hydrogen isotope ratios of water in rain, rivers and the atmosphere from samples and satellite measurements to conclude that of all precipitation over land – excluding river runoff to the oceans—these amounts are released by other means:
• 64 percent (55,000 cubic kilometers or 13,200 cubic miles) is released or essentially exhaled by plants, a process called transpiration. This is lower than estimated by recent research, which concluded plant transpiration accounted for more than 80 percent of water that falls on land and does not flow to the seas, Bowen says.
• 6 percent (5,000 cubic kilometers or 1,200 cubic miles) evaporates from soils.
• 3 percent (2,000 cubic kilometers or 480 cubic miles) evaporates from lakes, streams and rivers.
• Previous research indicated the other 27 percent (23,000 cubic kilometers or 5,520 cubic miles) falls on leaves and evaporates, a process called interception.
“It’s important to understand the amount of water that goes through each of these pathways,” Good says. “The most important pathway is the water that passes through plants because it is directly related to the productivity of natural and agricultural plants.”
In another key finding, the researchers showed how much rainwater or snowmelt passing through soils is available for plants to use before it enters groundwater, lakes or streams. They found this “connectivity” is 38 percent: Only 38 percent of water entering groundwater, lakes or rivers interacts with soil, and the rest “moves rapidly into groundwater and lakes and rivers without spending much time in the soil,” Bowen says.
“Lot of things happen in soils: nutrients, fertilizers, contaminants, various biological processes,” he adds. “If water that goes to streams and groundwater moves rapidly through soil, it has less interaction with those processes. It means the soils and rest of the hydrologic cycle are somewhat separated. If we want to predict future climate change, hydrologic change and water quality, we need to account for the fact that most water doesn’t interact with soils before it reaches streams and groundwater.”
Significance: for agriculture, water supplies, climate
Good is a research assistant professor and Bowen is an associate professor of geology and geophysics at the University of Utah. They conducted the study with David Noone, of Oregon State University, where Good joins the faculty this fall. Funding came from the Department of Defense and the National Science Foundation, where two program directors praised the findings.
“These scientists found a way to answer basic questions about what happens to rainwater when it falls on land,” says Eric DeWeaver, of NSF’s Division of Atmospheric and Geospace Sciences. “The answers have important implications for water quality, plant productivity and peak streamflow. They give us a window on the inner workings of ecosystems and watersheds that’s scientifically fascinating and useful.”
“Getting what’s called Earth’s ‘water balance’ right is the key to understanding how our climate and ecosystems interact,” says Henry Gholz, of NSF’s Division of Environmental Biology. “This new analysis offers an estimate of hard-to-come-by global water measurements: water used by plants and water that evaporates from land. By knowing these amounts, we can better understand how ecosystems, including watersheds, work. In a decade when our reserves of freshwater are declining – in some cases to critically low levels – this information couldn’t be timelier.”
Good says that knowing how much water plants release or transpire is important “so that we can have an understanding how productive ecosystems and agriculture are, because how much water plants use determines how much food we get and how many leaves are on the trees.”
Earth’s water cycle is changing as climate warms, “so given shifts in future water availability, we also will see shifts in ecosystems and agriculture,” Good says. “So understanding the connection between the water cycle and plant growth is important.
For example, when leaves release water, they consume carbon dioxide, the major climate-warming gas. Soil doesn’t do that. So knowing how much water plants transpire “helps us understand how plants contribute to reducing global warming,” Bowen says.
Evapotranspiration from land – in context
To put the new study in context, consider previous research showing every year about 496,000 cubic kilometers or 119,000 cubic miles of water evaporates from the oceans and continents and then becomes rain that falls over the oceans and continents. Of the global rainfall amount, 77 percent of precipitation falls over oceans and 23 percent over continents. Because some continental precipitation runs off to the seas, 83 percent of global evaporation comes from the oceans and only 17 percent from continents.
The new study deals with the fate of that 17 percent, which amounts to 85,000 cubic kilometers or 20,400 cubic miles of water. In other words, all the water that doesn’t fall or flow into the oceans would fill 20,400 cubes of water 1 mile on each side. (The study excluded water evaporating to the atmosphere from snow because earlier research indicates it is less than 1 percent, Good says.)
How the study was performed
The study used data from two sources. First, a global network of isotopes and precipitation collected since the 1950s by the International Atomic Energy Agency. It includes measurements of deuterium – the heavy form or isotope of hydrogen. Deuterium is hydrogen-2 rather than the common isotope hydrogen-1. The IAEA data include measurements of deuterium in rainfall from about 500 stations around the world.
Second, the researchers used measurements made by NASA’s Aura satellite of deuterium concentrations in water vapor near Earth’s surface.
Each form of water has a distinct deuterium-hydrogen ratio, some of which Good and Bowen determined in a related study in another journal. Water vapor evaporated after being intercepted by leaves has deuterium-hydrogen ratios the same as rainwater. Water evaporated from lakes and streams has a relatively low deuterium-hydrogen ratio. Water evaporated from soil is similar, but the water left behind has a higher deuterium-hydrogen ratio, and thus so does water taken up and then transpired by plants, Bowen says.
The new study accounted for each of these isotopic signatures in a computer simulation of global movements of water between the land and atmosphere. By running the simulation thousands of times and testing the resulting estimates of river water and evapotranspiration isotope ratios against independent data, Good was able to show that a limited number of simulations matched the data. These gave a narrow range of estimates for how much water was released to the atmosphere by each pathway.
In this 2013 image, Ken Mankoff, then at the University of California, Santa Cruz, monitors the borehole for the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) program. Credit: Reed Scherer, NSF
The amount of heat flowing toward the base of the West Antarctic ice sheet from geothermal sources deep within the Earth is surprisingly high, according to a new study led by researchers at the University of California (UC), Santa Cruz.
The results, published on July 10 in the online journal Science Advances, provide important data for researchers trying to predict the fate of the ice sheet, which has experienced rapid melting over the past decade.
Lead author Andrew Fisher, a professor of Earth and planetary sciences at UC Santa Cruz, emphasized that the geothermal heating reported in this study does not explain the alarming loss of ice from West Antarctica that has been documented by other researchers.
“The ice sheet developed and evolved with the geothermal heat flux coming up from below–it’s part of the system. But this could help explain why the ice sheet is so unstable,” he said.
The study draws upon data collected by a large Antarctic drilling project, funded by an award from the National Science Foundation’s Division of Polar Programs, called WISSARD (Whillans Ice Stream Subglacial Access Research Drilling), for which UC Santa Cruz is one of three lead institutions, the others being Montana State University and Northern Illinois University. The Division manages the U.S. Antarctic Program, through which it coordinates all U.S. scientific research on the southernmost continent.
Scott Borg, who heads the Division’s Antarctic sciences section, noted that the multidiscplinary WISSARD project has produced a number of significant research results in recent years that are helping to advance scientific understanding in disparate fields, from biology to the geosciences.
“The WISSARD findings, including this latest discovery about geothermal heat,” he said, “are helping us to assemble a deeper understanding of the nature of extreme ecosystems in Antarctica, and, possibly, similar ecosystems elsewhere in the solar system, as well helping us to understand some of the many dynamic processes that govern the behavior of the massive Antarctic ice sheets.”
The research team used a special thermal probe, designed and built at UC Santa Cruz, to measure temperatures in sediments below Subglacial Lake Whillans, which lies beneath half a mile of ice. After boring through the ice sheet with a special hot-water drill, researchers lowered the probe through the borehole until it buried itself in the sediments below the subglacial lake. The probe measured temperatures at different depths in the sediments, revealing a rate of change in temperature with depth about five times higher than that typically found on continents. The results indicate a relatively rapid flow of heat towards the bottom of the ice sheet.
High heat flow below the West Antarctic ice sheet may also help explain the presence of lakes beneath it and why parts of the ice sheet flow rapidly as ice streams. Water at the base of the ice streams is thought to provide the lubrication that speeds their motion, carrying large volumes of ice out onto the floating ice shelves at the edges of the ice sheet. Fisher noted that the geothermal measurement was from only one location, and heat flux is likely to vary from place to place beneath the ice sheet.
“This is the first geothermal heat flux measurement made below the West Antarctic ice sheet, so we don’t know how localized these warm geothermal conditions might be. This is a region where there is volcanic activity, so this measurement may be due to a local heat source in the crust,” Fisher said.
This geothermal heating contributes to melting of basal ice, which supplies water to a network of subglacial lakes and wetlands that scientists have discovered underlies a large region of the ice sheet. In a separate study published last year in Nature, the WISSARD microbiology team reported an abundant and diverse microbial ecosystem in the same lake. Warm geothermal conditions may help to make subglacial habitats more supportive of microbial life, and could also drive fluid flow that delivers heat, carbon, and nutrients to these communities.
According to co-author Slawek Tulaczyk, a professor of Earth and planetary sciences at UC Santa Cruz and one of the WISSARD project leaders, the geothermal heat flux is an important value for the computer models scientists are using to understand why and how quickly the West Antarctic ice sheet is shrinking.
“It is important that we get this number right if we are going to make accurate predictions of how the West Antarctic ice sheet will behave in the future, how much it is melting, how quickly ice streams flow, and what the impact might be on sea level rise,” Tulaczyk said. “I waited for many years to see a directly measured value of geothermal flux from beneath this ice sheet.”
Antarctica’s huge ice sheets are fed by snow falling in the interior of the continent. The ice gradually flows out toward the edges. The West Antarctic ice sheet is considered less stable than the larger East Antarctic ice sheet because much of it rests on land that is below sea level, and the ice shelves at its outer edges are floating on the sea. Recent studies by other research teams have found that the ice shelves are melting due to warm ocean currents now circulating under the ice, and the rate at which the ice shelves are shrinking is accelerating. These findings have heightened concerns about the overall stability of the West Antarctic ice sheet.
The geothermal heat flux measured in the new study was about 285 milliwatts per square meter, which is like the heat from one small LED Christmas-tree light per square meter, Fisher said. The researchers also measured the upward heat flux through the ice sheet (about 105 milliwatts per square meter) using an instrument developed by coauthor Scott Tyler at the University of Nevada, Reno. That instrument was left behind in the WISSARD borehole as it refroze, and the measurements, based on laser light scattering in a fiber-optic cable, were taken a year later. Combining the measurements both below and within the ice enabled calculation of the rate at which melt water is produced at the base of the ice sheet at the drill site, yielding a rate of about half an inch per year.
In addition to Fisher, Tulaczyk and Tyler, the coauthors of the paper include Ken Mankoff, who earned his doctorate at UC Santa Cruz and is now a research associate at Pennsylvania State University, and current UC Santa Cruz graduate student Neil Foley.
Head-butting and canine display during male-male combat first appeared some 270 million years ago.
This is what researchers from the Evolutionary Studies Institute at Wits found when they conducted an updated and more in-depth study of the herbivorous mammalian ancestor, Tiarajudens eccentricus, discovered four years ago.
Through this study, the Brazil and South Africa researchers can now present a meticulous description of the skull, skeleton and dental replacement of this Brazilian species. And they learned that 270 million years ago, the interspecific combat and fighting we see between male deer today were already present in these forerunners of mammals.
The Brazilian researcher, Dr Juan Carlos Cisneros, and his co-researchers from the Evolutionary Studies Institute at the University of the Witwatersrand, Professor Fernando Abdala and Dr Tea Jashasvili, have published their results in the journal Royal Society Open Science on 15 July 2015.
Saber-teeth are known to belong to the large Permian predators’ gorgonopsians (also known as saber-tooth reptiles), and in the famous saber-tooth cats from the Ice Age.
When Tiarajudens eccentricus was discovered it had some surprises install: Despite large protruding saber-tooth canines and occluding postcanine teeth, it was an herbivore.
The discovery of this Brazilian species also allowed for a reanalysis of the South African species Anomocephalus africanus, discovered 10 years earlier. The two species have several similar features that clearly indicated they are closely related but the African species lack of the saber-tooth canines of its Brazilian cousin. In the Middle Permian, where these Gondwana cousins were living, around 270 million years ago, the first communities with diverse, abundant tetrapod herbivores were evolving.
Male-male fighting
In deer today enlarged canines are used in male-male displays during fighting. The long canine in the herbivore T. eccentricus is interpreted as an indication of its use in a similar way, and is the oldest evidence where male herbivores have used their canines during fights with rivals.
“It is incredible to think that features found in deer such as the water deer, musk deer and muntjacs today were already represented 270 million years ago,” says Cisneros.
The researchers found the Tiarajudens’ marginal teeth are also located in a bone from the palate called epipterygoid. “This is an extraordinary condition as no other animal in the lineage leading to mammals show marginal dentition in a bone from the palate,” says Abdala.
Head-butting
In another group of mammal fossil relatives, dinocephalians – that lived at the same time as anomodonts, some of the bones in their foreheads were massively thickened. This can be interpreted as being used in head-butting combat, a modern behaviour displayed by several deer species today.
“Fossils are always surprising us. Now they show us unexpectedly that 270 million years ago two forms of interspecific combat represented in deer today, were already present in the forerunners of mammals,” says Cisneros.
Reference:
“Tiarajudens eccentricus and Anomocephalus africanus, two bizarre anomodonts (Synapsida, Therapsida) with dental occlusion from the Permian of Gondwana.” DOI: 10.1098/rsos.150090
Igneous clast named Harrison embedded in a conglomerate rock in Gale crater, Mars, shows elongated light-toned feldspar crystals. The mosaic merges an image from Mastcam with higher-resolution images from ChemCam’s Remote Micro-Imager. Credit: NASA/JPL-Caltech/LANL/IRAP/U. Nantes/IAS/MSSS.
The ChemCam laser instrument on NASA’s Curiosity rover has turned its beam onto some unusually light-colored rocks on Mars, and the results are surprisingly similar to Earth’s granitic continental crust rocks. This is the first discovery of a potential “continental crust” on Mars.
“Along the rover’s path we have seen some beautiful rocks with large, bright crystals, quite unexpected on Mars” said Roger Wiens of Los Alamos National Laboratory, lead scientist on the ChemCam instrument. “As a general rule, light-colored crystals are lower density, and these are abundant in igneous rocks that make up the Earth’s continents.”
Mars has been viewed as an almost entirely basaltic planet, with igneous rocks that are dark and relatively dense, similar to those forming the Earth’s oceanic crust, Wiens noted. However, Gale crater, where the Curiosity rover landed, contains fragments of very ancient igneous rocks (around 4 billion years old) that are distinctly light in color, which were analyzed by the ChemCam instrument.
French and US scientists observed images and chemical results of 22 of these rock fragments. They determined that these pale rocks are rich in feldspar, possibly with some quartz, and they are unexpectedly similar to Earth’s granitic continental crust. According to the paper’s first author, Violaine Sautter, these primitive Martian crustal components bear a strong resemblance to a terrestrial rock type known to geologists as TTG (Tonalite-Trondhjemite-Granodiorite), rocks that predominated in the terrestrial continental crust in the Archean era (more than 2.5 billion years ago).
The results were published this week in Nature Geoscience, “In situ evidence for continental crust on early Mars.”
Gale crater, excavated about 3.6 billion years ago into rocks of greater age, provided a window into the Red Planet’s primitive crust. The crater walls provided a natural geological cut-away view 1-2 miles down into the crust. Access to some of these rocks, strewn along the rover’s path, provided critical information that could not be observed by other means, such as by orbiting satellites.
Reference:
V. Sautter, M. J. Toplis, R. C. Wiens, A. Cousin, C. Fabre, O. Gasnault, S. Maurice, O. Forni, J. Lasue, A. Ollila, J. C. Bridges, N. Mangold, S. Le Mouélic, M. Fisk, P.-Y. Meslin, P. Beck, P. Pinet, L. Le Deit, W. Rapin, E. M. Stolper, H. Newsom, D. Dyar, N. Lanza, D. Vaniman, S. Clegg, J. J. Wray. In situ evidence for continental crust on early Mars. Nature Geoscience, 2015; DOI: 10.1038/ngeo2474
First use of NanoSIMS ion probe measurements to understand volcanic cycles at Yellowstone
Super-eruptions are not the only type of eruption to be considered when evaluating hazards at volcanoes with protracted eruption histories, such as the Yellowstone (Wyoming), Long Valley (California), and Valles (New Mexico) calderas. There have been more than 23 effusive eruptions of rhyolite lava at Yellowstone since the last caldera-forming eruption ~640,000 years ago, all of similar or greater magnitude than the largest volcanic eruptions of the 20th century.
This study by Christy B. Till and colleagues is innovative because it is the first to use NanoSIMS ion probe measurements to document very sharp concentration gradients over very short distances in igneous minerals, which allow a calculation of the timescale between reheating and eruption for the magma body of interest.
Their results suggest that an eruption at the beginning of Yellowstone’s most recent volcanic cycle was triggered within 10 months after reheating of a mostly crystallized magma reservoir following a 220,000-year period of volcanic quiescence. A similarly energetic reheating of Yellowstone’s current subsurface magma bodies could end ~70,000 years of volcanic repose and lead to a future eruption over similar timescales. Fortunately, write the authors, any significant reheating event is likely to be identifiable by geophysical monitoring.
Reference:
Months between rejuvenation and volcanic eruption at Yellowstone caldera, Wyoming
Christy B. Till et al., Arizona State University, Tempe, Arizona 85287, USA. Published online ahead of print on 1 July 2015; DOI: 10.1130/G36862.1
Crevassed glacier terminus in West Greenland. Credit: Sam Doyle
According to a new study published in Nature Geoscience, the Greenland ice sheet has been shown to accelerate in response to surface rainfall and melt associated with late-summer and autumnal cyclonic weather events.
Samuel Doyle and an international team of colleagues led from Aberystwyth University’s Centre for Glaciology combined records of ice motion, water pressure at the ice sheet bed, and river discharge with surface meteorology across the western margin of the Greenland ice sheet and captured the wide-scale effects of an unusual week of warm, wet weather in late August and early September, 2011.
They found that the cyclonic weather system led to extreme surface runoff — a combination of ice melt and rain — that overwhelmed the ice sheet’s basal drainage system, driving a marked increase in ice flow across the entire western sector of the ice sheet and extending 140 km into the ice sheet’s interior.
“It is like an urban sewerage system that is temporarily overwhelmed by an intense rain-storm. The ice sheet plumbing — literally a network of pipes, cavities and channels — gets backed up by the sheer quantity of runoff draining into it, leading to flooding and high water pressures, which literally hydraulically lifts the ice sheet up off its bed, reducing basal friction and sending it on its way,” said Prof Alun Hubbard the principal investigator who led the 4-year project which was funded by Natural Environment Research Council (NERC) and the Royal Geographical Society amongst others.
This particular depression prevailed across a broad swathe of southern and western Greenland, and a correspondingly-widespread acceleration in ice motion was reported from all available satellite and GPS tracking stations. This response was apparent at glaciers that terminate on dry land as well as those that calve into the sea.
Cyclonic systems, or depressions, are no great surprise to us in the UK and western Europe where, even in summer, they are unfortunately part and parcel of our everyday weather — commonly bringing wind and rain. In contrast, such conditions are less common across Greenland, which is normally dominated by a stable, high-pressure system centred over the ice sheet.
The influence of such rainfall events has not, until now, been considered in assessments of the melt and flow response of any ice sheet. This is an important omission because, although such cyclonic conditions are currently rare across Greenland, they are predicted to increase in the future, therefore likely playing an increasing role in driving mass loss from the Greenland ice sheet, which currently contributes over 0.7 mm per year to global sea-level — a rate at least double that of Antarctica.
“The late-summer timing was critical. The event occurred after the end of the melt season and the ice-sheet’s drainage system had started to close down. In this state the ice sheet’s drainage system just couldn’t cope,” said Dr Samuel Doyle, lead author of the study.
Since the 1980s when rainfall measurements began in the west Greenland town of Kangerlussuaq, the focus of the study, the proportion of precipitation now falling as rain rather than snow has both increased and extended into the late summer and autumn in line with increased circulation and moisture availability within a warmer, more energetic atmosphere.
“We’re seeing that warm wet weather is increasing with climate change and is driving more melt of the Greenland ice-sheet than we thought. And worryingly, this melt is now reaching ever higher elevations on the ice sheet” says Prof. Jason Box, one of the co- authors of the study.
“The jury is out as to whether the ‘rainfall’ events identified in our study had a lasting influence on the evolution of the Greenland ice sheet. Just like in many regions of the planet, observed climate warming doesn’t just mean hotter summers and milder winters; it’s more complex than that and more often it means more intense storm events at unusual times of the year just like we’ve witnessed here in the UK. These events are predicted to increase in the future and under a succession of such autumnal storm events there is no doubt the ice sheet will experience accelerated melt and flow which could only hasten its eventual demise,” commented Alun Hubbard.
Reference:
Samuel H. Doyle, Alun Hubbard, Roderik S.W. van de Wal, Jason E. Box, Dirk van As, Killian Scharrer, Toby W. Meierbachtol, Paul C.J.P. Smeets, Joel T. Harper, Emma Johansson, Ruth H. Mottram, Andreas B. Mikkelsen, Frank Wilhelms, Henry Patton, Poul Christoffersen, and Bryn Hubbard. Amplified melt and flow of the Greenland ice sheet driven by late-summer cyclonic rainfall. Nature Geoscience, July 2015 DOI: 10.1038/ngeo2482
July GSA Today cover image: Khosoumi Mountains in the southern part of the Chapedony metamorphic core complex of Central Iran. The high mountains in the back are represented by Eocene plutonic rocks of the footwall unit. Eocene volcaniclastic rocks in the foreground form the hanging-wall unit. Credit: Franz Neubauer of the University of Salzburg and Fariba Kargaranbafghi of the University of Yazd, and GSA Today.
In the July issue of GSA Today, Franz Neubauer of the University of Salzburg and Fariba Kargaranbafghi of the University of Yazd describe thinning of the lithosphere that they associate with the formation of a metamorphic core complex in the Central Iranian plateau.
The core complex is located within a continental rift and was exhumed at a rate of approx. 0.75 to 1.3 km per million years during the main phase of oceanic subduction of the Arabian plate beneath the Central Iranian block between ca. 30 and 49 million years ago.
The authors indicate that lithosphere and continental crust were thinned beneath regions of surface extension.
The thinning of the underlying lithosphere appears to have been compensated by hot asthenosphere, as indicated by low seismic velocities in the Central Iranian block.
The authors conclude that the development of the core complex involved lithospheric removal associated with extension and upwelling of hot asthenosphere. Later processes, like slab break-off and associated uplift of the Central Iranian plateau, may have modified the structure.
Reference:
Fariba Kargaranbafghi, Franz Neubauer. Lithospheric thinning associated with formation of a metamorphic core complex and subsequent formation of the Iranian plateau. GSA Today, 2015; 4 DOI: 10.1130/GSATG229A.1
Australia’s new ocean-going research vessel Investigator has discovered extinct volcanoes likely to be 50 million years old about 250 kilometres off the coast of Sydney. The largest is 1.5 kilometres across the rim and rises 700 metres from the sea floor. Credit: Marine National Facility
Australia’s new ocean-going research vessel Investigator has discovered extinct volcanoes likely to be 50 million years old about 250 kilometres off the coast of Sydney.
The chief scientist for the voyage, UNSW Australia marine biologist Professor Iain Suthers, said the volcanoes were discovered in 4,900 meters of water during a search for nursery grounds for larval lobsters. At the same time the ship was also routinely mapping the seafloor.
“The voyage was enormously successful. Not only did we discover a cluster of volcanoes on Sydney’s doorstep, we were amazed to find that an eddy off Sydney was a hotspot for lobster larvae at a time of the year when we were not expecting them,” Professor Suthers said.
The four extinct volcanoes in the cluster are calderas, which form after a volcano erupts and the land around them collapses, forming a crater. The largest is 1.5 kilometres across the rim and it rises 700 metres from the sea floor.
Professor Richard Arculus from the Australian National University, an igneous petrologist and a world-leading expert on volcanoes, said these particular types of volcanoes are really important to geoscientists because they are like windows into the seafloor.
“They tell us part of the story of how New Zealand and Australia separated around 40-80 million years ago and they’ll now help scientists target future exploration of the sea floor to unlock the secrets of the Earth’s crust,” Professor Arculus said.
“They haven’t been found before now because the sonar on the previous Marine National Facility (MNF) research vessel, Southern Surveyor, could only map the sea floor to 3,000 metres, which left half of Australia’s ocean territory out of reach.” ”
On board the new MNF vessel, Investigator, we have sonar that can map the sea floor to any depth, so all of Australia’s vast ocean territory is now within reach, and that is enormously exciting,” Professor Arculus said.
Professor Suthers said the 94-metre Investigator has other capabilities that marine scientists in Australia have never had before, and the vessel will be key to unlocking the secrets of the oceans around our continent and beyond.
“Investigator is able to send and receive data while we’re at sea, which meant the team back on base at UNSW in Sydney could analyse the information we were collecting at sea and send back their analysis, along with satellite imagery, so we could chase the eddies as they formed,” Professor Suthers said.
“This is the first time we’ve been able to respond directly to the changing dynamics of the ocean and, for a biological oceanographer like me, it doesn’t get more thrilling,” Professor Suthers said.
“It was astounding to find juvenile commercial fish species like bream and tailor 150 kilometres offshore, as we had thought that once they were swept out to sea that was end of them. But in fact these eddies are nursery grounds along the east coast of Australia.”
The research voyage led by Professor Iain Suthers departed Brisbane on 3 June and concluded on 18 June in Sydney, with 28 scientists from UNSW, La Trobe University, the University of British Columbia, the University of Sydney, the University of Auckland, the University of Technology Sydney, and Southern Cross University.
The centre of the volcanic cluster is 33 31 S, 153 52 E, which is 248 kilometres from Sydney Heads. The cluster is 20 kilometres long and six kilometres wide and the seafloor is 4890 metres deep, with the highest point in the cluster rising up to 3,998 metres.
Video
UNSW Researchers discovered a volcanic cluster off the coast of Sydney in 2015 at 33 31 S, 153 52 E.
The RV Investigator crew have discovered extinct volcanoes likely to be 50 million years old, about 250 km off the coast of Sydney in 4,900 m of water. While scientists were searching for the nursery grounds for larval lobsters, the ship was also routinely mapping the seafloor when the volcanoes were discovered. They haven’t been found before now, because the sonar on the previous Marine National Facility (MNF) research vessel, Southern Surveyor, could only map the sea floor to 3,000 m, which left half of Australia’s ocean territory out of reach. The centre of the volcanic cluster is 33 31 S, 153 52 E, which is 248 km from Sydney Heads. The cluster is 20 km long and six km wide and the seafloor 4890 metres deep, with the highest point in the cluster rising up to 3998 metres.
A piece of amber from El Soplao cave with a specimen of the species Buccinatormyia magnifica. Credit: Image courtesy of Universidad de Barcelona
When we think about pollination, the image that comes first to our mind is a bee or a butterfly covered by pollen. However, in the Cretaceous — about 105 million years ago — bees and butterflies did not exist, and most terrestrial ecosystems were dominated by non-flowering plants (gymnosperms).
An international research team has recently discovered some amber fly specimens in El Soplao cave (Cantabria, Spain). According to an article published in the scientific journal Current Biology, these specimens fed on nectar and pollinized gymnosperm plants 105 million years ago. Xavier Delclòs, professor in the Department ofStratigraphy, Paleontology and Marine Geosciences and researcher at the Biodiversity Research Institute (IRBio) of the University of Barcelona, is one of the authors of the study. The article is also authored by Enrique Peñalver and Eduardo Barron (Geological and Mining Institute of Spain, IGME); Antonio Arillo (Complutense University of Madrid, UCM); David Grimaldi (American Museum of Natural History); Ricardo Pérez de la Fuente (Harvard University, USA,) and Mark L. Riccioi (Cornell (University, USA).
Plants attract insects with different strategies — for example, with their sweet and nutritious nectar — in order to get them transport pollen and enable the process of pollination. By this way, plants and insects establish a fundamental symbiotic relationship that plays a key role in the preservation of terrestrial ecosystems. Besides bees and other similar species, the most important pollinators in current ecosystems — where flowering plants predominate — are proboscid butterflies, beetles, thrips and flies. On the contrary, in Cretaceous landscapes, dominant species were gymnosperms (for examples, pines, firs, cycads) and the main agent of pollination was the wind.
Flies that pollinated Cretaceous plants
Amber from El Soplao (Cantabria) is providing traces of new insect species key to understand how was life in Cretaceous forests, when today’s Iberian Peninsula was a giant island. The study describes two species of flies, well preserved in amber, which present a long specialized proboscis and belong to the family Zhangsolvidae, extinct before dinosaurs. One of the specimens has hundreds of grains from a Bennettitalean species, an extinct order of gymnosperms.
The study proves that the internal structure of flies’ proboscis has been preserved at a microscopic level, according to evidence provided by computed tomography and transmission electron microscopy. The scientific team has showed that these flies took nectar from plants by approaching them in beating flight, like hummingbirds do.
When angiosperms began to dominate terrestrial ecosystems
There are few known cases of insects that fossilized when they were transporting pollen from one flower to another. The new fossils found in Cantabria show that flies and Bennettitales held a close partnership 105 million years ago. Why amber insects carrying angiosperm pollen have not been found? According to experts, this is an outstanding scientific finding because at that moment angiosperms were beginning to dominate terrestrial ecosystems and diversify in many species.
“If insects were able to feed on gymnosperms flower structures, it is probably true that the transition to angiosperms took place then,” affirm the authors of the study.
Video
Reference:
Enrique Peñalver, Antonio Arillo, Ricardo Pérez-de la Fuente, Mark L. Riccio, Xavier Delclòs, Eduardo Barrón, David A. Grimaldi. Long-Proboscid Flies as Pollinators of Cretaceous Gymnosperms. Current Biology, 2015; DOI: 10.1016/j.cub.2015.05.062
Relicanthus sp. — a new species from a new order of Cnidaria collected at 4,100 meters in the Clarion-Clipperton Fracture Zone (CCZ) that lives on sponge stalks attached to nodules. Credit: Craig Smith and Diva Amon, ABYSSLINE Project
Thousands of feet below the ocean’s surface lies a hidden world of undiscovered species and unique seabed habitats–as well as a vast untapped store of natural resources including valuable metals and rare-earth minerals. Technology and infrastructure development worldwide is dramatically increasing demand for these resources, which are key components in everything from cars and modern buildings to computers and smartphones. This demand has catalyzed interest in mining huge areas of the deep-sea floor.
In a paper published this week in Science, researchers from the Center for Ocean Solutions and co-authors from leading institutions around the world propose a strategy for balancing commercial extraction of deep-sea resources with protection of diverse seabed habitats. The paper is intended to inform upcoming discussions by the International Seabed Authority (ISA) that will set the groundwork for future deep-sea environmental protection and mining regulations.
“Our purpose is to point out that the ISA has an important opportunity to create networks of no-mining Marine Protected Areas (MPAs) as part of the regulatory framework they are considering at their July meeting,” says lead author Lisa Wedding, an early career science fellow at the Center for Ocean Solutions. “The establishment of regional MPA networks in the deep sea could potentially benefit both mining and biodiversity interests by providing more economic certainty and ecosystem protection.”
The ISA is charged with managing the seabed and its resources outside of national jurisdictions for the benefit of humankind. According to the United Nations Convention on the Law of the Sea (UNCLOS), the deep seabed is legally a part of the “common heritage of humankind,” meaning that it belongs to each and every human on the planet.
“The ISA is the only body with the legal standing and responsibility to manage mining beyond national jurisdiction,” said Kristina Gjerde, an international high-seas lawyer and co-author on the Science paper.
Since 2001, the ISA has granted 26 mining exploration contracts covering more than one million square kilometers of seabed, with 18 of these contracts granted in the last four years. Researchers recommend that the ISA, as part of its strategic plans to protect deep-seabed habitats and manage mining impacts, take a precautionary approach and set up networks of MPAs before additional large claim areas are granted for deep seabed mining.
“Given our paltry understanding of deep-sea environments, regional networks of MPAs that designate significant portions of the deep seabed as off-limits to mining would provide key insurance against unanticipated environmental impacts,” said co-author Steven Gaines, dean of the Bren School of Environmental Science & Management at the University of California at Santa Barbara.
Mining impacts could affect important environmental benefits that the deep sea provides to human beings. For example, the deep sea is a key player in our planet’s carbon cycle, capturing a substantial amount of human-emitted carbon which impacts both weather and climate. Mining activities could disturb these deep-sea carbon sinks, releasing excess carbon back into the atmosphere. The deep sea also sustains economically important fisheries, and harbors microorganisms which have proven valuable in a number of pharmaceutical, medical and industrial applications.
“Deep-sea areas targeted by mining claims frequently harbor high biodiversity and fragile habitats, and may have very slow rates of recovery from physical disturbance,” said Craig Smith, a co-author and professor of oceanography at the University of Hawaii at Manoa. Smith and a team of scientists, helped the ISA pioneer the deep sea’s first regional environmental management plan in 2012. Located in an area of the Pacific Ocean known as the Clarion-Clipperton Zone (CCZ), the plan honored existing mining exploration claims while protecting delicate habitats by creating a network of MPAs. The CCZ serves as a model for how future deep-sea ecosystem management could unfold.
“This kind of precautionary approach achieves a balance of economic interests and conservation benefits,” said Sarah Reiter, a co-author and former early career law and policy fellow at the Center for Ocean Solutions who now works as an ocean policy analyst at the Monterey Bay Aquarium.
The upcoming ISA session on July 15th represents a critical juncture for defining the future of deep-sea mining and protection.
“The time is now to protect this important part of the planet for current and future generations,” said Larry Crowder, a co-author and science director at the Center for Ocean Solutions and senior fellow at the Stanford Woods Institute for the Environment. “Decisions that affect us all will be made by the ISA this summer.”
Reference:
L. M. Wedding, S. M. Reiter, C. R. Smith, K. M. Gjerde, J. N. Kittinger, A. M. Friedlander, S. D. Gaines, M. R. Clark, A. M. Thurnherr, S. M. Hardy, and L. B. Crowder. Managing mining of the deep seabed. Science, July 2015 DOI: 10.1126/science.aac6647
The presence of the mineral actinolite in the caprock of Campi Flegrei provided the crucial clue to unraveling the chemical processes that formed the concrete-like rock beneath the caldera. Credit: Courtesy of Tiziana Vanorio
The discovery of a fiber-reinforced, concrete-like rock formed in the depths of a dormant supervolcano could help explain the unusual ground swelling that led to the evacuation of an Italian port city and inspire durable building materials in the future, Stanford scientists say.
The “natural concrete” at the Campi Flegrei volcano is similar to Roman concrete, a legendary compound invented by the Romans and used to construct the Pantheon, the Coliseum, and ancient shipping ports throughout the Mediterranean.
“This implies the existence of a natural process in the subsurface of Campi Flegrei that is similar to the one that is used to produce concrete,” said Tiziana Vanorio, an experimental geophysicist at Stanford’s School of Earth, Energy & Environmental Sciences.
Campi Flegrei lies at the center of a large depression, or caldera, that is pockmarked by craters formed during past eruptions, the last of which occurred nearly 500 years ago. Nestled within this caldera is the colorful port city of Pozzuoli, which was founded in 600 B.C. by the Greeks and called “Puteoli” by the Romans.
Beginning in 1982, the ground beneath Pozzuoli began rising at an alarming rate. Within a two-year span, the uplift exceeded six feet-an amount unprecedented anywhere in the world. “The rising sea bottom rendered the Bay of Pozzuoli too shallow for large craft,” Vanorio said.
Making matters worse, the ground swelling was accompanied by swarms of micro-earthquakes. Many of the tremors were too small to be felt, but when a magnitude 4 quake juddered Pozzuoli, officials evacuated the city’s historic downtown. Pozzuoli became a ghost town overnight.
A teenager at the time, Vanorio was among the approximately 40,000 residents forced to flee Pozzuoli and settle in towns scattered between Naples and Rome. The event made an impression on the young Vanorio, and inspired her interests in the geosciences. Now an assistant professor at Stanford, Vanorio decided to apply her knowledge about how rocks in the deep Earth respond to mechanical and chemical changes to investigate how the ground beneath Pozzuoli was able to withstand so much warping before cracking and setting off micro-earthquakes.
“Ground swelling occurs at other calderas such as Yellowstone or Long Valley in the United States, but never to this degree, and it usually requires far less uplift to trigger earthquakes at other places,” Vanorio said. “At Campi Flegrei, the micro-earthquakes were delayed by months despite really large ground deformations.”
To understand why the surface of the caldera was able to accommodate incredible strain without suddenly cracking, Vanorio and a post-doctoral associate, Waruntorn Kanitpanyacharoen, studied rock cores from the region. In the early 1980s, a deep drilling program probed the active geothermal system of Campi Flegrei to a depth of about 2 miles. When the pair analyzed the rock samples, they discovered that Campi Flegrei’s caprock-a hard rock layer located near the caldera’s surface-is rich in pozzolana, or volcanic ash from the region.
The scientists also noticed that the caprock contained tobermorite and ettringite-fibrous minerals that are also found in manmade concrete. These minerals would have made Campi Flegrei’s caprock more ductile, and their presence explains why the ground beneath Pozzuoli was able to withstand significant bending before breaking and shearing. But how did tobermorite and ettringite come to form in the caprock?
Once again, the drill cores provided the crucial clue. The samples showed that the deep basement of the caldera-the “wall” of the bowl-like depression-consisted of carbonate-bearing rocks similar to limestone, and that interspersed within the carbonate rocks was a needle-shaped mineral called actinolite.
“The actinolite was the key to understanding all of the other chemical reactions that had to take place to form the natural cement at Campi Flegrei,” said Kanitpanyacharoen, who is now at Chulalongkorn University in Thailand.
From the actinolite and graphite, the scientists deduced that a chemical reaction called decarbonation was occurring beneath Campi Flegrei. They believe that the combination of heat and circulating mineral-rich waters decarbonates the deep basement, prompting the formation of actinolite as well as carbon dioxide gas. As the CO2 mixes with calcium-carbonate and hydrogen in the basement rocks, it triggers a chemical cascade that produces several compounds, one of which is calcium hydroxide. Calcium hydroxide, also known as portlandite or hydrated lime, is one of the two key ingredients in manmade concrete, including Roman concrete. Circulating geothermal fluids transport this naturally occurring lime up to shallower depths, where it combines with the pozzolana ash in the caprock to form an impenetrable, concrete-like rock capable of withstanding very strong forces.
“This is the same chemical reaction that the ancient Romans unwittingly exploited to create their famous concrete, but in Campi Flegrei it happens naturally,” Vanorio said.
In fact, Vanorio suspects that the inspiration for Roman concrete came from observing interactions between the volcanic ash at Pozzuoli and seawater in the region. The Roman philosopher Seneca, for example, noted that the “dust at Puteoli becomes stone if it touches water.”
“The Romans were keen observers of the natural world and fine empiricists,” Vanorio said. “Seneca, and before him Vitruvius, understood that there was something special about the ash at Pozzuoli, and the Romans used the pozzolana to create their own concrete, albeit with a different source of lime.”
Pozzuoli was the main commercial and military port for the Roman Empire, and it was common for ships to use pozzolana as ballast while trading grain from the eastern Mediterranean. As a result of this practice, volcanic ash from Campi Flegrei-and the use of Roman concrete-spread across the ancient world. Archeologists have recently found that piers in Alexandria, Caesarea, and Cyprus are all made from Roman concrete and have pozzolana as a primary ingredient.
Interestingly, the same chemical reaction that is responsible for the unique properties of the Campi Flegrei’s caprock can also trigger its downfall. If too much decarbonation occurs-as might happen if a large amount of saltwater, or brine, gets injected into the system-an excess of carbon dioxide, methane and steam is produced. As these gases rise toward the surface, they bump up against the natural cement layer, warping the caprock. This is what lifted Pozzuoli in the 1980s. When strain from the pressure buildup exceeded the strength of the caprock, the rock sheared and cracked, setting off swarms of micro-earthquakes. As pent-up gases and fluids vent into the atmosphere, the ground swelling subsided. Vanorio and Kanitpanyacharoen suspect that as more calcium hydroxide was produced at depth and transported to the surface, the damaged caprock was slowly repaired, its cracks “healed” as more natural cement was produced.
Vanorio believes the conditions and processes responsible for the exceptional rock properties at Campi Flegrei could be present at other calderas around the world. A better understanding of the conditions and processes that formed Campi Flegrei’s caprock could also allow scientists to recreate it in the lab, and perhaps even improve upon it to engineer more durable and resilient concretes that are better able to withstand large stresses and shaking, or to heal themselves after damage.
“There is a need for eco-friendly materials and concretes that can accommodate stresses more easily,” Vanorio said. “For example, extracting natural gas by hydraulic fracturing can cause rapid stress changes that cause concrete well casings to fail and lead to gas leaks and water contamination.”
Video
The discovery beneath Campi Flegrei, a dormant supervolcano in southern Italy, of a concrete-like rock that is similar to Roman concrete explains why the ground beneath the town of Pozzuoli rose by several meters in the 1980s, forcing the evacuation of 40,000 people.
A series of chemical reactions occurring beneath Italy’s Campi Flegrei is creating lime that then reacts with volcanic ash in the caprock to form a concrete-like substance.
UCSC researchers lowered a geothermal probe through a borehole in the West Antarctic ice sheet to measure temperatures in the sediments beneath half a mile of ice. Credit: WISSARD/UCSC
The amount of heat flowing toward the base of the West Antarctic ice sheet from geothermal sources deep within the Earth is surprisingly high, according to a new study led by UC Santa Cruz researchers. The results, published July 10 in Science Advances, provide important data for researchers trying to predict the fate of the ice sheet, which has experienced rapid melting over the past decade.
Lead author Andrew Fisher, professor of Earth and planetary sciences at UC Santa Cruz, emphasized that the geothermal heating reported in this study does not explain the alarming loss of ice from West Antarctica that has been documented by other researchers. “The ice sheet developed and evolved with the geothermal heat flux coming up from below—it’s part of the system. But this could help explain why the ice sheet is so unstable. When you add the effects of global warming, things can start to change quickly,” he said.
High heat flow below the West Antarctic ice sheet may also help explain the presence of lakes beneath it and why parts of the ice sheet flow rapidly as ice streams. Water at the base of the ice streams is thought to provide the lubrication that speeds their motion, carrying large volumes of ice out onto the floating ice shelves at the edges of the ice sheet. Fisher noted that the geothermal measurement was from only one location, and heat flux is likely to vary from place to place beneath the ice sheet.
“This is the first geothermal heat flux measurement made below the West Antarctic ice sheet, so we don’t know how localized these warm geothermal conditions might be. This is a region where there is volcanic activity, so this measurement may be due to a local heat source in the crust,” Fisher said.
The study was part of a large Antarctic drilling project funded by the National Science Foundation called WISSARD (Whillans Ice Stream Subglacial Access Research Drilling), for which UC Santa Cruz is one of three lead institutions. The research team used a special thermal probe, designed and built at UC Santa Cruz, to measure temperatures in sediments below Subglacial Lake Whillans, which lies beneath half a mile of ice. After boring through the ice sheet with a special hot-water drill, researchers lowered the probe through the borehole until it buried itself in the sediments below the subglacial lake. The probe measured temperatures at different depths in the sediments, revealing a rate of change in temperature with depth about five times higher than that typically found on continents. The results indicate a relatively rapid flow of heat towards the bottom of the ice sheet.
This geothermal heating contributes to melting of basal ice, which supplies water to a network of subglacial lakes and wetlands that scientists have discovered underlies a large region of the ice sheet. In a separate study published last year in Nature, the WISSARD microbiology team reported an abundant and diverse microbial ecosystem in the same lake. Warm geothermal conditions may help to make subglacial habitats more supportive of microbial life, and could also drive fluid flow that delivers heat, carbon, and nutrients to these communities.
According to coauthor Slawek Tulaczyk, professor of Earth and planetary sciences at UC Santa Cruz and one of the WISSARD project leaders, the geothermal heat flux is an important value for the computer models scientists are using to understand why and how quickly the West Antarctic ice sheet is shrinking.
“It is important that we get this number right if we are going to make accurate predictions of how the West Antarctic ice sheet will behave in the future, how much it is melting, how quickly ice streams flow, and what the impact might be on sea level rise,” Tulaczyk said. “I waited for many years to see a directly measured value of geothermal flux from beneath this ice sheet.”
Antarctica’s huge ice sheets are fed by snow falling in the interior of the continent. The ice gradually flows out toward the edges. The West Antarctic ice sheet is considered less stable than the larger East Antarctic ice sheet because much of it rests on land that is below sea level, and the ice shelves at its outer edges are floating on the sea. Recent studies by other research teams have found that the ice shelves are melting due to warm ocean currents now circulating under the ice, and the rate at which the ice shelves are shrinking is accelerating. These findings have heightened concerns about the overall stability of the West Antarctic ice sheet.
The geothermal heat flux measured in the new study was about 285 milliwatts per square meter, which is like the heat from one small LED Christmas-tree light per square meter, Fisher said. The researchers also measured the upward heat flux through the ice sheet (about 105 milliwatts per square meter) using an instrument developed by coauthor Scott Tyler at the University of Nevada, Reno. That instrument was left behind in the WISSARD borehole as it refroze, and the measurements, based on laser light scattering in a fiber-optic cable, were taken a year later. Combining the measurements both below and within the ice enabled calculation of the rate at which melt water is produced at the base of the ice sheet at the drill site, yielding a rate of about half an inch per year.
This is a ife reconstruction of Wendiceratops pinhornensis. Credit: Danielle Dufault
Scientists have discovered a striking new species of horned dinosaur (ceratopsian) based on fossils collected from a bone bed in southern Alberta, Canada. Wendiceratops (WEN-dee-SARE-ah-TOPS) pinhornensis was approximately 6 meters (20 feet) long and weighed more than a ton. It lived about 79 million years ago, making it one of the oldest known members of the family of large-bodied horned dinosaurs that includes the famous Triceratops, the Ceratopsidae. Research describing the new species is published online in the open access journal, PLOS ONE.
The new dinosaur, named Wendiceratops pinhornensis, is described from over 200 bones representing the remains of at least four individuals (three adults and one juvenile) collected from a bonebed in the Oldman Formation of southern Alberta, near the border with Montana, USA. It was a herbivore, and would crop low-lying plants with a parrot-like beak, and slice them up with dozens of leaf-shaped teeth. Wendiceratops had a fantastically adorned skull, particularly for an early member of the horned dinosaur family. Its most distinctive feature is a series of forward-curling hook-like horns along the margin of the wide, shield-like frill that projects from the back of its skull. The new find ranks among other recent discoveries in having some of the most spectacular skull ornamentation in the horned dinosaur group.
“Wendiceratops helps us understand the early evolution of skull ornamentation in an iconic group of dinosaurs characterized by their horned faces,” said Dr. David Evans, Temerty Chair and Curator of Vertebrate Palaeontology at the Royal Ontario Museum in Toronto, Canada, and co-author of the study. “The wide frill of Wendiceratops is ringed by numerous curled horns, the nose had a large, upright horn, and it’s likely there were horns over the eyes too. The number of gnarly frill projections and horns makes it one of the most striking horned dinosaurs ever found.”
The horn on the nose is the most interesting feature of Wendiceratops. Although the nasal bone is represented by fragmentary specimens and its complete shape is unknown, it is clear that it supported a prominent, upright nasal horncore. This represents the earliest documented occurrence of a tall nose horn in Ceratopsia. Not only does it tell scientists when the nose horn evolved, the research reveals that an enlarged conical nasal horn evolved at least twice in the horned dinosaur family, once in the short-frilled Centrosaurinae group that includes Wendiceratops, and again in the long-frilled Chasmosaurinae group which includes Triceratops. A nose horn has been generally thought to characterize Ceratopsidae, and be present in their common ancestor.
“Beyond its odd, hook-like frill, Wendiceratops has a unique horn ornamentation above its nose that shows the intermediate evolutionary development between low, rounded forms of the earliest horned dinosaurs and the large, tall horns of Styracosaurus, and its relatives,” said Dr. Michael Ryan, Curator of Vertebrate Paleontology at the Cleveland Museum of Natural History, and co-author of the study. “The locked horns of two Wendiceratops could have been used in combat between males to gain access to territory or females.”
The recognition of Wendiceratops affirms a high diversity of ceratopsids likely associated with a rapid evolutionary radiation in the group. It also helps document high faunal turnover rates of ceratopsid taxa early in their evolution, coupled with some degree of ecological niche partitioning during this time.
The name Wendiceratops (Wendi + ceratops) means “Wendy’s horned-face,” and celebrates renowned Alberta fossil hunter Wendy Sloboda, who discovered the site in 2010. This is a well-deserved honor for Sloboda, who has discovered hundreds of important fossils in the last three decades, including several new species. “Wendy Sloboda has a sixth sense for discovering important fossils. She is easily one of the very best dinosaur hunters in the world,” said Evans.
This dinosaur is the latest in a series of new finds being made by Evans and Ryan as part of their Southern Alberta Dinosaur Project, which is designed to fill in gaps in our knowledge of Late Cretaceous dinosaurs in North America and study their evolution. This project focuses on the paleontology of some of oldest dinosaur-bearing rocks in Alberta, as well as rocks of neighboring Montana that are of the same age. A full-sized skeleton and exhibit profiling Wendiceratops is currently on display at the Royal Ontario Museum in Toronto, and the dig uncovering it appeared in the HISTORY Channel documentary series Dino Hunt Canada.
Video
Reference:
David C. Evans, Michael J. Ryan. Cranial Anatomy of Wendiceratops pinhornensis gen. et sp. nov., a Centrosaurine Ceratopsid (Dinosauria: Ornithischia) from the Oldman Formation (Campanian), Alberta, Canada, and the Evolution of Ceratopsid Nasal Ornamentation. PLOS ONE, 2015; 10 (7): e0130007 DOI: 10.1371/journal.pone.0130007
The 57-day voyage in late 2013 followed a route where previous research had followed the track of hydrothermal fluids. Credit: J. Resing / Univ. of Washington
At the bottom of the sea, volcanic and magmatic forces create hot springs that spew super-heated water into the deep sea. The hot, acidic water scours metals from Earth’s crust, and the warm chemical-rich water from these remote geysers supports exotic deep-sea ecosystems.
It had been widely thought the story stopped there. Metals such as iron and manganese were thought to quickly react and form particles that would either clump together or stick to other things, causing them to sink to the seafloor close to the source. But new research proves that the metals remain dissolved and follow deep-sea currents to provide a major source of iron to the world’s oceans. The findings are published on the cover of Nature.
“This proves that hydrothermal activity at the mid-ocean ridges impacts global ocean chemistry of important trace metals,” said lead author Joseph Resing, a senior research scientist at the University of Washington’s Joint Institute for the Study of the Atmosphere and Ocean, a partnership with the National Oceanic and Atmospheric Administration. “On longer timescales, it also impacts the productivity of the oceans.”
Metals, especially iron, are crucial to the growth of phytoplankton in the oceans. In many parts of the ocean iron controls the growth of marine life even though it is only present at concentrations of parts per trillion.
Most of the iron in the ocean comes from dust blown off deserts, or from rivers that discharge into the sea. But recent research, some conducted by co-author Christopher German at Woods Hole Oceanographic Institution, hinted that iron might also be escaping from the volcanic ridge crest by exploiting some type of chemical trick to make the long-distance voyage.
The new study, part of the U.S. National Science Foundation’s GEOTRACES program, locates the “smoking gun” — a plume of hydrothermal metals drawn westward by a slow-moving, deep-ocean current that carries these metals for decades to distant parts of the ocean.
A 57-day cruise in fall 2013 aboard the UW’s research vessel, the Thomas G. Thompson, tracked water venting from the East Pacific Rise, a chain of underwater volcanoes west of Ecuador that is one of the most volcanically active places on Earth. The oceanographers followed the trail for more than 4,000 kilometers (2,500 miles) west across the South Pacific to Tahiti, using extremely sensitive tools to make measurements of the metals from the ocean”s surface to the seafloor.
While the aluminum eventually petered out, every station west of the ridge crest revealed evidence of hydrothermal manganese and, surprisingly, of iron, at about 2.5 kilometers (1.5 miles) depth.
“Every single day we were out there, we were surprised to see that the plume of dissolved iron was still present,” Resing said. “We have never before documented dissolved iron carried so far in the ocean currents.”
The finding is especially important for the Southern Ocean, circling Antarctica, where massive phytoplankton blooms are known to be limited by iron supplies, and where winds are less likely to carry iron-rich dust.
Co-author Alessandro Tagliabue at the University of Liverpool, England, placed the results within an ocean model and found that phytoplankton growth in the Southern Ocean is supported by iron from deep-sea vents. Iron from vent systems thus helps sustain a major ecosystem that consumes carbon dioxide from the atmosphere. Much of this carbon is exported from the ocean surface to the deep sea, and in the Southern Ocean 15 to 30 percent of this carbon export is supported by hydrothermal iron.
“To properly model the uptake of carbon dioxide by the Southern Ocean and to understand how this uptake impacts climate, you must account for this iron,” Resing said.
Ongoing research by other collaborators will analyze additional water samples collected during the same cruise to figure out what allows the iron to be transported so far. Two leading theories are that it attaches to large organic molecules, similar to how iron clings to hemoglobin in our bloodstream, or that it separates into tiny nanoparticles that can remain suspended in the water for decades.
Reference:
Joseph A. Resing, Peter N. Sedwick, Christopher R. German, William J. Jenkins, James W. Moffett, Bettina M. Sohst, Alessandro Tagliabue. Basin-scale transport of hydrothermal dissolved metals across the South Pacific Ocean. Nature, 2015; 523 (7559): 200 DOI: 10.1038/nature14577
Note: The above post is reprinted from materials provided by University of Washington. The original item was written by Hannah Hickey.
Narrow and distorted tree-rings from long living bristlecone-pines (Snake Mountains, Nevada, USA), indicating extreme cooling after a large volcanic eruption in 44 BCE, the year of Julius Cesar’s death. Credit: Matthew Salzer
It is well known that large volcanic eruptions contribute to climate variability. However, quantifying these contributions has proven challenging due to inconsistencies in both historic atmospheric data observed in ice cores and corresponding temperature variations seen in climate proxies such as tree rings.
Published today in the journal Nature, a new study led by scientists from the Desert Research Institute (DRI) and collaborating international institutions, resolves these inconsistencies with a new reconstruction of the timing and associated radiative forcing of nearly 300 individual volcanic eruptions extending as far back as the early Roman period.
“Using new records we are able to show that large volcanic eruptions in the tropics and high latitudes were the dominant drivers of climate variability, responsible for numerous and widespread summer cooling extremes over the past 2,500 years,” said the study’s lead author Michael Sigl, Ph.D., an assistant research professor at DRI and postdoctoral fellow with the Paul Scherrer Institute in Switzerland.
“These cooler temperatures were caused by large amounts of volcanic sulfate particles injected into the upper atmosphere,” Sigl added, “shielding the Earth’s surface from incoming solar radiation.”
The study shows that 15 of the 16 coldest summers recorded between 500 BC and 1,000 AD followed large volcanic eruptions — with four of the coldest occurring shortly after the largest volcanic events found in record.
This new reconstruction is derived from more than 20 individual ice cores extracted from ice sheets in Greenland and Antarctica and analyzed for volcanic sulfate primarily using DRI’s state-of-the-art, ultra-trace chemical ice-core analytical system.
These ice-core records provide a year-by-year history of atmospheric sulfate levels through time. Additional measurements including other chemical parameters were made at collaborating institutions.
“We used a new method for producing the timescale,” explained Mai Winstrup, Ph.D., a postdoctoral researcher at the University of Washington, Seattle. “Previously, this has been done by hand, but we used a statistical algorithm instead. Together with the state-of-the-art ice core chemistry measurements, this resulted in a more accurate dating of the ice cores.”
“Using a multidisciplinary approach was key to the success of this project,” added Sigl.
In total, a diverse research group of 24 scientists from 18 universities and research institutes in the United States, United Kingdom, Switzerland, Germany, Denmark, and Sweden contributed to this work — including specialists from the solar, space, climate, and geological sciences, as well as historians.
The authors note that identification of new evidence found in both ice cores and corresponding tree rings allowed constraints and verification of their new age scale.
“With the discovery of a distinctive signature in the ice-core records from an extra-terrestrial cosmic ray event, we had a critical time marker that we used to significantly improve the dating accuracy of the ice-core chronologies,” explained Kees Welten, Ph.D., an associate research chemist from the University of California, Berkeley.
A signature from this same event had been identified earlier in various tree-ring chronologies dating to 774-775 Common Era (CE).
“Ice-core timescales had been misdated previously by five to ten years during the first millennium leading to inconsistencies in the proposed timing of volcanic eruptions relative to written documentary and tree-ring evidence recording the climatic responses to the same eruptions,” explained Francis Ludlow, Ph.D., a postdoctoral fellow from the Yale Climate & Energy Institute.
Throughout human history, sustained volcanic cooling effects on climate have triggered crop failures and famines. These events may have also contributed to pandemics and societal decline in agriculture-based communities.
Together with Conor Kostick, Ph.D. from the University of Nottingham, Ludlow translated and interpreted ancient and medieval documentary records from China, Babylon (Iraq), and Europe that described unusual atmospheric observations as early as 254 years before Common Era (BCE). These phenomena included diminished sunlight, discoloration of the solar disk, the presence of solar coronae, and deeply red twilight skies.
Tropical volcanoes and large eruptions in the Northern Hemisphere high latitudes (such as Iceland and North America) — in 536, 626, and 939 CE, for example — often caused severe and widespread summer cooling in the Northern Hemisphere by injecting sulfate and ash into the high atmosphere. These particles also dimmed the atmosphere over Europe to such an extent that the effect was noted and recorded in independent archives by numerous historical eyewitnesses.
Climatic impact was strongest and most persistent after clusters of two or more large eruptions.
The authors note that their findings also resolve a long-standing debate regarding the causes of one of the most severe climate crises in recent human history, starting with an 18-month “mystery cloud” or dust veil observed in the Mediterranean region beginning in March, 536, the product of a large eruption in the high-latitudes of the Northern Hemisphere.
The initial cooling was intensified when a second volcano located somewhere in the tropics erupted only four years later. In the aftermath, exceptionally cold summers were observed throughout the Northern Hemisphere.
This pattern persisted for almost fifteen years, with subsequent crop failures and famines — likely contributing to the outbreak of the Justinian plague that spread throughout the Eastern Roman Empire from 541 to 543 CE, and which ultimately decimated the human population across Eurasia.
“This new reconstruction of volcanic forcing will lead to improved climate model simulations through better quantification of the sensitivity of the climate system to volcanic influences during the past 2,500 years,” noted Joe McConnell, Ph.D., a DRI research professor who developed the continuous-flow analysis system used to analyze the ice cores.
“As a result,” McConnell added, “climate variability observed during more recent times can be put into a multi-millennial perspective — including time periods such as the Roman Warm Period and the times of significant cultural change such as Great Migration Period of the 6th century in Europe.”
This reconciliation of ice-core records and other records of past environmental change will help define the role that large climatic perturbations may have had in the rise and fall of civilizations throughout human history.
“With new high-resolution records emerging from ice cores in Greenland and Antarctica, it will be possible to extend this reconstruction of volcanic forcing probably all the way back into the last Ice Age,” said Sigl.
This research was largely funded by the U.S. National Science Foundation’s Polar Program; with contributions from additional funding agencies and institutions in Belgium, Canada, China, Denmark, France, Germany, Iceland, Japan, Korea, The Netherlands, Sweden, Switzerland, and the United Kingdom.
Reference:
M. Sigl, M. Winstrup, J. R. McConnell, K. C. Welten, G. Plunkett, F. Ludlow, U. Büntgen, M. Caffee, N. Chellman, D. Dahl-Jensen, H. Fischer, S. Kipfstuhl, C. Kostick, O. J. Maselli, F. Mekhaldi, R. Mulvaney, R. Muscheler, D. R. Pasteris, J. R. Pilcher, M. Salzer, S. Schüpbach, J. P. Steffensen, B. M. Vinther, T. E. Woodruff. Timing and climate forcing of volcanic eruptions for the past 2,500 years. Nature, 2015; DOI: 10.1038/nature14565
