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Tropical air circulation drives fall warming on Antarctic Peninsula

A German research vessel, Polarstern, is shown off the Rothera station on the west coast of the Antarctic Peninsula. Rothera is one of eight stations that provided temperature data for this research. (Credit: Hannes Grobe/Alfred Wegener Institute for Polar and Marine Research)

The eastern side of the Antarctic Peninsula, a finger of the southern polar continent that juts toward South America, has experienced summer warming of perhaps a half-degree per decade — a greater rate than possibly anywhere else on Earth — in the last 50 years, and that warming is largely attributed to human causes.

But new University of Washington research shows that the Southern Hemisphere’s fall months — March, April and May — are the only time when there has been extensive warming over the entire peninsula, and that is largely governed by atmospheric circulation patterns originating in the tropics.

The autumn warming also brings a notable reduction in sea ice cover in the Bellingshausen Sea off the peninsula’s west coast, and more open water leads to warmer temperatures on nearby land in winter and spring (June through November), said Qinghua Ding, a UW research associate in Earth and space sciences. In fact, the most significant warming on the west side of the peninsula in recent decades has occurred during the winter.

“Local northerly wind pushes warmer air from midlatitudes of the Southern Ocean to the peninsula, and the northern wind favors warming of the land and sea ice reduction,” said Ding.

He is the lead author of a paper explaining the findings, published online this month in the Journal of Climate. Eric Steig, a UW professor of Earth and space sciences, is co-author. The work was funded by the National Science Foundation.

The scientists analyzed temperature data gathered from 1979 through 2009 at eight stations on the Antarctic Peninsula. The stations were selected because each has reliable monthly data for at least 95 percent of the study period. They also used two different sets of data, one from Europe and the other from NASA, that combine surface observations, satellite temperature data and modeling.

The researchers concluded that the nonsummer Antarctic Peninsula warming is being driven by large-scale atmospheric circulation originating in the equatorial Pacific Ocean. There, the warm sea surface generates an atmospheric phenomenon called a Rossby wave train, which reaches the Antarctic Peninsula and alters the local circulation to warm the region.

The sea-surface temperature trend in the tropical Pacific is related to natural phenomena such as the El Niño Southern Oscillation (El Niño and La Niña) and cycles that occur on longer timescales, sometimes decades. But it is not clear whether human causes play a role in that trend.

“We still lack a very clear understanding of the tropical natural variability, of what that dynamic is,” Ding said.

He said that in the next two or three decades it is quite possible that natural variability and forcing from human factors will play equivalent roles in temperature changes on the Antarctic Peninsula, but after that the forcing from human causes will likely play a larger role.

“If these trends continue, we will continue to see warming in the peninsular region, there is no doubt,” Ding said.

Note : The above story is reprinted from materials provided by University of Washington. The original article was written by Vince Stricherz. 

Could Carbon Dioxide Be Injected in Sandstone?

Sandstone can crack if it is filled with too much CO2. To be certain that this will not happen, NTNU Professors Martin Landrø and Ole Torsæter take X-rays of sandstone while it is being pumped full of CO2. (Credit: Ole Morten Melgård)

As CO2 levels in Earth’s atmosphere top 400 parts per million, options such as storing the greenhouse gas in porous sandstone rock formations found in abundance on the sea floor are of increasing interest. But how do we know if CO2 can be safely injected into spongy sandstone, and that once it is there, that it will stay there?

Two petroleum engineering and applied geophysics professors at the Norwegian University of Science and Technology (NTNU) are using X-rays and CAT scanners to probe the secrets of undersea rock formations and their ability to store CO2 safely in perpetuity. Their results are promising.

Earth has a fever

CO2 is formed when any kind of organic material or fossil fuel, such as natural gas, petroleum, coal or gasoline, is burned. A cozy bonfire or a little fire in the wood stove on a cold winter’s day will add to the amount of CO2 in the atmosphere.
At the same time, if you were in an area with a CO2 leak, you’d die of CO2 poisoning before you’d die from a lack of oxygen.

CO2 has another important characteristic: too much of it in the atmosphere is causing global temperatures to rise. The last time the average atmospheric CO2 levels were around 400 ppm, as they are now, was 3 million years ago. Earth has a fever, and by burning fossil fuels, we are causing it.

Checking for leaks

“I think it is important to remember that CO2 isn’t radioactive, but part of the air that we all exhale,” says Martin Landrø, a professor of petroleum engineering and applied geophysics at NTNU, and one of the world’s leading seismic experts — that is, in geophysical surveys of bedrock. Landrø has been engaged in monitoring underwater CO2 storage areas for more than ten years.

The goal of storing CO2 is to deposit it deep enough so that it becomes liquid. The gas needs to be buried under so many layers of sand and clay that it can’t escape, and stay encapsulated in a bubble under the sea forever.

But sometimes it doesn’t go according to plan. After a few years, the CO2 may begin to seep up and out. Sometimes small amounts manage to escape completely, appearing as small bubbles on the sea floor. This is one of the reasons that the petroleum professors at NTNU have acquired a giant X-ray machine — a CAT scanner.

This particular X-ray machine has previously served its duty at St Olavs Hospital in Trondheim, working steadily to reveal bone fractures and joint injuries. At NTNU it is being used to determine how much CO2 can be stored in various rock formations found under the sea. But taking X-rays of CO2 is not all that the professors are doing — they’re also measuring the speed of sound in different types of stone.

Patient — and pill

“This is our X-ray patient,” says Ole Torsæter, who is also a professor of petroleum engineering and applied geophysics at NTNU, and holds up a small piece of sandstone.

But this patient contains its own medicine — Earth’s own fever-reducing pill. This porous stone, found in abundance at the bottom of the sea, can store large amounts of CO2. Sandstone is porous, like a sponge — a sponge that oil companies can fill with CO2.

“Some sandstone can be filled with as much as 80 per cent CO2, while others can only hold about 30 per cent. These variations in capacity are exactly what we’re trying to figure out,” says Torsæter.

And here’s how they do it: they take sandstone and put it in water, so that all the pores are filled. They then put the stone into a thin, condom-like plastic cover. The cover has several holes in it that are sealed using microphones.

The entire thing is then placed in a box that simulates the pressure in the seabed, which is then placed in the X-ray machine. As the X-ray scanner is on, the researchers inject CO2 into the rock, filling the porous stone with it and pressing out the water.

The X-ray images show how much CO2 has penetrated the rock’s pores. Since CO2 has a different density than water, the speed of sound will be slower when the rock is saturated with CO2. Therefore, the researchers measure the speed of sound in the rocks, watching how it changes as CO2 enters the pores. The goal is to fill up the stone without cracking it.

Two years of CO2 emissions

“If the pressure in the stone is too high, it can crack. To relieve the pressure we need to remove the water, the same way a doctor would drain fluid from a patient’s cyst. We do that too. When CO2 is injected into the seabed, sometimes we need to remove the water being pressed out of the rocks through a new well,” say Landrø and Torsæter.
 
It has now been 14 years since the first CO2 was injected into a seabed formation in the North Sea. Since then, Statoil has stored more than 12 million tons of CO2 in such formations. In 2011, the Norwegian Petroleum Directorate presented an atlas showing that Norway may be able to store as much as 50 gigatons of CO2 in geological formations under the sea.

Annual global CO2 emissions are usually about 30 gigatons, meaning that Norway may be able to store almost two years of global emissions under the North Sea.

Norway is responsible for 0.17 per cent of global CO2 emissions. China accounts for 23 per cent.

Consumers are key

“I think it’s important to look at it from a practical standpoint. Storing CO2 in geological formations under the sea may be a good alternative to sending it straight into the atmosphere. If we do that, some of it is absorbed by the ocean anyway, so it is better store it under the sea, even though small quantities may still seep out,” says Landrø.

Consumers account for the largest emissions worldwide, he says: Heating and electricity generation account for about 40 per cent of global CO2 emissions, while transportation accounts for 25 per cent. “This means we as consumers can help to determine how much CO2 is emitted,” Landrø says. “That’s one reason why I bike to work every day.”

Note : The above story is reprinted from materials provided by The Norwegian University of Science and Technology (NTNU).

Climate record from bottom of Russian lake shows Arctic was warmer millions of years ago

The Lake El’gygytgyn drilling rig is shown at night. – The Lake El’gygytgyn Drilling Project

The Arctic was very warm during a period roughly 3.5 to 2 million years ago–a time when research suggests that the level of carbon dioxide in the atmosphere was roughly comparable to today’s–leading to the conclusion that relatively small fluctuations in carbon dioxide levels can have a major influence on Arctic climate, according to a new analysis of the longest terrestrial sediment core ever collected in the Arctic.

“One of our major findings is that the Arctic was very warm in the middle Pliocene and Early Pleistocene–roughly 3.6 to 2.2 million years ago–when others have suggested atmospheric carbon dioxide was not much higher than levels we see today,” said Julie Brigham-Grette, of the University of Massachusetts Amherst.

Brigham-Grette is a National Science Foundation- (NSF) funded researcher on the sediment core project and a lead author of a new paper published this week in the journal Science that describes the results.

She added that “this could tell us where we are going in the near future. In other words, the Earth system response to small changes in carbon dioxide is bigger than suggested by earlier climate models.”

The data come from the analysis of a continuous cylinder of sediments collected by NSF-funded researchers from the bottom of ice-covered Lake El’gygytgyn, pronounced El-Guh-Git-Kin, the oldest deep lake in the northeast Russian Arctic, located 100 kilometers (62 miles) north of the Arctic Circle. The drilling was an international project.

Drilling took place in the early months of 2009. The Earth Sciences and Polar Programs divisions of NSF’s Geosciences Directorate funded the drilling and analysis.

Analysis of the sediment core provides “an exceptional window into environmental dynamics” never before possible, noted Brigham-Grette.

“While existing geologic records from the Arctic contain important hints about this time period, what we are presenting is the most continuous archive of information about past climate change from the entire Arctic borderlands,” she said. “Like reading a detective novel, we can go back in time and reconstruct how the Arctic evolved with only a few pages missing here and there.”

Results of the core analysis, according to Brigham-Grette, have “major implications for understanding how the Arctic transitioned from a forested landscape without ice sheets to the ice- and snow-covered land we know today.”

“Lake E,” as it is often called, was formed 3.6 million years ago when a meteorite, perhaps a kilometer in diameter, hit the Earth and blasted out an 18-kilometer (11-mile) wide crater. The lake bottom has been accumulating layers of sediment ever since the initial impact.

The lake also is situated in one of the few areas of the Arctic that was not eroded by continental ice sheets during ice ages. So a thick, continuous sediment record was left remarkably undisturbed. Cores from Lake E reach back in geologic time nearly 25 times farther than Greenland ice cores that span only the past 140,000 years.

Important to the story are the fossil pollen found in the core, including Douglas fir and hemlock, clearly not found in this part of the Arctic today. The pollen allows the reconstruction of the vegetation living around the lake in the past, which in turn paints a picture of past temperatures and precipitation.

Another significant finding is documentation of sustained warmth in the Middle Pliocene, with summer temperatures of about 15 to 16 degrees Celsius (59 to 61 degrees Fahrenheit), about 8 degrees Celsius (14.4 degrees Fahrenheit) warmer than today, and regional precipitation three times higher.

“We show that this exceptional warmth well north of the Arctic Circle occurred throughout both warm and cold orbital cycles and coincides with a long interval of 1.2 million years when other researchers from the ANDRILL project have shown the West Antarctic Ice Sheet did not exist,” the authors point out.

Hence both poles share some common history, but the pace of change differed.

Along with Brigham-Grette, her co-authors Martin Melles of the University of Cologne, Germany, and Pavel Minyuk of Russia’s Northeast Interdisciplinary Scientific Research Institute, Magadan, led research teams on the project. Robert DeConto, also at the University of Massachusetts, led the climate-modeling efforts. These data were compared with ecosystem reconstructions performed by collaborators at University of Berlin and University of Cologne.

The Lake E cores provide a terrestrial perspective on the stepped pacing of several portions of the climate system through the transition from a warm, forested Arctic to the first occurrence of land ice, Brigham-Grette says, and the eventual onset of major glacial-interglacial cycles.

“It is very impressive that summer temperatures during warm intervals even as late as 2.2 million years ago were always warmer than in our pre-Industrial reconstructions,” she added.

Minyuk notes that they also observed a major drop in Arctic precipitation at around the same time large Northern Hemispheric ice sheets first expanded and ocean conditions changed in the North Pacific. This has major implications for understanding what drove the onset of the ice ages.

The sediment core also reveals that even during the first major “cold snap” to show up in the record 3.3 million years ago, temperatures in the western Arctic were similar to recent averages of the past 12,000 years. “Most importantly, conditions were not ‘glacial,’ raising new questions as to the timing of the first appearance of ice sheets in the Northern Hemisphere,” the authors add.

This week’s paper is the second article published in Science by these authors using data from the Lake E project. Their first in July 2012 covered the period from the present to 2.8 million years ago, while the current work addresses the record from 2.2 to 3.6 million years.

“This latest paper completes our goal of providing an overview of new knowledge of the evolution of Arctic change across the Western borderlands back to 3.6 million years and places this record into a global context with comparisons to records in the Pacific, the Atlantic and Antarctica,” Melles points out.

The Lake E paleoclimate reconstructions and climate modeling are consistent with estimates made by other research groups that support the idea that Earth’s climate sensitivity to carbon dioxide may well be higher than suggested by the 2007 report of the Intergovernmental Panel on Climate Change.

Note: This story has been adapted from a news release issued by the National Science Foundation

Western Indian Ocean Earthquake and Tsunami Hazard Potential Greater Than Previously Thought

Makran map earthquakes. (Credit: Image courtesy of National Oceanography Centre)

Earthquakes similar in magnitude to the 2004 Sumatra earthquake could occur in an area beneath the Arabian Sea at the Makran subduction zone, according to recent research published in Geophysical Research Letters.

The primary tectonic plates and plate boundaries in the Arabian Sea region

The research was carried out by scientists from the University of Southampton based at the National Oceanography Centre Southampton (NOCS), and the Pacific Geoscience Centre, Natural Resources Canada.

The study suggests that the risk from undersea earthquakes and associated tsunami in this area of the
Western Indian Ocean — which could threaten the coastlines of Pakistan, Iran, Oman, India and potentially further afield — has been previously underestimated. The results highlight the need for further investigation of pre-historic earthquakes and should be fed into hazard assessment and planning for the region.

Subduction zones are areas where two of Earth’s tectonic plates collide and one is pushed beneath the other. When an earthquake occurs here, the seabed moves horizontally and vertically as the pressure is released, displacing large volumes of water that can result in a tsunami.

The Makran subduction zone has shown little earthquake activity since a magnitude 8.1 earthquake in 1945 and magnitude 7.3 in 1947. Because of its relatively low seismicity and limited recorded historic earthquakes it has often been considered incapable of generating major earthquakes.

Plate boundary faults at subduction zones are expected to be prone to rupture generating earthquakes at temperatures of between 150 and 450 °C. The scientists used this relationship to map out the area of the potential fault rupture zone beneath the Makran by calculating the temperatures where the plates meet. Larger fault rupture zones result in larger magnitude earthquakes.

“Thermal modelling suggests that the potential earthquake rupture zone extends a long way northward, to a width of up to 350 kilometres which is unusually wide relative to most other subduction zones,” says Gemma Smith, lead author and PhD student at University of Southampton School of Ocean and Earth Science, which is based at NOCS.

The team also found that the thickness of the sediment on the subducting plate could be a contributing factor to the magnitude of an earthquake and tsunami there.

“If the sediments between the plates are too weak then they might not be strong enough to allow the strain between the two plates to build up,” says Smith. “But here we see much thicker sediments than usual, which means the deeper sediments will be more compressed and warmer. The heat and pressure make the sediments stronger. This results in the shallowest part of the subduction zone fault being potentially capable of slipping during an earthquake.

“These combined factors mean the Makran subduction zone is potentially capable of producing major earthquakes, up to magnitude 8.7-9.2. Past assumptions may have significantly underestimated the earthquake and tsunami hazard in this region.”

Note : The above story is reprinted from materials provided by National Oceanography Centre.

The effect of climate change on iceberg production by Greenland glaciers

Image Caption: Natural-color satellite image of the ice island that calved off the glacier on August 5, 2010. Credit: Jesse Allen & Robert Simmon, NASA Earth Observatory

While the impact of climate change on the surface of the Greenland ice sheet has been widely studied, a clear understanding of the key process of iceberg production has eluded researchers for many yearsWhile the impact of climate change on the surface of the Greenland ice sheet has been widely studied, a clear understanding of the key process of iceberg production has eluded researchers for many years. Published in Nature this week, a new study presents a sophisticated computer model that provides a fresh insight into the impact of climate change on the production of icebergs by Greenland glaciers, and reveals that the shape of the ground beneath the ice has a strong effect on its movement.

Over the past decade, ice-loss from the Greenland Ice Sheet has been accelerating, raising concerns about runaway losses and consequent sea-level rise. But research into the four major Greenland fast-flowing glaciers has enabled scientists to show that while these glaciers may show several bursts of retreat and periods of high iceberg formation in future, the rapid acceleration seen in recent years is unlikely to continue unchecked.

This is a crucial step forward in understanding how Greenland’s glaciers will contribute to sea-level rise in the future and indicates, say the scientists, how important a more detailed knowledge of such glaciers is. The scientists first investigated the current behaviour of the four glaciers and found that the rate at which they lose ice depends critically on the shape of the fjords in which they sit, and the topography of the rock below them.

A computer model for fast-flowing outlet glaciers was then specifically designed from their investigations. It gave a projected sea-level-rise contribution from these glaciers of 2cm to 5cm by the year 2200, which is lower than estimates based solely on the extrapolation of current trends.

Lead author Dr Faezeh Nick, of the Université Libre de Bruxelles, says,

“I am excited by the way we have managed to create a detailed picture of the workings of the glaciers. It turns out that if the fjord a glacier sits in is wide or narrow it really affects the way the glacier reacts. The important role of the terrain below the ice shows we need to get a much clearer picture of the rest of Greenland’s glaciers before we have the whole story.”

The scientists chose the four glaciers, Petermann, Kangerdlugssuaq, Helheim and Jakobshavn Isbræ, as together these drain around 20 per cent of the Greenland ice sheet. The model, which was developed within the EU funded ice2sea programme, predicts that, together these glaciers will lose on average, 30Gt of ice per year to 47Gt per year over the 21st century. A Gigaton (Gt) is the equivalent of 1 cubic kilometre (km3) of water. For comparison Lake Geneva contains about 90Gt of water.

Professor David Vaughan, who works at the British Antarctic Survey in Cambridge and is head of the ice2sea programme says,

“We know that the breaking off of icebergs from glaciers is influenced by climate, but this is the first time we’ve been able make projections of how the most important glaciers in Greenland will be affected by future climate change. The ice2sea research led by Dr Nick shows how a truly international programme can make it possible for scientists to work together across different institutions to make significant steps forward.”

Note : This story has been adapted from a news release issued by the British Antarctic Survey

Dying Trees Set Stage For Erosion And Water Loss

Image Caption: Pinyon pine forests near Los Alamos, N.M., had already begun to turn brown from drought stress in the image at left, in 2002, and another photo taken in 2004 from the same vantage point, at right, show them largely grey and dead. (Photo by Craig Allen, U.S. Geological Survey)

New research concludes that a one-two punch of drought and mountain pine beetle attacks are the primary forces that have killed more than 2.5 million acres of pinyon pine and juniper trees in the American Southwest during the past 15 years, setting the stage for further ecological disruption.

The widespread dieback of these tree species is a special concern, scientists say, because they are some of the last trees that can hold together a fragile ecosystem, nourish other plant and animal species, and prevent serious soil erosion.

The major form of soil erosion in this region is wind erosion. Dust blowing from eroded hills can cover snowpacks, cause them to absorb heat from the sun and melt more quickly, and further reduce critically-short water supplies in the Colorado River basin.

The findings were published in the journal Ecohydrology by scientists from the College of Forestry at Oregon State University and the Conservation Biology Institute in Oregon. NASA supported the work.

“Pinyon pine and juniper are naturally drought-resistant, so when these tree species die from lack of water, it means something pretty serious is happening,” said Wendy Peterman, an OSU doctoral student and soil scientist with the Conservation Biology Institute. “They are the last bastion, the last trees standing and in some cases the only thing still holding soils in place.”

“These areas could ultimately turn from forests to grasslands, and in the meantime people are getting pretty desperate about these soil erosion issues,” she said. “And anything that further reduces flows in the Colorado River is also a significant concern.”

It’s not certain whether or not the recent tree die-offs are related to global warming, Peterman said. However, the 2007 report of the Intergovernmental Panel on Climate Change projected that while most of the United States was getting warmer and wetter, the Southwest will get warmer and drier. Major droughts have in fact occurred there, and the loss of pinyon pine and juniper trees would be consistent with the climate change projections, Peterman said.

Pinyon pine and juniper are the dominant trees species in much of the Southwest, routinely able to withstand a year or two of drought, and able to grow in many mountainous areas at moderate elevation. The trees are common in Utah, Colorado, New Mexico and Arizona, and may have expanded their range in the past century during conditions that were somewhat wetter than normal.

In some places up to 90 percent of these trees have now died, many of them during a major drought in 2003 and 2004. The new research concluded that most of the mortality occurred in shallow soils having less than four inches of available water in about the top five feet of the soil column.

Most of the tree mortality, the scientists said, was caused by trees being sufficiently weakened by drought that opportunistic bark beetle epidemics were able to kill the pinyon pine, and the vascular system of the juniper ceased to function.

Traditionally, pinyon pine and juniper were not considered trees of significant value. They were occasionally used for firewood, but otherwise small and not particularly impressive.

They perform key ecosystem functions, however, not the least of which is stabilizing soils and preventing erosion. They also provide some food in the form of pine nuts and juniper berries, and store carbon in their biomass, and in the soils beneath their canopies.

Note : The above story is reprinted from materials provided by Oregon State University

Sediment Cores From Russian Lake Hint At A Future Ice-free Arctic

Image Caption: Lake El’gygytgyn in Russia. Credit: NASA

An international team of scientists, led by Julie Brigham-Grette of the University of Amherst, has analyzed the longest continental sediment core ever collected in the Arctic to provide “absolutely new knowledge” of Arctic climate from 2.2 million to 3.6 million years ago.

“While existing geologic records from the Arctic contain important hints about this time period, what we are presenting is the most continuous archive of information about past climate change from the entire Arctic borderlands. As if reading a detective novel, we can go back in time and reconstruct how the Arctic evolved with only a few pages missing here and there,” says Brigham-Grette.

The results of this study, published in Science, provide “an exceptional window into environmental dynamics” never before possible. Brigham-Grette claims that their findings have “major implications for understanding how the Arctic transitioned from a forested landscape without ice sheets to the ice- and snow-covered land we know today.”

The sediment cores used in this study were collected in the winter of 2009 from ice-covered Lake El’gygytgyn, the oldest deep lake in the northeast Russian Arctic. “Lake E”, located 62 miles north of the Arctic Circle, was formed 3.6 million years ago when a meteorite of approximately a half mile in diameter hit the Earth, blasting out an 11-mile wide crater. Fortunately for geologists, the lake lies in one of the few Arctic areas not eroded by continental ice sheets during the ice ages. This leaves a thick, continuous sediment record remarkably undisturbed along the lake bed. Cores obtained from Lake E reach nearly 25 times farther back in geologic time than the Greenland ice cores, which only span the past 140,000 years.

“One of our major findings is that the Arctic was very warm in the middle Pliocene and Early Pleistocene [~ 3.6 to 2.2 million years ago] when others have suggested atmospheric CO2 was not much higher than levels we see today. This could tell us where we are going in the near future. In other words, the Earth system response to small changes in carbon dioxide is bigger than suggested by earlier climate models,” stated Brigham-Grette.

The team also found that the cores supplied documentation of sustained warmth in the middle Pliocene, with summer temperatures of about 59 to 61 degrees Fahrenheit – approximately 14.4 degrees Fahrenheit warmer than today. Regional precipitation was about three times higher than now, as well.

“We show that this exceptional warmth well north of the Arctic Circle occurred throughout both warm and cold orbital cycles and coincides with a long interval of 1.2 million years when other researchers have shown the West Antarctic Ice Sheet did not exist,” Brigham-Grette notes. This indicates that while both poles share some common history, the pace of change differed between them.

Research teams on the project were led by Martin Melles of the University of Cologne and Pavel Minyuk of Russia’s Northeast Interdisciplinary Scientific Research Institute, Magadan, while the modeling efforts were led by Robert DeConto, at UMass Amherst. Collaborators at the universities of Bern and Cologne performed ecosystem reconstructions which were compared to the data of both the research teams and the modeling team.

Brigham-Grette says the Lake E cores provide a terrestrial perspective on the stepped pacing of several portions of the climate system. The cores demonstrate the transition from a warm, forested Arctic to the first occurrence of land ice and the eventual onset of major glacial/interglacial cycles. “It is very impressive that summer temperatures during warm intervals even as late as 2.2 million years ago were always warmer than in our pre-Industrial reconstructions.”

The team also observed a major drop in Arctic precipitation at around the same time large Northern Hemispheric ice sheets first expanded, according to Minyuk, and ocean conditions changed in the North Pacific. These findings have major implications for understanding what drove the onset of the ice ages.

During the first major “cold snap” to show up in the record 3.3 million years ago, the sediment core also revealed that temperatures in the western Arctic were similar to recent averages of the past 12,000 years. “Most importantly, conditions were not ‘glacial,’ raising new questions as to the timing of the first appearance of ice sheets in the Northern Hemisphere,” the authors add.

This is the second article published by the team based on the Lake E project. The first covered the time period from the present to 2.8 million years ago. The most recent paper covers the record from 2.2 to 3.6 million years ago.

Melles says, “This latest paper completes our goal of providing an overview of new knowledge of the evolution of Arctic change across the western borderlands back to 3.6 million years and places this record into a global context with comparisons to records in the Pacific, the Atlantic and Antarctica.”

The findings of the Lake E paleoclimate reconstructions and climate modeling are consistent with estimates made by other research groups, supporting the idea that Earth’s climate sensitivity to CO2 might be higher than suggested by the 2007 Intergovernmental Panel on Climate Change (IPCC). Much of the funding for this project was obtained from the National Science Foundation (NSF).

 Note : The above story is reprinted from materials provided by April Flowers for redOrbit

Moon and Earth Have Common Water Source

The Moon’s water did not come from comets but was already present on Earth 4.5 billion years ago, when a giant collision sent material from Earth to form the Moon, new research shows. (Credit: NASA/JPL)

Researchers used a multicollector ion microprobe to study hydrogen-deuterium ratios in lunar rock and on Earth. Their conclusion: The Moon’s water did not come from comets but was already present on Earth 4.5 billion years ago, when a giant collision sent material from Earth to form the Moon.
Water inside the Moon’s mantle came from primitive meteorites, new research finds, the same source thought to have supplied most of the water on Earth. The findings raise new questions about the process that formed the Moon.

The Moon is thought to have formed from a disc of debris left when a giant object hit Earth 4.5 billion years ago, very early in Earth’s history. Scientists have long assumed that the heat from an impact of that size would cause hydrogen and other volatile elements to boil off into space, meaning the Moon must have started off completely dry. But recently, NASA spacecraft and new research on samples from the Apollo missions have shown that the Moon actually has water, both on its surface and beneath.

By showing that water on the Moon and on Earth came from the same source, this new study offers yet more evidence that the Moon’s water has been there all along.

“The simplest explanation for what we found is that there was water on the proto-Earth at the time of the giant impact,” said Alberto Saal, associate professor of Geological Sciences at Brown University and the study’s lead author. “Some of that water survived the impact, and that’s what we see in the Moon.”

The research was co-authored by Erik Hauri of the Carnegie Institution of Washington, James Van Orman of Case Western Reserve University, and Malcolm Rutherford from Brown and published online in Science Express.

To find the origin of the Moon’s water, Saal and his colleagues looked at melt inclusions found in samples brought back from the Apollo missions. Melt inclusions are tiny dots of volcanic glass trapped within crystals called olivine. The crystals prevent water escaping during an eruption and enable researchers to get an idea of what the inside of the Moon is like.

Research from 2011 led by Hauri found that the melt inclusions have plenty of water — as much water in fact as lavas forming on Earth’s ocean floor. This study aimed to find the origin of that water. To do that, Saal and his colleagues looked at the isotopic composition of the hydrogen trapped in the inclusions. “In order to understand the origin of the hydrogen, we needed a fingerprint,” Saal said. “What is used as a fingerprint is the isotopic composition.”

Using a Cameca NanoSIMS 50L multicollector ion microprobe at Carnegie, the researchers measured the amount of deuterium in the samples compared to the amount of regular hydrogen. Deuterium is an isotope of hydrogen with an extra neutron. Water molecules originating from different places in the solar system have different amounts of deuterium. In general, things formed closer to the sun have less deuterium than things formed farther out.

Saal and his colleagues found that the deuterium/hydrogen ratio in the melt inclusions was relatively low and matched the ratio found in carbonaceous chondrites, meteorites originating in the asteroid belt near Jupiter and thought to be among the oldest objects in the solar system. That means the source of the water on the Moon is primitive meteorites, not comets as some scientists thought.

Comets, like meteorites, are known to carry water and other volatiles, but most comets formed in the far reaches of the solar system in a formation called the Oort Cloud. Because they formed so far from the sun, they tend to have high deuterium/hydrogen ratios — much higher ratios than in the Moon’s interior, where the samples in this study came from.

“The measurements themselves were very difficult,” Hauri said, “but the new data provide the best evidence yet that the carbon-bearing chondrites were a common source for the volatiles in the Earth and Moon, and perhaps the entire inner solar system.”

Recent research, Saal said, has found that as much as 98 percent of the water on Earth also comes from primitive meteorites, suggesting a common source for water on Earth and water on Moon. The easiest way to explain that, Saal says, is that the water was already present on the early Earth and was transferred to the Moon.

The finding is not necessarily inconsistent with the idea that the Moon was formed by a giant impact with the early Earth, but presents a problem. If the Moon is made from material that came from Earth, it makes sense that the water in both would share a common source. However, there’s still the question of how that water was able to survive such a violent collision.

“The impact somehow didn’t cause all the water to be lost,” Saal said. “But we don’t know what that process would be.”

It suggests, the researchers say, that there are some important processes we don’t yet understand about how planets and satellites are formed.

“Our work suggests that even highly volatile elements may not be lost completely during a giant impact,” said Van Orman. “We need to go back to the drawing board and discover more about what giant impacts do, and we also need a better handle on volatile inventories in the Moon.”

Funding for the research came from NASA’s Cosmochemistry and LASER programs and the NASA Lunar Science Institute.

 Note : The above story is reprinted from materials provided by Brown University. 

Geologists Study Mystery of ‘Eternal Flames’

A gas-fired flame shines through a waterfall at Chestnut Ridge Park in Erie County, N.Y. (Credit: Indiana University)

“Eternal flames” fueled by hydrocarbon gas could shine a light on the presence of natural gas in underground rock layers and conditions that let it seep to the surface, according to research by geologists at the Department of Geological Sciences and the Indiana Geological Survey at Indiana University Bloomington.

 

A little-known but spectacular flame in Erie County, N.Y., is the focus of an article in the journal Marine and Petroleum Geology, co-authored by Agnieszka Drobniak, research scientist with the Indiana Geological Survey, and Arndt Schimmelmann, senior scientist in the Department of Geological Sciences in the College of Arts and Sciences.

The article results from a U.S. Department of Energy research grant to Schimmelmann and Maria Mastalerz, senior scientist with the Indiana Geological Survey and graduate faculty member at the Department of Geological Sciences. The project seeks to identify natural gas seeps in Indiana and nearby states and assess their contributions to atmospheric concentrations of greenhouse gases.

The researchers said much remains to be learned about the passage of gas from underground rock layers to Earth’s surface — occasionally in “macro seeps” strong and abundant enough to produce a continuous flame like the one in western New York.

“The story is developing,” Schimmelmann said.

Giuseppe Etiope of the National Institute of Geophysics and Volcanology in Italy is lead author of the Marine and Petroleum Geology article, “Natural seepage of shale gas and the origin of ‘eternal flames’ in the Northern Appalachian Basin, USA.” Etiope, who has studied eternal flames around the world, said the New York flame, behind a waterfall in Chestnut Ridge Park, is the most beautiful he has seen.

Not only that, but it may feature the highest concentrations of ethane and propane of any known natural gas seep. Approximately 35 percent of the gas is ethane and propane, as opposed to methane, the dominant constituent in natural gas. Ethane and propane can be valuable byproducts in the processing of natural gas.

By analyzing the gases and comparing them with gas well records from the region, the researchers concluded the gas fueling the Chestnut Ridge Park flame originates from Rhinestreet Shale, an Upper Devonian formation about 400 meters deep. It reaches the surface through passages associated with faulting caused by tectonic activity.

At the New York site, the researchers identified numerous “micro seeps” of gas, apparently from the same source that fuels the eternal flame. This suggests that such seeps, if they are numerous and widespread, could make a significant contribution to atmospheric concentrations of greenhouse gases and other pollutants.

The researchers also studied a larger eternal flame at Cook Forest State Park in northwestern Pennsylvania. They determined that flame, in a continuously burning fire pit, is not a natural seep but a leak from an abandoned gas well. The source is thought to be a conventional gas reservoir, not shale.

Mastalerz said naturally occurring methane sources are believed to account for about 30 percent of the total methane emissions in Earth’s atmosphere. Natural gas seeps are thought to be the second most significant source of naturally occurring methane emissions, after wetlands.

But finding seeps is like searching for a needle in a haystack. Last year, the researchers surveyed a region of Kentucky that is geologically similar to western New York — and where “burning springs” figure in local history and folklore — but turned up no evidence of escaping natural gas.

Schimmelmann said researchers have found elevated levels of carbon dioxide in caves, possibly resulting from methane that is converted by microorganisms to carbon dioxide gas as it seeps slowly toward the surface. Carbon dioxide is also a greenhouse gas, but it is 20 times less effective at trapping heat than methane.

The findings suggest natural gas seeps occur in areas that have experienced tectonic activity, and it may be easier to find them in caves, which capture and concentrate gas when it reaches the surface. A next step in the research, planned for this summer, is to continue the search in areas of Pennsylvania, West Virginia and Virginia where gas-bearing shale underlies cave systems.

Funding for the research comes from the U.S. Department of Energy.

Note : The above story is reprinted from materials provided by Indiana University, via Newswise. 

Four New Dinosaur Species Identified

CMN 0210 is the holotype of Euoplocephalus tutus, CMN 8530 is the holotype of Anodontosaurus lambei, MOR 433 is the holotype of Oohkotokia horneri, and ROM 784 is the holotype of Dyoplosaurus acutosquameus. AMNH 5337, AMNH 5405, CMN 0210, ROM 784, ROM 1930, TMP 1979.14.74, TMP 1991.127.1, TMP 1997.132.1, and UALVP 31 are from the Dinosaur Park Formation. AMNH 5238 and UALVP 47977 are of uncertain stratigraphic position within Dinosaur Provincial Park. AMNH 5223, CMN 8530, ROM 832, and TMP 1997.59.1 are from the Horseshoe Canyon Formation. NHMUK R4947 is from an unknown stratigraphic position in Alberta. MOR 433, TMP 2001.42.9 (much of the anterior rostrum in heavily reconstructed), and USNM 11892 are from the Upper Two Medicine Formation in Montana. Scale equals 10 cm. (Credit: Victoria M. Arbour, Philip J. Currie; Photograph of ROM 832 by C. Brown, and of ROM 1930 by J. Arbour)

Just when dinosaur researchers thought they had a thorough knowledge of ankylosaurs, a family of squat, armour plated, plant eaters, along comes University of Alberta graduate student, Victoria Arbour.

 

Arbour visited dinosaur fossil collections from Alberta to the U.K. examining skull armour and comparing those head details with other features of the fossilized ankylosaur remains. She made a breakthrough that resurrected research done more than 70 years ago.

Arbour explains that between 1900 and 1930 researchers had determined that small variations in the skull armour and the tail clubs in some ankylosaurs constituted four individual species of the dinosaurs.

“In the 1970s the earlier work was discarded and those four species were lumped into one called species Euoplocephalus,” said Arbour.

“I examined many fossils and found I could group some fossils together because their skull armour corresponded with a particular shape of their tail club,” said Arbour.

Finding common features in fossils that come from the same geologic time is evidence that the original researchers were right says Arbour. “There were in fact four different species represented by what scientists previously thought was only one species, Euoplocephalus.”

The four species span a period of about 10 million years. Arbour’s research shows three of those ankylosaurs species lived at the same time in what is now Dinosaur Provincial Park in southern Alberta.

Arbour says this opens the door to new questions.

“How did these three species shared their habitat, how did they divide food resources and manage to survive?” said Arbour.

Arbour will also look into how slight differences in skull ornamentation and tail shape between the species influenced the animals’ long reign on Earth.

Arbour’s research was published May 8, in the journal PLOS ONE.

Note : The above story is reprinted from materials provided by University of Alberta, via EurekAlert!, a service of AAAS. 

Bone-Headed Dinosaur Hinting at Higher Diversity of Small Dinosaurs

Life reconstruction of Acrotholus audeti in its environment. (Credit: © Julius Csotonyi)

Scientists have named a new species of bone-headed dinosaur (pachycephalosaur) from Alberta, Canada. Acrotholus audeti (Ack-RHO-tho-LUS) was identified from both recently discovered and historically collected fossils. Approximately six feet long and weighing about 40 kilograms in life, the newly identified plant-eating dinosaur represents the oldest bone-headed dinosaur in North America, and possibly the world.

 

Dr. Michael Ryan, curator of vertebrate paleontology at The Cleveland Museum of Natural History, co-authored research describing the new species, which was published May 7, 2013 in the journal Nature Communications.

Acrotholus means “high dome,” referring to its dome-shaped skull, which is composed of solid bone over 10 centimeters (two inches) thick. The name Acrotholus audeti also honors Alberta rancher Roy Audet, on whose land the best specimen was discovered in 2008. Acrotholus walked on two legs and had a greatly thickened, domed skull above its eyes, which was used for display to other members of its species, and may have also been used in head-butting contests. Acrotholus lived about 85 million years ago.

The new dinosaur discovery is based on two skull ‘caps’ from the Milk River Formation of southern Alberta. One of these was collected by the Royal Ontario Museum (ROM) more than 50 years ago. However, a better specimen was found in 2008 by University of Toronto graduate student Caleb Brown during a field expedition organized by Dr. David Evans of the Royal Ontario Museum and University of Toronto, and Ryan.

“Acrotholus provides a wealth of new information on the evolution of bone-headed dinosaurs. Although it is one of the earliest known members this group, its thickened skull dome is surprisingly well-developed for its geological age,” said lead author Evans, ROM curator, vertebrate palaeontology. “More importantly, the unique fossil record of these animals suggests that we are only beginning to understand the diversity of small-bodied plant-eating dinosaurs.”

Small mammals and reptiles can be very diverse and abundant in modern ecosystems, but small dinosaurs (less than 100 kg) are considerably less common than large ones in the fossil record. Whether this pattern is a true reflection of dinosaur communities, or is related to the greater potential for small bones to be destroyed by carnivores and natural decay, has been debated. The massively constructed skull domes of pachycephalosaurs are resistant to destruction, and are much more common than their relatively delicate skeletons — which resemble those of other small plant-eating dinosaurs. Therefore, the researchers suggest that the pachycephalosaur fossil record can provide valuable insights into the diversity of small, plant-eating dinosaurs as a whole.

“We can predict that many new small dinosaur species like Acrotholus are waiting to be discovered by researchers willing to sort through the many small bones that they pick up in the field,” said co-author Ryan of The Cleveland Museum of Natural History. “This fully domed and mature individual suggests that there is an undiscovered, hidden diversity of small-bodied dinosaurs. So when we look back, we need to reimagine the paleoenvironment. There is an evolutionary history that we just don’t know because the fossil record is incomplete. This discovery also highlights the importance of landowners, like Roy Audet, who grant access to their land and allow scientifically important finds to be made.”

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 aims to fill in gaps in of the record of Late Cretaceous dinosaurs and study their evolution. This project focuses on the palaeontology of some of the oldest dinosaur-bearing rocks in Alberta, which have been studied less intensely than those of the famous badlands of Dinosaur Provincial Park and Drumheller.

Acrotholus was identified by a team comprising of palaeontologists Evans, of the Royal Ontario Museum; and Ryan, of The Cleveland Museum of Natural History; as well as Ryan Schott, Caleb Brown, and Derek Larson, all graduate students at the University of Toronto who studied under Evans.

Note : The above story is reprinted from materials provided by Cleveland Museum of Natural History. 

Landsat Thermal Sensor Lights Up from Volcano’s Heat

An ash plume drifts from Paluweh volcano in Indonesia in this image, taken April 29, 2013 from the Landsat Data Continuity Misison’s Operational Land Imager instrument. (Credit: Robert Simmon, NASA’s Earth Observatory, using data from USGS and NASA)

As the Landsat Data Continuity Mission satellite flew over Indonesia’s Flores Sea April 29, it captured an image of Paluweh volcano spewing ash into the air. The satellite’s Operational Land Imager detected the white cloud of smoke and ash drifting northwest, over the green forests of the island and the blue waters of the tropical sea. The Thermal Infrared Sensor on LDCM picked up even more.By imaging the heat emanating from the 5-mile-wide volcanic island, TIRS revealed a hot spot at the top of the volcano where lava has been oozing in recent months.

The two LDCM instruments, working together, illustrate a quote from Aristotle: The whole is greater than the sum of its parts, said Betsy Forsbacka, TIRS instrument manager at NASA’s Goddard Space Flight Center in Greenbelt, Md.

“Each instrument by itself is magnificent,” she said. “When you put them together, with the clues that each give you on what you’re seeing on Earth’s surface, it’s greater than either could do by themselves.”

The image of Paluweh also illuminates TIRS’ abilities to capture the boundaries between the hot volcanic activity and the cooler volcanic ash without the signal from the hot spot bleeding over into pixels imaging the cooler surrounding areas. TIRS engineers tested and refined the instrument pre-launch to ensure each pixel correctly represents the heat source it images on Earth’s surface. Otherwise, Forsbacka said, it would be like shining a flashlight in your eyes — the bright light can leave you seeing spots and halos where it should be dark. The same effect can occur with detectors. But the contrast is sharp on the Paluweh image.

“We can image the white, representing the very hot lava, and right next to it we image the gray and black from the cooler surrounding ash,” Forsbacka said. “It’s exciting that we’re imaging such diverse thermal activity so well.”

The TIRS instrument can also pick up subtle shifts of temperatures, within a 10th of a degree Celsius. And, with two different thermal bands instead of the one band on previous Landsat satellites, LDCM is poised to make it easier for scientists to subtract out the effects of the atmosphere on the signal, obtaining a more accurate temperature of Earth’s surface.

Taking Earth’s temperature from space can be difficult because the atmosphere gets in the way and alters the thermal signals, Forsbacka said. Scientists looking to estimate surface temperatures with the single thermal band on previous Landsat instruments needed measurements or assumptions about atmospheric conditions.

TIRS has two thermal bands, however. The atmosphere affects each band slightly differently, resulting in one thermal image that’s a hair darker than the other. By measuring that difference, and plugging it into algorithms, scientists can better address atmospheric effects and create a more accurate temperature record of Earth’s surface.

The Landsat program is a joint mission of NASA and the U.S. Geological Survey. Once LDCM completes its onboard calibration and check-out phase in late May, the satellite will be handed over to the USGS and renamed Landsat 8. Data from TIRS and OLI will be processed, archived and distributed from the USGS Earth Resources and Observation Science Center in Sioux Falls, S.D., for free over the Internet.

Note : The above story is reprinted from materials provided by NASA/Goddard Space Flight Center. 

Research at Mines Unearths New Dinosaur Species

Clint Boyd, Ph.D., of the South Dakota School of Mines & Technology, points to a crocodyliform tooth embedded in the femur of a young dinosaur. (Credit: South Dakota School of Mines & Technology)

First fossil evidence shows small crocs fed on baby dinosaursA South Dakota School of Mines & Technology assistant professor and his team have discovered a new species of herbivorous dinosaur and today published the first fossil evidence of prehistoric crocodyliforms feeding on small dinosaurs.
Research by Clint Boyd, Ph.D., provides the first definitive evidence that plant-eating baby ornithopod dinosaurs were a food of choice for the crocodyliform, a now extinct relative of the crocodile family. While conducting their research, the team also discovered that this dinosaur prey was a previously unrecognized species of a small ornithopod dinosaur, which has yet to be named.

The evidence found in what is now known as the Grand Staircase Escalante-National Monument in southern Utah dates back to the late Cretaceous period, toward the end of the age of dinosaurs, and was published today in the online journal PLOS ONE. The complete research findings of Boyd and Stephanie K. Drumheller, of the University of Iowa and the University of Tennessee, and Terry A. Gates, of North Carolina State University and the Natural History Museum of Utah, can be accessed online (see journal reference below).

A large number of mostly tiny bits of dinosaur bones were recovered in groups at four locations within the Utah park — which paleontologists and geologists know as the Upper Cretaceous (Campanian) Kaiparowits Formation — leading paleontologists to believe that crocodyliforms had fed on baby dinosaurs 1-2 meters in total length.

Evidence shows bite marks on bone joints, as well as breakthrough proof of a crocodyliform tooth still embedded in a dinosaur femur.

The findings are significant because historically dinosaurs have been depicted as the dominant species. “The traditional ideas you see in popular literature are that when little baby dinosaurs are either coming out of a nesting grounds or out somewhere on their own, they are normally having to worry about the theropod dinosaurs, the things like raptors or, on bigger scales, the T. rex. So this kind of adds a new dimension,” Boyd said. “You had your dominant riverine carnivores, the crocodyliforms, attacking these herbivores as well, so they kind of had it coming from all sides.”

Based on teeth marks left on bones and the large amounts of fragments left behind, it is believed the crocodyliforms were also diminutive in size, perhaps no more than 2 meters long. A larger species of crocodyliform would have been more likely to gulp down its prey without leaving behind traces of “busted up” bone fragments.

Until now, paleontologists had direct evidence only of “very large crocodyliforms” interacting with “very large dinosaurs.”

“It’s not often that you get events from the fossil record that are action-related,” Boyd explained. “While you generally assume there was probably a lot more interaction going on, we didn’t have any of that preserved in the fossil record yet. This is the first time that we have definitive evidence that you had this kind of partitioning, of your smaller crocodyliforms attacking the smaller herbivorous dinosaurs,” he said, adding that this is only the second published instance of a crocodyliform tooth embedded in any prey animal in the fossil record.

“A lot of times you find material in close association or you can find some feeding marks or traces on the outside of the bone and you can hypothesize that maybe it was a certain animal doing this, but this was only the second time we have really good definitive evidence of a crocodyliform feeding on a prey animal and in this case an ornithischian dinosaur,” Boyd said.

The high concentrations of tiny dinosaur bones led researchers to conclude a type of selection occurred, that crocodyliforms were preferentially feeding on these miniature dinosaurs. “Maybe it was closer to a nesting ground where baby dinosaurs would have been more abundant, and so the smaller crocodyliforms were hanging out there getting a lunch,” Boyd added.

“When we started looking at all the other bones, we starting finding marks that are known to be diagnostic for crocodyliform feeding traces, so all that evidence coming together suddenly started to make sense as to why we were not finding good complete specimens of these little ornithischian dinosaurs,” Boyd explained. “Most of the bites marks are concentrated around the joints, which is where the crocodyliform would tend to bite, and then, when they do their pulling or the death roll that they tend to do, the ends of the bones tend to snap off more often than not in those actions. That’s why we were finding these fragmentary bones.”

In the process of their research, the team discovered through diagnostic cranial material that these baby prey are a new, as yet-to-be-named dinosaur species. Details on this new species will soon be published in another paper.

*Release Date Wednesday, February 27, 2013

Note : The above story is reprinted from materials provided by South Dakota School of Mines and Technology.

Dinosaur Whodunit: Solving A 77-Million-Year-Old Mystery

Reconstruction of the dinosaur nest and the two possible theropod egg layers. Credit: Julius T. Csotonyi

It has all the hallmarks of a Cretaceous melodrama. A dinosaur sits on her nest of a dozen eggs on a sandy river beach. Water levels rise, and the mother is faced with a dilemma: Stay or abandon her unhatched offspring to the flood and scramble to safety?
Seventy-seven million years later, scientific detective work conducted by University of Calgary and Royal Tyrrell Museum researchers used this unique fossil nest and eggs to learn more about how nest building, brooding and eggs evolved. But there is a big unresolved question: Who was the egg-layer?

“Working out who the culprit was in this egg abandonment tragedy is a difficult problem to crack,” says Darla Zelenitsky, U of C paleontologist and the lead author of a paper published today in the journal Palaeontology. “After further investigation, we discovered that this find is rarer than we first thought. It is a one of a kind fossil. In fact, it is the first nest of its kind in the world.”

Zelenitsky says she first saw the nest in a private collection which had been collected in Montana in the 1990s. The nest was labeled as belonging to a hadrosaur (duck-billed) dinosaur, but she soon discovered it was mistakenly identified. In putting all the data together, she realized they had a small theropod (meat-eating) dinosaur nest. “Nests of small theropods are rare in North America and only those of the dinosaur Troodon have been identified previously,” says Zelenitsky. “Based on characteristics of the eggs and nest, we know that the nest belonged to either a caenagnathid or a small raptor, both small meat-eating dinosaurs closely related to birds. Either way, it is the first nest known for these small dinosaurs.”

The nest tells scientists more about the behaviour of the animal as well as some valuable information relating to the characteristics of modern birds. “Our research tells us a lot about the dinosaur that laid the eggs and how it built its nest,” says Francois Therrien, a co-investigator in the study and curator of dinosaur palaeoecology at the Royal Tyrrell Museum in Drumheller, Alta.

The fossil nest is a mound of sand about half a metre across and weighing as much as a small person. The eggs were laid two at a time, on the sloping sides of the mound, and form a ring around its flat top, where the nesting dinosaur would have sat and brooded its clutch.

“Based on features of the nest, we know that the mother dug in freshly deposited sand, possibly the shore of a river, to build a mound against which she laid her eggs and on which she sat to brood the eggs,” says Therrien. “Some characteristics of the nest are shared with birds, and our analysis can tell us how far back in time these features, such as brooding, nest building, and eggs with a pointed end, evolved – partial answers to the old question of which came first, the chicken or the egg.”

Note : The above story is reprinted from materials provided by University of Calgary, via EurekAlert!, a service of AAAS. 

Dinosaur Egg Study Supports Evolutionary Link Between Birds and Dinosaurs

Darla Zelenitsky from the University of Calgary collaborated with David Varricchio at Montana State University to closely examined the shells of fossil eggs from a small meat-eating dinosaur called Troodon. (Credit: Jay Im (University of Calgary))

A small, bird-like North American dinosaur incubated its eggs in a similar way to brooding birds — bolstering the evolutionary link between birds and dinosaurs, researchers at the University of Calgary and Montana State University study have found.

Among the many mysteries paleontologists have tried to uncover is how dinosaurs hatched their young. Was it in eggs completely buried in nest materials, like crocodiles? Or was it in eggs in open or non-covered nests, like brooding birds?

Using egg clutches found in Alberta and Montana, researchers Darla Zelenitsky at the University of Calgary and David Varricchio at Montana State University closely examined the shells of fossil eggs from a small meat-eating dinosaur called Troodon.

In a finding published in the spring issue of Paleobiology, they concluded that this specific dinosaur species, which was known to lay its eggs almost vertically, would have only buried the egg bottoms in mud.

“Based on our calculations, the eggshells of Troodon were very similar to those of brooding birds, which tells us that this dinosaur did not completely bury its eggs in nesting materials like crocodiles do,” says study co-author Zelenitsky, assistant professor of geoscience

“Both the eggs and the surrounding sediments indicate only partial burial; thus an adult would have directly contacted the exposed parts of the eggs during incubation,” says lead author Varricchio, associate professor of paleontology.

Varricchio says while the nesting style for Troodon is unusual, “there are similarities with a peculiar nester among birds called the Egyptian Plover that broods its eggs while they’re partially buried in sandy substrate of the nest.”

Paleontologists have always struggled to answer the question of how dinosaurs incubated their eggs, because of the scarcity of evidence for incubation behaviours.

As dinosaurs’ closest living relatives, crocodiles and birds offer some insights.

Scientists know that crocodiles and birds that completely bury their eggs for hatching have eggs with many pores or holes in the eggshell, to allow for respiration.

This is unlike brooding birds which don’t bury their eggs; consequently, their eggs have far fewer pores.

The researchers counted and measured the pores in the shells of Troodon eggs to assess how water vapour would have been conducted through the shell compared with eggs from contemporary crocodiles, mound-nesting birds and brooding birds.

They are optimistic their methods can be applied to other dinosaur species’ fossil eggs to show how they may have been incubated.

“For now, this particular study helps substantiate that some bird-like nesting behaviors evolved in meat-eating dinosaurs prior to the origin of birds. It also adds to the growing body of evidence that shows a close evolutionary relationship between birds and dinosaurs,” Zelenitsky says.

Note : The above story is reprinted from materials provided by University of Calgary, via EurekAlert!, a service of AAAS.  

Archeologists Explain Mystery Of Ancient ‘Cave Of Death’

Image Credit: panyajampatong / Shutterstock

For over 20 years, archeologists have been recovering an unusually high number of large carnivore fossils from a cave near Madrid, Spain. According to a new report in the open access journal PLOS ONE, the saber-toothed cat, hyena and red panda ancestor remains found at the site are the result of these animals purposely wandering into the cave and then becoming trapped under mysterious conditions between 9 and 10 million years ago.

Fossils at the cave were first discovered in 1991, and archeologists subsequently uncovered over 18,000 fossils between 1991 and 2008 during two major excavations. Many theories have attempted to explain why such a large number of predator remains have been found in one location. These theories have included the animals falling into the cave and dying, carcasses being washed into the cave by water, and entrapment by an apex predator.

Another bizarre aspect of the site is the near absence of any herbivores, as about 98 percent of the fossils recovered are meat-eaters.

To examine potential causes of death, the Spanish and American researchers examined the geologic history of the cave, the age of the cave fossils, and the time frame of the animals’ demises. They started by looking into the fossilization process of over 6,700 preserved bones from different archeological levels in the cave.

By looking at the types of animals recovered, where the fossils were found, and the lack of fractured bones, the researchers concluded that the animals probably decided to enter the cave in search of prey and became unable to make their way out.

The team also suggested that the lack of herbivore remains may be due to the fact that the clearly visible cave opening was simply not attractive to animals in search of vegetation. The lack of herbivore remains was important for the researchers in ruling out the theory that the animal remains were transported to the cave by water.

“Most probably, carnivores got trapped and remained alive for some time,” the authors wrote. “Also, it is possible that carnivores were searching for water during drought periods and not necessarily for food.”

As the millennia passed, layers of sediment poured into the cave – covering up the animal remains and eventually filling in the cave. The researchers said this would explain why the cave’s ‘window of death’ only covers a certain time span.

The team also noted that fossils in this site are well preserved, most likely as a result of their deposition in the isolated and protective environment of the chamber.

In their conclusion, the team advocated further study of both the cave and the fossils that have been found there.

“Further research is needed in order to ascertain the causes of death of carnivorans inside the cavity but exhaustion, hypothermia or poisoning from drinking water or toxic gases are options to consider,” they wrote.

The team, which included Spanish researchers from the Museo Nacional de Ciencias Naturales-Consejo Superior de Investigaciones Científicas in Madrid, was led by M. Soledad Domingo, a paleontologist from the University of Michigan.

Note: This story has been adapted from a news release issued by Brett Smith for redOrbit

Unique Sulfur Isotopes in Plume Lavas Reveal Deep Mantle Storage of Archean Crust

Sulfur isotopes within iron sulfide inclusions in volcanic rocks, like this one from Iceland, demonstrate that sulfur derived from the Earth’s ancient atmosphere was preserved within the mantle for at least 2.54 billion years before coming back to the surface in eruptions at Mangaia volcano, South Pacific Ocean (Rita A. Cabral et al)

An international team of researchers, led by scientists at Boston University’s Department of Earth and Environment, has found evidence that material contained in young oceanic lava flows originated at the Earth’s surface in the Archean (>2.45 billions years ago).

The new finding helps constrain the timing of the initiation of plate tectonics, the origin of some of the chemical heterogeneity in the Earth’s mantle, and may shed light on how the chaotically convecting mantle could preserve such material for so long. The study appears in the April 25 issue of the journal Nature.

Tectonic plates at the Earth’s surface move around and collide at areas called subduction zones. In these areas, one plate is forced beneath the other and is transported into the Earth’s mantle. It has long been suggested that this subducted material must be re-erupted at a later time. However, the residence time of the subducted material in the mantle is uncertain and convincing evidence of its return to the surface has been lacking.

Sulfur isotopes provide the key to the authors’ discovery. According to the researchers, because mass-independently fractionated (MIF) sulfur isotope signatures were generated exclusively through atmospheric photochemical reactions until about 2.5 billion years ago, material containing such isotope signatures must have originated at the Earth’s surface in the Archean. In the new study, the researchers found MIF sulfur-isotope signatures in olivine-hosted sulfides from relatively young (20-million-year-old) ocean island basalts (OIB) from Mangaia, Cook Islands (Polynesia), providing evidence that material once at the Earth’s surface has been recycled through the mantle and re-erupted at a young ocean island.

“The discovery of MIF-S isotope in these young oceanic lavas suggests that sulfur—likely derived from the hydrothermally-altered oceanic crust—was subducted into the mantle more than 2.5 billion years ago and recycled into the mantle source of the Mangaia lavas,” says Rita Cabral, the study’s primary author and a graduate student in BU’s Department of Earth and Environment.

The data also complement evidence for sulfur recycling of ancient sedimentary materials to the subcontinental lithospheric mantle previously identified in diamond inclusions.

Note : The above story is reprinted from materials provided by Boston University College of Arts & Sciences, via Newswise.

Rethinking early atmospheric oxygen

This photo shows researchers doing field sampling of a pyrite-rich black shale outcrop in China. The weathering of such sediments, which contain sulfur originally buried from the ocean, transfers sulfur isotope signals to the ocean to be buried again in marine sediments. – Chu Research Group, Institute of Geology and Geophysics, Chinese Academy of Sciences.

A research team of biogeochemists at the University of California, Riverside has provided a new view on the relationship between the earliest accumulation of oxygen in the atmosphere, arguably the most important biological event in Earth history, and its relationship to the sulfur cycle.

A general consensus exists that appreciable oxygen first accumulated in Earth’s atmosphere around 2.4 to 2.3 billion years ago. Though this paradigm is built upon a wide range of geological and geochemical observations, the famous “smoking gun” for what has come to be known as the “Great Oxidation Event” (GOE) comes from the disappearance of anomalous fractionations in rare sulfur isotopes.

“These isotope fractionations, often referred to as ‘mass-independent fractionations,’ or ‘MIF’ signals, require both the destruction of sulfur dioxide by ultraviolet energy from the sun in an atmosphere without ozone and very low atmospheric oxygen levels in order to be transported and deposited in marine sediments,” said Christopher T. Reinhard, the lead author of the research paper and a former UC Riverside graduate student. “As a result, their presence in ancient rocks is interpreted to reflect vanishingly low atmospheric oxygen levels continuously for the first ~2 billion years of Earth’s history.”

However, diverse types of data are emerging that point to the presence of atmospheric oxygen, and, by inference, the early emergence of oxygenic photosynthesis hundreds of millions of years before these MIF signals disappear from the rock record. These observations motivated Reinhard and colleagues to explore the possible conditions under which inherited MIF signatures may have persisted in the rock record long after oxygen accumulated in the atmosphere.

Using a simple quantitative model describing how sulfur and its isotopes cycle through the Earth’s crust, the researchers discovered that under certain conditions these MIF signatures can persist within the ocean and marine sediments long after O2 increases in the atmosphere. Simply put, the weathering of rocks on the continents can transfer the MIF signal to the oceans and their sediments long after production of this fingerprint has ceased in an oxygenated atmosphere.

“This lag would blur our ability to date the timing of the GOE and would allow for dynamic rising and falling oxygen levels during a protracted transition from an atmosphere without oxygen to one rich in this life-giving gas,” Reinhard said.

Study results appear in Nature‘s advanced online publication on April 24.

Reinhard explained that once MIF signals formed in an oxygen-poor atmosphere are captured in pyrite and other minerals in sedimentary rocks, they are recycled when those rocks are later uplifted as mountain ranges and the pyrite is oxidized.

“Under certain conditions, this will create a sort of ‘memory effect’ of these MIF signatures, providing a decoupling in time between the burial of MIF in sediments and oxygen accumulation at Earth’s surface,” he said.

According to the researchers, the key here is burying a distinct MIF signal in deep sea sediments, which are then subducted and removed from Earth’s surface.

“This would create a complementary signal in minerals that are weathered and delivered to the oceans, something that we actually see evidence of in the rock record,” said Noah Planavsky, the second author of the research paper and a former UC Riverside graduate student now at Caltech. “This signal can then be perpetuated through time without the need to generate it within the atmosphere contemporaneously.”

Reinhard, now a postdoctoral fellow at Caltech and soon to be an assistant professor at Georgia Institute of Technology, explained that although the researchers’ new model provides a plausible mechanism for reconciling recent conflicting data, this can only occur when certain key conditions are met – and these conditions are likely to have changed through time during Earth’s long early history.

“There is obviously much further work to do, but we hope that our model is one step toward a more integrated view of how Earth’s crust, mantle and atmosphere interact in the global sulfur cycle,” he said.

Timothy W. Lyons, a professor of biogeochemistry at UCR and the principal investigator of the research project noted that this is a fundamentally new and potentially very important way of looking at the sulfur isotope record and its relationship to biospheric oxygenation.

“The message is that sulfur isotope records, when viewed through the filter of sedimentary recycling, may challenge efforts to precisely date the GOE and its relationship to early life, while opening the door to the wonderful unknowns we should expect and embrace,” he said.

Note: This story has been adapted from a news release issued by the University of California – Riverside

New Dinosaur Fossil Discovered in China

The meat-eating dinosaur from the Late Jurassic Period was less than a year old. (Credit: Photo courtesy of James Clark, George Washington University)

Fossil remains found by a George Washington University biologist in northwestern China have been identified as a new species of small theropod, or meat-eating, dinosaur.

 

The discovery was made by James Clark, the Ronald B. Weintraub Professor of Biology, in the Department of Biological Sciences of GW’s Columbian College of Arts and Sciences. Dr. Clark, along with his then doctoral student Jonah Choiniere and a team of international researchers, found the dinosaur specimen in a remote region of Xinjiang in China in 2006.
In a research paper published in the Journal of Systematic Palaeontology, Drs. Clark and Choiniere explain recovering the skull, mandible and partial skeleton of the dinosaur. The new theropod was an estimated 1 meter or just over 3 feet long and probably weighed about 3 pounds.

“All that was exposed on the surface was a bit of the leg,” said Dr. Clark. “We were pleasantly surprised to find a skull buried in the rock too.”

The dinosaur is named Aorun zhaoi, after the Dragon King in the Chinese epic tale Journey to the West. It wasn’t necessarily a small dinosaur species, though, because Aorun was still a youngster when it became a fossil.

“We were able to look at microscopic details of Aorun’s bones and they showed that the animal was less than a year old when it died on the banks of a stream,” said Dr. Choiniere.

Dr. Choiniere, now a senior researcher at the Evolutionary Studies Institute at the University of the Witwatersrand in Johannesburg, South Africa, was a doctoral student in Biological Studies at GW when the discovery was made. He was also a Kalbfleisch Fellow and Gerstner Scholar at the American Museum of Natural History.

Aorun lived more than 161 million years ago, in the earliest part of the Late Jurassic Period. Its small, numerous teeth suggest that it would have eaten prey like lizards and small relatives of today’s mammals and crocodilians.

This is the fifth new theropod discovered at the Wucaiwan locality by the team, co-led by Dr. Clark and Dr. Xu Xing of the Chinese Academy of Sciences.

This research was funded by the National Science Foundation Division of Earth Sciences and the Chinese National Natural Science Foundation.

Note : The above story is reprinted from materials provided by George Washington University. 

Lava Erupting On Sea Floor Linked to Deep-Carbon Cycle

Molten magma erupted onto the seafloor freezes to glass that contains clues to its origin in Earth’s deep interior and ancient past (field of view ~1 cm). Volcanic glasses like this one may reveal a link between Earth’s oxidation state and the deep carbon cycle. (Credit: Glenn Macpherson and Tim Gooding)

Scientists from the Smithsonian and the University of Rhode Island have found unsuspected linkages between the oxidation state of iron in volcanic rocks and variations in the chemistry of the deep Earth. Not only do the trends run counter to predictions from recent decades of study, they belie a role for carbon circulating in the deep Earth.

 

The team’s research was published May 2 in Science Express.

Elizabeth Cottrell, lead author and research geologist at the Smithsonian’s National Museum of Natural History, and Katherine Kelley at the University of Rhode Island’s Graduate School of Oceanography measured the oxidation state of iron, which is the amount of iron that has a 3+ versus a 2+ electronic charge, in bits of magma that froze to a glass when they hit the freezing waters and crushing pressures of the sea floor. Due to the high precision afforded by the spectroscopic technique they used, the researchers found very subtle variations in the iron-oxidation state that had been overlooked by previous investigations.

The variations correlate with what Cottrell described as the “fingerprints” of the deep Earth rocks that melted to produce the lavas — but not in the way previous researchers had predicted. The erupted lavas that have lower concentrations of 3+ iron also have higher concentrations of elements such as barium, thorium, rubidium and lanthanum, that concentrate in the lavas, rather than staying in their deep Earth home. More importantly, the oxidation state of iron also correlates with elements that became enriched in lavas long ago, and now, after billions of years, show elevated ratios of radiogenic isotopes. Because radiogenic isotopic ratios cannot be modified during rock melting and eruption, Cottrell called this “a dead ringer for the source of the melt itself.”

Carbon is one of the “geochemical goodies” that tends to become enriched in the lava when rocks melt. “Despite is importance to life on this planet, carbon is a really tricky element to get a handle on in melts from the deep Earth,” said Cottrell. “That is because carbon also volatilizes and is lost to the ocean waters such that it can’t easily be quantified in the lavas themselves. As humans we are very focused on what we see up here on the surface. Most people probably don’t recognize that the vast majority of carbon — the backbone of all life — is located in the deep Earth, below the surface — maybe even 90 percent of it.”

The rocks that the team analyzed that were reduced also showed a greater influence of having melted in the presence of carbon than those that were oxidized. “And this makes sense because for every atom of carbon present at depth it has to steal oxygen away from iron as it ascends toward the surface,” said Cottrell. This is because carbon is not associated with oxygen at depth, it exists on its own, like in the mineral diamond. But by the time carbon erupts in lava, it is surrounded by oxygen. In this way, concludes Cottrell, “carbon provides both a mechanism to reduce the iron and also a reasonable explanation for why these reduced lavas are enriched in ways we might expect from melting a carbon-bearing rock.”

Note : The above story is reprinted from materials provided by Smithsonian, via EurekAlert!, a service of AAAS. 

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