Dust may settle unanswered questions on Antarctica

Dust trapped deep in Antarctic ice sheets is helping scientists unravel details of past climate change.

Researchers have found that dust blown south to Antarctica from the windy plains of Patagonia – and deposited in the ice periodically over 80,000 years – provides vital information about glacier activity.

Scientists hope the findings will help them to better understand how the global climate has changed during the past ice age, and so help predict environmental changes in the future.

The study indicates that the ebb and flow of glaciers in the Chilean and Argentinian region is a rich source of information about past climates – which had not until now been fully appreciated by scientists.

The study, carried out by the Universities of Edinburgh, Stirling and Lille, shows that the very coldest periods of the last ice age correspond with the dustiest periods in Antarctica’s past.

During these times, glaciers in Patagonia were at their biggest and released their meltwater, containing dust particles, on to barren windy plains, from where dust was blown to Antarctica. When the glaciers retreated even slightly, their meltwater ran into lakes at the edge of the ice, which trapped the dust, so that fewer particles were blown across the ocean to Antarctica.

Dust from the ice cores was analysed and found to be a close match with mud of the same age in the Magellan Straits, showing that most of the dust originated in this region.

The study was supported by the Natural Environment Research Council. The findings were published in Nature Geoscience.

Professor David Sugden, of the University of Edinburgh, said: “Ice cores from the Antarctic ice sheet act as a record of global environment. However, the dust levels showed some sudden changes which had us puzzled – until we realised that the Patagonian glaciers were acting as an on/off switch for releasing dust into the atmosphere.”

Deep sea floor mining is subject of international colloquium at WHOI

Scientists, policymakers, environmentalists, and industry representatives will gather next week at Woods Hole Oceanographic Institution (WHOI) to discuss the issue of mining precious metals from the seafloor. A public colloquium, which will feature keynote addresses from leading voices on the subject and a panel discussion, will be held on Thursday, April 2, from 2 to 5 p.m. in WHOI’s Redfield Auditorium, Woods Hole, MA. The event, the 5th Elisabeth and Henry Morss Jr. Colloquium, is free and open to the public and will also be broadcast in real time on the Web.

Recent proposals for seafloor mining have centered on massive sulfide deposits-rich in copper, gold, silver, and zinc-that are found at deep-sea hydrothermal vent systems.

Vent systems are part of the planet’s plumbing system and form in places where there is volcanic activity, such as along Mid-Ocean Ridges. Water seeps into cracked seafloor and is heated by hot, and sometimes molten rock deep in the ocean crust. The hot fluid becomes buoyant, rises rapidly back to the seafloor, and gushes out of the vent openings at temperatures as high as 400°C. This hydrothermal fluid carries with it dissolved metals and other chemicals from deep beneath the ocean floor, but, at just below the seabed, these metals can precipitate to form seafloor massive sulfide (SMS) deposits.

“Scientists are still in the early stages of studying these SMS deposits, but the active vent sites that generate them can often also play host to species and ecosystems that were previously unknown to science,” said Maurice Tivey, a senior scientist at WHOI. “The new frontier of deep-sea exploration and mining raises questions about the sustainable use of these resources and potential environmental impacts. This colloquium represents an invaluable-and extremely timely-opportunity to discuss all of the various scientific, political, legal, and economic implications of mining with the people most knowledgeable about it.”

Working with the Census of Marine Life’s ChEss (Chemosynthetic Ecosystems) project, InterRidge, Ridge 2000, and the Deep Ocean Exploration Institute at WHOI, Tivey and colleagues have organized a scientific workshop that has attracted more than 100 participants from 20 countries to explore the subject. During the workshop, which will be held the day before the public event, scientists and students of all disciplines will exchange ideas and research results arising from investigations of hydrothermal vent systems and the seafloor deposits that form around them.

“The enthusiastic response of the international community to this meeting highlights sea floor mining as an issue of important global implications,” said Jian Lin, a WHOI geophysicist and InterRidge Chair.

The public colloquium will provide a summary of the previous day’s workshop.

Commercial sea floor mining is already being planned offshore Papua New Guinea, and in May, the International Seabed Authority, which implements the UN Convention on the Law of the Sea, will finalize its rules opening up the high seas to these activities. The U.S. currently has not ratified the Law of the Sea convention.

Among the speakers at next week’s colloquium is Nii Allotey Odunton, the Secretary-General for the International Seabed Authority, which will oversee the regulation of the world’s seafloor resources. Also speaking are Caitlyn Antrim, the executive director for the Rule of Law Committee for the Oceans, Rod Eggert, the division director for economics and business at the Colorado School of Mines, and Maurice Tivey, a geologist at WHOI who studies these unique deep sea environments. They will be joined by Samantha Smith, environmental manager of Nautilus Minerals Inc., Sabine Christiansen of the World Wildlife Fund, and Chris German, a WHOI geochemist who is co-chair of ChEss and InterRidge, for a panel discussion and Q&A with the audience.

“The issue of deep-sea mining of SMS is of global importance, connected to the global economy, society, and the conservation of unique marine life,” said German. “Before these unique environments are altered by industrial processes, we scientists hope to gain and exchange as much information as we can about the formation, preservation, and distribution of SMS deposits to determine the gaps in our scientific knowledge.”

UK robot sub searches for signs of melting 60 km into an Antarctic ice shelf cavity

Autosub, a robot submarine built and developed by the UK’s National Oceanography Centre, Southampton, has successfully completed a high-risk campaign of six missions travelling under an Antarctic glacier.

Autosub has been exploring Pine Island Glacier, a floating extension of the West Antarctic ice sheet, using sonar scanners to map the seabed and the underside of the ice as it juts into the sea. Scientists hope to learn why the glacier has been thinning and accelerating over recent decades. Pine Island Glacier is in the Amundsen Sea, part of the South Pacific bordering West Antarctica. Changes in its flow have been observed since the early 1970s, and together with neighbouring glaciers it is currently contributing about 0.25 mm a year to global sea level rise.

Steve McPhail led the Autosub team during the ten-day survey. He said:

“Autosub is a completely autonomous robot: there are no connecting wires with the ship and no pilot. Autosub has to avoid collisions with the jagged ice overhead and the unknown seabed below, and return to a pre-defined rendezvous point, where we crane it back onboard the ship.

“Adding to the problems are the sub zero water temperatures and the crushing pressures at 1000 m depth. All systems on the vehicle must work perfectly while under the ice or it would be lost. There is no hope of rescue 60 km in, with 500 metres of ice overhead.”

An international team of scientists led by Dr Adrian Jenkins of British Antarctic Survey and Stan Jacobs of the Lamont-Doherty Earth Observatory, Columbia University, New York on the American ship, the RVIB Nathaniel B Palmer, has been using the robot sub to investigate the underside of the ice and measure changes in salinity and temperature of the surrounding water.

After a test mission in unusually ice-free seas in front of the face of the glacier, they started with three 60km forays under the floating glacier and extended the length of missions to 110km round-trip. In all, a distance over 500km beneath the ice was studied.

Using its sonar, the Autosub picks its way through the water, while creating a three-dimensional map that the scientists will use to determine where and how the warmth of the ocean waters drives melting of the glacier base.

“There is still much work to be done on the processing of the data”, said Adrian Jenkins, “but the picture we should get of the ocean beneath the glacier will be unprecedented in its extent and detail. It should help us answer critical questions about the role played by the ocean in driving the ongoing thinning of the glacier.”

The lead US researcher on the project, Stan Jacobs, is studying the Pine Island Glacier with International Polar Year (IPY) funding from the National Science Foundation (NSF). One of the IPY research goals is to better understand the dynamics of the world’s massive ice sheets, including the massive West Antarctic Ice Sheet. If this were to melt completely global sea levels would rise significantly. The most recent report of the Intergovernmental Panel on Climate Change (IPCC) noted that because so little is understood about ice-sheet behaviour it is difficult to predict how ice sheets will contribute to sea level rise in a warming world. The behaviour of ice sheets the IPCC report said is one of the major uncertainties in predicting exactly how the warming of the global will affect human populations.

Complementing the Autosub exploration, other work during the 53-day NB Palmer cruise included setting out 15 moored instrument arrays to record the variability in ocean properties and circulation over the next two years, extensive profiling of ‘warm’ and melt-laden seawater, sampling the perennial sea ice and swath-mapping deep, glacially-scoured troughs on the sea floor.

Autosub is an AUV – Automated Underwater Vehicle, designed, developed and built at the National Oceanography Centre, Southampton with funding from the Natural Environment Research Council. Autosub has a maximum range of 400km and is powered by 5,000 ordinary D-cell batteries. The batteries are packed in bundles in pressure-tested housings. Either end of the seven-metre sub there are free-flooding areas where the payload of instruments are installed. It carries a multibeam sonar system that builds up a 3D map of the ice above and the seabed below.. It also carries precision instruments for measuring the salinity, temperature, and oxygen concentrations in the sea water within the ice cavity, which are vital to understanding the flow of water within the ice cavity and the rate of melting. Autosub is 7m long and weighs 3.5 tonnes. Travelling at 6km hour it is capable of diving up to 1600 m deep, and can operate for 72 hours (400 km) between battery changes.

Rotation is key to understanding volcanic plumes, scientists say

A 200-year-old report by a sea captain and a stunning photograph of the 2008 eruption of Mount Chaiten are helping scientists at the University of Illinois better understand strong volcanic plumes.

In a paper to appear in the March 26 issue of the journal Nature, the scientists show that the spontaneous formation of a “volcanic mesocyclone” – a cyclonically rotating columnar vortex – causes the volcanic plume to rotate about its axis. The rotation, in turn, triggers a sheath of lightning and creates waterspouts or dust devils. The origins of these volcanic phenomena were previously unexplained.

“Rotation is an essential element of a strong volcanic plume,” said Pinaki Chakraborty, a postdoctoral researcher and the paper’s lead author. “By taking into account the rotation, we can better predict the effects of volcanic eruptions.”

In 2008, a photograph of the Mount Chaiten eruption in southern Chile showed what appeared to be a volcanic plume wrapped in a sheath of lightning. A search for references to other occurrences of lightning sheaths led Chakraborty, mechanical science and engineering professor Gustavo Gioia and geology professor Susan W. Kieffer to an obscure paper by a sea captain, published in 1811.

In that paper, the sea captain reported his observations of a volcanic vent that emerged from the sea in the Azores archipelago and formed a large volcanic plume.

According to the captain, the plume rotated on the water “like an (sic) horizontal wheel” and was accompanied by continuous “flashes of lightning” and a “quantity of waterspouts.”

This conjunction of rotation, lightning and waterspouts (or dust devils on land) is characteristic of a familiar meteorological phenomenon seemingly unrelated to volcanic plumes: a tornadic thunderstorm.

The same process that creates a mesocyclone in a tornadic thunderstorm also creates a volcanic mesocyclone in a strong volcanic plume, Chakraborty said. “What happens in tornadic thunderstorms is analogous to what happens in strong volcanic plumes.”

A strong volcanic plume consists of a vertical column of hot gases and dust topped with a horizontal “umbrella.” A volcanic mesocyclone sets the entire plume rotating about its axis. The mesocyclone spawns waterspouts or dust devils, and groups the electric charges in the plume to form a sheath of lightning, as was so prominently displayed in the eruption of Mount Chaiten.

The rotation of strong volcanic plumes may be verified by observations from space, the scientists report. On June 15, 1991, the eruption of Mount Pinatubo in the Philippines was recorded by a satellite snapping hourly images. The images show that the edge of Pinatubo’s umbrella was rotating about its center, consistent with the presence of a volcanic mesocyclone.

The images also show that after rotating for a while, the umbrella lost axial symmetry and became lobate in plan view. This loss of axial symmetry is another effect of the rotation, which destabilizes the edge of the umbrella and makes it lobate, the scientists report.

Lobate umbrellas have been found in satellite images of other volcanoes, including Mount Manam in Papua New Guinea, Mount Reventador in Ecuador and Mount Okmok in the Aleutian Islands.

Satellite images of future volcanic plumes taken at intervals of a few minutes would make it possible to trace the evolution of umbrellas in detail, Gioia said. In addition, some of the tools commonly used in the study of thunderstorms could be deployed for the study of volcanic eruptions.

“The structure and dynamics of volcanic mesocyclones, as well as the presence of lightning sheaths, might be verified with Doppler radar and lightning mapping arrays, two technologies that have been scarcely used in volcanology,” Gioia said.

Finding trapped miners

This diagram shows the layout of a system that University of Utah scientists developed to find miners trapped by mine cave-ins. The system was tested in a utility tunnel on campus, and at an abandoned copper mine near Tucson, Ariz. The diagram shows how sound receivers known as geophones are lined up on the ground surface above a mine tunnel. Each red star within the tunnel represents a 'base station' comprised of a sledgehammer and an iron plate bolted to the mine wall. In the event of a mine collapse, the miners try to reach the nearest base station, where they use the sledgehammer to bang on the iron plate. The pattern of seismic waves 'heard' by the geophones is analyzed in a computer to pinpoint the miners' location. -  University of Utah.
This diagram shows the layout of a system that University of Utah scientists developed to find miners trapped by mine cave-ins. The system was tested in a utility tunnel on campus, and at an abandoned copper mine near Tucson, Ariz. The diagram shows how sound receivers known as geophones are lined up on the ground surface above a mine tunnel. Each red star within the tunnel represents a ‘base station’ comprised of a sledgehammer and an iron plate bolted to the mine wall. In the event of a mine collapse, the miners try to reach the nearest base station, where they use the sledgehammer to bang on the iron plate. The pattern of seismic waves ‘heard’ by the geophones is analyzed in a computer to pinpoint the miners’ location. – University of Utah.

University of Utah scientists devised a new way to find miners trapped by cave-ins. The method involves installing iron plates and sledgehammers at regular intervals inside mines, and sensitive listening devices on the ground overhead.

“We developed an approach to find the location of trapped miners inside a collapsed mine, regardless of noise from the environment around the mine,” says Sherif Hanafy, an adjunct associate professor of geology and geophysics at the University of Utah and first author of a study demonstrating the technique.

The method records “seismic ‘fingerprints’ generated by a trapped miner banging on the mine wall, and uses those fingerprints to locate him. Each different location in the mine that is banged has a unique fingerprint,” says Gerard Schuster, a professor of geology and geophysics at the University of Utah and the study’s senior author.

“We hope to make it easier to find out if miners are alive after a collapse and, if they are alive, where they are located,” he adds. “It’s not guaranteed to work every time, but looks promising from the tests we did. This is not rocket science; it’s rock science.”

The new study was published in this month’s issue of The Leading Edge, a journal of the Society of Exploration Geophysicists.

The researchers and a number of Utah graduate students tested the system twice. One test was in a utility tunnel beneath the University of Utah campus. The other test was in much deeper tunnels in an abandoned copper mine near Tucson, Ariz.

“We got 100 percent accuracy,” Hanafy says.

Schuster says more testing is needed to make sure the method will work in deeper mines, such as coal mines, which can be a few thousand feet deep. He says that while the method was tested only in horizontal mines tunnels, it also should work in vertical shafts.

Along with Hanafy and Schuster, the study’s coauthors are Weiping Cao, a doctoral student in geology and geophysics, and M.K. “Kim” McCarter, a professor of mining engineering at the University of Utah. In addition to his Utah affiliation, Hanafy is an associate professor of geophysics at Cairo University in Egypt.

How the Method Can Find Trapped Miners

The system developed by the Utah researchers would be installed in stages as a mine is excavated. Components include:

  • each tunnel’s length. At each station, a 4-inch-by-4-inch iron plate is bolted to the wall, and a sledgehammer is placed near each plate.

  • On the surface, cables are strung along the ground above each tunnel or shaft, and “geophones” are spaced at regular intervals along the cables. Geophones listen for seismic waves created when miners use the sledgehammer to bang on an iron plate.
  • Once the system is installed, and as the mine expands and base stations are added, each base station is “calibrated,” meaning its plate is whacked and the seismic waves are recorded by the geophones overhead. Each base station has a distinct seismic wave “fingerprint.” So if miners are trapped and bang the metal plate at the nearest base station, the resulting seismic recording will allow rescuers to determine precisely which base station plate was thumped, and thus where the miners are located.

Listening stations would record the seismic wave pattern from each geophone. The collective pattern would be compared – by a computer – with the calibration seismograph recordings collected prior to the collapse. A match identifies the base station or stations where survivors have gathered and walloped the iron plate.

Schuster hopes a company will commercialize the miner-location system. A patent is pending on the method, and University of Utah technology commercialization officials have discussed it with a variety of mining companies.

The system would include perhaps 100 geophones and 100 base stations, and cost about $100,000 for a typical mine – an amount Schuster considers inexpensive.

“It’s like having a fire extinguisher on every floor. How much does that cost?”

Schuster says the system could be expanded – at about double the cost – to allow two-way communications, instead of just signals from trapped miners to rescuers on the surface. Two-way communication would require a computer and geophone at each underground base station to pick up signals from people on the surface.

Hanafy says if miners were unable to reach the nearest base station, simply banging on a mine wall with a rock should produce a “fingerprint” that identifies the nearest base station.

A Method Born from Oil Exploration and the Crandall Canyon Mine Disaster

Schuster’s research, which is funded by 20 oil and gas companies, focuses on developing improved methods to use seismic waves to make three-dimensional images identifying the location of oil, gas and mineral deposits. He will switch to adjunct status at the University of Utah this summer to become a geosciences professor at King Abdullah University of Science and Technology in oil-rich Saudi Arabia.

His work on the miner-locating method was triggered by Utah’s Aug. 6, 2007, Crandall Canyon coal mine collapse, which resulted in the deaths of six miners and, 10 days later, three rescuers. Schuster had just returned from a five-month sabbatical in Saudi Arabia, working on a system to use seismic signals to locate the “fluid front” of underground oil being pushed toward a well by injected steam or carbon dioxide gas.

Schuster says the technology in the miner-locating system is one that exploration geophysicists have used since the 1970s to search for oil, and later was adapted by the military to locate submarines with quiet propulsion systems. Just as efforts to determine an earthquake’s location looked at only a small part of the seismic wave signal, so did old efforts to look for submarines by using sound generated by sonar, he says.

With the new technology, “we look at the entire signal,” which Schuster compares with analyzing an entire fingerprint rather than one or two whorls in that fingerprint.

The researchers first tested their system in November 2007 near the David Eccles School of Business on the University of Utah campus. Graduate students set up 25 base stations in a 150-foot-long stretch of tunnel that carries steam pipes and other utilities 10 feet beneath the surface.

Hanafy says they spaced the base stations anywhere from 1.6 feet to 13 feet apart, and whacked each one with a 16-pound sledgehammer while geophones on the surface recorded the seismic waves. Geophones were aligned 115 feet away instead of directly over the tunnel – a way to mimic recording seismic waves from a much deeper tunnel.

“We had 25 base stations inside the tunnel, and we calculated the result for each one assuming a trapped miner was at each one of these,” he says. “We were able to locate exactly where each bang was coming from,” even when stations were only 1.6 feet apart.

The Utah scientists tested the method at more realistic depths at the old Arizona copper mine, where they placed 25 base stations 1.6 feet apart in a 100-foot-deep tunnel, and another 25 base stations 2.5 feet apart in an underlying 150-foot-deep tunnel. On the surface, 120 geophones were set up along a 200-foot-long line running above the two tunnels. Every bang on a base station was accurately located.

Schuster says that to “simulate battlefield conditions” at a working mine, a computer was used to simulate “white noise” that drowned out the real seismic signals by a 2,000-to-1 ratio. He says the seismic signature of a bang on a base station plate still could be distinguished.

“It’s like at a cocktail party you have 2,000 people talking at the same time in different conversations, and somehow you can home in on one conversation,” he says.

Deep-sea rocks point to early oxygen on Earth

This is the location of the core drilling in the Pilbara Craton, West Australia. -  Hiroshi Ohmoto/Yumiko Watanabe
This is the location of the core drilling in the Pilbara Craton, West Australia. – Hiroshi Ohmoto/Yumiko Watanabe

Red jasper cored from layers 3.46 billion years old suggests that not only did the oceans contain abundant oxygen then, but that the atmosphere was as oxygen rich as it is today, according to geologists.

This jasper or hematite-rich chert formed in ways similar to the way this rock forms around hydrothermal vents in the deep oceans today.

“Many people have assumed that the hematite in ancient rocks formed by the oxidation of siderite in the modern atmosphere,” said Hiroshi Ohmoto, professor of geochemistry, Penn State. “That is why we wanted to drill deeper, below the water table and recover unweathered rocks.”

The researchers drilled diagonally into the base of a hill in the Pilbara Craton in northwest Western Australia to obtain samples of jasper that could not have been exposed to the atmosphere or water. These jaspers could be dated to 3.46 billion years ago.

“Everyone agrees that this jasper is 3.46 billion years old,” said Ohmoto. “If hematite were formed by the oxidation of siderite at any time, the hematite would be found on the outside of the siderite, but it is found inside,” he reported in a recent issue of Nature Geoscience.

The next step was to determine if the hematite formed near the water’s surface or in the depths. Iron compounds exposed to ultra violet light can form ferric hydroxide, which can sink to the bottom as tiny particles and then converted to hematite at temperatures of at least 140 degrees Fahrenheit.

“There are a number of cases around the world where hematite is formed in this way,” says Ohmoto. “So just because there is hematite, there is not necessarily oxygen in the water or the atmosphere.”

The key to determining if ultra violet light or oxygen formed the hematite is the crystalline structure of the hematite itself. If the precursors of hematite were formed at the surface, the crystalline structure of the rock would have formed from small particles aggregating producing large crystals with lots of empty spaces between. Using transmission electron microscopy, the researchers did not find that crystalline structure.

“We found that the hematite from this core was made of a single crystal and therefore was not hematite made by ultra violet radiation,” said Ohmoto.

This could only happen if the deep ocean contained oxygen and the iron rich fluids came into contact at high temperatures. Ohmoto and his team believe that this specific layer of hematite formed when a plume of heated water, like those found today at hydrothermal vents, converted the iron compounds into hematite using oxygen dissolved in the deep ocean water.

“This explains why this hematite is only found in areas with active submarine volcanism,” said Ohmoto. “It also means that there was oxygen in the atmosphere 3.46 billion years ago, because the only mechanism for oxygen to exist in the deep oceans is for there to be oxygen in the atmosphere.”

In fact, the researchers suggest that to have sufficient oxygen at depth, there had to be as much oxygen in the atmosphere 3.46 billion years ago as there is in today’s atmosphere. To have this amount of oxygen, the Earth must have had oxygen producing organisms like cyanobacteria actively producing it, placing these organisms much earlier in Earth’s history than previously thought.

“Usually, we look at the remnant of what we think is biological activity to understand the Earth’s biology,” said Ohmoto. “Our approach is unique because we look at the mineral ferric oxide to decipher biological activity.”

Ohmoto suggests that this approach eliminates the problems trying to decide if carbon residues found in sediments were biologically created or simply chemical artifacts.

‘Ice that burns’ may yield clean, sustainable bridge to global energy future

Gas hydrates, known as 'ice that burns,' may provide a clean, sustainable fuel source in the future. -  J. Pinkston and L. Stern/US Geological Survey
Gas hydrates, known as ‘ice that burns,’ may provide a clean, sustainable fuel source in the future. – J. Pinkston and L. Stern/US Geological Survey

In the future, natural gas derived from chunks of ice that workers collect from beneath the ocean floor and beneath the arctic permafrost may fuel cars, heat homes, and power factories. Government researchers are reporting that these so-called “gas hydrates,” a frozen form of natural gas that bursts into flames at the touch of a match, show increasing promise as an abundant, untapped source of clean, sustainable energy. The icy chunks could supplement traditional energy sources that are in short supply and which produce large amounts of carbon dioxide linked to global warming, the scientists say.

“These gas hydrates could serve as a bridge to our energy future until cleaner fuel sources, such as hydrogen and solar energy, are more fully realized,” says study co-leader Tim Collett, Ph.D., a research geologist with the U.S. Geological Survey (USGS) in Denver, Colo. Gas hydrates, known as “ice that burns,” hold special promise for helping to combat global warming by leaving a smaller carbon dioxide footprint than other fossil fuels, Collett and colleagues note.

They will present research on gas hydrates here today at the American Chemical Society’s 237th National Meeting. It is among two dozen papers on the topic scheduled for a two-day symposium, “Gas Hydrates and Clathrates,” March 23-24, held at the Hilton Salt Lake City, Grand Ballroom A. The symposium begins at 8 a.m. on Monday, March 23.

Last November, a team of USGS researchers that included Collett announced a giant step toward that bridge to the future. In a landmark study, the USGS scientists estimated that 85.4 trillion cubic feet of natural gas could potentially be extracted from gas hydrates in Alaska’s North Slope region, enough to heat more than 100 million average homes for more than a decade.

“It’s definitely a vast storehouse of energy,” Collett says. “But it is still unknown how much of this volume can actually be produced on an industrial scale.” That volume, he says, depends on the ability of scientists to extract useful methane, the main ingredient in natural gas, from gas hydrate formations in an efficient and cost-effective manner. Scientists worldwide are now doing research on gas hydrates in order to understand how this strange material forms and how it might be used to supplement coal, oil, and traditional natural gas.

Although scientists have known about gas hydrates for decades, they’ve only recently begun to try to use them as an alternative energy source. Gas hydrates, also known as “clathrates,” form when methane gas from the decomposition of organic material comes into contact with water at low temperatures and high pressures. Those cold, high-pressure conditions exist deep below the oceans and underground on land in certain parts of the world, including the ocean floor and permafrost areas of the Arctic.

Today, researchers are finding tremendous stores of gas hydrates throughout the world, including United States, India, and Japan. In addition to Alaska, the United States has vast gas hydrate deposits in the Gulf of Mexico and off its eastern coast. Interest in and support of hydrate research is now growing worldwide. Japan and India currently have among the largest, most well-funded hydrate research programs in the world.

“Once we have learned better how to find the most promising gas hydrate deposits, we will need to know how to produce it in a safe and commercially-viable way,” says study co-author Ray Boswell, Ph.D. He manages the National Methane Hydrate R&D Program of the U.S. Department of Energy’s National Energy Technology Laboratory in Morgantown, W. Va. “Chemistry will be a big part of understanding just how the hydrates will respond to various production methods.”

One of the more promising techniques for extracting methane from hydrates involves simply depressurizing the deposits, Boswell says. Another method involves exchanging the methane molecules in the “clathrate” structure with carbon dioxide. Workers can, in theory, collect the gas using the same drilling technology used for conventional oil and gas drilling.

Under the Methane Hydrate Research and Development Act of 2000, the U.S. government has already spent several million dollars, in collaboration with universities and private companies, to investigate gas hydrates as an alternative energy source. Scientists are particularly optimistic about the vast stores of gas hydrates located in Alaska and in the Gulf of Mexico. Research is also accelerating under the U.S. Department of Energy and USGS to better understand gas hydrate’s role in the natural environment and in climate change.

“Gas hydrates are totally doable,” Collett says. “But when and where we will see them depends on need, motivation, and our supply of other energy resources. In the next five to ten years, the research potential of gas hydrates will be more fully realized.”

Other highlights in the symposium include:

Expert provides overview of gas hydrates for energy production, climate change – Scientists predict that natural gas hydrates will play a major role in both energy and climate change in the future. E. Dendy Sloan, Ph.D., of the Colorado School of Mines, will provide an overview of this rapidly evolving field. He is the author over 200 publications, including the third edition of “Clathrate Hydrates of Natural Gases,” (2008), co-authored by Carolyn Koh. (FUEL 041, Monday, March 23, 8:05 a.m., at the Hilton, Grand Ballroom A, during the symposium “Gas Hydrates and Clathrates.”)

Japan’s promising national gas hydrate program – Japan has one of the world’s largest gas hydrate research programs and is well on its way toward using these hydrates as an important fuel source. Masanori Kurihara, Ph.D., of Japan Oil Engineering Co., Ltd., will describe Japan’s National Methane Hydrate Exploitation Program, including research on promising methane hydrate deposits in the Eastern Nankai Trough of offshore Japan. (FUEL 042, Monday, March 23, 8:45 a.m., at the Hilton, Grand Ballroom A, during the symposium, “Gas Hydrates and Clathrates.”)

Overview of gas hydrate research in Canada – Canada has been involved in gas hydrates research since the 1970s and now plays a leading role in hydrate production technology. Scott R. Dallimore, of Geological Survey of Canada, will provide an overview of the country’s contributions toward gas hydrate production. (FUEL 045, Monday, March 23, 11:05 a.m., at the Hilton, Grand Ballroom A, during the symposium, “Gas Hydrates and Clathrates.”)

Great Basin’s Bear Lake reveals records of past climate

This is the cover of 'Paleoenvironments of Bear Lake, Utah and Idaho, and Its Catchment,'
by Joseph G. Rosenbaum and Darrell S. Kaufman. -  Geological Society or America
This is the cover of ‘Paleoenvironments of Bear Lake, Utah and Idaho, and Its Catchment,’
by Joseph G. Rosenbaum and Darrell S. Kaufman. – Geological Society or America

The Geological Society of America presents a new Special Paper, Paleoenvironments of Bear Lake, Utah and Idaho, and Its Catchment. This volume is the culmination of more than a decade of coordinated investigations aimed at a holistic understanding of the long-lived Bear Lake, which is located 100 km northeast of Salt Lake City, along the course of the Bear River, the largest river in the Great Basin of the western United States.

One of the oldest existing lakes in North America, Bear Lake lies within an asymmetric, tectonically active basin that contains hundreds of meters of sediment accumulated over the past several million years. This volume’s 14 chapters, with 20 contributing authors, contain geological, mineralogical, geochemical, paleontological, and limnological studies extending from the drainage basin to the depocenter. The studies span both modern and paleoenvironments, including a 120-m-long sediment core that captures a continuous record of the last two glacial-interglacial cycles.

According to editors Joseph Rosenbaum of the U.S. Geological Survey in Denver and Darrell S. Kaufman of Northern Arizona University, understanding Bear Lake and the paleorecords revealed there yields information about past climate for the larger region, including the Upper Colorado River Basin, the source of much of the water for the southwestern United States.

Scientists cable seafloor seismometer into California’s earthquake network

A newly-laid, 32-mile underwater cable finally links the state’s only seafloor seismic station with the University of California, Berkeley’s seismic network, merging real-time data from west of the San Andreas fault with data from 31 other land stations sprinkled around Northern and Central California.

Laying of the MARS (Monterey Accelerated Research System) fiber-optic cable was completed in 2007 by the Monterey Bay Aquarium Research Institute (MBARI) to power and collect data from a cluster of scientific instruments nearly 3,000 feet below the surface of Monterey Bay, 23 miles from the coastal town of Moss Landing. A broadband seismometer that had been placed on the seafloor in 2002 was connected to the cable on Feb. 27, 2009, obviating the need to send a remotely operated vehicle (ROV) every three months to replace the battery and collect data.

“Before, we had to wait three months to even know if the instruments were alive,” said Barbara Romanowicz, director of the Berkeley Seismological Laboratory and a UC Berkeley professor of earth and planetary science. Now, she said, “we can use the data from the seafloor station in real time together with those from the rest of the Berkeley Digital Seismic Network” to determine the location, magnitude and mechanism of offshore earthquakes, learn about the crust at the edge of the continental plate and understand better the hazards of the San Andreas fault system that runs north and south through the state.

According to Romanowicz, earthquake monitoring systems around the world have been trying to place seismometers on the seafloor for decades to cover the 71 percent of the Earth’s surface that is beneath the oceans. Islands have generally provided the only offshore data – the Berkeley network has one seismic station on the Farallon Islands – but these provide only spotty coverage.

Because the state’s main fault system, the San Andreas, runs along the Northern California coast, seafloor monitors are particularly critical. All but one station – the Farallon station – are east of the fault, making it hard to gain a comprehensive view of the fault system.

“Even though we correct for this lopsidedness, the calculations would be even more reliable if we could include data from more stations west of the fault; with the addition of MOBB, we achieve this goal,” wrote Berkeley Seismological Laboratory research geophysicist Peggy Hellweg on the lab’s SeismoBlog, http://seismo.berkeley.edu/blogs/seismoblog.php.

Also, while basic, disposable seismometers can be thrown overboard to collect data for short periods of time, more expensive broadband seismometers, which can detect a wide range of vibrational frequencies and a large amplitude range, are preferred. The latter are necessary to gather the data needed for modeling earthquakes and eventually providing a few tens of seconds’ warning of impending ground shaking.

Romanowicz teamed up with the institute more than 12 years ago to develop a seafloor seismic observatory. For three months in 1997, in collaboration with the Berkeley Seismological Laboratory and a team from France, MBARI placed a broadband seismometer on the floor of Monterey Bay to test the equipment and installation procedures. The Monterey Ocean Bottom Broadband (MOBB) station was permanently situated on an underwater ridge in April 2002.

With MOBB data coming back to UC Berkeley only once every three months, it could not be used in real-time earthquake monitoring. It has proved valuable in other studies, however, including an investigation of long-period ocean waves, called infragravity waves, that are thought to generate a low-frequency hum in Earth.

This hum – which has a period of 100-500 seconds, too low for humans to hear – was discovered in 1998 and ascribed to atmospheric turbulence. But in 2004, Romanowicz and UC Berkeley colleague Junkee Rhie showed that the source of the hum was in the oceans and related to storms. Somehow, 10-second ocean waves generated by storms interact with each other to produce longer period infragravity waves, which then interact locally to thump the seafloor and create the hum. The specifics are still unclear, although the interactions of the long waves with the ground likely occur near the shore.

“How the interactions of waves couple to the ground is still an open question,” said Romanowicz. “MOBB will allow us to compare seismic data with data from buoys to determine the temporal and spatial relationships between ocean waves, infragravity waves and seismic waves.”

Earth’s hum as well as ocean currents and breaking surf all make the seismic data from MOBB noisier than data from land stations, Romanowicz said, which means MOBB data must be processed to remove the noise before it can be integrated with other seismic data in the network. She and UC Berkeley colleagues are working on real-time algorithms that can do such processing quickly. The data from the ocean floor seismometer will soon be available, along with other broadband seismic data from land-based stations, at the Northern California Earthquake Data Center: http://www.ncedc.org/), an archive of earthquake date maintained by UC Berkeley and the U.S. Geological Survey.

If MOBB turns out to provide useful data for the Northern California seismic network, it will be a prototype for other seafloor seismic stations she hopes to emplace along the coast from below Monterey to Point Reyes.

West Antarctic ice comes and goes, rapidly

Modeled Antarctic ice sheet at particular times through the warm Marine Isotope Stage 31 event, around 1.07 million years ago. Ice-sheet elevations and floating ice-shelf thicknesses shown by two different color scales, 'yr BP' is
'years before present.' -  David Pollard, Penn State
Modeled Antarctic ice sheet at particular times through the warm Marine Isotope Stage 31 event, around 1.07 million years ago. Ice-sheet elevations and floating ice-shelf thicknesses shown by two different color scales, ‘yr BP’ is
‘years before present.’ – David Pollard, Penn State

Researchers today worry about the collapse of West Antarctic ice shelves and loss of the West Antarctic ice sheet, but little is known about the past movements of this ice. Now climatologists from Penn State and the University of Massachusetts have modeled the past 5 million years of the West Antarctic ice sheet and found the ice expanse changes rapidly and is most influenced by ocean temperatures near the continent.

“We found that the West Antarctic ice sheet varied a lot, collapsed and regrew multiple times over that period,” said David Pollard, senior scientist, Penn State’s College of Earth and Mineral Sciences’ Earth and Environmental Systems Institute. “The ice sheets in our model changed in ways that agree well with the data collected by the ANDRILL project.”

Pollard and Robert M. DeConto, professor of climatology, U. Mass, report their findings in today’s (Mar. 19) issue of Nature. The results of the first ANDRILL drill core near McMurdo Station, Antarctica, are reported in a companion paper in the same issue. The ANtarctic geological DRILLing project is a multinational collaboration to drill back in time into sediment to recover a history of paleoenvironmental changes.

“We found, as expected, that the East Antarctic ice sheet is stable and did not change,” said Pollard.

The East Antarctic ice sheet does not slide into the sea and melt away because most of the bedrock below East Antarctic ice is above sea level. However, on the other side of the continent, to the Pacific side of the Transantarctic Mountain Range, much of the bedrock below the ice lies from several hundred to several thousand feet below sea level, leaving the West Antarctic ice vulnerable to melting.

“We found that the ocean’s warming and melting the bottom of the floating ice shelves has been the dominant control on West Antarctic ice variations,” said Pollard.

When the floating ice shelves melt sufficiently, they no longer buttress the grounded ice upstream, which then flows faster and rapidly drains the massive interior ice. The grounding line, the junction between the floating ice shelf and upstream ice resting on bedrock, retreats converting more grounded ice to floating ice shelves. Eventually, nearly all of the ice sheet on the Pacific side of Antarctica can disappear as it has in the past.

The researchers’ computer model needs past variations of snowfall, snow melt and ocean melting below the floating ice to be specified. These are not obtained from the General Circulation Models often used in climate reconstruction because running those models to create 5 million years of climate history would take years. Instead, the researchers related past variations of these quantities to records of deep sea oxygen isotope ratios that indicate temperature changes in the oceans.

“We assume this is all driven by global-scale climate variations including Northern Hemispheric glacial cycles, so we used the changes in the oxygen 18 record to deduce the Antarctic changes,” says Pollard. “Our next step will be to test whether this record really represents sea temperatures around Antarctica.”

The researchers compared their model’s output with the sediment core record from ANDRILL. In these cores, coarse pebbly glacial till represent the glacial periods, while intervals filled with the shells of tiny ocean-living diatoms represent the nonglacial periods. One way the ANDRILL researchers date the layers is using existing datable volcanic layers within the core.

Pollard and DeConto not only looked at the modeling of the overall West Antarctic ice sheet, they also looked at the nearest grid point in their model to the ANDRILL drilling location. They found that, for the most part, the data trend at that grid point matched the data obtained from the sediment core.

“Our modeling extends the reach of the drilling data to justify that the data represent the entire West Antarctic area and not just the spot where they drilled,” said Pollard.

Along with the rapid appearance and disappearance of the ice, the researchers noted that both in the ANDRILL record and the model results, during the early portion of the 5 million years, the periodicity of the glaciation and melting was about 40,000 years which matches the Northern Hemisphere’s pattern of glaciation and glacier retreat. The basic driver is very likely the tilt of the Earth’s axis which varies with the same period, according to Pollard. However, nearer to the present, the cycle time increased to about 100,000 years as expected, driven by Northern Hemispheric ice age cycles.

During past warm periods, the major collapses in the model take a few thousand years. This is also the expected time scale of future collapse of the West Antarctic ice sheet if ocean temperatures warm sufficiently – longer than a few centuries but shorter than ten thousand years.

The researchers note that when atmospheric carbon dioxide levels in the past were about 400 parts per million, in the early part of the ANDRILL record, West Antarctic ice sheet collapses were much more frequent..

“We are a little below 400 parts per million now and heading higher,” says Pollard. “One of the next steps is to determine if human activity will make it warm enough to start the collapse.”