Tackling mysteries about carbon, possible oil formation and more deep inside Earth

How do diamonds the size of potatoes shoot up at 40 miles per hour from their birthplace 100 miles below Earth’s surface? Does a secret realm of life exist inside the Earth? Is there more oil and natural gas than anyone dreams, with oil forming not from the remains of ancient fossilized plants and animals near the surface, but naturally deep, deep down there? Can the greenhouse gas, carbon dioxide, be transformed into a pure solid mineral?

Those are among the mysteries being tackled in a real-life version of the science fiction classic, A Journey to the Center of the Earth, that was among the topics of a presentation here today at the 242nd National Meeting & Exposition of the American Chemical Society (ACS). Russell Hemley, Ph.D., said that hundreds of scientists will work together on an international project, called the Deep Carbon Observatory (DCO), to probe the chemical element that’s in the news more often than perhaps any other. That’s carbon as in carbon dioxide.

“Concerns about climate change have made millions of people aware of carbon’s role on the surface of the Earth, in the atmosphere and in the oceans,” Hemley said. “The Deep Carbon Observatory will uncover critical information about the movement and fate of carbon hundreds and thousands of miles below Earth’s surface. We call that the deep carbon cycle.”

Hemley said this basic research could have practical implications in the future. Using laboratory equipment that reproduces pressures deep within the Earth, which are thousands to millions of times higher than on the surface, scientists in these labs have discovered a way to convert carbon dioxide into a rock-like material called polymeric carbon dioxide. With further refinements, scientists could enhance its stability closer to the Earth’s surface.

The findings also may lead to new materials for commercial and industrial products. Hemley’s laboratory, for instance, has developed a way to produce “super” diamonds, or high-quality diamonds that are bigger and better than existing ones. Natural diamonds form slowly under the high-pressure, high-temperature conditions that exist deep within the Earth, while today’s synthetic diamonds form under similar conditions in the laboratory. Using a process called chemical vapor deposition, Hemley’s research group made diamonds rapidly and at low pressure. The new diamonds have superior qualities, including extreme hardness, improved transparency and better electrical and temperature properties. The diamonds could lead to improved computer chips that run faster and generate less heat than existing silicon chips, Hemley said. They also show promise for use in advanced cutting-tools, more durable and heat-resistant windows for spacecraft and other applications, he noted.

The DCO project will probe the big mystery about the formation of natural diamonds, including their chemical composition and how they shoot up quickly from deep within the Earth. Scientists can’t directly observe that process at present, as there’s no practical way to travel down 100 miles beneath the surface of the planet. Observations are limited to laboratory simulations of this process for now, said Hemley, who is director of the Geophysical Laboratory at the Carnegie Institution of Washington in Washington, D.C. His laboratory specializes in the chemistry and physics of materials under extreme conditions. Hemley’s presentation at the ACS meeting, entitled “Chemistry of Planetary Gases, Liquids, and Ices in Extreme Environments,” focused on what happens to planetary material under conditions of extreme pressure and temperature, as well as other insights relevant to Earth.

Another area that the DCO will explore is energy. The extent to which hydrocarbons in the Earth form from inorganic processes deep within the Earth rather than only from the fossilized remains of plants and animals remains an important unanswered question. Exploring the nature of carbon deep within the Earth may provide clues on how and to what extent this abiotic process might contribute to energy reserves, Hemley said.

Finally, DCO research has implications in the search for other life forms on Earth and even outer space. Scientists have already identified microbes at about a mile or so deep within the Earth under high temperatures. They suspect that some forms may exist at even deeper levels.

Past studies suggest that bacteria and other life forms can’t survive beyond several thousand atmospheres of pressure. But new studies by scientists in Hemley’s lab show that some bacteria are capable of surviving pressures of up to 20,000 atmospheres. That supports the theory that life might exist in extreme extraterrestrial environments, Hemley noted.

A math-based model for deep-water oil drilling

Oil well control is one of the most important processes during drilling operations. In deepwater drilling, controlling pressure in the oil well is crucial, as excessive pressures in the drilled hole can result in blowouts, leading to disastrous events like the 2010 Gulf of Mexico Oil Spill.

The deeper the well, the higher the pressure, and the higher the risks associated with tapping oil from wells. During drilling, when the pressure applied to balance the hydrocarbon pressure in a well is not great enough to overcome that exerted by gas and fluids in the rock formation drilled, water, gas, oil, or other formation fluid can enter the hole. This is called a “gas kick,” which in worst-case scenarios can lead to blowouts.

In a paper published earlier this month in the SIAM Journal on Mathematical Analysis, author Steinar Evje presents new analysis of a mathematical model that has applications to the study of such gas kicks in deep-water oil wells.

The use of mathematical models is important for the development of tools that can help simulate, and hence, increase control in deep-water well operations. “Various gas kick simulators are being developed for the purpose of studying well control aspects during exploratory and development drilling,” says Evje. “Simulators have become an important tool for the development of new, more efficient and safer drilling methods.”

“A simulator for drilling operations is composed of a set of nonlinear coupled partial differential equations that describe the simultaneous flow of hydrocarbons in a well. This mathematical model represents a ‘virtual laboratory’ where the finer mechanisms related to a number of different physical effects can be studied in detail,” Evje goes on to explain.

The main challenge presented in many of these models is the precise prediction of the pressure profile in addition to liquid/gas volumes and flow rates at various points along the oil well. “This issue becomes even more critical as many drilling operations today involve long and deep wells with corresponding high pressures and high temperatures,” Evje explains. Regions along the well that are open to crevices and deformities in the rock formations present specific challenges, as it is critical to maintain well pressure at these positions within certain limits. Thus, in the case of inflow of gas from surrounding rock formations, it would be important to safely transport this gas out of the well.

The starting point for Evje’s proposed mathematical model is a one-dimensional two-phase model, which is often used to simulate unsteady, compressible liquid and gas flow in pipes and wells. Unlike previously analyzed models, in this gas-liquid model, the two phases may have unequal fluid velocity and a generalized term to jointly represent liquid and gas pressure.

This allows a model that can describe the ascent of a gas slug (conglomerate of high pressure gas bubbles) due to buoyancy forces in a vertical well. A gas-kick situation is usually accompanied by such a flow scenario.

In order to compute reliable solutions, it is crucial to have a model that is well defined mathematically. Mathematical methods are applied in order to derive upper and lower limits for various quantities like masses and fluid velocities, which provide insight into the parameters that are important for the control of these quantities. In addition, they allow proof of the existence of solutions for the model in a strict mathematical sense. In this paper, the author demonstrates that under certain assumptions, a solution exists.

Conditions are assumed to be isothermal, and relevant physical mechanisms are factored into the model, such as frictional forces, hydrostatic pressure, force of gravity, and compression and decompression of gas.

Such mathematical analysis is essential to optimize and evaluate drilling operations and well-control practices in order to minimize the possibility of oil well disasters, especially in deep-water wells. “The possibility of blowout occurrences needs to be mitigated in order to avoid human casualties, financial losses, and finally but not least, environmental damage,” says Evje.

Newly discovered Icelandic current could change North Atlantic climate picture

An international team of researchers, including physical oceanographers from the Woods Hole Oceanographic Institution (WHOI), has confirmed the presence of a deep-reaching ocean circulation system off Iceland that could significantly influence the ocean’s response to climate change in previously unforeseen ways.

The current, called the North Icelandic Jet (NIJ), contributes to a key component of the Atlantic Meridional Overturning Circulation (AMOC), also known as the “great ocean conveyor belt,” which is critically important for regulating Earth’s climate. As part of the planet’s reciprocal relationship between ocean circulation and climate, this conveyor belt transports warm surface water to high latitudes where the water warms the air, then cools, sinks, and returns towards the equator as a deep flow.

Crucial to this warm-to-cold oceanographic choreography is the Denmark Strait Overflow Water (DSOW), the largest of the deep, overflow plumes that feed the lower limb of the conveyor belt and return the dense water south through gaps in the Greenland-Scotland Ridge.

For years it has been thought that the primary source of the Denmark Overflow is a current adjacent to Greenland known as the East Greenland Current. However, this view was recently called into question by two oceanographers from Iceland who discovered a deep current flowing southward along the continental slope of Iceland. They named the current the North Icelandic Jet and hypothesized that it formed a significant part of the overflow water.

Now, in a paper published in the Aug. 21 online issue of the journal Nature Geoscience, the team of researchers-including the two Icelanders who discovered it-has confirmed that the Icelandic Jet is not only a major contributor to the DSOW but “is the primary source of the densest overflow water.”

“In our paper we present the first comprehensive measurements of the NIJ,” said Robert S. Pickart of WHOI, one of the authors of the study. “Our data demonstrate that the NIJ indeed carries overflow water into Denmark Strait and is distinct from the East Greenland Current. We show that the NIJ constitutes approximately half of the total overflow transport and nearly all of the densest component.

The researchers used a numerical model to hypothesize where and how the NIJ is formed. “We’ve identified a new paradigm,” he said. “We’re hypothesizing a new, overturning loop” of warm water to cold.

The results, Pickart says, have “important ramifications” for ocean circulation’s impact on climate. Climate specialists have been concerned that the conveyor belt is slowing down due to a rise in global temperatures. They suggest that increasing amounts of fresh water from melting ice and other warming-related phenomena are making their way into the northern North Atlantic, where it could freeze, which would prevent the water from sinking and decrease the need for the loop to deliver as much warm water as it does now. Eventually, this could lead to a colder climate in the northern hemisphere.

While this scenario is far from certain, it is critical that researchers understand the overturning process, he said, to be able to make accurate predictions about the future of climate and circulation interaction. “If a large fraction of the overflow water comes from the NIJ, then we need to re-think how quickly the warm-to-cold conversion of the AMOC occurs, as well as how this process might be altered under a warming climate,” Pickart said.

“These results implicate local water mass transformation and exchange near Iceland as central contributors to the deep limb of the Atlantic Meridional Overturning Circulation, and raise new questions about how global ocean circulation will respond to future climate change,” said Eric Itsweire, program director in the U.S. National Science Foundation (NSF)’s Division of Ocean Sciences, which funded the research.

The Research Council of Norway also funded the analysis of the data.

Pickart and a team of scientists from the U.S., Iceland, Norway, and the Netherlands are scheduled to embark on Aug. 22 on a cruise aboard the WHOI-operated R/V Knorr to collect new information on the overturning in the Iceland Sea.

“During our upcoming cruise on the Knorr we will, for the first time, deploy an array of year-long moorings across the entire Denmark Strait to quantify the NIJ and distinguish it from the East Greenland Current,” Pickart said. “Then we will collect shipboard measurements in the Iceland Sea to the north of the mooring line to determine more precisely where and how the NIJ originates.”

Research finds Greenland glacier melting faster than expected

A key glacier in Greenland is melting faster than previously expected, according to findings by a team of academics, including Dr Edward Hanna from University of Sheffield.

Dr Hanna, from the University of Sheffield’s Department of Geography, was part of a team of researchers that also included Dr Sebastian Mernild from the Los Alamos Laboratory, USA, and Professor Niels Tvis Knudsen from the University of Aarhus, Denmark. The team’s new findings present crucial insight into the effects of climate change.

The researchers found that Greenland’s longest-observed glacier, Mittivakkat Glacier, made two consecutive record losses in mass observations for 2010 and 2011. The observations indicate that the total 2011 mass budget loss was 2.45 metres, 0.29 metres higher than the previous observed record loss in 2010. The 2011 value was also significantly above the 16-year average observed loss of 0.97 metres per year.

The 2011 observations further illustrate, even comparing the mass balance value against simulated glacier mass balance values back to 1898, that 2011 is a record-breaking glacier mass loss year.

Mittivakkat Glacier has been surveyed for mass balance and glacier front fluctuations since 1995 and 1931 respectively. In 2011 the glacier terminus has retreated about 22 metres, 12 metres less than the observed record of 34 metres in 2010, and approximately 1,300 metres in total since the first photographic observations in 1931.

These observations suggest that recent Mittivakkat Glacier mass losses, which have been driven largely by higher surface temperatures and low precipitation, are representative of the broader region, which includes many hundreds of local glaciers in Greenland. Observations of other glaciers in Greenland show terminus retreats comparable to that of Mittivakkat Glacier. These glaciers are similar to the Mittivakkat Glacier in size and elevation range.

Local glacier observations in Greenland are rare, and the Mittivakkat Glacier is the only glacier in Greenland for which long-term observations of both the surface mass balance and glacier front fluctuations exist.

Since 1995, the general trend for the Mittivakkat Glacier has been toward higher temperatures, less snowfall, and a more negative glacier mass balance, with record mass loss in 2011. In 14 of the last 16 years, the Mittivakkat Glacier had a negative surface mass balance.

Principal Investigator on this summer’s fieldwork, Dr Edward Hanna, commented: “Our fieldwork results are a key indication of the rapid changes now being seen in and around Greenland, which are evident not just on this glacier but also on many surrounding small glaciers. It’s clear that this is now a very dynamic environment in terms of its response and mass wastage to ongoing climate change.

“The retreat of these small glaciers also makes the nearby Greenland Ice Sheet more vulnerable to further summer warming which is likely to occur. There could also be an effect on North Atlantic Ocean circulation and weather patterns through melting so much extra ice. An extended glacier observation programme in east Greenland for the next few years is clearly needed to improve understanding of the links between climate change and response of the glaciers in this important region.”

The project marks an important practical collaborative venture of both the joint research centre of the Universities of Sheffield and Aarhus, and Los Alamos, with funding support provided by the European Community’s Seventh Framework Programme.

Moon and Earth may be younger than originally thought

New research using a technique that measures the isotopes of lead and neodymium in lunar crustal rocks shows that the moon and Earth may be millions of years younger than originally thought.

The common estimate of the moon’s age is as old as 4.5 billion years old (roughly the same age as the solar system) as determined by mineralogy and chemical analysis of moon rocks gathered during the Apollo missions. However, Lawrence Livermore National Laboratory scientist Lars Borg and international collaborators have analyzed three isotopic systems, including the elements lead, samarium and neodymium found in ancient lunar rocks, and determined that the moon could be much younger than originally estimated. In fact, its age may be 4.36 billion years old.

The new research has implications for the age of Earth as well. Common belief is that the moon formed from a giant impact into the Earth and then solidified from an ocean of molten rock (magma).

“If our analysis represents the age of the moon, then the Earth must be fairly young as well,” said chemist Borg. “This is in stark contrast to a planet like Mars, which is argued to have formed around 4.53 billion years ago. If the age we report is from one of the first formed lunar rocks, then the moon is about 165 million years younger than Mars and about 200 million years younger than large asteroids.”

The isotopic measurements were made by taking samples of ferroan anorthosite (FAN), a type of moon crustal rock, which is considered to represent the oldest lunar crustal rock type.

Borg said that these analyses showed that the moon likely solidified significantly later than most previous estimates or that the long-held belief that FANs are flotation cumulates of a primordial magma ocean is incorrect.

Chemical evolution of planetary bodies ranging from asteroids to large rocky planets is thought to begin with differentiation through solidification of magma oceans hundreds of kilometers in depth. The Earth’s moon is the typical example of this type of differentiation. However, one interpretation of Borg’s findings is that this may not have occurred on the moon.

“The moon is supposed to be old and have a lunar magma ocean, but our new measurements show the moon is young and did not have a magma ocean,” Borg said.

“The isotopic measurements showed that a specific FAN yields consistent ages from multiple isotopic dating techniques and strongly suggest that the ages record the time at which the rock crystallized,” Borg said. “Other studies have not been able to do this.”

Researchers chart long-shrouded glacial reaches of Antarctica

A vast network of previously unmapped glaciers on the move from thousands of miles inland to the Antarctic coast has been charted for the first time by UC Irvine scientists. The findings will be critical to tracking future sea rise from climate change.

“This is like seeing a map of all the oceans’ currents for the first time. It’s a game changer for glaciology,” said UCI earth system science professor Eric Rignot, lead author of a paper on the ice flow published online today in Science Express. “We’re seeing amazing flows from the heart of the continent that had never been described before.”

Rignot, who is also with NASA’s Jet Propulsion Laboratory, and UCI associate project scientists Jeremie Mouginot and Bernd Scheuchl used billions of points of data captured by European, Japanese and Canadian satellites to weed out cloud cover, solar glare and land features. With the aid of NASA technology, they painstakingly pieced together the shape and velocity of glacial formations, including the huge bulk of previously uncharted East Antarctica, which comprises 77 percent of the continent.

Like viewing a completed jigsaw puzzle, Rignot said, the men were stunned when they stood back and took in the full picture. They discovered a new ridge splitting the 5.4 million-square-mile landmass from east to west. They found unnamed formations moving up to 800 feet each year across immense plains sloping toward the Southern Ocean – and in a different manner than past models of ice migration.

“These researchers created something deceptively simple: a map of the speed and direction of ice in Antarctica,” said Thomas Wagner, a cryospheric program scientist with NASA’s MEaSUREs program, which funded the work. “But they used it to figure out something fundamentally new: that ice moves by slipping at its bed, not just at the coast but all the way to the deep interior of Antarctica.”

“That’s critical knowledge for predicting future sea-level rise,” he added. “It means that if we lose ice at the coasts from the warming ocean, we open the tap to the ice in the interior.”

The work was completed during a period called the International Polar Year, and is the first such study since 1957. Collaborators working under the aegis of the Space Task Group were NASA, European Space Agency, Canadian Space Agency, Japanese Aerospace Exploration Agency, as well as the Alaska Satellite Facility, and MacDonald, Dettwiler & Associates Ltd.

“To our knowledge, this is the first time that a tightly knit collaboration of civilian space agencies has worked together to create such a huge dataset of this type,” said Yves Crevier of the Canadian Space Agency. “It is a dataset of lasting scientific value in assessing the extent and rate of change in polar regions.”

Model shows polar ice caps can recover from warmer climate-induced melting

A growing body of recent research indicates that, in Earth’s warming climate, there is no “tipping point,” or threshold warm temperature, beyond which polar sea ice cannot recover if temperatures come back down. New University of Washington research indicates that even if Earth warmed enough to melt all polar sea ice, the ice could recover if the planet cooled again.

In recent years scientists have closely monitored the shrinking area of the Arctic covered by sea ice in warmer summer months, a development that has created new shipping lanes but also raised concerns about humans living in the region and the survival of species such as polar bears.

In the new research, scientists used one of two computer-generated global climate models that accurately reflect the rate of sea-ice loss under current climate conditions, a model so sensitive to warming that it projects the complete loss of September Arctic sea ice by the middle of this century.

However, the model takes several more centuries of warming to completely lose winter sea ice, and doing so required carbon dioxide levels to be gradually raised to a level nearly nine times greater than today. When the model’s carbon dioxide levels then were gradually reduced, temperatures slowly came down and the sea ice eventually returned.

“We expected the sea ice to be completely gone in winter at four times the current level of carbon dioxide but we had to raise it by more than eight times,” said Cecilia Bitz, a UW associate professor of atmospheric sciences.

“All that carbon dioxide made a very, very warm planet. It was about 6 degrees Celsius (11 degrees Fahrenheit) warmer than it is now, which caused the Arctic to be completely free of sea ice in winter.”

Bitz and members of her research group are co-authors of a paper about the research that is to be published in Geophysical Research Letters. The lead author is Kyle Armour, a UW graduate student in physics, and other co-authors are Edward Blanchard-Wrigglesworth and Kelly McCusker, UW graduate students in atmospheric sciences, and Ian Eisenman, a postdoctoral researcher from the California Institute of Technology and UW.

In the model, the scientists raised atmospheric carbon dioxide 1 percent each year, which resulted in doubling the levels of the greenhouse gas about every 70 years. The model began with an atmospheric carbon dioxide level of 355 parts per million (in July the actual figure stood at 392 ppm).

In that scenario, it took about 230 years to reach temperatures at which the Earth was free of sea ice during winter. At that point, atmospheric carbon dioxide was greater than 3,100 parts per million.

Then the model’s carbon dioxide level was reduced at a rate of 1 percent a year until, eventually, temperatures retreated to closer to today’s levels. Bitz noted that the team’s carbon dioxide-reduction scenario would require more than just a reduction in emissions that could be achieved by placing limits on the burning of fossil fuels. The carbon dioxide would have to be drawn out of the atmosphere, either naturally or mechanically.

“It is really hard to turn carbon dioxide down in reality like we did in the model. It’s just an exercise, but it’s a useful one to explore the physics of the system.”

While the lack of a “tipping point” could be considered good news, she said, the increasing greenhouse gases leave plenty of room for concern.

“Climate change doesn’t have to exhibit exotic phenomena to be dangerous,” Bitz said, adding that while sea ice loss can have some positive effects, it is proving harmful to species such as polar bears that live on the ice and to some people who have been forced to relocate entire villages.

“The sea ice cover will continue to shrink so long as the Earth continues to warm,” she said. “We don’t have to hypothesize dramatic phenomena such as tipping points for this situation to become challenging.”

Arctic ice melt could pause in coming decades

Scientists are finding some surprising results about sea ice in the Arctic. -  NOAA
Scientists are finding some surprising results about sea ice in the Arctic. – NOAA

Despite the rapid retreat of Arctic sea ice in recent years, the ice may temporarily stabilize or somewhat expand at times over the next few decades, new research indicates.

Results of a study by scientists at the National Center for Atmospheric Research (NCAR) appear this week in the journal Geophysical Research Letters (GRL), published by the American Geophysical Union.

The National Science Foundation (NSF), NCAR’s sponsor, funded the work.

“As we learn more about climate variability, new and unexpected research results are coming to light,” says Sarah Ruth, program director in the Division of Atmospheric and Geospace Sciences, which funds NCAR for NSF. “What’s needed now are longer-term observations to better understand the effect of climate change on Arctic sea ice.”

The computer modeling study reinforces previous findings by other researchers that the level of Arctic sea ice loss observed in recent decades cannot be explained by natural causes alone, and that the ice will eventually melt away during summer if the climate continues to warm.

But in an unexpected new result, the NCAR research team found that Arctic ice under current climate conditions is as likely to expand as it is to contract for periods of up to about a decade.

“One of the results that surprised us all was the number of computer simulations that indicated a temporary halt to the loss of the ice,” says NCAR scientist Jennifer Kay, the lead researcher.

“The computer simulations suggest that we could see a 10-year period of stable ice or even a slight increase in the extent of the ice.

“Even though the observed ice loss has accelerated over the last decade, the fate of sea ice over the next decade depends not only on human activity but also on climate variability that cannot be predicted.”

Kay explains that variations in atmospheric conditions such as wind patterns could, for example, temporarily halt the sea ice loss. Still, the ultimate fate of the ice in a warming world is clear, she says.

“When you start looking at longer-term trends, 50 or 60 years, there’s no escaping the loss of ice in the summer.”

Kay and her colleagues also ran computer simulations to answer a fundamental question: why did Arctic sea ice melt far more rapidly in the late 20th century than projected by computer models?

By analyzing multiple realizations of the 20th century from a single climate model, they attribute approximately half the observed decline to human emissions of greenhouse gases, and the other half to climate variability.

These findings point to climate change and variability working together equally to accelerate the observed sea ice loss during the late 20th century.

Since accurate satellite measurements became available in 1979, the extent of summertime Arctic sea ice has shrunk by about one third.

The ice returns each winter, but the extent shrank to a record low in September 2007 and is again extremely low this year, already setting a monthly record low for July.

Scientists warned just a few years ago that the Arctic could lose its summertime ice cover by the end of the century.

Some research has indicated that Arctic summers could be largely ice-free within the next several decades.

To simulate what is happening with the ice, the NCAR team used a newly updated version of one of the world’s most powerful computer climate models.

The software, known as the Community Climate System Model, was developed at NCAR in collaboration with scientists at multiple organizations and with funding by NSF and the Department of Energy.

The research team first evaluated whether the model was a credible tool for the study.

By comparing the computer results with Arctic observations, they verified that, though the model has certain biases, it can capture observed late 20th century sea ice trends and the observed thickness and seasonal variations in the extent of the ice.

Kay and her colleagues then conducted a series of future simulations that looked at how Arctic sea ice was affected both by natural conditions and by the increased level of greenhouse gases in the atmosphere.

The computer studies indicated that the year-to-year and decade-to-decade trends in the extent of sea ice are likely to fluctuate increasingly as temperatures warm and the ice thins.

“Over periods up to a decade, both positive and negative trends become more pronounced in a warming world,” says NCAR scientist Marika Holland, a co-author of the GRL paper.

The simulations also indicated that Arctic sea ice is equally likely to expand or contract over short time periods under the climate conditions of the late 20th and early 21st century.

Although the Community Climate System Model simulations provide new insights, the paper cautions that more modeling studies and longer-term observations are needed to better understand the impacts of climate change and weather variability on Arctic ice.

The authors note that it is also difficult to disentangle the variability of weather systems and sea ice patterns from the ongoing impacts of human emissions of greenhouse gases.

“The changing Arctic climate is complicating matters,” Kay says. “We can’t measure natural variability now because, when temperatures warm and the ice thins, the ice variability changes and is not entirely natural.”

Tsunami observed by radar

The tsunami that devastated Japan on March 11 was picked up by high-frequency radar in California and Japan as it swept toward their coasts, according to U.S. and Japanese scientists. This is the first time that a tsunami has been observed by radar, raising the possibility of new early warning systems.

“It could be really useful in areas such as south-east Asia where there are huge areas of shallow continental shelf,” said Professor John Largier, an oceanographer at the University of California, Davis, Bodega Marine Laboratory, and an author of a new paper describing the work. The paper appears this month in the journal Remote Sensing.


Largier and his colleagues have been using a high-frequency radar array at the Bodega Marine Lab to study ocean currents for the last 10 years. The Bodega lab is part of a network of coastal radar sites funded by the State of California for oceanographic research.

Largier, together with collaborators from Hokkaido and Kyoto universities in Japan and San Francisco State University, used data from radar sites at Bodega Bay, Trinidad, Calif., and two sites in Hokkaido, Japan, to look for the tsunami offshore.

The scientists found that the radar picks up not the actual tsunami wave – which is small in height while out at sea – but changes in currents as the wave passes.

The researchers found they could see the tsunami once it entered shallower coastal waters over the continental shelf. As the waves enter shallower water, they slow down, increase in height and decrease in wavelength until finally hitting the coast.

The continental shelf off the California coast is quite narrow, and approaches to the coast are already well-monitored by pressure gauges, Largier noted. But he said radar detection could be useful, for example, on the East Coast or in Southeast Asia, where there are wide expanses of shallow seas.

Oxygen’s watery past

Today, oxygen takes up a hefty portion of Earth’s atmosphere: Life-sustaining O2 molecules make up 21 percent of the air we breathe. However, very early in Earth’s history, O2 was a rare – if not completely absent – player in the turbulent mix of primordial gases. It wasn’t until the “Great Oxidation Event” (GOE), nearly 2.3 billion years ago, when oxygen made any measurable dent in the atmosphere, stimulating the evolution of air-breathing organisms and, ultimately, complex life as we know it today.

Now, new research from MIT suggests O2 may have been made on Earth hundreds of millions of years before its debut in the atmosphere, keeping a low profile in “oxygen oases” in the oceans. The MIT researchers found evidence that tiny aerobic organisms may have evolved to survive on extremely low levels of the gas in these undersea oases.

In laboratory experiments, former MIT graduate student Jacob Waldbauer, working with Professor of Geobiology Roger Summons and Dianne Newman, formerly of MIT’s Department of Biology and now at the California Institute of Technology, found that yeast – an organism that can survive with or without oxygen – is able to produce key oxygen-dependent compounds, even with only miniscule puffs of the gas.

The findings suggest that early ancestors of yeast could have been similarly resourceful, working with whatever small amounts of O2 may have been circulating in the oceans before the gas was detectable in the atmosphere. The team published its findings last week in the Proceedings of the National Academy of Sciences.

“The time at which oxygen became an integral factor in cellular metabolism was a pivotal point in Earth history,” Summons says. “The fact that you could have oxygen-dependent biosynthesis very early on in the Earth’s history has significant implications.”

The group’s results may help reconcile a debate within the earth sciences community: About a decade ago, geochemists encountered sedimentary rocks containing fossil steroids, an essential component of some organisms’ cell membranes. Making a single molecule of a sterol, such as cholesterol, from scratch requires at least 10 molecules of O2; since the molecular fossils date back to 300 million years before the GOE, some have interpreted them as the earliest evidence of oxygen’s presence on Earth. But because other evidence for the presence of oxygen in rocks of similar age is inconclusive, many geologists have questioned whether the fossilized steroids are indeed proof of early oxygen.

Waldbauer and colleagues suggest that perhaps O2 was in fact present on Earth 300 million years before it spiked in the atmosphere – just at extremely low concentrations that wouldn’t have left much of a trace in the rock record. They reasoned that, even at such low levels, this O2 may have been sufficient to feed aerobic, sterol-producing organisms.

To test their theory, they looked to modern yeast as a model. Yeast naturally uses O2, in combination with sugars, to synthesize ergosterol, its primary sterol. Yeast can also grow without O2, so long as a source of ergosterol is provided. To find the lowest level of O2 yeast can consume, the team set up an experiment to identify the point at which yeast switches from anaerobic to aerobic activity.

Waldbauer grew yeast cells with a mixture of essential ingredients, including ergosterol as well as glucose labeled with carbon-13. They found that, without oxygen present, yeast happily took up sterol from the medium but made none from scratch. When Waldbauer pumped in tiny amounts of oxygen, a switch occurred, and yeast began using O2 in combination with glucose to produce its own sterols. The presence of carbon-13 differentiates the biosynthesized sterol from that acquired from the growth medium.

The scientists found that yeast are able to make steroids using vanishingly small, nanomolar concentrations of O2, supporting the theory that oxygen – and its producers and consumers – may have indeed been around long before the gas made an appearance in the atmosphere.

Waldbauer and Summons surmise that oxygen production and consumption may have occurred in the oceans for hundreds of millions of years before the atmosphere saw even a trace of the gas. They say that in all likelihood, cyanobacteria, blue-green algae living at the ocean surface, evolved the ability to produce O2 via sunlight in a process known as oxygenic photosynthesis. But instead of building up in the oceans and then seeping into the atmosphere, O2 may have been rapidly consumed by early aerobic organisms. Large oceanic and atmospheric sinks, such as iron and sulfide spewing out of subsea volcanoes, likely consumed whatever O2 was left over.

“We know all kinds of biology happens without any O2 at all,” says Waldbauer, now a postdoc at Caltech. “But it’s quite possible there was a vigorous cycle of O2 happening in some places, and other places it might have been completely absent.