Study hints that ancient Earth made its own water — geologically

A new study is helping to answer a longstanding question that has recently moved to the forefront of earth science: Did our planet make its own water through geologic processes, or did water come to us via icy comets from the far reaches of the solar system?

The answer is likely “both,” according to researchers at The Ohio State University– and the same amount of water that currently fills the Pacific Ocean could be buried deep inside the planet right now.

At the American Geophysical Union (AGU) meeting on Wednesday, Dec. 17, they report the discovery of a previously unknown geochemical pathway by which the Earth can sequester water in its interior for billions of years and still release small amounts to the surface via plate tectonics, feeding our oceans from within.

In trying to understand the formation of the early Earth, some researchers have suggested that the planet was dry and inhospitable to life until icy comets pelted the earth and deposited water on the surface.

Wendy Panero, associate professor of earth sciences at Ohio State, and doctoral student Jeff Pigott are pursuing a different hypothesis: that Earth was formed with entire oceans of water in its interior, and has been continuously supplying water to the surface via plate tectonics ever since.

Researchers have long accepted that the mantle contains some water, but how much water is a mystery. And, if some geological mechanism has been supplying water to the surface all this time, wouldn’t the mantle have run out of water by now?

Because there’s no way to directly study deep mantle rocks, Panero and Pigott are probing the question with high-pressure physics experiments and computer calculations.

“When we look into the origins of water on Earth, what we’re really asking is, why are we so different than all the other planets?” Panero said. “In this solar system, Earth is unique because we have liquid water on the surface. We’re also the only planet with active plate tectonics. Maybe this water in the mantle is key to plate tectonics, and that’s part of what makes Earth habitable.”

Central to the study is the idea that rocks that appear dry to the human eye can actually contain water–in the form of hydrogen atoms trapped inside natural voids and crystal defects. Oxygen is plentiful in minerals, so when a mineral contains some hydrogen, certain chemical reactions can free the hydrogen to bond with the oxygen and make water.

Stray atoms of hydrogen could make up only a tiny fraction of mantle rock, the researchers explained. Given that the mantle is more than 80 percent of the planet’s total volume, however, those stray atoms add up to a lot of potential water.

In a lab at Ohio State, the researchers compress different minerals that are common to the mantle and subject them to high pressures and temperatures using a diamond anvil cell–a device that squeezes a tiny sample of material between two diamonds and heats it with a laser–to simulate conditions in the deep Earth. They examine how the minerals’ crystal structures change as they are compressed, and use that information to gauge the minerals’ relative capacities for storing hydrogen. Then, they extend their experimental results using computer calculations to uncover the geochemical processes that would enable these minerals to rise through the mantle to the surface–a necessary condition for water to escape into the oceans.

In a paper now submitted to a peer-reviewed academic journal, they reported their recent tests of the mineral bridgmanite, a high-pressure form of olivine. While bridgmanite is the most abundant mineral in the lower mantle, they found that it contains too little hydrogen to play an important role in Earth’s water supply.

Another research group recently found that ringwoodite, another form of olivine, does contain enough hydrogen to make it a good candidate for deep-earth water storage. So Panero and Pigott focused their study on the depth where ringwoodite is found–a place 325-500 miles below the surface that researchers call the “transition zone”–as the most likely region that can hold a planet’s worth of water. From there, the same convection of mantle rock that produces plate tectonics could carry the water to the surface.

One problem: If all the water in ringwoodite is continually drained to the surface via plate tectonics, how could the planet hold any in reserve?

For the research presented at AGU, Panero and Pigott performed new computer calculations of the geochemistry in the lowest portion of the mantle, some 500 miles deep and more. There, another mineral, garnet, emerged as a likely water-carrier–a go-between that could deliver some of the water from ringwoodite down into the otherwise dry lower mantle.

If this scenario is accurate, the Earth may today hold half as much water in its depths as is currently flowing in oceans on the surface, Panero said–an amount that would approximately equal the volume of the Pacific Ocean. This water is continuously cycled through the transition zone as a result of plate tectonics.

“One way to look at this research is that we’re putting constraints on the amount of water that could be down there,” Pigott added.

Panero called the complex relationship between plate tectonics and surface water “one of the great mysteries in the geosciences.” But this new study supports researchers’ growing suspicion that mantle convection somehow regulates the amount of water in the oceans. It also vastly expands the timeline for Earth’s water cycle.

“If all of the Earth’s water is on the surface, that gives us one interpretation of the water cycle, where we can think of water cycling from oceans into the atmosphere and into the groundwater over millions of years,” she said. “But if mantle circulation is also part of the water cycle, the total cycle time for our planet’s water has to be billions of years.”

Hidden movements of Greenland Ice Sheet, runoff revealed

For years NASA has tracked changes in the massive Greenland Ice Sheet. This week scientists using NASA data released the most detailed picture ever of how the ice sheet moves toward the sea and new insights into the hidden plumbing of melt water flowing under the snowy surface.

The results of these studies are expected to improve predictions of the future of the entire Greenland ice sheet and its contribution to sea level rise as researchers revamp their computer models of how the ice sheet reacts to a warming climate.

“With the help of NASA satellite and airborne remote sensing instruments, the Greenland Ice Sheet is finally yielding its secrets,” said Tom Wagner, program scientist for NASA’s cryosphere program in Washington. “These studies represent new leaps in our knowledge of how the ice sheet is losing ice. It turns out the ice sheet is a lot more complex than we ever thought.”

University at Buffalo geophysicist Beata Csatho led an international team that produced the first comprehensive study of how the ice sheet is losing mass based on NASA satellite and airborne data at nearly 100,000 locations across Greenland. The study found that the ice sheet shed about 243 gigatons of ice per year from 2003-09, which agrees with other studies using different techniques. The study was published today in the Proceedings of the National Academy of Sciences.

The study suggests that current ice sheet modeling is too simplistic to accurately predict the future contribution of the Greenland ice sheet to sea level rise, and that current models may underestimate ice loss in the near future.

The project was a massive undertaking, using satellite and aerial data from NASA’s ICESat spacecraft, which measured the elevation of the ice sheet starting in 2003, and the Operation IceBridge field campaign that has flown annually since 2009. Additional airborne data from 1993-2008, collected by NASA’s Program for Arctic Regional Climate Assessment, were also included to extend the timeline of the study.

Current computer simulations of the Greenland Ice Sheet use the activity of four well-studied glaciers — Jakobshavn, Helheim, Kangerlussuaq and Petermann — to forecast how the entire ice sheet will dump ice into the oceans. The new research shows that activity at these four locations may not be representative of what is happening with glaciers across the ice sheet. In fact, glaciers undergo patterns of thinning and thickening that current climate change simulations fail to address, Csatho says.

As a step toward building better models of sea level rise, the research team divided Greenland’s 242 glaciers into 7 major groups based on their behavior from 2003-09.

“Understanding the groupings will help us pick out examples of glaciers that are representative of the whole,” Csatho says. “We can then use data from these representative glaciers in models to provide a more complete picture of what is happening.”

The team also identified areas of rapid shrinkage in southeast Greenland that today’s models don’t acknowledge. This leads Csatho to believe that the ice sheet could lose ice faster in the future than today’s simulations would suggest.

In separate studies presented today at the American Geophysical Union annual meeting in San Francisco, scientists using data from Operation IceBridge found permanent bodies of liquid water in the porous, partially compacted firn layer just below the surface of the ice sheet. Lora Koenig at the National Snow and Ice Data Center in Boulder, Colorado, and Rick Forster at the University of Utah in Salt Lake City, found signatures of near-surface liquid water using ice-penetrating radar.

Across wide areas of Greenland, water can remain liquid, hiding in layers of snow just below the surface, even through cold, harsh winters, researchers are finding. The discoveries by the teams led by Koenig and Forster mean that scientists seeking to understand the future of the Greenland ice sheet need to account for relatively warm liquid water retained in the ice.

Although the total volume of water is small compared to overall melting in Greenland, the presence of liquid water throughout the year could help kick off melt in the spring and summer. “More year-round water means more heat is available to warm the ice,” Koenig said.

Koenig and her colleagues found that sub-surface liquid water are common on the western edges of the Greenland Ice Sheet. At roughly the same time, Forster used similar ground-based radars to find a large aquifer in southeastern Greenland. These studies show that liquid water can persist near the surface around the perimeter of the ice sheet year round.

Another researcher participating in the briefing found that near-surface layers can also contain masses of solid ice that can lead to flooding events. Michael MacFerrin, a scientist at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder, and colleagues studying radar data from IceBridge and surface based instruments found near surface patches of ice known as ice lenses more than 25 miles farther inland than previously recorded.

Ice lenses form when firn collects surface meltwater like a sponge. When this shallow ice melts, as was seen during July 2012, they can release large amounts of water that can lead to flooding. Warm summers and resulting increased surface melt in recent years have likely caused ice lenses to grow thicker and spread farther inland. “This represents a rapid feedback mechanism. If current trends continue, the flooding will get worse,” MacFerrin said.




Video
Click on this image to view the .mp4 video
This animation (from March 2014) portrays the changes occurring in the surface elevation of the Greenland Ice Sheet since 2003 in three drainage areas: the southeast, the northeast and the Jakobshavn regions. In each region, the time advances to show the accumulated change in elevation, 2003-2012.

Downloadable video: http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=4022 – NASA SVS NASA’s Goddard Space Flight Center

Massive study provides first detailed look at how Greenland’s ice is vanishing

The surface of the Greenland Ice Sheet. A new study uses NASA data to provide the first detailed reconstruction of how the ice sheet and its many glaciers are changing. The research was led by University at Buffalo geologist Beata Csatho. -  Beata Csatho
The surface of the Greenland Ice Sheet. A new study uses NASA data to provide the first detailed reconstruction of how the ice sheet and its many glaciers are changing. The research was led by University at Buffalo geologist Beata Csatho. – Beata Csatho

The Greenland Ice Sheet is the second-largest body of ice on Earth. It covers an area about five times the size of New York State and Kansas combined, and if it melts completely, oceans could rise by 20 feet. Coastal communities from Florida to Bangladesh would suffer extensive damage.

Now, a new study is revealing just how little we understand this northern behemoth.

Led by geophysicist Beata Csatho, PhD, an associate professor of geology at the University at Buffalo, the research provides what the authors think is the first comprehensive picture of how Greenland’s ice is vanishing. It suggests that current ice sheet modeling studies are too simplistic to accurately predict the future contributions of the entire Greenland Ice Sheet to sea level rise, and that Greenland may lose ice more rapidly in the near future than previously thought.

“The great importance of our data is that for the first time, we have a comprehensive picture of how all of Greenland’s glaciers have changed over the past decade,” Csatho says.

“This information is crucial for developing and validating numerical models that predict how the ice sheet may change and contribute to global sea level over the next few hundred years,” says Cornelis J. van der Veen, PhD, professor in the Department of Geography at the University of Kansas, who played a key role in interpreting glaciological changes.

The project was a massive undertaking, using satellite and aerial data from NASA’s ICESat spacecraft and Operation IceBridge field campaign to reconstruct how the height of the Greenland Ice Sheet changed at nearly 100,000 locations from 1993 to 2012.

Ice loss takes place in a complex manner, with the ice sheet both melting and calving ice into the ocean.
The study had two major findings:

  • First, the scientists were able to provide new estimates of annual ice loss at high spatial resolution (see below).

  • Second, the research revealed that current models fail to accurately capture how the entire Greenland Ice Sheet is changing and contributing to rising oceans.

The second point is crucial to climate change modelers.

Today’s simulations use the activity of four well-studied glaciers — Jakobshavn, Helheim, Kangerlussuaq and Petermann — to forecast how the entire ice sheet will dump ice into the oceans.

But the new research shows that activity at these four locations may not be representative of what is happening with glaciers across the ice sheet. In fact, glaciers undergo patterns of thinning and thickening that current climate change simulations fail to address, Csatho says.

“There are 242 outlet glaciers wider than 1.5 km on the Greenland Ice Sheet, and what we see is that their behavior is complex in space and time,” Csatho says. “The local climate and geological conditions, the local hydrology — all of these factors have an effect. The current models do not address this complexity.”

The team identified areas of rapid shrinkage in southeast Greenland that today’s models don’t acknowledge. This leads Csatho to believe that the ice sheet could lose ice faster in the future than today’s simulations would suggest.

The results will be published on Dec. 15 in the Proceedings of the National Academy of Sciences, and the study and all information in this press release are embargoed until 3 p.m. Eastern Time that day.

Photos, data visualizations and video are available by contacting Charlotte Hsu at the University at Buffalo at chsu22@buffalo.edu.

How much ice is the Greenland Ice Sheet losing?

To analyze how the height of the ice sheet was changing, Csatho and UB research professor and photogrammetrist Anton Schenk, PhD, developed a computational technique called Surface Elevation Reconstruction And Change detection to fuse together data from NASA satellite and aerial missions.

The analysis found that the Greenland Ice Sheet lost about 243 metric gigatons of ice annually — equivalent to about 277 cubic kilometers of ice per year — from 2003-09, the period for which the team had the most comprehensive data. This loss is estimated to have added about 0.68 millimeters of water to the oceans annually.

The figures are averages, and ice loss varied from year to year, and from region to region.

Why are today’s projections of sea level rise flawed, and how can we fix them?

Glaciers don’t just gradually lose mass when the temperature rises. That’s one reason it’s difficult to predict their response to global warming.

In the study, scientists found that some of Greenland’s glaciers thickened even when the temperature rose. Others exhibited accelerated thinning. Some displayed both thinning and thickening, with sudden reversals.

As a step toward building better models of sea level rise, the research team divided Greenland’s 242 glaciers into 7 major groups based on their behavior from 2003-09.

“Understanding the groupings will help us pick out examples of glaciers that are representative of the whole,” Csatho says. “We can then use data from these representative glaciers in models to provide a more complete picture of what is happening.”

In a new project, she and colleagues are investigating why different glaciers respond differently to warming. Factors could include the temperature of the surrounding ocean; the level of friction between a glacier and the bedrock below; the amount of water under a glacier; and the geometry of the fjord.

“The physics of these processes are not well understood,” Csatho says.

The NASA missions: A colossal undertaking

The study combined data from various NASA missions, including:

  • NASA’s Ice, Cloud and Land Elevation Satellite (ICESat), which measured the ice sheet’s elevation multiple times a year at each of the nearly 100,000 locations from 2003-09.

  • NASA’s, massive aerial survey that employs highly specialized research aircrafts to collect data at less frequent intervals than ICESat. These missions began measuring the Greenland Ice Sheet’s elevation in 1993. Operation IceBridge was started in 2009 to bridge the time between ICESat-1 and ICESat-2, and will continue until at least 2017, when NASA’s next generation ICESat-2 satellite is expected to come online.

Csatho says the new study shows why careful monitoring is critical: Given the complex nature of glacier behavior, good data is crucial to building better models.

Collaborators

Besides Csatho, Schenk and van der Veen, the project included additional researchers from the University at Buffalo, Utrecht University in The Netherlands, the Technical University of Denmark and Florida Atlantic University.

Research links soil mineral surfaces to key atmospheric processes

Pictured are, from left, are David Bish, Melissa Donaldson and Jonathan Raff. -  Indiana University
Pictured are, from left, are David Bish, Melissa Donaldson and Jonathan Raff. – Indiana University

Research by Indiana University scientists finds that soil may be a significant and underappreciated source of nitrous acid, a chemical that plays a pivotal role in atmospheric processes such as the formation of smog and determining the lifetime of greenhouse gases.

The study shows for the first time that the surface acidity of common minerals found in soil determines whether the gas nitrous acid will be released into the atmosphere. The finding could contribute to improved models for understanding and controlling air pollution, a significant public health concern.

“We find that the surfaces of minerals in the soil can be much more acidic than the overall pH of the soil would suggest,” said Jonathan Raff, assistant professor in the School of Public and Environmental Affairs and Department of Chemistry. “It’s the acidity of the soil minerals that acts as a knob or a control lever, and that determines whether nitrous acid outgasses from soil or remains as nitrite.”

The article, “Soil surface acidity plays a determining role in the atmospheric-terrestrial exchange of nitrous acid,” will be published this week in the journal Proceedings of the National Academy of Sciences. Melissa A. Donaldson, a Ph.D. student in the School of Public and Environmental Affairs, is the lead author. Co-authors are Raff and David L. Bish, the Haydn Murray Chair of Applied Clay Mineralogy in the Department of Geological Sciences.

Nitrous acid, or HONO, plays a key role in regulating atmospheric processes. Sunlight causes it to break down into nitric oxide and the hydroxyl radical, OH. The latter controls the atmospheric lifetime of gases important to air quality and climate change and initiates the chemistry leading to the formation of ground-level ozone, a primary component of smog.

Scientists have known about the nitrous acid’s role in air pollution for 40 years, but they haven’t fully understood how it is produced and destroyed or how it interacts with other substances, because HONO is unstable and difficult to measure.

“Only in the last 10 years have we had the technology to study nitrous acid under environmentally relevant conditions,” Raff said.

Recent studies have shown nitrous acid to be emitted from soil in many locations. But this was unexpected because, according to basic chemistry, the reactions that release nitrous acid should take place only in extremely acidic soils, typically found in rain forests or the taiga of North America and Eurasia.

The standard method to determine the acidity of soil is to mix bulk soil with water and measure the overall pH. But the IU researchers show that the crucial factor is not overall pH but the acidity at the surface of soil minerals, especially iron oxides and aluminum oxides. At the molecular level, the water adsorbed directly to these minerals is unusually acidic and facilitates the conversion of nitrite in the soil to nitrous acid, which then volatilizes.

“With the traditional approach of calculating soil pH, we were severely underestimating nitrous acid emissions from soil,” Raff said. “I think the source is going to turn out to be more important than was previously imagined.”

The research was carried out using soil from a farm field near Columbus, Ind. But aluminum and iron oxides are ubiquitous in soil, and the researchers say the results suggest that about 70 percent of Earth’s soils could be sources of nitrous acid.

Ultimately, the research will contribute to a better understanding of how nitrous acid is produced and how it affects atmospheric processes. That in turn will improve the computer models used by the U.S. Environmental Protection Agency and other regulatory agencies to control air pollution, which the World Health Organization estimates contributes to 7 million premature deaths annually.

“With improved models, policymakers can make better judgments about the costs and benefits of regulations,” Raff said. “If we don’t get the chemistry right, we’re not going to get the right answers to our policy questions regarding air pollution.”

Migrating ‘supraglacial’ lakes could trigger future Greenland ice loss

Supraglacial lakes on the Greenland ice sheet can be seen as dark blue specks in the center and to the right of this satellite image. -  USGS/NASA Landsat
Supraglacial lakes on the Greenland ice sheet can be seen as dark blue specks in the center and to the right of this satellite image. – USGS/NASA Landsat

Predictions of Greenland ice loss and its impact on rising sea levels may have been greatly underestimated, according to scientists at the University of Leeds.

The finding follows a new study, which is published today in Nature Climate Change, in which the future distribution of lakes that form on the ice sheet surface from melted snow and ice – called supraglacial lakes – have been simulated for the first time.

Previously, the impact of supraglacial lakes on Greenland ice loss had been assumed to be small, but the new research has shown that they will migrate farther inland over the next half century, potentially altering the ice sheet flow in dramatic ways.

Dr Amber Leeson from the School of Earth and Environment and a member of the Centre for Polar Observation and Modelling (CPOM) team, who led the study, said: “Supraglacial lakes can increase the speed at which the ice sheet melts and flows, and our research shows that by 2060 the area of Greenland covered by them will double.”

Supraglacial lakes are darker than ice, so they absorb more of the Sun’s heat, which leads to increased melting. When the lakes reach a critical size, they drain through ice fractures, allowing water to reach the ice sheet base which causes it to slide more quickly into the oceans. These changes can also trigger further melting.

Dr Leeson explained: “When you pour pancake batter into a pan, if it rushes quickly to the edges of the pan, you end up with a thin pancake. It’s similar to what happens with ice sheets: the faster it flows, the thinner it will be.

“When the ice sheet is thinner, it is at a slightly lower elevation and at the mercy of warmer air temperatures than it would have been if it were thicker, increasing the size of the melt zone around the edge of the ice sheet.”

Until now, supraglacial lakes have formed at low elevations around the coastline of Greenland, in a band that is roughly 100 km wide. At higher elevations, today’s climate is just too cold for lakes to form.

In the study, the scientists used observations of the ice sheet from the Environmental Remote Sensing satellites operated by the European Space Agency and estimates of future ice melting drawn from a climate model to drive simulations of how meltwater will flow and pool on the ice surface to form supraglacial lakes.

Since the 1970s, the band in which supraglacial lakes can form on Greenland has crept 56km further inland. From the results of the new study, the researchers predict that, as Arctic temperatures rise, supraglacial lakes will spread much farther inland – up to 110 km by 2060 – doubling the area of Greenland that they cover today.

Dr Leeson said: “The location of these new lakes is important; they will be far enough inland so that water leaking from them will not drain into the oceans as effectively as it does from today’s lakes that are near to the coastline and connected to a network of drainage channels.”

“In contrast, water draining from lakes farther inland could lubricate the ice more effectively, causing it to speed up.”

Ice losses from Greenland had been expected to contribute 22cm to global sea-level rise by 2100. However, the models used to make this projection did not account for changes in the distribution of supraglacial lakes, which Dr Leeson’s study reveals will be considerable.

If new lakes trigger further increases in ice melting and flow, then Greenland’s future ice losses and its contribution to global sea-level rise have been underestimated.

The Director of CPOM, Professor Andrew Shepherd, who is also from the School of Earth and Environment at the University of Leeds and is a co-author of the study, said: “Because ice losses from Greenland are a key signal of global climate change, it’s important that we consider all factors that could affect the rate at which it will lose ice as climate warms.

“Our findings will help to improve the next generation of ice sheet models, so that we can have greater confidence in projections of future sea-level rise. In the meantime, we will continue to monitor changes in the ice sheet losses using satellite measurements.”

Further information:


The study was funded by the Natural Environment Research Council (NERC) through their support of the Centre for Polar Observation and Modelling and the National Centre for Earth Observation.

The research paper, Supraglacial lakes on the Greenland ice sheet advance inland under warming climate, is published in Nature Climate Change on 15 December 2014.

Dr Amber Leeson and Professor Andrew Shepherd are available for interview. Please contact the University of Leeds Press Office on 0113 343 4031 or email pressoffice@leeds.ac.uk

Technology-dependent emissions of gas extraction in the US

The KIT measurement instrument on board of a minivan directly measures atmospheric emissions on site with a high temporal resolution. -  Photo: F. Geiger/KIT
The KIT measurement instrument on board of a minivan directly measures atmospheric emissions on site with a high temporal resolution. – Photo: F. Geiger/KIT

Not all boreholes are the same. Scientists of the Karlsruhe Institute of Technology (KIT) used mobile measurement equipment to analyze gaseous compounds emitted by the extraction of oil and natural gas in the USA. For the first time, organic pollutants emitted during a fracking process were measured at a high temporal resolution. The highest values measured exceeded typical mean values in urban air by a factor of one thousand, as was reported in ACP journal. (DOI 10.5194/acp-14-10977-2014)

Emission of trace gases by oil and gas fields was studied by the KIT researchers in the USA (Utah and Colorado) together with US institutes. Background concentrations and the waste gas plumes of single extraction plants and fracking facilities were analyzed. The air quality measurements of several weeks duration took place under the “Uintah Basin Winter Ozone Study” coordinated by the National Oceanic and Atmospheric Administration (NOAA).

The KIT measurements focused on health-damaging aromatic hydrocarbons in air, such as carcinogenic benzene. Maximum concentrations were determined in the waste gas plumes of boreholes. Some extraction plants emitted up to about a hundred times more benzene than others. The highest values of some milligrams of benzene per cubic meter air were measured downstream of an open fracking facility, where returning drilling fluid is stored in open tanks and basins. Much better results were reached by oil and gas extraction plants and plants with closed production processes. In Germany, benzene concentration at the workplace is subject to strict limits: The Federal Emission Control Ordinance gives an annual benzene limit of five micrograms per cubic meter for the protection of human health, which is smaller than the values now measured at the open fracking facility in the US by a factor of about one thousand. The researchers published the results measured in the journal Atmospheric Chemistry and Physics ACP.

“Characteristic emissions of trace gases are encountered everywhere. These are symptomatic of gas and gas extraction. But the values measured for different technologies differ considerably,” Felix Geiger of the Institute of Meteorology and Climate Research (IMK) of KIT explains. He is one of the first authors of the study. By means of closed collection tanks and so-called vapor capture systems, for instance, the gases released during operation can be collected and reduced significantly.

“The gas fields in the sparsely populated areas of North America are a good showcase for estimating the range of impacts of different extraction and fracking technologies,” explains Professor Johannes Orphal, Head of IMK. “In the densely populated Germany, framework conditions are much stricter and much more attention is paid to reducing and monitoring emissions.”

Fracking is increasingly discussed as a technology to extract fossil resources from unconventional deposits. Hydraulic breaking of suitable shale stone layers opens up the fossil fuels stored there and makes them accessible for economically efficient use. For this purpose, boreholes are drilled into these rock formations. Then, they are subjected to high pressure using large amounts of water and auxiliary materials, such as sand, cement, and chemicals. The oil or gas can flow to the surface through the opened microstructures in the rock. Typically, the return flow of the aqueous fracking liquid with the dissolved oil and gas constituents to the surface lasts several days until the production phase proper of purer oil or natural gas. This return flow is collected and then reused until it finally has to be disposed of. Air pollution mainly depends on the treatment of this return flow at the extraction plant. In this respect, currently practiced fracking technologies differ considerably. For the first time now, the resulting local atmospheric emissions were studied at a high temporary resolution. Based on the results, emissions can be assigned directly to the different plant sections of an extraction plant. For measurement, the newly developed, compact, and highly sensitive instrument, a so-called proton transfer reaction mass spectrometer (PTR-MS), of KIT was installed on board of a minivan and driven closer to the different extraction points, the distances being a few tens of meters. In this way, the waste gas plumes of individual extraction sources and fracking processes were studied in detail.

Warneke, C., Geiger, F., Edwards, P. M., Dube, W., Pétron, G., Kofler, J., Zahn, A., Brown, S. S., Graus, M., Gilman, J. B., Lerner, B. M., Peischl, J., Ryerson, T. B., de Gouw, J. A., and Roberts, J. M.: Volatile organic compound emissions from the oil and natural gas industry in the Uintah Basin, Utah: oil and gas well pad emissions compared to ambient air composition, Atmos. Chem. Phys., 14, 10977-10988, doi:10.5194/acp-14-10977-2014, 2014.

Antarctica: Heat comes from the deep

The Antarctic ice sheet is a giant water reservoir. The ice cap on the southern continent is on average 2,100 meters thick and contains about 70 percent of the world’s fresh water. If this ice mass were to melt completely, it could raise the global sea level by 60 meters. Therefore scientists carefully observe changes in the Antarctic. In the renowned international journal Science, researchers from Germany, the UK, the US and Japan are now publishing data according to which water temperatures, in particular on the shallow shelf seas of West Antarctica, are rising. “There are many large glaciers in the area. The elevated temperatures have accelerated the melting and sliding of these glaciers in recent decades and there are no indications that this trend is changing,” says the lead author of the study, Dr. Sunke Schmidtko from GEOMAR Helmholtz Centre for Ocean Research Kiel.

For their study, he and his colleagues of the University of East Anglia, the California Institute of Technology and the University of Hokkaido (Japan) evaluated all oceanographic data from the waters around Antarctica from 1960 to 2014 that were available in public databases. These data show that five decades ago, the water masses in the West Antarctic shelf seas were already warmer than in other parts of Antarctica, for example, in the Weddell Sea. However, the temperature difference is not constant. Since 1960, the temperatures in the West Antarctic Amundsen Sea and the Bellingshausen Sea have been rising. “Based on the data we were able to see that this shelf process is induced from the open ocean,” says Dr. Schmidtko.

Around Antarctica in greater depth along the continental slope water masses with temperatures from 0.5 to 1.5°C (33-35°F) are predominant. These temperatures are very warm for Antarctic conditions. “These waters have warmed in West Antarctica over the past 50 years. And they are significant shallower than 50 years ago,” says Schmidtko. Especially in the Amundsen Sea and Bellingshausen Sea they now increasingly spill onto the shelf and warm the shelf.

“These are the regions in which accelerated glacial melting has been observed for some time. We show that oceanographic changes over the past 50 years have probably caused this melting. If the water continues to warm, the increased penetration of warmer water masses onto the shelf will likely further accelerate this process, with an impact on the rate of global sea level rise ” explains Professor Karen Heywood from the University of East Anglia.

The scientists also draw attention to the rising up of warm water masses in the southwestern Weddell Sea. Here very cold temperatures (less than minus 1.5°C or 29°F) prevail on the shelf and a large-scale melting of shelf ice has not been observed yet. If the shoaling of warm water masses continues, it is expected that there will be major environmental changes with dramatic consequences for the Filchner or Ronne Ice Shelf, too. For the first time glaciers outside the West Antarctic could experience enhanced melting from below.

To what extent the diverse biology of the Southern Ocean is influenced by the observed changes is not fully understood. The shelf areas include spawning areas for the Antarctic krill, a shrimp species widespread in the Southern Ocean, which plays a key role in the Antarctic food chain. Research results have shown that spawning cycles could change in warmer conditions. A final assessment of the impact has not yet been made.

The exact reasons for the increase of the heating and the rising of warm water masses has not yet been completely resolved. “We suspect that they are related to large-scale variations in wind systems over the southern hemisphere. But which processes specifically play a role must be evaluated in more detail.” says Dr. Schmidtko.

West Antarctic melt rate has tripled: UC Irvine-NASA

A comprehensive, 21-year analysis of the fastest-melting region of Antarctica has found that the melt rate of glaciers there has tripled during the last decade.

The glaciers in the Amundsen Sea Embayment in West Antarctica are hemorrhaging ice faster than any other part of Antarctica and are the most significant Antarctic contributors to sea level rise. This study is the first to evaluate and reconcile observations from four different measurement techniques to produce an authoritative estimate of the amount and the rate of loss over the last two decades.

“The mass loss of these glaciers is increasing at an amazing rate,” said scientist Isabella Velicogna, jointly of the UC Irvine and NASA’s Jet Propulsion Laboratory. Velicogna is a coauthor of a paper on the results, which has been accepted for Dec. 5 publication in the journal Geophysical Research Letters.

Lead author Tyler Sutterley, a UCI doctoral candidate, and his team did the analysis to verify that the melting in this part of Antarctica is shifting into high gear. “Previous studies had suggested that this region is starting to change very dramatically since the 1990s, and we wanted to see how all the different techniques compared,” Sutterley said. “The remarkable agreement among the techniques gave us confidence that we are getting this right.”

The researchers reconciled measurements of the mass balance of glaciers flowing into the Amundsen Sea Embayment. Mass balance is a measure of how much ice the glaciers gain and lose over time from accumulating or melting snow, discharges of ice as icebergs, and other causes. Measurements from all four techniques were available from 2003 to 2009. Combined, the four data sets span the years 1992 to 2013.

The glaciers in the embayment lost mass throughout the entire period. The researchers calculated two separate quantities: the total amount of loss, and the changes in the rate of loss.

The total amount of loss averaged 83 gigatons per year (91.5 billion U.S. tons). By comparison, Mt. Everest weighs about 161 gigatons, meaning the Antarctic glaciers lost a Mt.-Everest’s-worth amount of water weight every two years over the last 21 years.

The rate of loss accelerated an average of 6.1 gigatons (6.7 billion U.S. tons) per year since 1992.

From 2003 to 2009, when all four observational techniques overlapped, the melt rate increased an average of 16.3 gigatons per year — almost three times the rate of increase for the full 21-year period. The total amount of loss was close to the average at 84 gigatons.

The four sets of observations include NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites, laser altimetry from NASA’s Operation IceBridge airborne campaign and earlier ICESat satellite, radar altimetry from the European Space Agency’s Envisat satellite, and mass budget analyses using radars and the University of Utrecht’s Regional Atmospheric Climate Model.

The scientists noted that glacier and ice sheet behavior worldwide is by far the greatest uncertainty in predicting future sea level. “We have an excellent observing network now. It’s critical that we maintain this network to continue monitoring the changes,” Velicogna said, “because the changes are proceeding very fast.”

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Fountain of youth underlies Antarctic Mountains

Images of the ice-covered Gamburtsev Mountains revealed water-filled valleys, as seen by the cluster of vertical lines in this image. -  Tim Creyts
Images of the ice-covered Gamburtsev Mountains revealed water-filled valleys, as seen by the cluster of vertical lines in this image. – Tim Creyts

Time ravages mountains, as it does people. Sharp features soften, and bodies grow shorter and rounder. But under the right conditions, some mountains refuse to age. In a new study, scientists explain why the ice-covered Gamburtsev Mountains in the middle of Antarctica looks as young as they do.

The Gamburtsevs were discovered in the 1950s, but remained unexplored until scientists flew ice-penetrating instruments over the mountains 60 years later. As this ancient hidden landscape came into focus, scientists were stunned to see the saw-toothed and towering crags of much younger mountains. Though the Gamburtsevs are contemporaries of the largely worn-down Appalachians, they looked more like the Rockies, which are nearly 200 million years younger.

More surprising still, the scientists discovered a vast network of lakes and rivers at the mountains’ base. Though water usually speeds erosion, here it seems to have kept erosion at bay. The reason, researchers now say, has to do with the thick ice that has entombed the Gamburtsevs since Antarctica went into a deep freeze 35 million years ago.

“The ice sheet acts like an anti-aging cream,” said the study’s lead author, Timothy Creyts, a geophysicist at Columbia University’s Lamont-Doherty Earth Observatory. “It triggers a series of thermodynamic processes that have almost perfectly preserved the Gamburtsevs since ice began spreading across the continent.”

The study, which appears in the latest issue of the journal Geophysical Research Letters, explains how the blanket of ice covering the Gamburtsevs has preserved its rugged ridgelines.

Snow falling at the surface of the ice sheet draws colder temperatures down, closer to protruding peaks in a process called divergent cooling. At the same time, heat radiating from bedrock beneath the ice sheet melts ice in the deep valleys to form rivers and lakes. As rivers course along the base of the ice sheet, high pressures from the overlying ice sheet push water up valleys in reverse. This uphill flow refreezes as it meets colder temperature from above. Thus, ridgelines are cryogenically preserved.

The oldest rocks in the Gamburtsevs formed more than a billion years ago, in the collision of several continents. Though these prototype mountains eroded away, a lingering crustal root became reactivated when the supercontinent Gondwana ripped apart, starting about 200 million years ago. Tectonic forces pushed the land up again to form the modern Gamburtsevs, which range across an area the size of the Alps. Erosion again chewed away at the mountains until earth entered a cooling phase 35 million years ago. Expanding outward from the Gamburtsevs, a growing layer of ice joined several other nucleation points to cover the entire continent in ice.

The researchers say that the mechanism that stalled aging of the Gamburtsevs at higher elevations may explain why some ridgelines in the Torngat Mountains on Canada’s Labrador Peninsula and the Scandinavian Mountains running through Norway, Sweden and Finland appear strikingly untouched. Massive ice sheets covered both landscapes during the last ice age, which peaked about 20,000 years ago, but many high-altitude features bear little trace of this event.

“The authors identify a mechanism whereby larger parts of mountains ranges in glaciated regions–not just Antarctica–could be spared from erosion,” said Stewart Jamieson, a glaciologist at Durham University who was not involved in the study. “This is important because these uplands are nucleation centers for ice sheets. If they were to gradually erode during glacial cycles, they would become less effective as nucleation points during later ice ages.”

Ice sheet behavior, then, may influence climate change in ways that scientists and computer models have yet to appreciate. As study coauthor Fausto Ferraccioli, head of the British Antarctic Survey’s airborne geophysics group, put it: “If these mountains in interior East Antarctica had been more significantly eroded then the ice sheet itself
may have had a different history.”

Other Authors


Hugh Carr and Tom Jordan of the British Antarctic Survey; Robin Bell, Michael Wolovick and Nicholas Frearson of Lamont-Doherty; Kathryn Rose of University of Bristol; Detlef Damaske of Germany’s Federal Institute for Geosciences and Natural Resources; David Braaten of Kansas University; and Carol Finn of the U.S. Geological Survey.

Copies of the paper, “Freezing of ridges and water networks preserves the Gamburtsev Subglacial Mountains for millions of years,” are available from the authors.

Scientist Contact


Tim Creyts

845-365-8368

tcreyts@ldeo.columbia.edu

Climate capers of the past 600,000 years

The researchers remove samples from a core segment taken from Lake Van at the center for Marine environmental sciences MARUM in Bremen, where all of the cores from the PALEOVAN project are stored. -  Photo: Nadine Pickarski/Uni Bonn
The researchers remove samples from a core segment taken from Lake Van at the center for Marine environmental sciences MARUM in Bremen, where all of the cores from the PALEOVAN project are stored. – Photo: Nadine Pickarski/Uni Bonn

If you want to see into the future, you have to understand the past. An international consortium of researchers under the auspices of the University of Bonn has drilled deposits on the bed of Lake Van (Eastern Turkey) which provide unique insights into the last 600,000 years. The samples reveal that the climate has done its fair share of mischief-making in the past. Furthermore, there have been numerous earthquakes and volcanic eruptions. The results of the drilling project also provide a basis for assessing the risk of how dangerous natural hazards are for today’s population. In a special edition of the highly regarded publication Quaternary Science Reviews, the scientists have now published their findings in a number of journal articles.

In the sediments of Lake Van, the lighter-colored, lime-containing summer layers are clearly distinguishable from the darker, clay-rich winter layers — also called varves. In 2010, from a floating platform an international consortium of researchers drilled a 220 m deep sediment profile from the lake floor at a water depth of 360 m and analyzed the varves. The samples they recovered are a unique scientific treasure because the climate conditions, earthquakes and volcanic eruptions of the past 600,000 years can be read in outstanding quality from the cores.

The team of scientists under the auspices of the University of Bonn has analyzed some 5,000 samples in total. “The results show that the climate over the past hundred thousand years has been a roller coaster. Within just a few decades, the climate could tip from an ice age into a warm period,” says Doctor Thomas Litt of the University of Bonn’s Steinmann Institute and spokesman for the PALEOVAN international consortium of researchers. Unbroken continental climate archives from the ice age which encompass several hundred thousand years are extremely rare on a global scale. “There has never before in all of the Middle East and Central Asia been a continental drilling operation going so far back into the past,” says Doctor Litt. In the northern hemisphere, climate data from ice-cores drilled in Greenland encompass the last 120,000 years. The Lake Van project closes a gap in the scientific climate record.

The sediments reveal six cycles of cold and warm periods


Scientists found evidence for a total of six cycles of warm and cold periods in the sediments of Lake Van. The University of Bonn paleoecologist and his colleagues analyzed the pollen preserved in the sediments. Under a microscope they were able to determine which plants around the eastern Anatolian Lake the pollen came from. “Pollen is amazingly durable and is preserved over very long periods when protected in the sediments,” Doctor Litt explained. Insight into the age of the individual layers was gleaned through radiometric age measurements that use the decay of radioactive elements as a geologic clock. Based on the type of pollen and the age, the scientists were able to determine when oak forests typical of warm periods grew around Lake Van and when ice-age steppe made up of grasses, mugwort and goosefoot surrounded the lake.

Once they determine the composition of the vegetation present and the requirements of the plants, the scientists can reconstruct with a high degree of accuracy the temperature and amount of rainfall during different epochs. These analyses enable the team of researchers to read the varves of Lake Van like thousands of pages of an archive. With these data, the team was able to demonstrate that fluctuations in climate were due in large part to periodic changes in the Earth’s orbit parameters and the commensurate changes in solar insolation levels. However, the influence of North Atlantic currents was also evident. “The analysis of the Lake Van sediments has presented us with an image of how an ecosystem reacts to abrupt changes in climate. This fundamental data will help us to develop potential scenarios of future climate effects,” says Doctor Litt.

Risks of earthquakes and volcanic eruptions in the region of Van

Such risk assessments can also be made for other natural forces. “Deposits of volcanic ash with thicknesses of up to 10 m in the Lake Van sediments show us that approximately 270,000 years ago there was a massive eruption,” the University of Bonn paleoecologist said. The team struck some 300 different volcanic events in its drillings. Statistically, that corresponds to one explosive volcanic eruption in the region every 2000 years. Deformations in the sediment layers show that the area is subject to frequent, strong earthquakes. “The area around Lake Van is very densely populated. The data from the core samples show that volcanic activity and earthquakes present a relatively high risk for the region,” Doctor Litt says. According to media reports, in 2011 a 7.2 magnitude earthquake in the Van province claimed the lives of more than 500 people and injured more than 2,500.

Publication: “Results from the PALEOVAN drilling project: A 600,000 year long continental archive in the Near East”, Quaternary Science Reviews, Volume 104, online publication: (http://dx.doi.org/10.1016/j.quascirev.2014.09.026)