By Sarah Charley

The surface waters of a major portion of the Arctic Ocean are becoming saturated with carbon dioxide sooner than many scientists expected, all but halting the watery region’s ability to sop up more of the greenhouse gas from Earth’s atmosphere, new research finds.

Previously, scientists theorized that the Arctic Ocean would act like a CO₂-absorbing sponge—once its protective skin of sea ice melted—and join the rest of the world’s unfrozen oceans as they draw in and impound this greenhouse gas. Deposition of carbon dioxide in the oceans slows the rise in average global surface temperature that greenhouse gases in Earth’s atmosphere are causing.

However, the new findings from a marine zone called the Canada Basin, which accounts for about 20 percent of the Arctic Ocean, add to prior indications that that ocean can’t take in copious amounts of carbon dioxide as expected.

Randall Scharien surveys melting sea ice near Resolute, Canada. Photo by Brent Else.

“Scientists thought that this region Arctic Ocean would be able to absorb a lot of carbon dioxide—the equivalent of shutting down one hundred coal-fired electrical plants,” said Brent Else from the University of Manitoba in Winnipeg, Canada, who led the new study. “However, in reality, it will only absorb the equivalent of shutting down two plants.”

In 2008, Wei-Jun Cai from the University of Georgia in Athens, Georgia, and his colleagues measured the concentration of carbon dioxide in the Canada Basin and calculated that this region of the Arctic had a limited ability to absorb carbon dioxide and predicted that this ability would become even more limited over time—a prediction this new study confirms.

Still, some anticipated changes accompanying the loss of summer sea ice in the Arctic Ocean, such as cycles of freezing and unfreezing, could to some degree promote CO₂  uptake by Arctic waters, Else said.

He and his colleagues visited the Canada Basin in 2009 and measured the concentration of carbon dioxide gas in the surface water. It was “surprisingly high,” the team notes in a paper recently published in Geophysical Research Letters, a journal of the American Geophysical Union.

During this 2009 visit to the Arctic, Else and his team took detailed measurements of the depth, salinity, pH, and ice extent, as well as the concentrations of not just CO₂, but also of other compounds, such as nitrate and phosphate, at four different stations. After plugging these values into a simple model, Else and his team determined the rate of air-sea gas exchange and found that the CO₂ capacity of the Canada Basin will actually decrease as the sea becomes more and more ice free.

Ocean waters sequester carbon dioxide in two main ways: Phytoplankton convert carbon dioxide into organic matter and ocean currents slowly cycle carbon-dioxide-rich surface water deep below the surface. But, in the Canada Basin, neither of these two processes is very active.

Else explains that as the sea-ice melts in the Arctic, it turns into a layer of fresh water that floats on top of the less buoyant salt water. This thick skin of fresh water doesn’t mix with salty ocean water below. Without that mixing, the newly ice-free sea doesn’t get nutrients cycling up from the deep ocean to stimulate biological productivity, nor the churning of currents what would normally carry the carbon dioxide-rich surface water down.

“The top layer of fresh water doesn’t communicate very well with the deep ocean,” Else said. “Once this surface layer gets filled with CO₂, that’s it.”

— Sarah Charley is AGU’s science writing intern

Mark Zoback, a geophysicist at Stanford University, cringes at the word “fracking”. He doesn’t oppose this controversial process of extracting fossil fuels from shale rock, or hydraulic fracturing. He just laments the stigma of its nickname.

“I am a very strong believer that shale gas can be produced in an environmentally responsible way, and it’s extremely important that we do so,” Zoback said during a lecture held by the Northern California Science Writer’s Association in San Francisco on April 17th. “It’s an essential component of our energy mix for the first half of this century before we can hopefully get away from fossil

Mark Zoback, a professor at Stanford University, researches geological aspects of oil and gas development. Photo credit: Stanford University

fuels altogether.”

Zoback’s optimism did not seem to immediately resonate with his Bay Area audience. Californians, like many citizens across the country, are increasingly wary of the push to extract untapped gas and oil in this way, particularly within their already water-stressed land. They fear the pollution that has been associated with fracking, and its potential threat to their health and to the state’s agricultural economy.

But Zoback dismisses these apprehensions as ill-informed. He has studied geophysics with an emphasis on shale gas and oil production for more than 30 years and, in 2011, sat on a committee appointed by then-U.S. Secretary of Energy Steven Chu to inform President Obama of the environmental risks associated with fracking. The committee concluded that, with thoughtful engineering and robust regulations, hydraulic fracturing can, indeed, be done safely.

“The three keys to developing shale gas in an environmentally responsible manner are well construction, well construction, and well construction,” Zoback said.

Some Californians worry that toxic fracking fluid could leak out of deep cracks and contaminate drinking water, regardless of how the wells are constructed higher up. But Zoback argued that, while this may be a risk elsewhere in the world, it is not a serious threat in the U.S. Our frackable shale lies about one mile underground. This thick layer of rock provides a safe buffer between deep toxic fluids and near-surface aquifer water, he said.

Still, problems can — and do — occur closer to the surface. If companies don’t line their well-heads properly, gas can leak and travel upward into groundwater. The American Petroleum Institute acknowledges this, and recommends that companies line the upper portion of their wells with steel casing and a 500-foot-long layer of cement. Zoback thinks additional steel layers, and up to 2,000 feet of cement, would be even better.

“[Fracking] is a complicated process, and it needs to be done properly and needs to be regulated properly,” Zoback said during his talk.

In California, the Senate is currently considering a bill that would create new state fracking regulations, including restrictions on water use and disposal. And, earlier this month, the Sierra Club and the Center for Biological Diversity — an Arizona-based environmental law nonprofit with an office in San Francisco — won a lawsuit against the federal Bureau of Land Management for failing to adequately assess the environmental impacts of leasing land to oil and gas companies planning to hydraulically fracture California plots in 2011.

Finding neither those movements nor Zoback’s optimism reassuring, some skeptics in the audience last week challenged the speaker’s reasoning. The speed and magnitude of the expected surge in California fracking could pose unforeseen environmental issues, one audience member pointed out. Others doubted that new regulations would be as robust as they need to be.

Zoback remained resolutely upbeat.

“I think like an engineer,” he said. “I look at a system, identify the problems, and then I try to find solutions to the problems. If there are problems associated with hydraulic fracturing, I will seek solutions.”

Laura Poppick is a graduate student in the University of California Santa Cruz Graduate Program in Science Communication, where she reported on Zoback’s talk for the student blog Out of the Fog . Poppick, who has a B.S. in geology from Bates College in Lewiston, ME., also covers science and technology as an intern at Wired Science.

Mark Zoback is an AGU member, and was named an AGU Fellow in 1998.

Two Texas coastal houses located on the former Brazos River Delta are experiencing lack of sediment accumulation and rising seas. Photo by Kristan Uhlenbrock, American Geophysical Union.

Galveston, Texas – Over 80 scientists gathered at a conference here this week to share their latest research on past, current, and projected future sea level rise and to discuss how this information can be used to shape policy. Despite their diverse perspectives and expertise, one thing the scientists agreed on for sure: the rates and impacts of sea level rise are local and communities are facing a growing risk.

Throughout the week, it was emphasized that the rise of sea level is not a smooth line, but is better characterized as having upsurges and pulses happening over different time scales.

“We are seeing the beginning of a new pulse of rapid sea level rise,” said Hal Wanless of the University of Miami, in Coral Gables, Fla., comparing the last interglacial period to today. Over the last century, we have seen a five- to six-fold increase in the rate of sea level rise, he noted, which is more rapid than what had been anticipated.

Scientists explore the Galveston, Texas, seawall built in response to the 1900 storm. Up to about 30 meters (100 feet) of shore used to be present here. Photo by Kristan Uhlenbrock, American Geophysical Union.

To see some examples of sea level rise impacting a community and how different shoreline structures interact, the group took to the road Wednesday (17 April) for a field trip to Galveston and Follets Islands.

The first stop was the former Brazos River Delta, which shifted in 1929 when the U.S. Army Corps of Engineers diverted the Brazos River, altering the delta and sediment transport from the river to form a new delta southwest of Freeport, Texas. This river is a major source of sediment to the upper Texas coast. In addition to the engineering diversion, saltwater intrusion in the lower river inhibits sediment export from the river, recent research indicates.

The studies also show that, due to decreased sedimentation, current sediments on the shelf are being carried greater distances away from the mouth. With shorelines in the Galveston area currently receding between 3 and 4 meters (10 and 13 feet) per year and sediment not accumulating, the shifting shoreline and rising seas are impacting, or putting at risk, houses built in the old delta area.

At the turn of the 20th century, one of the deadliest storms in U.S. history hit Galveston, killing over 6,000 people. In response to that disaster, the city built a seawall 5 meters (16 feet) high and 11 kilometers (7 miles) long and raised parts of the city by 1 to 2 meters (about 3 to 6 feet).

At the time the seawall was built, the beach extended about 30 meters (about 100 feet) seaward; however, due to a highly active coastal environment, much of the beach is gone. Within the last century, the shoreline has degraded and the local sea level has risen by about 0.5 meters (1 to 2 feet), reaching the seawall in many places and threatening the infrastructure it was meant to protect.

Galveston is under direct and immediate threat. Rates of sea level rise there, due to human influence, are “unprecedented and unsustainable,” said John Anderson of Rice University, in Houston, Texas, one of the conference organizers.

This geohazard map of Galveston Island shows areas of vulnerability on the island. Areas in red are the most at risk to the impact of rising water. Graphic from the University of Texas Bureau of Economic Geology.

One of the only areas of the island that seems to be holding its own is the east end. This is due to the fact that beaches there have been trapping additional sand from jetties and building up some land. However, the amount of sediment accessible to Galveston Island is not enough to keep up with future sea level rise projections. Engineering of the coasts brings about possibilities for adapting to sea level rise, but also provokes challenges and questions about long-term stability of coastal lands.

-Kristan Uhlenbrock, an oceanographer by training, is a public affairs coordinator at the American Geophysical Union. She is currently attending the Joint Penrose / Chapman Conference on Coastal Processes and Environments Under Sea-Level Rise and Changing Climate: Science to Inform Management in Galveston, Texas.

Scientist have found a chamber beneath Old Faithful that might help fuel its predictable eruptions. Photo by Barbara Richman, American Geophysical Union.

By Sarah Charley

A previously unknown underground cavity might help trigger the timely eruptions of the famous Yellowstone geyser Old Faithful, a new study shows. The researchers who uncovered new evidence of a chamber suspect that it stores the pressurized near-boiling water, steam, and other gases that propel Old Faithful’s eruptions.

“The first model of geysers made by early explorers one century ago showed a cavity, but no one was able to find the cavity or prove that it existed,” said Jean Vandemeulebrouck of the Université de Savoie in Le Bourget du Lac, France.

Since then, scientists who first studied Old Faithful concluded that the narrowing of a subterranean passage through which the geyser’s searing fluids pass “was enough to provoke the choked flow and produce a regular eruption,” said Vandemeulebrouck, a hydrothermal systems researcher in Savoie’s Institut des Sciences de la Terre who led the new investigation.

But within the last year, new evidence of geyser-associated cavities turning up in several studies, including this one, has prompted scientists to re-evaluate their understanding of geysers and modify their models to include subterranean reservoirs that store the pressurized steam and gas that fuels the eruptions, Vandemeulebrouck explained.

Now with fresh signs that a cavity may be present beneath Old Faithful, Vandemeulebrouck and his colleagues speculate that this cavity might act as such a reservoir, or bubble chamber, where the roiling, sulfurous brew that becomes the geyser accumulates and builds up pressure.

The researchers discovered the cavity after reprocessing old seismic data and locating the origin of previously overlooked subterranean shaking. The results are to be published in Geophysical Research letters –a publication of the American Geophysical Union.

Because experiments are no longer allowed at Old Faithful, Vandemeulebrouck and his colleagues re-analyzed 3 hours of seismic recordings taken by seismologist Sharon Kedar in 1992 as part of his PhD research.

“We used a technique that was originally developed to locate sources of sound in the ocean,” Vandemeulebrouck said. “The cavity was revealed piece by piece—one tremor at a time,” he noted.

Inside Old Faithful’s underground plumbing, ground water is continually boiling and bubbling, producing tiny tremors that shake the surrounding earth. By analyzing the intensity and arrival times of these tremors at 96 seismic sensors located around the geyser, Vandemeulebrouck and his colleagues were able to reconstruct where each tremor originated.

This image by researchers studying Old Faithful shows the estimated shape of a subterranean cavity beneath the geyser.

As they did so, they found that many bubble-triggered tremors did not originate in Old Faithful’s main channel. Instead, they arose from an underground zone located between Old Faithful Geyser and Split Cone, a weakly active geyser to the southwest, indicating that there is a hollow chamber there, some 10 meters in diameter, holding bubbling water. Gas bubbles in the cavity apparently explode as they collide with the roof and walls, generating the small amounts of seismic activity that the research team interpreted to reconstruct the cavity’s shape and location.

Vandemeulebrouck explains that volcanic activity below the geyser vaporizes groundwater and turns it into steam, which then rises through underground channels toward the surface. Cooler condensed water near the surface blocks the steam’s escape and pushes it back down, creating a pressurized system.

“Geysers function like a mass on a spring,” Vandemeulebrouck said. “The water in the upper part of the conduit is the mass pushing down, and the hot steam is the spring, pushing up.”

The interplay between a growing weight of water and the increasing pressure of the ultra-hot pressurized steam pushes the surface water up and down, Vandemeulebrouck said. Eventually, some of the water escapes through the geyser, which reduces the pressure and allows the steam to rapidly expand, triggering an eruption.

When scientists first studied Old Faithful in the late 1980s and 1990s, they suspected that the complex structure of the main channel was sufficient to account for the geyser’s eruptions. But other recent research shows that geysers need large amounts of pressurized steam, gas and water to fuel the spray of water—and that the storage space in the main channel might not be enough.

Last September, a California study showed that heated groundwater stored in underground reservoirs 42 meters below the surface of a geyser provided the fire-power necessary to propel the geyser’s eruptions.

Russian scientists also recently filmed the inner plumbing of four geysers in Kamchatka by lowering video cameras into the geysers’ mouths. Inside, their films showed, bubbling horizontal channels branched off of the main conduits—leading them to believe that these channels connect the main conduits of the geysers they studied to gas-and-steam-filled bubble chambers.

Vandemeulebrouck suspects that the cavity he and his team discovered below Old Faithful plays a large role in propelling the geyser’s eruptions and is further evidence supporting the existence of subterranean bubble chambers that fuel geyser eruptions.

— Sarah Charley is AGU’s science writing intern

Melting sea ice negatively impacts Arctic communities, a panel of experts said at a recent congressional briefing. (Credit: Brent Else)

By Sarah Charley

Melting Arctic sea ice is threatening local communities and Arctic habitats, experts stressed at a congressional briefing on March 20. The American Geophysical Union co-hosted the briefing to help inform members of Congress and their staffers about the state of the Arctic and the repercussions of sea ice loss due to global warming. The experts stressed that the consequences are already evident in Arctic communities, and will continue to compound as more sea ice is lost.

“We are in unique times,” said John E. Walsh, chief scientist at the International Arctic Research Center in the University of Alaska Fairbanks. “The increase in Arctic temperatures is more than double the global increase over the last century and is unprecedented in the long-term, 2,000-year timescale.”

Sea ice acts as a storm buffer and stymies Arctic weather events. As the sea ice melts, Arctic communities are at greater risk for flooding and erosion, Walsh said.

“There are villages along the Alaskan coast…literally threatened down to the infrastructure level to the point where they are considering re-location,” Walsh said.

Also, with less summer sea ice to act as a base, the ice that forms in the winter months is thin, brittle and melts earlier in the season.

“Hunting and fishing activities that the communities have been engaging in for centuries are challenged because the ice is unstable and dangerous,” Walsh said.

Brendan P. Kelly, a biologist and the assistant director for polar sciences for the White House, said he is concerned the loss of summer sea ice will destroy the rich cultural history and biological diversity of Arctic communities. “The Arctic is not a barren wasteland,” Kelly said. “Its riches have supported human inhabitants for millennia. In fact, for over 10,000 years.”

But an ice-free Arctic has implications beyond climate and habitat change. Without the ice, the Arctic is an exposed and open ocean—and one which is partially under the United States’ jurisdiction.

“We’re an Arctic nation, and the Alaskan Arctic is part of our waters,” said Lt. Commander Kenneth J. Boda of the U.S. Coast Guard. “As the Coast Guard we protect [the Arctic waters].”

An open Arctic will present opportunities for shipping and drilling, he said — but it’s still a dangerous environment. “Just because the sea ice is diminishing does not mean that the sea ice is not a problem,” Boda said. “The ice is drifting quite a lot more than expected.” And the shifting ice can damage equipment and trap ships between ice floes.

In addition to remaining cautious about the opportunities, Boda emphasized that protecting the culture and habitat of the Arctic is the U.S. Coast Guard’s No. 1 priority in that region.

“Putting the ecosystem and survival of species first is really the key to future development in the Arctic,” Boda said.

— Sarah Charley is AGU’s science writing intern

A new study examines the effects of global warming on water availability for farmers worldwide (Credit: NRCS)

Rising global temperatures will concentrate arable land in southern Africa, northern China and the west coast of South America – but leave the United States’ Midwest desiccated, according to new research.

Two scientists used computer models to forecast the future water budget for farming worldwide. For several future climate scenarios, they calculated the combined effect of precipitation and farmland water consumption. Their findings show that the time period 2070 to 2099 will experience a slight increase in the global water budget available for farming. However, much of the lushest land in the future will be located in regions that could face difficulties sustaining the growing demand for food, said Ximing Cai, a professor of water resources engineering at the University of Illinois, Urbana-Champaign.

Many researchers who study climate change and agriculture “have predicted that Africa will have a greater opportunity for agricultural development, and that the water deficits in the Midwest will continue to worsen,” said Cai, author of the new study recently published in Geophysical Research Letters, a journal of the American Geophysical Union. “Our study not only confirms these predictions, but also shows the impacts of climate change on farming in every region of the world.”

Cai’s previous research tested and evaluated climate change models. He and PhD candidate Xiao Zhang have now applied the results from this past work to global crop data to create a comprehensive analysis of the future effects of climate change on agriculture.

“For ten years, my team has worked to extract meaning from climate-change models and evaluate their accuracy based on how close their predictions align with reality and the likelihood they can predict the future,” Cai said. “This way we minimize model uncertainty and get better climate-change predictions.”

After evaluating 20 different climate-change models, Cai and his team aggregated the results from the six best models under two emission scenarios to estimate future rainfall and temperatures in four possible future climates. They then determined the resulting balance between crop water consumption and precipitation for 26 crops—such as corn fields in Iowa and sugar cane in the Caribbean—under each potential climate and under both rain-fed and irrigated conditions.

Agricultural water availability will change in the future due to global warming, according to a new study. Regions in red are projected to have a drop in available water for farming, while those in blue are projected to see an increase. (Credit: Cai, GRL)

All four climate-change scenarios agree that Africa, China and South America will have an average increase in the amount of water available for farming, but the results for the United States and Europe are less clear-cut. Within the United States, the simulations predict an increasingly disparate distribution of water—with more in the Northwest and a sharp decline in states bordering the Mississippi River.

Overall, the global water budget for farming is expected to increase slightly. This slight increase is counter-intuitive, Cai said, but as the Earth continues to warm, the gap between the highest and lowest daily temperatures has decreased in past decades. And scientists expect it to continue to decrease in the future.

“Studies have shown that when there is less temperature variation throughout the day, there is more cloud cover and higher humidity, which reduces the rate of evaporation,” Cai said.

Despite the ominous forecasts of a drier Midwest, Cai said farmers will undoubtedly adapt to changing conditions by planting crops that don’t need as much water, or by changing the times they plant and harvest. It also shows that global warming will not have a universally desiccating effect, but affect every region of the world uniquely, Cai said.

“Global warming will give some regions a great opportunity for agricultural development,” Cai said. “But a concern is whether these regions, such as Africa, will have the infrastructure to support it. The world may need to pay attention to the new infrastructure development requirements to optimize opportunities in some regions, as well as face the challenges in other regions.”

- Sarah Charley is AGU’s science writing intern

The famous “kite with key” experiment Ben Franklin conducted in 1752 is more than just a legend for lightning researchers around the world—it’s a procedure. Sure, the kite has been replaced by a rocket, and the string-with-key contraption by a spool of wire, but the intent is still the same—to better understand nature’s flashes of electricity. Recently, an unusual rocket-triggered lightning strike was caught on video by lightning researchers in Florida, and its curious course from cloud to ground is described in a new scientific paper.

To induce a lightning strike, researchers fire a rocket dragging a wire into an approaching electrical storm. If they are lucky, current will flow from the cloud, through the wire, to the ground, and vaporize the wire. If scientists witness a second lightning strike, it typically follows the path of the vaporized wire…but not always. On this particular dark and stormy afternoon in Florida, most of the wire exploded. But a second bolt, which burst from where the top of the wire had been, took a circuitous route, fracturing into multiple branches as it approached ground, said William Gamerota, a Ph.D. candidate at the University of Florida and lead author of the paper about this uncommon event.

Out of 410 previously triggered lightning strikes, this is the first off-course strike ever observed by researchers at the university’s International Center for Lightning Research and Testing, according to Gamerota. Lightning scientists in France and New Mexico have witnessed similar strikes, but the atmospheric and experimental differences between the sites make a direct comparison of the events difficult.

“It’s tough to tell why this happens, but it does happen,” Gamerota said. “Typically, the leader follows the path of the vaporized wire because it is apparently the path of least resistance, but this time, that was not the case.” Why this particular bolt broke the rules and meandered through virgin air instead of following the path of the vaporized wire is still a mystery. “I have a couple ideas,” Gamerota said, “but you’ll have to wait for my dissertation.”

He and his colleagues report on the anomalous lightning strike in an article accepted for publication in the Journal of Geophysical Research – Atmospheres, a publication of the American Geophysical Union (AGU).

-Sarah Charley is AGU’s current science writing intern

Ozone concentrations over the Arctic in March 2010 (left) and March 2011 (right), from the Ozone Monitoring Instrument on NASA’s Aura satellite. (Credit: NASA)

Guest author Maria-José Viñas is a science writer with NASA’s Earth Science News Team at the Goddard Space Flight Center in Greenbelt, Md.

A combination of extreme cold temperatures, man-made chemicals and a stagnant atmosphere were behind what became known as the Arctic ozone hole of 2011, a new study finds.

Even when both poles of the planet undergo ozone losses during the winter, the Arctic’s ozone depletion tends to be milder and shorter-lived than the Antarctic’s. This is because the three key ingredients needed for ozone-destroying chemical reactions —chlorine from man-made chlorofluorocarbons (CFCs), frigid temperatures and sunlight— are not usually present in the Arctic at the same time: the northernmost latitudes are generally not cold enough when the sun reappears in the sky in early spring. Still, in 2011, ozone concentrations in the Arctic atmosphere were about 20 percent lower than its late winter average.

The new study shows that, while chlorine in the Arctic stratosphere was the ultimate culprit of the severe ozone loss of winter of 2011, unusually cold and persistent temperatures also spurred ozone destruction. Furthermore, uncommon atmospheric conditions blocked wind-driven transport of ozone from the tropics, halting the seasonal ozone resupply until April.

“You can safely say that 2011 was very atypical: In over 30 years of satellite records, we hadn’t seen any time where it was this cold for this long,” said Susan E. Strahan, an atmospheric scientist at NASA Goddard Space Flight Center in Greenbelt, Md., and main author of the new paper, which was recently published in the Journal of Geophysical Research-Atmospheres, a publication of the American Geophysical Union (AGU).

“Arctic ozone levels were possibly the lowest ever recorded, but they were still significantly higher than the Antarctic’s,” Strahan said. “There was about half as much ozone loss as in the Antarctic and the ozone levels remained well above 220 Dobson units, which is the threshold for calling the ozone loss a ‘hole’ in the Antarctic – so the Arctic ozone loss of 2011 didn’t constitute an ozone hole.”

The majority of ozone depletion in the Arctic happens inside the so-called polar vortex: a region of fast-blowing circular winds that intensify in the fall and isolate the air mass within the vortex, keeping it very cold.

Most years, atmospheric waves knock the vortex to lower latitudes in later winter, where it breaks up. In comparison, the Antarctic vortex is very stable and lasts until the middle of spring. But in 2011, an unusually quiescent atmosphere allowed the Arctic vortex to remain strong for four months, maintaining frigid temperatures even after the sun reappeared in March and promoting the chemical processes that deplete ozone.

The vortex also played another role in the record ozone low.

“Most ozone found in the Arctic is produced in the tropics and is transported to the Arctic,” Strahan said. “But if you have a strong vortex, it’s like locking the door — the ozone can’t get in.”

To determine whether the mix of man-made chemicals and extreme cold or the unusually stagnant atmospheric conditions was primarily responsible for the low ozone levels observed, Strahan and her collaborators used an atmospheric chemistry and transport model (CTM) called the Global Modeling Initiative (GMI) CTM.

The team ran two simulations: One included the low-temperature chemical reactions that occur on polar stratospheric clouds, which are billows of tiny ice particles that form inside the vortex only when it’s very cold. The other didn’t. The researchers then compared their results to ozone observations from NASA’s Aura satellite.

The results from the first simulation reproduced the observed ozone levels very closely, but the second simulation showed that, even without chemical reactions from chlorine pollution, ozone levels would still have been low due to lack of transport from the tropics. Strahan’s team calculated that the chemical reactions resulting from chlorine pollution and extreme cold caused two thirds of the ozone loss, while the remaining third was due to the atypical atmospheric conditions that blocked ozone resupply.

Once the vortex broke down and transport from the tropics resumed, the ozone concentrations rose quickly and reached normal levels in April 2011.

Strahan, who now wants to use the GMI model to study the behavior of the ozone layer at both poles during the past three decades, doesn’t think it’s likely there will be frequent large ozone losses in the Arctic in the future.

“It was meteorologically a very unusual year, and similar conditions might not happen again for 30 years,” Strahan said. “Also, chlorine levels are going down in the atmosphere because we’ve stopped producing a lot of CFCs as a result of the Montreal Protocol. If 30 years from now we had the same meteorological conditions again, there would actually be less chlorine in the atmosphere, so the ozone depletion probably wouldn’t be as severe.”

– Maria-José Viñas, NASA Goddard Space Flight Center science writer. (This feature is also available on NASA’s website)

A meteor leaves a trail over Russia on Feb. 15, 2013. With a monitoring array designed to detect nuclear tests, scientists have been able to estimate its size at around 10,000 tons. (Credit: Flickr user alexeya)

BOSTON — On 12 February, North Korea detonated a nuclear device beneath a remote mountain range – and scientists in Norway were able to pinpoint the blast’s location within hundreds of meters. Three days later, a meteor roared through Earth’s atmosphere above Russia – and researchers turned to the same monitoring network to estimate its weight of 10,000 tons.

It was a busy week for the seismometers, ocean-monitoring acoustic stations and other instruments associated with the preparatory commission for the Comprehensive Nuclear-Test-Ban Treaty Organization – or CTBTO – monitoring rogue nuclear tests worldwide. At the American Association for the Advancement of Science (AAAS) meeting in Boston on Sunday, researchers showed that the 288-instrument CTBTO array can tackle scientific research as well as nuclear detective work.

“It’s an amazing system around the world,” said Raymond Jeanloz, a professor of Earth and planetary science and astronomy at the University of California, Santa Cruz.

Scientists studying a Utah mine collapse in 2007, for example, examined the seismic waves detected by the array to determine that the accident was caused by the mine’s ceiling falling in, not an explosion or earthquake. The 2004 Sumatra tsunami was recorded “roaring across the Indian Ocean,” Jeanloz said.

And last week, the seismic monitoring stations captured the shock wave caused when space rock crashed through the atmosphere over Russia.

With information streaming in from different stations, scientists were able to triangulate the location of the meteor, and are now using the recorded information to refine estimates of the fireball’s size.

“These non-treaty implications are incredibly important,” Jeanloz said.

The network of seismometers is also put to work with basic science research. Miaki Ishii, an associate professor of Earth and planetary sciences at Harvard University, and her colleagues are looking at how seismic waves reflect off the Earth’s solid inner core – and return to instruments on the Earth’s surface – to learn more about the planet’s depths.

Still, Jeanloz noted that the network of monitoring stations is designed to be on the lookout for nuclear tests – like the one in North Korea’s mountains – and researchers are aware that they can’t let these other uses distract from the program’s main mission of detecting nuclear weapons testing.

–Kate Ramsayer, AGU science writer

Dr. Hayes at the W. M. Keck Observatory on Mauna Kea in Hawai'i.

This post is the fifth of a series of profiles on planetary scientists by Mark Hilverda, geoscientist and web manager for AGU’s Planetary Sciences Section. A more complete version of this interview that includes a list of reading resources was published on the Planetary Sciences website.

Dr. Alex Hayes is Assistant Professor of Astronomy at Cornell University. Hayes uses spacecraft-based remote sensing to study the properties of planetary surfaces, their interactions with the interior, and if present, atmosphere. Recently, he has focused on studying the coupling of surface, subsurface, and atmospheric processes on Titan and Mars.

Was there a person or event that ignited your interest in planetary science?

While in high school, I contacted professors at a number of colleges to ask about undergraduate research opportunities. By far, the most enthusiastic response I received was from Steve Squyres of Cornell University. At the time, Steve was developing a Mars mission that would eventually become the Mars Exploration Rovers (MER) Spirit and Opportunity. His response, which both welcomed and challenged me to work on his project, was the deciding factor in my decision to attend Cornell and pursue a BA in Astronomy. Steve, along with colleague Jim Bell, were both strong supporters of undergraduate research and let a number of us become intimately involved in the MER mission at an incredibly early stage of our careers. To this day, I maintain strong ties with many of the scientists involved in MER (currently approaching sol 3200 of its nominal 90 sol mission).

Since working on MER, I have had the good fortune to study with a collection of awe-inspiring scientists who have both supported my research and helped to reaffirm my interest in planetary science. Credit for igniting my initial interest, however, must go to Steve Squyres and Jim Bell. The experiences that they provided through the MER mission solidified my desire to pursue a career in solar system exploration.

What topics are your pursuing in some of your latest and upcoming research?

We just finished a paper on the physics of generating waves on Titan’s hydrocarbon lakes. One of the most intriguing observations of the Cassini Mission to Saturn has been the mirror-like reflections seen from of many of Titan’s lake surfaces. These observations are in stark contrast to the discovery of vast equatorial dune fields, which require winds capable of saltating sand-sized particles. On Earth, even light winds will create ripples on a lake that would inhibit mirror-like reflections. As it turns out, the winds predicted in Titan’s polar regions during the observed specular reflections are below the threshold required to generate waves. Over the next few years, however, the winds are expected to pick up and potentially cross the wave generation threshold for the most probable liquid compositions.

Another current project, pursued in collaboration with Ryan Ewing of the University of Alabama, involves Titan’s vast equatorial dune fields. These dunes, which are believed to consist of solid hydrocarbon particles (i.e., plastic!), form patterns that are indistinguishable from dune field patterns observed on Earth and Mars. By studying the detailed morphometry of these patterns, we are able to probe both the wind directions and timescales over which the dunes evolved. This study will lead to important constraints that can help to understand Titan’s long-term climate and hydrocarbon budget. The morphologies of individual dunes also reveal aspects of the sediment transport system and provide insight into parameters such as sediment supply and degree of equilibration with the modern wind regime.

On Mars, I have been collaborating with various members of the MSL science team to study the Curiosity landing site using a combination of orbital and rover-based images. Some specific projects include the origin and evolution of the Peace Vallis Alluvial Fan, quantification of fans generated from debris flows on the east side of Gale, photometric properties of Martian soils, and structure of Gale Crater. I look forward to developing these projects as the MSL mission matures.

LEFT: SEASAT-L Band (HH Polarization) SAR image southeast of Nantucket Island obtained in August 1978. The only dry land is Nantucket Island near the top right of the image, everything else is wave structure on the Ocean. (Credit: NASA/JPL) RIGHT: Cassini RADAR Ku-Band (HH Polarization) SAR image of Ligeia Mare on Titan acquired in 2006/2007. Note that the entire lake surfaces dark to the RADAR, suggesting little to no wave activity (Credit: NASA/JPL, Cornell).

As far as upcoming research goes, we were recently funded to study the evolution of Titan’s polar landscapes using a combination of radar and infrared cameras on the Cassini spacecraft. The innovative part of this project is the incorporation of newly generated Digital Terrain Models (DTMs). The topographic information provided by DTMs has opened new doors for Titan research by allowing the quantitative analysis of morphologic form. For the first time, three-dimensional landscape relationships can be used to study surface evolution on Titan. Previous work on Titan’s geology has been limited to a description of the observed morphologies. In our work, we will use topographic information to study the relationships between these morphologies and use that information to read the history of the landscape. I am very excited about this project not only because of the topic, but also because the proposal included a collection of well-known experts who will all be working together to solve this problem.

There are also a collection of smaller projects that involve Venus, Europa, and Io. Ultimately, however, I am most excited about the projects that I do not yet know about. In January I joined the faculty of Cornell’s Astronomy Department. As a result, the interests of my students will drive the direction of my future research. I cannot express how excited I am to be heading back to Cornell and have the chance to work with both undergraduate and graduate students.

How useful are Earth analogs for studying processes on other worlds such as your sedimentology research on Mars? Do they provide a useful starting point or sometimes provide too much bias on initial interpretations?

If treated carefully, Earth analogs are invaluable for studying processes on other bodies. Sedimentary rock outcrops observed by the MER and MSL rovers are a great example. The geometry, scale, and distribution of the bedding layers in these outcrops are strikingly similar to deposits found on Earth and allow the methods and principles of terrestrial-based sedimentology to be utilized on their Martian analogs. Where you have to be careful, however, is when you blindly apply Earth analogs to other bodies without understanding the physics behind the underlying process that generated the structure you are studying. If any of the underlying mechanisms have a strong dependence on environmental parameters such gravity or atmospheric density, you need to scale your models appropriately.

In addition to Mars, your research has a strong focus on Saturn’s moon Titan. What attracted you to this hazy, hydrocarbon world?

Titan is a fascinating and dynamic place whose surface and atmosphere are affected by the same processes that we are familiar with here on Earth. On Titan you have active pluvial (rain), fluvial (rivers), lacustrine (lakes), aeolian (dunes), impact (craters), and potentially cyrovolcanic processes. It is the only moon with a substantial atmosphere (four times denser than Earth’s) and the only place other than Earth that we know to have standing bodies of liquid. This makes Titan a natural laboratory for studying the basic principles behind the processes that affect our own surface-atmosphere system on Earth. Titan may also represent a hydrologic system that is common among extra-solar planets, as cooler M-Dwarfs are the most numerous stars in the galaxy and planets with water-based hydrologic systems orbiting M-Dwarfs would have to be too close their parent stars. In truth, however, my initial interest in Titan came from a meeting with the Cassini RADAR Principal Investigator Charles Elachi. He rolled a radar image of Titan’s lakes across the hall in front of my graduate student office and told my advisor, Oded Aharonson, and I that he needed someone to analyze the data.

Planetary science often focuses individually on specific systems such as subsurface, surface or atmosphere. What are some of the challenges you face when studying the big picture, such as the interaction of multiple systems?

My research focuses on quantitative analysis of remote sensing data. This is a very broad topic that can be applied to many problems across subfields including optics, geomorphology, atmospheric science, oceanography, mineralogy, material science, etc. I cannot hope to be an expert in all of these topics, so when I need additional information for specific research projects I often partner with topical experts. An example is my recent paper on generating wind-waves on Titan’s hydrocarbon seas. For this work, I collaborated with an oceanographer named Mark Donelan (University of Miami). Mark is an expert on the physics behind terrestrial wind-waves. For my current work on Titan’s dunes I’ve partnered with aeolian expert Ryan Ewing (University of Alabama) and for the upcoming work on Titan’s polar landscape evolution I’ll be working with, among others, renowned geomorphologist Bill Dietrich (University of California, Berkeley). I enjoy working on a range of topics and learning from my collaborators.

You are the first recipient of the newly created Ronald Greeley Early Career Award in Planetary Science. What kind of influence did Dr. Greeley have on your career?

Ronald Greeley was an icon in the field of planetary science. In addition to his fundamental scientific contributions in the field of planetary surface geomorphology (from which I benefited greatly), Ron is also remembered for his mentorship and support of early-career scientists. Though I never worked with him directly Ron always took the time, whether we met during a conference or a Viennese concert, to stop what he was doing and ask me how things were going. That kind of genuine interest is rare among scientists of Ron’s caliber and reputation and can go a long way toward encouraging early-career scientists.

Students from the Immaculate Conception School, who visited SPIF on June 15th, 2012. (Credit: Rick Kline, Cornell SPIF)

You have recently become the director of the Spacecraft Planetary Imaging Facility (SPIF) at Cornell. In addition to supporting research activities, SPIF also focuses on public education and outreach. Which topics seem to be most popular in SPIF’s outreach programs? What are some of the most successful approaches to distilling the vast amounts of available information to the public?

SPIF is one of NASA’s Regional Planetary Imaging Facilities (RPIF). These centers are dedicated to disseminating and popularizing planetary spacecraft data to researchers, K-12 students, and the general public. SPIF’s most popular outreach programs center around presentations and workshops given by our data manager Rick Kline using images from the latest planetary missions (e.g., MER, MSL, and Cassini). Over the next year, however, we will attempt to reach a wider audience.

The Paleontological Research Institute (PRI) is an Ithaca-based museum and research center that has been working with the National Science Foundation to bring Virtual Field Experiences (VFEs) to thousands of Earth Science classrooms across the country. A VFE is a collection of digital data obtained at a field site (e.g, the Mississippi River) and digitized in such a fashion that students can ask questions and learn about the landscape remotely. At SPIF, we will generate extraterrestrial VFEs (EVFEs) using data from the MER and MSL spacecraft. These EVEFs will then be disseminated using PRI’s existing distribution network, allowing us interact with thousands of students in a short time frame! If this program works, we’ll try looking for additional collaborations where we can use existing distribution networks to popularize data from spacecraft missions (e.g., Khan Academy).

Based on your public outreach work, what level of interest do you think exists for people to pursue careers in planetary science? Any recommendations and advice for those considering planetary science as a career?

Planetary Science is a broad field that covers many potential research areas. In terms of interest, I would imagine that many people would find working on active NASA missions as exciting and invigorating as I do. However, I would also point out that an education in Planetary Science is applicable to a broad range of career choices that extend beyond NASA and traditional academia. Before returning to graduate school, I spent a few years working at MIT Lincoln Laboratory (MITLL) on ballistic missile and other tactical defense projects for the US Air Force. The skills I obtained while working on the MER mission were directly applicable to my work at MITLL. Other career options for Planetary Scientists include resource management, aerospace, and exploratory geology.

A concluding, fun “what-if” question: If you could design any mission to Titan, what type of data would you be most interested in collecting?

This one is easy as the mission has already been designed. The Titan Mare Explorer (TiME) was a mission proposal to send a floating capsule to a Titan sea (Ligeia Mare). TiME was selected as one of the three finalists in NASA’s recent discovery proposal. As many of you know InSight, a mission to send a seismometer to Mars, eventually won. In other words, NASA was on verge of launching the first extraterrestrial boat! In addition to being sensationally innovative, this mission was also scientifically compelling. We know very little about Titan, so even the most simplistic measurements of its surface would provide fundamental scientific advances.

If I could design any mission to Titan, it would be a lake lander that both sampled the liquid and took high resolution stereo images of the shoreline and surrounding terrain during its descent. If I could have two missions or one flagship class mission like Cassini, I would include an orbiter that could map the surface at 10 m resolution and generate global topographic maps.