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Tracking Dissolved Organic Matter in Coastal Ecosystems

Thu, 06/06/2019 - 12:10

Aquatic life depends on the tiniest of building blocks: dissolved organic matter (DOM). These dissolved molecules sustain the microbes and phytoplankton that form the foundation of aquatic food chains. The DOM in Earth’s waters holds about as much carbon as the atmosphere, and DOM can also be a major source of nitrogen and phosphorous, key ingredients in healthy aquatic ecosystems.

To track this major player in the carbon cycle, benchmark studies must monitor DOM’s status in sensitive coastal ecosystems. As the climate changes, scientists expect precipitation in areas such as the inland United States to also change, which will alter the delivery of organic matter by rivers out to the coasts. At the same time, rising sea levels will bring marine DOM toward the coast.

Letourneau and Medeiros examined DOM along Georgia’s coastline, focusing on the mouth of the Altamaha River and the Sapelo Sound estuary. The researchers collected surface samples each month for a year, running each sample through a battery of tests, including optical and molecular (ultrahigh-resolution mass spectrometry) analyses, to determine the DOM composition.

They found that DOM composition at both sites changed with the seasons. River flow increases over the winter, peaking in early spring. During high-flow times, DOM was made up of aromatic, earthy molecules eroded from terrestrial sources upstream, and the concentration of dissolved organic carbon increased. These changes were related not to local rainfall patterns but to the seasonal changes in river flow. The same pattern appeared in the estuary site, although the correlation wasn’t as strong.

During the rest of the year, when river discharge was lower, other environmental DOM sources became more important. In the river system, marshes contributed a greater percentage of DOM composition. In the estuary, lower river discharge meant greater influence of DOM flowing in from the sea.

After Hurricane Matthew, a category 4 storm that hit the East Coast in the fall of 2016, the scientists noticed that DOM followed the high-discharge patterns even though the storm occurred at a low-discharge time of year. The hurricane brought twice as much dissolved carbon as the year’s maximum, and terrestrial material again outstripped marsh and marine materials to become the dominant source of DOM.

Although local rainfall was not related to DOM, seasonal flow from inland sources and an extreme storm both boosted dissolved organic carbon levels and changed DOM composition along Georgia’s coast. The carbon bump also led to increased bacterial consumption during times of heavy river flow.

This study demonstrates that changing seasons and extreme weather affect DOM dynamics and microbial carbon processing along Georgia’s coast. (Journal of Geophysical Research: Biogeosciences, https://doi.org/10.1029/2018JG004982, 2019)

—Elizabeth Thompson, Freelance Writer

Variations in Creep Along One of Earth’s Most Active Faults

Thu, 06/06/2019 - 12:08

As part of the earthquake cycle, most active faults suddenly release strain that has gradually accumulated for extended periods of time. Some faults, however, may experience aseismic slip, or creep, which sometimes begins after a major seismic event and then steadily declines over time. Determining the relative proportion of seismic and aseismic slip occurring along an active fault is critical for accurately estimating its potential seismic hazard.

This map shows changes in horizontal velocity parallel to the North Anatolian Fault for the period 2011–2017, 2 decades after the 1999 Izmit earthquake, which killed more than 20,000 people in Turkey. These data help scientists monitor how quickly faults in this region are creeping in between major earthquakes. Acceleration of creep can be detected at one location (star). Credit: Aslan et al.

In a new study, Aslan et al. used recent, high-resolution interferometric synthetic aperture radar data to characterize aseismic slip occurring along Turkey’s North Anatolian Fault, the 1,600-kilometer-long strike-slip feature separating the Eurasian and Arabian plates that has produced seven large (magnitude > 7) earthquakes since 1939. The most recent event, the 1999 magnitude 7.4 Izmit earthquake that occurred roughly 100 kilometers east of Istanbul, ruptured five segments and killed more than 20,000 people.

Using 307 images acquired by the Sentinel-1 and TerraSAR-X satellites, the researchers examined ground velocity changes in space and time across the central segment of the 1999 rupture for the period spanning 2011 to 2017. The results indicate this segment continues to creep nearly 2 decades after the earthquake but that its maximum rate in the fault-parallel horizontal direction has tapered to an average of roughly 8 millimeters per year, about two thirds the rate measured during the previous decade.

The team also presented evidence for a transient “creep burst” that occurred along the same fault segment in November 2016. During this spike, the surface slip totaled 10 millimeters—a distance that corresponds to 1.25 years of average creep—in just 3 weeks.

Collectively, these findings indicate that postseismic slip along the North Anatolian Fault is more complex than has previously been suggested. By providing evidence that creep is not necessarily a steady process, this study offers new insight into long-term, postseismic deformation following a major earthquake along one of Earth’s most active strike-slip faults. (Journal of Geophysical Research: Solid Earth, https://doi.org/10.1029/2018JB017022, 2019)

—Terri Cook, Freelance Writer

Using GPS Sensors to Capture Key Snowpack Properties

Thu, 06/06/2019 - 12:07

GPS isn’t just for drivers navigating city streets or surveyors making maps.

Monitoring GPS microwave signals and the way they behave when interacting with different materials can reveal a host of additional information, including the properties of fallen snow. In a new paper, Koch et al. present a novel strategy for using GPS sensors to simultaneously capture three key snow cover properties: snow water equivalent, liquid water content, and snow depth.

The snow water equivalent of a snowpack is the amount of water that would result from melting it, whereas the liquid water content indicates the wetness of a snowpack. These properties, along with snow depth, are crucial for many applications, such as predicting natural hazards like avalanches and floods or anticipating river runoff that replenishes water supplies and hydropower forecasts. However, measuring them precisely can be invasive and expensive.

The new research builds on a decade of efforts to use GPS sensors to measure snow properties nondestructively and inexpensively. These methods take advantage of the signals emitted by GPS satellites that usually enable a receiver to determine its spatial position. Traveling through snow alters the properties of GPS signals, and measuring these signal changes can reveal key characteristics of the snowpack.

The authors had previously developed GPS-based strategies for measuring single snow cover properties, but now it is possible for the first time to reliably capture snow water equivalent, liquid water content, and snow depth all at once for both dry snow—consisting of just ice and air—and wet snow, which also includes some liquid water. The new approach uses a two-antenna setup to capture all three features, with one antenna on a pole above the maximum snow height and the other on the ground, where it is buried under snow throughout the entire winter season.

The researchers installed this setup at a high-elevation site near Davos, Switzerland, and collected data for three winters between October of 2015 and July of 2018. When snow was present, it altered the strength and speed of the GPS signals received by the buried sensor, whereas the pole-mounted sensor received unimpeded signals, allowing for a comparison to reveal how the snow affected the signals.

By applying knowledge of GPS signal properties, including how they are affected differently by wet versus dry snow, the researchers used the sensor data to calculate snow water equivalent, liquid water content, and snow depth. Their calculations agreed closely with validation data collected on site throughout the study period under both wet- and dry-snow conditions.

These findings demonstrate that a low-cost, two-antenna GPS setup could aid snow data collection at remote sites. Moreover, this technology was demonstrated regarding operational use during the European Space Agency’s Business Applications demo project SnowSense for further sites. Further research will focus on the determination of whether the technique also performs well at lower alpine elevations, where snow conditions can be more variable. (Water Resources Research, https://doi.org/10.1029/2018WR024431, 2019)

—Sarah Stanley, Freelance Writer

Creating Icebergs in Ocean Models Coupled to Ice Shelves

Thu, 06/06/2019 - 11:30

Large tabular icebergs that break off ice shelves in Antarctica drift north into the Southern Ocean. Standard ocean models assume that, regardless of its size, an iceberg can be treated as a “passive tracer” that follows the ocean currents that would be predicted in a model which ignored the iceberg. However, a large iceberg modifies the ocean around itself in ways that affect its path and the rate at which it melts.

Stern et al. [2019] describe a new model for the ocean, ice shelves, and icebergs that includes the feedbacks between the ocean and the ice as an iceberg breaks away from an ice shelf and begins to drift into the open ocean. Their model shows how the three-dimensional currents that are generated around the iceberg affect melting rates, iceberg drift and rotation, and the transport of water that is trapped under the iceberg.

This new approach to modeling icebergs should lead to better predictions of how ice that is lost from the Antarctic Ice Sheet is carried away from the Antarctic coast to influence the Southern Ocean’s stratification, sea ice and ecosystems, and its role in global climate.

Citation: Stern, A. A., Adcroft, A., & Sergienko, O. V. [2019]. Modeling ice shelf cavities and tabular icebergs using lagrangian elements. Journal of Geophysical Research: Oceans, 124. https://doi.org/10.1029/2018JC014876

—Laurence Padman, Editor, JGR: Oceans

House Hearing Focuses on Why Biodiversity Matters

Wed, 06/05/2019 - 20:40

A recent grim report about the fate of biodiversity worldwide states that about 1 million species are threatened with extinction, many within decades. It also found that the global rate of species extinction “is already at least tens to hundreds of times higher than the average rate over the past 10 million years and is accelerating” due to factors including changes in land and sea use, pollution, and climate change.

But at a 4 June congressional hearing, Rep. Ami Bera (D-Calif.) wanted to know how he could explain to his constituents why this report by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) is, as he put it, “incredibly important.”

At the hearing, conducted by the House Committee on Science, Space, and Technology, committee member Bera asked the expert witnesses to give it their best shot.

“When we destroy nature, we really undermine all of those life-support systems on which we depend.”“From the very food we eat to the way we define ourselves and our sense of place, nature is an incredibly integral part of all of our lives. And when we destroy nature, we really undermine all of those life-support systems on which we depend,” responded Kate Brauman, coordinating lead author for the IPBES Global Assessment and lead scientist with the Global Water Initiative at the University of Minnesota’s Institute on the Environment.

“Biodiversity fundamentally is not just an environmental issue,” IPBES immediate past chair Robert Watson weighed in. “Nature has economic value which we should take account of in our accounting systems. It also has development value: food, water, energy, security, human health. It is also a moral issue: We shouldn’t destroy nature. And it’s a social issue, as you’ve heard that the most disadvantaged people, poor people, are most adversely affected. So there are multiple reasons we should care about both climate change and biodiversity.”

“Totally Day and Night”

For Watson, the difference between this hearing and an earlier, divisive 22 May hearing conducted by the House Committee on Natural Resources was “totally day and night.”

The 4 June hearing was “incredibly constructive,” Watson told Eos, “where people are truly trying to understand what are the issues associated with the loss of biodiversity [and] what are some of the solutions. I would hope that all hearings would be like this one.”

“You have to bear in mind that there are different cultures on different committees.”The earlier hearing, Watson noted, “was very destructive. It was not a good conversation about facts and knowledge and evidence.”

“You have to bear in mind that there are different cultures on different committees,” Rep. Frank Lucas (R-Okla.), the ranking member on the science committee, told Eos. He said that the science and agriculture committees “have a more collegial perspective, generally. There are other committees—government oversight, judiciary—where they like to make lots of noise. [Natural] resources falls somewhere in the middle.”

Lucas added that the science committee hearing was an example of where he and committee chair Rep. Eddie Bernice Johnson (D-Texas) want the committee to go.

“This was very thoughtful. You had a diversity of perspectives focused on how to make a difference. The members were engaged. This is the way hearings are supposed to work,” he said.

Findings “Too Stark to Ignore”

Johnson, in her opening statement, called the IPBES findings “too stark to ignore.”

“Much of the reporting on the Global Assessment has focused on the devastating finding that almost 1 million species could potentially go extinct in the next few decades,” she continued. “But we would be remiss if we did not discuss what else this report lays out, especially its recommendations for potential solutions and pathways to addressing biodiversity loss.”

“If the oceans had not been the Earth’s punching bag to take this heat, then the average temperature outside this room today would be 122°F.”Johnson told Eos that she expects that the committee will continue to look into the report “and see what, if any, legislative approaches we can achieve” to reduce the threats to biodiversity.

Some of the most urgent threats to biodiversity are taking place in coral reefs, testified James Porter, professor emeritus of ecology at the University of Georgia’s Odum School of Ecology. Porter said that climate change is the key driver of diversity loss in the oceans.

“Of the warming heat that has been generated in the last 50 years, only 7% of that is in the air. The remaining 93% of the heat is in the oceans,” Porter said. “The oceans have absorbed this heat. We know this because we have indeed measured it. If the oceans had not been the Earth’s punching bag to take this heat, then the average temperature outside this room today would be 122°F. That is the physics of what we are dealing with.”

Porter added that if coral reefs are destroyed, people who depend on them as a source of income, protein, and livelihood may become climate refugees.

Not All Gloom and Doom

Porter and other witnesses also stressed the need to look for solutions.

The IPBES report essentially confirms what we have long known: Humans have made things very tough for nature,” testified Steven Monfort, director of the Smithsonian’s National Zoo and Conservation Biology Institute. However, he added, “if we just bombard the public with messages of gloom and doom, absent any focus on solutions, we risk fostering a sense that nothing anyone does is going to make a difference.”

Jeff Goodwin, conservation stewardship lead and agricultural consultant with the Noble Research Institute in Ardmore, Okla., was the sole Republican witness at the hearing. He noted one potential solution: a movement in the agricultural industry that he said is returning biodiversity to the land. Goodwin said that the movement “was not borne out of legislation or regulatory requirement. It was borne out of the recognition by innovative producers who understood [that] the adoption of ecologically and economically sustainable principles would enable them to remain on the land producing the food and fiber needed for an ever expanding population.”

Brauman testified that humanity’s “transformation of nature has been critical for both human nutrition and livelihoods. But we also must be clear-eyed about the impact. We have transformed the globe.”

Despite that transformation, however, she said that there are pathways forward.

“The headlines are dire, but the report is actually not that dire,” Brauman told Eos. “What we see is that there are many futures where there is lots of possibility. We will need to make change, but it’s absolutely doable.”

—Randy Showstack (@RandyShowstack), Staff Writer

The Tropical Atmosphere’s Balancing Act

Wed, 06/05/2019 - 12:07

Earth’s balmy, relatively stable temperature relies on a complex balancing act. Much of the Sun’s heat is lost to space through radiation emitted by Earth, a process called radiative cooling. Simultaneously, however, the atmosphere is warmed when water vapor condenses into droplets, releasing energy, and currents of air transfer heat from Earth’s surface into the atmosphere.

For decades, scientists attempting to simulate Earth’s climate have known that the global atmosphere as a whole maintains an idealized state called radiative-convective equilibrium (RCE), in which energy lost through radiation is balanced by heat released through the condensation of water vapor and the direct transfer of heat from the surface. When researchers observe Earth’s atmosphere at smaller scales, however, it is often out of equilibrium, raising concerns about whether RCE exists at local levels.

A new study by Jakob et al. identifies the scale at which RCE breaks down in the tropical atmosphere—around 1 million square kilometers. The team used several data sets to test whether RCE is present at different scales, including satellite observations of radiative cooling and convection, precipitation records, and images of clouds collected between 2001 and 2009.

As a whole, the tropical atmosphere remained close to RCE over the 9-year period, their analysis reveals. Clouds played a key role in maintaining RCE, which occurs frequently at 5,000 by 5,000 square kilometers or larger. It occurs most often when low clouds are widespread and there are a few convection hot spots: places where hot, moist air rapidly ascends and produces large amounts of rainfall. The two areas are connected through atmospheric circulation, which in turn provides the conditions for the different cloud types to exist.

RCE occurred less than 20% of the time in regions of the atmosphere smaller than 1,000 by 1,000 square kilometers, the team found. Many computer models used to study clouds focus on RCE for areas smaller than this scale when the real atmosphere is not likely to be in equilibrium. The finding could improve scientists’ understanding of the interaction of clouds and circulation, a complex and poorly understood factor in climate change. (Journal of Geophysical Research: Atmospheres, https://doi.org/10.1029/2018JD030092, 2019)

—Emily Underwood, Freelance Writer

Mountain Ecosystems and Communities Face Challenges Worldwide

Wed, 06/05/2019 - 12:06

More than half of the world’s population relies on resources from mountain ecosystems, such as timber and water. Rising like islands above the lowlands, mountain systems face unique threats to their sustainability. New research by Klein et al. explores these threats at a global scale for the very first time, illuminating strategies needed to improve sustainability. The work was led by Mountain Sentinels, a group focused on the sustainability of mountain environments and communities.

The project began with a workshop attended by experts from 12 different mountain systems, each with decades of experience. Working with additional scholars, they identified key facets of mountain systems around the world, including their common characteristics, stressors, paradoxes (such as being rich in resources but poor in income), and benefits to humans. This collaboration enabled the researchers to build a conceptual model of mountain systems.

The scientists then explored how their conceptual model applies to mountain systems around the world. They surveyed experts from 57 systems across 37 countries, collecting detailed data on land use, stressors, the role of local knowledge, and more. Using this information, they conducted a series of computational analyses to better understand the current state of mountain systems worldwide.

The analysis revealed that many mountain systems face both abrupt threats, such as extreme weather events and economic crises, and gradual threats, such as climate change and policy change. The most widespread threat comes from policies implemented by people who live outside of mountain systems and may lack important local knowledge about the mountain environment.

By categorizing mountain systems according to land use types, such as logging and tourism, the researchers were able to explore the different threats faced by different system types. They found that mountain systems in the developing world where people’s livelihoods are subsistence oriented—especially systems that mix agriculture and animal husbandry—are most at risk, despite the many benefits and resources they provide.

These findings point to the complex, cross-disciplinary, and cross-sector efforts necessary to ensure sustainability of Earth’s mountain systems. The authors suggest the need for scientists, local stakeholders, and policy makers to collaborate on decisions about what an ideal future looks like for a given mountain system and how best to achieve it. They highlight the importance of filling gaps in knowledge about mountain systems while also addressing poverty and food security. (Earth’s Future, https://doi.org/10.1029/2018EF001024, 2019)

—Sarah Stanley, Freelance Writer

Eruption in El Salvador Was One of the Holocene’s Largest

Wed, 06/05/2019 - 12:05

Scientists have sifted through the aftermath of an enormous volcanic eruption that rocked Central America a millennium and a half ago.

By meticulously cataloguing volcanic debris spewed across El Salvador, researchers have reconstructed the dynamics of the Tierra Blanca Joven (TBJ) eruption, as well as its impact on nearby Maya civilization. They showed that the eruption of the Ilopango caldera occurred in eight distinct phases, one of which blanketed the landscape in a layer of rock and ash roughly 70 meters thick, and that the tallest volcanic plume towered 49 kilometers into the atmosphere.

These results, published in June in the Journal of Volcanology and Geothermal Research, suggest that Maya settlements in the area were significantly affected by the eruption.

Dario Pedrazzi, a geologist at the Institute of Earth Sciences Jaume Almera of the Spanish Scientific Research Council in Barcelona, led the fieldwork for the study. In 2015 and 2016, Pedrazzi and his colleagues traveled to El Salvador three times to look for evidence of the TBJ eruption. This event, which the new paper’s authors date between roughly 270 and 535 CE, takes its name (meaning “young white earth”) from the white, acidic ash (tephra) it left behind.

Classical Stratigraphy

“It’s classical stratigraphy. We describe all of the different layers that we see in the field.”Working across roughly 20,000 square kilometers of El Salvador, Pedrazzi and his collaborators searched for exposed rock walls that might harbor evidence of the eruption. These rock walls were associated with, for example, road construction, quarries, and archaeological digs. The researchers focused on over 80 of these outcroppings that contained layers of tephra and larger pieces of rock known as lapilli.

“It’s classical stratigraphy,” said Pedrazzi. “We describe all of the different layers that we see in the field.” The researchers also collected samples from the layers to analyze back in the laboratory.

Confirming previous work, the scientists found eight layers (units) corresponding to different phases of the eruption, which likely lasted from a few days to a few weeks in total. The units included fallout debris and debris entrained in pyroclastic density currents. The latter—high-temperature mixtures of gases, lapilli, and tephra—had ripped down the sides of the caldera to distances of up to 40 kilometers, the team estimated.

Pedrazzi and his colleagues analyzed the size distribution of the ash and lapilli using sieves with meshes ranging in size from 0.25 to 64 millimeters. They also studied material by passing it through a particle analyzer that bounced laser beams off the particles to determine their dimensions.

“It’s potentially 1 of the 10 largest eruptions on the planet during the Holocene.”Pedrazzi and his colleagues found that the units ranged in thickness from a few centimeters to roughly 70 meters. Unsurprisingly, the largest debris, rocks measuring about a meter in size, was closest to the caldera. Fine-grained ash, on the other hand, was dispersed over 100 kilometers from the eruption site, the team showed. Other teams have found deposits from the TBJ eruption in Guatemala, Honduras, Nicaragua, Costa Rica, and the Pacific Ocean.

This eruption is one for the history books, said Robert Dull, a paleoecologist at the University of Texas at Austin who was not involved in the research. “It’s potentially 1 of the 10 largest eruptions on the planet during the Holocene.”

To the Top of the Stratosphere

Pedrazzi and his colleagues used software to reconstruct the TBJ eruption. They based their calculations on the varying thicknesses of volcanic products at different distances from the caldera.

They estimated that the tallest plume from the TBJ eruption, associated with the last unit, reached nearly 50 kilometers into the atmosphere. At that height, roughly the top of the stratosphere, the volcanic ash would have been entrained by air currents and transported far distances. These high-altitude air currents “allowed the material to fly around the world,” said Pedrazzi.

Other researchers have suggested that aerosols from this eruption might have remained lofted in the atmosphere for years, resulting in a temporary cooling of the planet that was recorded in the 6th century.

Pedrazzi and his colleagues also estimated how much magma erupted from Ilopango caldera during the TBJ event: roughly 30 cubic kilometers, about 120 times as much as the 1980 eruption of Mount St. Helens in Washington.

“It was a big eruption,” said Pedrazzi, who describes it as being larger than the 1991 eruption of Mount Pinatubo in the Philippines but smaller than the 1815 eruption of Tambora in Indonesia.

Displacement of Maya Communities

The TBJ eruption likely had widespread repercussions for local communities.

People living within 50 to 60 kilometers of the caldera were either killed or forced to move elsewhere when fallen ash and rock made farming impossible, Pedrazzi said.

Maya settlements, which dotted the region at the time, would have been among those displaced. In addition to forced relocation of those in the vicinity of the eruption, Maya construction projects and trade routes in the area were likely shut down.

Tazumal, above, was a complex within the Maya city of Chalchuapa. The Tierra Blanca Joven eruption forced the evacuation of cities and halted construction on Tazumal and other nearby Maya sites. Image credit: Mariordo (Mario Roberto Durán Ortiz), courtesy Wikimedia, CC BY-SA-3.0

“The magnitude of this eruption means that Mayan populations living in the region would have been considerably affected,” the researchers wrote.

“This was a massive natural catastrophe that had huge implications for Maya cultural evolution.”This thorough analysis of the dynamics and progress of the TBJ eruption “helps to bring the eruption to life and to really understand what the Maya were experiencing,” said Dull. “This was a massive natural catastrophe that had huge implications for Maya cultural evolution.”

A similar eruption today would be catastrophic, the researchers note: 3 million people currently live within 30 kilometers of the caldera. San Salvador, the capital of El Salvador, is fewer than 10 kilometers away. In fact, most of the San Salvador metropolitan area is built on tephra deposits from the TBJ eruption.

Pedrazzi and his colleagues aren’t finished with the Ilopango caldera yet. They’re now studying its eruptive history, looking as far back as 1.5 million years. The scientists want to understand the return period of eruptions and whether these events are clustered in time.

This work has “hazards implications in El Salvador and neighboring countries,” said Pedrazzi.

—Katherine Kornei (@katherinekornei), Freelance Science Journalist

Dinosaurs Roar Again, Now Including a Focus on Climate Change

Tue, 06/04/2019 - 20:31

You can almost hear the roars, or whatever sounds they made, of dinosaurs and the shrieks of delighted children when the Smithsonian Institution’s National Museum of Natural History reopens its nearly 2,900 square meter dinosaur and fossil hall in Washington, D.C., on Saturday, 8 June.

The dinosaurs that roamed the Earth millions of years ago have a message for us now, too.After a 7-year renovation, the charismatic megafaunae of yore have been dusted off and are on magnificent and, in some cases, terrifying display. The centerpiece apex predator Tyrannosaurus rex, for instance, is depicted eating a Triceratops.

Those dinosaurs, along with about 700 other intriguing plant and animal fossil specimens, are again telling their fascinating story in one of the most visited museums in the world.

It turns out that the dinosaurs that roamed Earth millions of years ago have a message for us now, too. .

“The planet has written its history in rocks and bones, so what you think is all this dusty stuff is really a key to understanding how the planet works. And we are in very desperate need of understanding how the planet works now,” Kirk Johnson, Sant Director of the natural history museum, told Eos in advance of the exhibit reopening.

Journeying back through 3.7 billion years of life on Earth and forward into the future, the exhibit “is really a story about the planet,” Johnson said.

Among the major exhibit themes outlined by the museum are evolution, extinction, and the connection of all life to other life and to Earth; ecosystem changes; Earth processes and global cycles; and the age of humans and global change, including “how humans are shaping the future and the fate of life on Earth.”

The exhibition “will inspire a new generation of dinosaur lovers and scientists. It will also prompt individuals to think about their own impact on the planet,” the exhibition website expounds. “Unlike past extinction and warming events, human activities are driving Earth’s rapidly changing climate today. The exhibition will give visitors tools to interpret the past, present, and future and see how the choices they make today will live far beyond them, in deep time.”

Because the exhibit “does not end in the past,” Johnson said it is dramatically different from any other fossil exhibit in the world. Humans “have a huge and growing population, we’re having a tremendous impact on biodiversity, we are impacting the content of the atmosphere, the chemistry of the oceans,” he said. “The history of life on Earth must include the human impact, and we must confront that. So the exhibit forces you to think about the future.”

A Gift “with No Strings Attached”

The renovation of the exhibition, which formally is known as the David H. Koch Hall of Fossils—Deep Time, received $70 million in federal appropriations and $40 million in private funds, including $35 million from Koch. Koch is a libertarian billionaire activist who helped fund a network opposing regulations on carbon emissions, according to the DeSmog blog.

“There is a firm line between donors and the content of exhibits,” Johnson said. “Come look at the exhibit. The exhibit is a very climate strong exhibit.”Johnson, however, told Eos that donations to the museum “come with no strings attached” and that there had been no discussions with Koch about any kind of limitations to the exhibit.

“There is a firm line between donors and the content of exhibits,” Johnson said. “Come look at the exhibit. The exhibit is a very climate strong exhibit. This exhibit was built on years of work by scientists who have put their life’s work into understanding the planet and developing a powerful exhibit about the history of the nature of life on Earth through time, and it is completely independent of the donor.”

Johnson did, however, say that receiving the gift itself was “tremendous because it allowed us to build the exhibit in the first place.”

Transforming the Hall of Extinct Monsters In its time, the Ceratosaurus (on its back, above) was a carnivorous lizard-like dinosaur that posed a threat to herbivores like the Stegosaurus. Now the two creatures are at odds with each other once more, as their skeletons are posed fighting one another in the David H. Koch Hall of Fossils—Deep Time at the Smithsonian’s National Museum of Natural History. Credit: Lucia Martino, Smithsonian Institution

The renovation transformed the cavernous space “that was once at least anecdotally called the ‘hall of extinct monsters,’” said Siobhan Starrs, the museum’s exhibition project manager, during a behind-the-scenes tour of the exhibit last week. That “outdated strange mishmash of science design and experience” has turned into “a gorgeous, modern, one-of-a-kind destination, a place for learning about Earth’s distant past and how it influences our future,” she said.

The exhibit, which showcases the origin and evolution of plants and animals, includes a fossil lab where visitors can watch experts prepare fossils, an interactive gallery to examine evidence and explore the scientific process, and an Age of Humans gallery that addresses ways in which humans are causing rapid and unprecedented changes to Earth.

The exhibit certainly includes lots of dinosaurs, such as a dramatic reimagining of a fight between a carnivorous Ceratosaurus and the herbivore Stegosaurus.

Dinosaurs are not the only startling fossils in the exhibit hall. A fossil palm leaf found in Alaska, for instance, attests to how warm that region once was.

Sixty million years ago, the climate was warmer than it is today—from the equator to the poles. Dense, wet forests covered North America all the way to Alaska. How is it known that the climate was warmer? Many types of warm-climate plants, including palms, grew in places too cold for them now. This fossil palm leaf (Sabalites sp.), discovered in Petersburg Borough, Alaska, will be on display in the David H. Koch Hall of Fossils—Deep Time at the Smithsonian’s National Museum of Natural History. Credit: Lucia Martino, Smithsonian Institution

Ecosystems have a very rich fossil record, and that understanding also is included in the exhibit, Anna “Kay” Behrensmeyer, the museum’s curator of fossil vertebrates, told Eos. Like many of the scientists who are involved with the exhibit, Behrensmeyer recalls her fascination with dinosaurs as a child. She said that she found her first marine fossil along Pigeon Creek in Illinois when she was 5 years old. That was the start of her interest in paleoecology, the study of ancient organisms and their environments.

The fossil hall tells “a marvelous story,” Behrensmeyer said. “It’s just totally awesome, but we also want people to leave feeling they have seen something that also gives them a perspective on where the planet may be heading and how fragile it is.”

Dinosaurs “Draw People into Science”

Other museum experts on the tour also emphasized the human connection to the exhibit.

“The idea that understanding the past helps us understand our future is built into nearly every corner of this exhibit.”“The idea that understanding the past helps us understand our future is built into nearly every corner of this exhibit. It’s in our treatment of mass extinctions, in exhibits on the formation of fossil fuels, and in panels on past global climate changes,” said Scott Wing, the museum curator of fossil plants.

Wing said that in putting together the exhibit, scientists have also highlighted the interconnected processes by which life and physical and chemical processes have changed Earth over billions of years. “Helping people understand these processes is now critical because they are the very same ones by which we’re changing the Earth at warp speed. Only by looking at those processes with the long view of a paleontologist or geologist can we appreciate that the consequences of our actions are going to ripple far into the future.”

Matthew Carrano, the museum’s curator of Dinosauria, told Eos that dinosaurs “draw people into science,” whether they are children or adults.

Woolly mammoths (Mammuthus primigenius), perhaps the best-known mammals of the ice ages, went extinct because of a combination of shifting climate, changing food sources, and a new predator: humans. This mammoth skeleton will be on display alongside more than 700 specimens when the David H. Koch Hall of Fossils—Deep Time opens at the Smithsonian’s National Museum of Natural History. Credit: Smithsonian Institution

Dinosaurs “are a really important fixture in museums. They used to be essentially trophies. Now they are starting points,” Carrano said, adding that there is hopefully something for everybody at the exhibit. “Whether you just want to see dinosaurs, we hopefully deliver for that level. If you want to really think about how climate has changed through time and how animals and plants have evolved in response, we can do that for you. If you want to think about the human future, there’s a lot of different ways in.”

Museum director Johnson, who found his first fossil, a fossil clam, when he was about 5 years old, agreed that dinosaurs are a way to draw people into science and into the museum. “You come for the dinosaurs. You stay for everything else,” he said.

—Randy Showstack (@RandyShowstack), Staff Writer

Pacific Carbon Ages During Long Journey Along Ocean Floor

Tue, 06/04/2019 - 11:30

The ocean contains a large reservoir of dissolved organic carbon (DOC) with an average radiocarbon age of about five thousand years. This “old” and abundant DOC reservoir sequesters carbon dioxide from the atmosphere, and thus any change in the DOC pool size or residence time can affect Earth’s carbon cycle that shapes the global climate.

Recent studies have challenged the paradigm that the main fate of DOC exported to the deep ocean is aging with deep ocean circulation. Druffel et al. [2019] respond to the debate by providing the first transect of radiocarbon age of DOC in the Pacific. Their findings confirm that the radiocarbon signal of DOC and DIC are tightly coupled in the deep Pacific and not substantially altered by other processes, including decomposition of sinking particulate carbon.

Thus, this study confirms that aging (radioactive decay) is the main control on DOC in the deep Pacific over a timescale of more than 600 years and distances of the entire Pacific basin. The finding may help constrain predictions on how future warming will affect deep ocean circulation, and, in turn, the deep ocean DOC reservoir.

Citation: Druffel, E. R. M., Griffin, S., Wang, N., Garcia, N. G., McNichol, A. P., Key, R. M., & Walker, B. D. [2019]. Dissolved organic radiocarbon in the Central Pacific Ocean. Geophysical Research Letters, 46. https://doi.org/10.1029/2019GL083149

—Rose Cory, Editor, Geophysical Research Letters

Sea Level Rise May Reactivate Growth of Some Reef Islands

Tue, 06/04/2019 - 11:24

Rising seas pose serious threats for low-lying coral reef island nations. Widespread assumptions hold that encroaching waters will affect all reef islands in the same way, with many disappearing beneath the waves. However, emerging evidence, including new research by East et al., suggests that reef islands form differently in different settings, and some might actually grow as waters rise.

The new paper builds on work performed in the Maldives, a 1,200-island nation that is home to about 436,000 people. There the researchers had previously studied islands that formed on small, ring-shaped reef structures known as faros. But 90% of Maldivians live on the islands that form on reef structures around atoll perimeters; how and when these rim-type reef islands originally formed were unclear.

To reconstruct rim reef island formation, the scientists selected two contrasting field sites in Huvadhoo Atoll, the second-largest atoll in the Maldives. One site included three islands on the southwestern, windward side of the atoll. The other site consisted of two islands on the northeastern, leeward side of the atoll.

At each site, the researchers used a variety of tools to peer into the past. These included topographic surveys using laser levels, examination of subsurface layers using ground-penetrating radar and coring, and radiocarbon dating of materials found in the core samples.

This analysis revealed that islands at both sites formed during the postglacial period when sea levels were higher than present levels. Before the islands formed, existing coral reefs grew vertically toward the sea surface. Then, intense wave action associated with the elevated waters deposited pieces of broken-off coral and other materials, which accumulated on the reef platform to initiate island formation.

Despite being in the same atoll, however, the two different settings gave rise to islands on different timescales. Islands on the leeward rim began to form about 4,200 years ago, whereas those on the windward rim initiated formation about 2,800 years ago. Accumulation of wave-deposited material followed different patterns between the two sites, suggesting that reef islands in different settings may respond differently to climate change.

This research suggests that in some settings, future sea level rise and associated wave action could reactivate island-building processes, spurring further growth of reef islands, which could enhance their resilience to climate change.

Still, the authors note that rising temperatures and associated coral bleaching events could stymie coral growth, limiting the supply of coral rubble and sand materials required for island building. Also, they studied island growth at a millennial scale, whereas shorter time periods are more important for existing island nations. And even with reactivated growth, the intense wave events required, as well as changes in island shape, could challenge island infrastructure and habitability.

Nonetheless, the findings could help inform vulnerability assessments and planning for the future of island nations facing the specter of rising seas. (Geophysical Research Letters, https://doi.org/10.1029/2018GL079589, 2018)

—Sarah Stanley, Freelance Writer

Missing Lakes Under Antarctic Ice Sheets

Tue, 06/04/2019 - 11:22

Ragged and remote, Recovery Glacier drains nearly 1 million square kilometers of the East Antarctic Ice Sheet (EAIS), a massive system of glaciers that makes up about two thirds of the Antarctic continent.  Past studies have suggested that there are a number of large lakes beneath the glacier, potentially contributing to its unusually fast westward flow along the Shackleton Range. Now, however, a new study suggests that many of these lakes do not exist.

Most previous studies that have suggested that large lakes are present beneath Recovery Glacier were based on altimetry—a satellite-based method that measures a glacier’s volume on the basis of its height. In the new study, however, Humbert et al. used a different technique, called radio echo sounding, to look for the lakes.

In radio echo sounding, an airplane broadcasts radio waves deep into ice and catches the signals as they bounce back, revealing a glacier’s interior structure. Large, flat reflections from the base of the ice sheet typically indicate liquid water. In January 2014, the team carried out an extensive, airborne, radio echo survey of Recovery Glacier and its tributaries, flying a total of 22,700 kilometers along the glacier’s path.

Although the team was able to accurately identify a few lakes beneath Recovery Glacier, they found no evidence of water at most of the sites where past studies have proposed large lakes. Computer models based on the new measurements suggest that the few large lakes that do exist beneath the ice sheet are not likely to be responsible for the glacier’s high velocity, the team reports.

The findings could help scientists more accurately predict how loss of ice from Recovery Glacier will contribute to sea level rise as global temperatures warm. Although the EAIS, which Recovery drains, has traditionally been considered less vulnerable to warming oceans than the Western Antarctic Ice Sheet, recent research suggests that it, too, is losing billions of tons of ice per year. (Journal of Geophysical Research: Earth Surface, https://doi.org/10.1029/2017JF004591, 2018)

—Emily Underwood, Freelance Writer

Improving Climate Predictions over Decades

Tue, 06/04/2019 - 11:21

Earth’s climate system is chaotic and nonlinear. This characteristic imposes limits on how well scientists can predict climate statistics related to temperature, precipitation, and other variables. (The degree to which skillful predictions can be made is called predictability.) The steady evolution of climate modeling over the past several decades has led to significant strides in seasonal climate prediction, but forecasting the climate over decades has proved more challenging.

At the timescale of decades, climate swings are driven by both internal dynamics, like the El Niño–Southern Oscillation, and external factors (e.g., volcanic eruptions). The limits and mechanisms of these phenomena are still not fully understood, which imposes boundaries on the climate’s long-term predictability.

Zhang and Kirtman recently explored climate predictability over decades. The authors applied an interactive ensemble coupling strategy to the Community Climate System Model (CCSM4) to create climate simulations with decreased atmospheric noise at the air-sea interface. In other words, they reduced short-term variability in the climate model. By reducing this noise, the authors isolated the climate signal in the model and were able to quantify how the noise affects predictability. To measure predictability, they used the nonlinear local Lyapunov exponent (NLLE) method, which was the first use of NLLE with state-of-the-art coupled climate models.

The study determined that the interactive ensemble approach underestimates decadal predictability compared to estimates generated from observational data. However, the results indicated that predictability varies by region. Forecasts from the North Atlantic were more predictable, for instance, whereas the Indian Ocean and the Southern Ocean were less predictable than the control simulations.

The authors also evaluated the predictability of subsurface ocean temperature in the North Atlantic. In regions without external climate forcings, the interactive ensemble method resulted in decreased predictability. In areas with both internal and external dynamics, predictability increased. The mechanisms for these patterns, however, require further investigation.

Although the study does not solve the challenge of long-term predictability of climate models, the findings do suggest that decadal predictability is related to both internal climate variability and ocean dynamics. (Geophysical Research Letters, https://doi.org/10.1029/2018GL081307, 2019)

—Aaron Sidder, Freelance Writer

Paleomagnetism Indicators May Be Flawed

Mon, 06/03/2019 - 12:09

Earth’s magnetic field varies through both space and time. The planet’s magnetic poles migrate through the years and sometimes even reverse, leading the north and south magnetic poles to switch places. The strength of the field also varies. Polarity reversals occur when the field’s intensity is low. Understanding the historical variations of the field helps reveal processes in Earth’s core and sheds light on the current behavior of the magnetic field.

Magnetic minerals in igneous rocks record the magnetic field at the time of their formation. Geophysicists can trace field changes by indirectly sensing these changes recorded in newly formed seafloor, for instance. On land, scientists often seek out volcanic features, like volcanic ash flow tuffs. Terrestrial samples can be particularly useful for identifying shifts in intensity, as well as in the direction of the field.

Recently, however, Avery et al. discovered that ash flow tuffs, which should preserve the strength of the magnetic field during a volcanic eruption, may actually be a flawed material for testing magnetic variations. The researchers examined samples from Bishop Tuff, located in eastern California, a frequent site for paleomagnetic and petrologic studies. Bishop Tuff formed 767,000 years ago when, over a few days, an erupting volcano deposited approximately 200 cubic kilometers of ash and lava: enough material to fill 80 million Olympic-sized swimming pools or the whole of Lake Tahoe. The authors tested the samples for variations in magnetic mineralogy.

The results indicated that although portions of the tuff produced high-quality paleointensity estimates, the estimates varied depending on where samples were collected and their magnetic mineralogy. The authors found that rocks in the ash flow became magnetized in fundamentally different ways—from venting volcanic gas, interactions between ash and water, varying eruption temperatures, and ash solidification and compaction. In turn, portions of the tuff yielded significantly higher paleointensity estimates than neighboring sections depending on how they formed. These differences in rock formation could generate up to a 20% overestimate of paleointensity.

Furthermore, the authors found that unsuitable magnetization in some samples may not be filtered out by the selection criteria typically applied in the experimental process. The limitations in the selection criteria could further complicate the use of ash flow tuffs for paleomagnetism research.

The study carries broad implications for a large body of research into paleomagnetism. The finding that rocks with reliable magnetic signatures formed in ways outside the scope of theory means that conclusions from past research may be called into question. The study will help guide future sampling efforts to avoid the pitfalls unveiled by the analysis. (Geochemistry, Geophysics, Geosystems, https://doi.org/10.1029/2018GC007665, 2018)

—Aaron Sidder, Freelance Writer

Déjà Vu: Understanding Subduction Zones’ Cycle of Seismicity

Mon, 06/03/2019 - 12:09

Along the southeastern edge of Japan’s Honshu Island, the Philippine Sea plate is diving beneath the Eurasian plate at the Nankai subduction zone. Seismicity there has unleashed numerous devastating, megathrust earthquakes in a cycle typically characterized by pairs of closely spaced tremors that have occurred every 146 years, on average, since 1361. The region’s most recent earthquakes were the magnitude 8.1 Tonankai and the magnitude 8.4 Nankai events, which occurred in 1944 and 1946, respectively.

The seismic cycle is the process of repeatedly building stress on a fault over a long period of time that is rapidly released in a large earthquake. Previous studies have recognized that mantle flow plays a crucial role in the seismic cycle by relaxing postseismic stresses as well as straining the fault during the interseismic buildup to the next tremor. The surface deformation that accompanies this cycle can vary considerably depending on the mantle’s viscosity. But inferring this parameter has proven difficult because of a lack of geodetic data sets that span the centuries-long timescales of most seismic cycles.

The only place in the world where a record exists that is long enough to potentially record a complete, postseismic phase is in southern Japan, where leveling surveys as well as tide gauge and GPS measurements collectively span the period from 1890 to the present. Johnson and Tebo have harnessed this unique data set to model vertical deformation in the Nankai region from 1947 to 2015.

The results indicate that following the 1940s earthquakes, subsidence was centered about 250 kilometers inland of the Nankai trench, and its rate gradually decreased from 1947 until approximately 1995. By contrast, postseismic uplift occurred within a narrow belt stretching along Honshu’s southeastern coast, but it slowed and then switched to subsidence by the mid-1960s.

According to the authors’ two-dimensional modeling results, the uplift is best explained by afterslip along the coast, whereas the inland subsidence is strongly indicative of postseismic flow within the mantle wedge. The best fit to this pattern requires a viscosity on the order of 1019 Pascal seconds, which corresponds to a mantle relaxation time of 5 to 15 years. As the first study to clearly capture 5 decades of postseismic mantle flow, this research offers a crucial contribution toward improving our understanding of the cycle of seismicity that occurs in Earth’s subduction zones. (Journal of Geophysical Research: Solid Earth, https://doi.org/10.1029/2018JB016345, 2018)

—Terri Cook, Freelance Writer

Afghanistan’s Blob Hunters

Mon, 06/03/2019 - 12:08

No one thought it could be done. After all, Afghanistan remains, more than 17 years after the U.S.-led invasion, a country at war.

The idea of sending scientists to do fieldwork there was, to the agencies from which University of Montana geophysicist Rebecca Bendick tried to secure research funding, ludicrous.

“People said, ‘If you go there, you’re gonna get killed, and therefore, you won’t have any data.’”“People said, ‘If you go there, you’re gonna get killed, and therefore, you won’t have any data.’”

But the mysteries swirling around Afghanistan’s geology are great, partly because of how hard it is to work there, and the pull of one of those mysteries—what’s behind the seemingly inexplicable earthquakes that rattle the Hindu Kush mountains in the northeast of the country—was strong enough that Bendick and her colleague Peter Molnar of the University of Colorado Boulder had to find out what was going on.

But how to do fieldwork in a war zone?

The answer: Enlist the help of Najibullah “Najib” Kakar, a civil engineer, and his crack team of fellow Afghan scientists.

“Gave Dylan about a thousand bucks in hundred-dollar bills and said, ‘Good luck, here’s a sat phone, call me if you’re in trouble.’”In 2015, Bendick, using a small amount of the prize money Molnar got when he won the Crafoord Prize, sent her then master’s student, field geologist Dylan Schmeelk, to Afghanistan to train Kakar and his team on how to set up field GPS stations. Bendick and Molnar, as part of their mission to unravel the mystery of the Hindu Kush quakes, needed data on how the crust in that part of the world is moving around.

“Gave Dylan about a thousand bucks in hundred-dollar bills and said, ‘Good luck, here’s a sat phone, call me if you’re in trouble,’” Bendick said.

“I was pretty darn nervous,” said Schmeelk, who explained that he almost did not board the plane to Afghanistan.

But Schmeelk made it to Kabul and met Kakar, and the two flew to Fayzabad, a city in northeast Afghanistan that sits on the Hindu Kush. It was there that he trained Kakar and his team, and on a hill above the city, they installed Afghanistan’s first GPS station that can monitor the crust’s motion.

Saifurrahman Saaid, one of the blob hunters, waited for a couple days for a remote GPS station to record data. Credit: M. Yatim Zaryab The Blob Emerges

In May, Eos reported on the discovery, made by Molnar and Bendick, of a giant blob of continental lithosphere that is dripping into the mantle, just beneath the Hindu Kush in Afghanistan.

The duo knew that there was something strange about the earthquakes that rattle those mountains. At first glance, it looks like the driver behind the earthquakes is the ongoing tectonic collision between the Indian subcontinent and Eurasia.

There are, however, no faults in the area that suggest this is the case, and the GPS data that Kakar and his team gathered for Bendick and Molnar confirmed that the crust’s motion is not what it should be if subduction of the Indian subcontinent is triggering the Hindu Kush quakes.

Without Kakar and his team’s GPS data, the discovery of the blob beneath the Hindu Kush would not have been possible, Bendick explained.

And getting those data was a bit trickier than pushing some buttons and downloading information from a satellite. “The instrument has to be fixed to the ground,” Bendick said.

The Blob Hunters

Northeast Afghanistan is rife with war, in which the United States has participated since 2001. To reach the places where the team needed to install GPS units on the Hindu Kush, they either had to drive on main roads (about an hour to the field sites, Kakar explained), which combatants are more likely to traffic, or had to take back roads (5 to 10 hours to the field sites), which are mostly unpaved and filled with holes.

One problem with carting around GPS units, according to Kakar, is that if combatants pull you over, they might mistake your GPS units for homing beacons that Hellfire missile–equipped U.S. drones might use to bomb them.

“We cannot go with the cars from the office,” Kakar said. “Usually, we have to rent local cars, not to be identified by the opposition groups.”

To avoid trouble, the team would take the back roads. “I remember it was 2017 when our car slipped off a cliff and it was stuck for 3 days,” Kakar said. “Luckily, our colleagues all were fine, but the equipment was damaged.”

At one point, the team’s 4Runner went off a backcountry road, down into a valley. Credit: Mir Ahmad Shah

Before his stint as a blob hunter, Kakar was, and remains, a civil engineer with the Norwegian Afghanistan Committee. One of his goals is to mitigate damage that natural hazards like earthquakes pose to Afghanistan’s budding infrastructure projects, even though the country’s ability to monitor things like seismic activity is very limited. There are, for instance, only two seismic monitoring stations in Afghanistan, and they are both in Kabul—thousands of kilometers away from the northeastern reaches of the country where a 1998 earthquake around the city of Rostaq killed thousands.

“Estimating seismic hazard strongly hinges on the availability of data,” Kakar said. “When you don’t have the scientific data, it’s hard for engineers to make decisions.”

“We are making history. We are opening the doors for the future scientists in Afghanistan.”This need for data is why Kakar wants to establish what he calls the Afghanistan Seismic Monitoring and Research Centre (ASEM). ASEM, he explains, will centralize activities like seismic monitoring into one office, and it will deploy seismic and GPS stations around the country.

This information will help scientists assess the hazards posed by faults that are close to infrastructure projects, like the Shah wa Arus Dam near Kabul, which Kakar explained has cracks that may be due to seismic activity along the nearby Paghman Fault. But there is pretty much zero funding for researchers to investigate what is truly behind the damage, which is why Kakar hopes that after helping discover the blob and thereby showing that his team can do successful geophysical work in Afghanistan, the country’s government will provide the funds he needs to launch ASEM.

“This is the first time ever such equipment or such studies are being done inside Afghanistan,” Kakar said. “We are making history. We are opening the doors for the future scientists in Afghanistan.”

—Lucas Joel, Freelance Journalist

4 June 2019: This article has been updated to correct the university affiliation of Rebecca Bendick.

The Mineralogical Society of America Turns 100

Mon, 06/03/2019 - 12:07

The year 1969 was a climactic one in the Earth sciences. A half century after the twin births of AGU and the Mineralogical Society of America (MSA), the promise that “problems of really fundamental significance” [Kraus, 1921] might be resolved through the formation of independent organizations seemed fully validated. Astronauts completed two lunar landings that year and returned Moon rocks that still drive research into planetary evolution. Equally significant, plate tectonics had emerged after decades of bruising controversy as the framework that would guide our understanding of terrestrial dynamics for the ensuing half century and beyond.

Watermelon tourmaline, or elbaite, has served as the basis for the Mineralogical Society of America’s logo for many decades. Credit: MSA

Mineralogy and petrology played integral roles in those transformative events. Harry Hess, the professor of geology at Princeton University whose work on seafloor spreading inspired the plate tectonic revolution, was as capable in the analysis of the atomic structure of pyroxenes [Hess, 1941] as he was in analyzing gravity anomalies near island arcs. His detailed petrographic studies of peridotite—which stretched from his Ph.D. work until his untimely passing in 1969—were critical to his insights into the processes that occur at mid-ocean ridges [James, 1973].

The Mineralogical Society of America celebrated this progress with a grand party for its 50th anniversary (see photo above). On 8 November 1969, MSA sponsored a Jubilee Banquet in Atlantic City, N.J., in connection, as always, with the annual meeting of the Geological Society of America. The “postprandial festive events” included a recognition of representatives from other societies and the reading of their letters of congratulation, the presentation of a painting (the depiction of a rustic cabin in the woods of New Jersey was last seen in 1975 in the office of George Switzer, the curator who started the National Gem Collection at the Smithsonian National Museum of Natural History), and the announcement of society awards: the Roebling Medal to Fritz Laves and the MSA Award to W. Gary Ernst. Harry Hess, who had served as MSA president in 1955, chaired the Symposia Committee, which organized three colloquia on upper mantle mineralogy, sulfides, and nonmarine evaporites [Morgan et al., 1970].The patrons of that dinner…must have sensed the fulfillment of Edward Kraus’s 1921 prediction that with the founding of MSA, “the future of mineralogy in America is assured.”

The program for the Jubilee Banquet makes it clear that this anniversary was an extended family affair. In addition to the Symposia Committee (13 members), the commemoration was brought to life by a Banquets Committee (11 members), an Invitations Committee (6 members), and an Honors Committee (9 members), all of which included many Roebling medalists and past presidents. Indeed, the opening speaker for the Sulfides Symposium was Linus Pauling, a two-time Nobel laureate. For the majority of us who were too young to attend, one imagines that as the patrons of that dinner basked in the success of the Apollo missions and in the fresh clarity of plate tectonics, they must have sensed the fulfillment of Edward Kraus’s 1921 prediction that with the founding of MSA, “the future of mineralogy in America is assured.”

Assessing Mineralogy and Petrology Through a Centennial Symposium

On 20 and 21 June 2019, members and friends of MSA will convene in Washington, D.C., to address the direction of our science and our society.As the wheel has turned another 50 years, do we share that same confidence in the forward trajectory of the solid Earth sciences? On 20 and 21 June 2019, members and friends of MSA will convene at the newly renovated Carnegie Institution for Science building in Washington, D.C., to address the direction of our science and our society. Fourteen themed colloquia will focus on exciting frontiers in mineralogy and petrology today (Figure 1). Some of these topics were scarcely more than a dream 50 years ago: Martian mineralogy based on in situ sampling, ultrahigh-sensitivity trace element and isotope analysis to reveal Earth’s many cycles of petrologic reinvention, and synchrotron-based spectroscopy and diffraction in the novel fields of nanomineralogy and biomineralogy. Other sessions will offer state-of-the-art perspectives on such areas as gemology and the artistic use of minerals, the health hazards of mineral dusts, and metamorphic petrology.

Fig. 1. MSA continues to pioneer research in the solid Earth sciences today. Credits: bottom right, Brookhaven National Laboratory; the remainder are owned by the authors or in the public domain

We have structured plenty of opportunity for group interactions during breaks, lunches, and, best of all, a private evening reception in the mineral and gem galleries of the Smithsonian’s National Museum of Natural History, supported by a generous leadership grant from the Gemological Institute of America. Full details of this event can be viewed on the Centennial web page of the Mineralogical Society of America.

Which topics will provoke vigorous debate? Beyond the important discussions that undoubtedly will follow the scientific presentations, we hope that delegates consider some of the broader issues that reflect on the health of our organization.

Demographics: Reasons to Worry and to Be Hopeful

At a time when mineralogical and petrological research is flourishing, fewer Earth scientists are actually calling themselves mineralogists and petrologists.MSA confronts a peculiar paradox that has not afflicted its sibling societies. At a time when mineralogical and petrological research is flourishing, fewer Earth scientists are actually calling themselves mineralogists and petrologists [Brady, 2015]. MSA membership in 1969 was 2,306; by 2018, it had decreased to 2,034. The past 50 years have witnessed an intellectual diaspora, as disciplines that once were encompassed within mineralogy have matured into thriving primary fields. We see this trend manifesting itself today in the area of human sustainability, which relies critically on mineralogical and petrological research. Many paleoclimate studies depend on mineral and rock proxies. Remediation of polluted soils, waters, and the atmosphere requires intimate knowledge of chemical reactions at rock-fluid-air-life interfaces. Geomimetic materials will continue to inspire solutions to environmental damage. But many mineralogical practitioners in these sustainability sciences identify with other clans.

The news is not all bad. When that 50th anniversary program is viewed with the modern eye, one discordant note is immediately apparent. Of the 44 scientists who organized the jubilee, only one woman participated: Alice Weeks, the “chairman” and sole member of the Arrangements Committee, as in floral arrangements. Likewise, of the 30 symposium speakers and authors, all but two were white males working at U.S. institutions. Today, women constitute one third of the MSA membership, and half the articles published in American Mineralogist have foreign authorship, revealing the international reach of our society. Although we must continue our efforts to diversify, the membership is in important respects healthier than in 1969.

Building Bridges to the Collecting and Industrial Communities

MSA needs to do a better job of closing the loop with the people who sometimes risk life and limb to find the minerals and rocks that provoke some of the most interesting scientific questions.MSA’s leadership has been engaged in ongoing discussions to address its unintentional isolation from some stakeholders, including the amateur mineralogy community and industrial mineralogists. The first publications in the American Mineralogist dealt mainly with the external morphology of minerals and the factors that control mineral growth. Our modern understanding of mineral growth processes has been guided through the examination of countless natural specimens provided to scientists by collectors. But crystal growth research has required such high levels of instrumental and theoretical sophistication that the collecting community has been edged out of the conversation. MSA needs to do a better job of closing the loop with the people who sometimes risk life and limb to find the minerals and rocks that provoke some of the most interesting scientific questions.

Likewise, when mineralogists see the letters IMA, they think of the International Mineralogical Association; however, there is another IMA—the Industrial Minerals Association. Whereas the former IMA has laid the ground rules for mineral classification worldwide since its creation in 1959, the latter IMA works to provide society with the raw materials we require for our everyday needs (e.g., aggregates and cement for buildings, roads, airports). From an academic perspective, it might be more stimulating to study minerals on Mars than to optimize the production of aggregate from a gravel pit, but there are many more jobs in resource processing and a much greater societal need for training in that area.

Moreover, mineral industries are struggling with litigation alleging the incorporation of asbestos or other toxic minerals into their products. Asbestos is a poorly defined term with no real mineralogical definition [Gunter, 2018], and identifying trace amounts of asbestos still requires the highest mineralogical expertise [Thompson et al., 2011; Gunter, 2010]. MSA missed the opportunity to play a nonpartisan role in clarifying the mineralogical terminology from the onset of federal and state regulations in the 1970s, but it still can contribute to the discussion concerning what is and what is not asbestos in natural versus occupational settings.

Mineralogy and Petrology as the Core of an Earth Sciences Curriculum

Everyone in the academic world is aware that traditional mineralogy and petrology courses have disappeared from university curricula over the past half century. This trend contrasts with an increasing need for scientists trained in classical mineralogical and petrological skills in the private sector. As a result, many positions that should be filled by mineralogists and petrologists instead are occupied by materials scientists, chemists, physicists, engineers, or even those with degrees in environmental science. It is particularly problematic in the specialized area of optical mineralogy, which typically constituted a full course for geology majors in 1969. Advocating for the resurrection of these courses is the surest way to induce groans at faculty meetings, but are we serving students better with modern Earth systems–based curricula? It is true that critical problems like climate change require a more holistic understanding than a conventional physical geology framework allows. But it is also true that some geoscience graduates are paying $2,000 to complete for-profit short courses to gain mineralogical skill sets that university degree programs once provided.

A Need for Reunion

Since that grand banquet in 1969, MSA has established itself as a juggernaut in the production of affordable and high-quality technical papers and books at the cutting edge of mineralogy, petrology, and geochemistry.Since that grand banquet in 1969, MSA has established itself as a juggernaut in the production of affordable and high-quality technical papers and books at the cutting edge of mineralogy, petrology, and geochemistry. Thanks largely to the foresight of retiring executive director J. Alexander Speer, we have navigated the transition from paper to virtual media with financial aplomb. But the ever-shifting sands of our fields require constant reassessment of our mission, and the best way to do that is to tap the creativity of our membership. That is why we invite all mineral and rock enthusiasts to join us in Washington, D.C., this June. We hope to see you there!

Peter J. Heaney is the chair of the MSA Centennial Committee and a past MSA president. Mickey E. Gunter is the 2019 MSA president.

Science in the Deep

Mon, 06/03/2019 - 11:57

Maurice Ewing was blowing things up in the name of science. With a little dynamite, the Lehigh University physics professor spent all the time he could find developing field experiments—specifically, ones using seismic waves to study subsurface geology. In 1934, he was approached by a couple of geologists who urged him to use his techniques to study the seafloor. Eager for any opportunity to probe Earth, Ewing and his explosions pioneered an entirely new way to study the oceans.

Ewing went on to have a distinguished career, including 25 years as director of the Lamont-Doherty Earth Observatory, where he lifted up the entire field of oceanography with his insight into instrument development. Ewing served as AGU’s president in the late 1950s, and since 1976, AGU has awarded a medal in his honor, recognizing significant original contributions to ocean science. This month, as we continue to celebrate our Centennial, Eos is recognizing the ongoing contributions by those who study Earth’s massive, interconnected ocean systems.

Scientists in Australia are building on nearly a century of seafloor mapping progress that began with Maurice Ewing, using modern techniques to create an entirely novel marine habitat map.Scientists in Australia are building on nearly a century of seafloor mapping progress that began with Ewing, using modern techniques to create an entirely novel marine habitat map. Read how the team at Seamap Australia is using high-resolution bathymetric data to extract information about seafloor geomorphology and using it to visualize which reefs, sea grasses, and other habitats need the most protection. This isn’t just about doing the science, but the heavy lifting of coordinating efforts across a continent to collect the data and develop a scalable, usable tool. That tool is already helping, the team writes, to “inform policies for a well-functioning ocean, one of the two major goals of the United Nations Decade of Ocean Science for Sustainable Development, which supports the 2030 Agenda for Sustainable Development.”

Studying our vast oceans demands innovation. When oceanographers needed a way to study deep-sea currents, they had to stray from techniques such as using satellites and surface floats. In the 1970s, scientists developed a way to track acoustic floats over long ranges, enabling them to make long-term observations under the surface. Today, fleets of these acoustic floats are anchored underwater and ballasted to drift at a certain pressure or density within a region for years before being released to the surface to send their data to a satellite for collection. These float studies have revealed a wealth of information about the complexity of deep-sea currents around the world—that archive of information has been collected into a new database.

Collaboration continues to be a hallmark of U.S. oceanographic research.Getting these instruments out into remote areas of the ocean is a major challenge to surmount before the science can even start. In our June cover story, a group of oceanographers reports on their recommendations to make everyone’s lives a bit easier when planning research cruises. They offer new protocols for navigating the increasingly complex coordination of large and diverse teams of scientists with governments around the world—on top of the typical challenges of sourcing a vessel, crew, and funding. As the authors write, “Collaboration continues to be a hallmark of U.S. oceanographic research,” and building on those skills to streamline access to research cruises will lay the course for the future of the field.

This month we look closer at the scientists whose creativity (and, in Ewing’s case, explosive innovation) has allowed us to know the oceans much more intimately than a glimpse from the shoreline. Our observations into space so far have shown us just how rare and special our oceans are. Every day, oceanographers look into the deep to show us again.

—Heather Goss (@heathermg), Editor in Chief, Eos

Un-bee-lievable Geoscience Words in Record-Breaking Spelling Bee

Fri, 05/31/2019 - 13:21

This week, National Harbor, Md., was swarmed by more than 560 elementary and middle schoolers who took to the stage to compete in the 92nd Scripps National Spelling Bee. This year’s bee moved into “uncharted territory” as round 18 commenced, according to the official pronouncer, Jacques Bailly, who said that they may run out of words difficult enough to challenge the remaining finalists.

Speller Zaara Noor from Detroit, Mich., was given the word “seism”—another word for earthquake—to spell in the third round of this year’s Scripps National Spelling Bee. Credit: Mark Bowen/Scripps National Spelling Bee, CC BY-NC 2.0

After 3 buzzing preliminary rounds, 5 high-flying finals rounds, and 12 stinging championship rounds, a record eight cochampion spellers were left standing.

None of the words given to the spellers were easy, but some of the competitors earned their stripes with Earth and space science words. From fossils to minerals to meteorology to Mars, these geoscience words from the bee will get your brain buzzing.

Tardigrade: four-legged microscopic invertebrate

Microscopic water bears couldn’t bring down Nicole Chowdhury.

Dolomite: calcium magnesium carbonate mineral

Honey Advani was solid as a rock spelling this component of compact limestone.

Stibnite: sulfide mineral containing antimony

Jeremiah Markose wasn’t antimon-ated by this slate-gray mineral.

Areology: the study of Mars

Vikram Goddla showed that his spelling skills weren’t rusty (like Mars’s surface).

Vayun Krishna from Palo Alto, Calif., correctly spelled two complicated geoscience words: “fossiliferous,” which means to contain fossils, and “pyrheliometer,” an instrument for measuring the Sun’s energy at Earth. Credit: Mark Bowen/Scripps National Spelling Bee, CC BY-NC 2.0

Pumice: pockmarked volcanic glass

This word couldn’t grind down Sophia Grierson’s confidence—it was smooth sailing.

Cirrocumulus: high-altitude rounded clouds

Correctly spelling this word had finalist Joseph Moran floating on a cloud.

Fluviatic: belonging to rivers or streams

Connor Greally’s spelling on this one didn’t quite flow, but things will get better downstream.

Frontogenesis: two air masses making a front

When this word collided with finalist Navneeth Murali, there were no stormy skies—just sunshine.

Ornithichnite: fossil imprint of a bird

Pavani Chittemsetty left a lasting impression by correctly spelling this one.

Chernozem: dark-colored zonal soils

After avoiding karst’s pitfalls earlier in the week, Aritra Banerjee kept it cool with this one—as cool as the climates these soils are found in.

Tufan: violent storm

Pranav Chandar was definitely tufan-ough for this one.

In round 6, Darian Douglas from Kingston, Jamaica, correctly spelled “schlieren,” an inception-like lithology of one rock type within another. Credit: Mark Bowen/Scripps National Spelling Bee, CC BY-NC 2.0

Bremsstrahlung: radiation from a charged particle’s rapid slowdown

This one didn’t slow down Saketh Sundar. He charged right on ahead.

Omphacite: a green variety of pyroxene

After clear skies with “frontogenesis” earlier in the day, Navneeth Murali put the “omph” in this championship round word.

Paulopost: changes in igneous rock after consolidation

Change is good: With her first geoscience word of the bee, Shruthika Padhy consolidated her place in round 12.

In round 3, Rina Olsen from Hagåtña, Guam, correctly spelled “fulgurant,” meaning to flash like lightning. Credit: Mark Bowen/Scripps National Spelling Bee, CC BY-NC 2.0

Trachyte: volcanic rock with potash feldspar

Sohum Sukhatankar “feld” that he was “spar”-ed a tough elimination with this one.

Allothimorph: bits of metamorphic rock with original crystal boundaries

Another rock-solid spelling from the mineral dictionary from Sohum Sukhatankar in round 14.

Cytherean: about the planet Venus

Saketh Sundar’s spelling of this round 15 word was out of this world.

Tjaele: permanently frozen ground

Rishik Gandhasri didn’t freeze on this round 16 word.

Moazagotl: clouds on a mountainside in warm, dry conditions

Warmed up after 16 prior rounds, Shruthika Padhy floated through this one.

How well would you have done in an all-geoscience spelling bee? Get together with your science hive and give it a try. It’s sure to bee a good time.

—Kimberly M. S. Cartier (@AstroKimCartier), Staff Writer

The Effect of Coral Bleaching Events in the Great Barrier Reef

Fri, 05/31/2019 - 11:34

Spanning more than 2,300 kilometers through the Pacific Ocean, the Great Barrier Reef is famous for its beautiful coral and diverse ecosystem.

More recently, the reef has become an example of the devastating power of climate change. From 2015 to 2016, ocean water off the northeast coast of Australia became dangerously warm for the coral. The heat stress made corals eject the symbiotic algae that live alongside the hard coral skeleton. When the algae leave, the remaining coral becomes a stark white color in a process known as bleaching.

Bleached coral is not dead; it can recover. However, without the algae, the ecosystem is much more vulnerable and more likely to die off in the near future. The 2015–2016 event resulted in the bleaching of more than half of all the coral in the Great Barrier Reef. Now, in a new study, McMahon et al. quantify the ecosystem-level impact of the event at Lizard Island, one of the most devastated sites in the Great Barrier Reef.

To analyze how the coral bleaching is affecting the Great Barrier Reef, the scientists quantified net ecosystem productivity and calcification (NEC) and compared the data to similar studies conducted before the 2015–2016 event began. NEC measures the flow of calcium carbonate through the environment, but it is difficult to measure directly. The researchers instead measured changes in seawater chemistry around the reef, including the total alkalinity and dissolved inorganic carbon. These data reveal whether more calcium carbonate is being removed from the water and added to the corals—an indication of growth—or more is being added to the water, indicating the reef’s skeleton is breaking down.

The authors calculated that the reef was taking up 44% less calcium carbonate compared to the prebleaching studies.

Although the authors say their results indicate a definite decrease in NEC as a result of the bleaching, they also caution that subtle differences in methodology and analysis can cause large changes when calculating NEC. The main problem, they say, is that the calculation is reliant on measuring the reef water residence time—how long water takes to flow through the reef system—which is extremely difficult to do.

Still, the study provides a rare and valuable window into the cost of coral bleaching events at the ecosystem scale. As global ocean temperatures continue to rise and mass bleaching events continue to skyrocket in number, these insights will become more relevant and far-reaching than ever. (Journal of Geophysical Research: Oceans, https://doi.org/10.1029/2018JC014698, 2019)

—David Shultz, Freelance Writer

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