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  • richardmitnick 12:31 pm on July 1, 2022 Permalink | Reply
    Tags: "Unlocking the Magmatic Secrets of Antarctica’s Mount Erebus", , , CO2-rich volcanic systems are less well understood than the more common H2O-rich arc volcanoes., Data taken by measuring natural electromagnetic waves traveling through Earth revealed the volcano’s magmatic system brings lava much closer to the surface than subduction arc volcanoes., , , Eos, , One of Antarctica’s only active volcanoes is home to one of the few long-lasting lava lakes on Earth., Past studies into Erebus relied on seismic data to probe its inner workings., Research has revealed the plumbing underneath Mount Erebus that keeps the lake full., The snow-covered Mount Erebus is the southernmost active volcano on Earth and shares Antarctica’s Ross Island with three other volcanoes-all dormant., Unlike arc volcanoes such as the Cascades in western North America Erebus has very little water in its magma. Instead it’s rich in carbon dioxide (CO2)., Unprecedented images of Mount Erebus’s inner workings show the unique trappings of a CO2-rich rift volcano.,   

    From “Eos” : “Unlocking the Magmatic Secrets of Antarctica’s Mount Erebus” 

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    From “Eos”

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    22 June 2022
    Jenessa Duncombe

    Unprecedented images of Mount Erebus’s inner workings show the unique trappings of a CO2-rich rift volcano.

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    Mount Erebus, Antarctica, is the most southerly active volcano on Earth. Credit: Josh Landis/National Science Foundation, Public Domain.

    One of Antarctica’s only active volcanoes is home to one of the few long-lasting lava lakes on Earth. The lake occasionally blasts out lava bombs from the summit crater of Mount Erebus, 3,794 meters high.

    Now, research has revealed the plumbing underneath Mount Erebus that keeps the lake full.

    Data taken by measuring natural electromagnetic waves traveling through Earth revealed the volcano’s magmatic system brings lava much closer to the surface than subduction arc volcanoes.

    Unlike arc volcanoes such as the Cascades in western North America Erebus has very little water in its magma. Instead it’s rich in carbon dioxide (CO2). This dryness allows magma to travel much closer to the surface than water (H2O)-rich volcanoes that stall out at about 5 kilometers below the surface.

    CO2-rich volcanic systems are less well understood than the more common H2O-rich arc volcanoes.

    “If we can also get an idea of where the magmatic system is, you can better understand the monitoring data when these systems enter periods of unrest,” said lead scientist and geophysicist Graham Hill at the Institute of Geophysics at the Czech Academy of Sciences.

    “This is the first great image of one,” said geophysicist Phil Wannamaker at the University of Utah, who participated in the work.

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    Erebus has long been familiar to polar explorers—this photo was taken by Robert Falcon Scott on his ill-fated expedition to the South Pole. Credit: Robert Falcon Scott/Wikimedia, Public Domain.

    Fire and Ice

    The snow-covered Mount Erebus is the southernmost active volcano on Earth and shares Antarctica’s Ross Island with three other volcanoes-all dormant. Mount Erebus overlooks McMurdo Station, and nearby sits the hut built by legendary polar explorer Ernest Shackleton and his men before they summited Erebus in 1908. Although its name ultimately harkens to Greek mythology’s personification of darkness, Captain James Ross named the volcano after one of his ships, the HMS Erebus, in 1841.

    Past studies into Erebus relied on seismic data to probe its inner workings. Scientists use seismic waves traveling through Earth to ascertain the material below. But Erebus has very few crustal-scale earthquakes, hamstringing the method to shallow depths.

    So Hill, Wannamaker, and their colleagues took a different approach: magnetotelluric data.

    During summers between 2014 and 2017, the team visited Erebus via helicopter. They visited 129 sites on Erebus and Ross Island, taking exhaustive measurements. “Hats off to Graham for the energy and drive to cover the entire island,” said Wannamaker.

    At each site, they’d recorded the natural electromagnetic waves that travel through Earth from the Sun and distant lightning bolts. “A lightning bolt is an impulsive antenna, if you will, and electromagnetic waves ripple out from that into your survey area,” said Wannamaker. Solar weather also produces waves that propagate through Earth.

    Captured by custom “voltmeters” on the surface and fed into a modeling algorithm, the waves can create a 3D picture of the electrical resistivity of material below, “kind of like a CT scan of the human body,” said Wannamaker.

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    Mount Erebus is fed by a column of hotter rock extending vertically from at least 100 kilometers deep (yellow) and melted magma that extends up through the crust (red). Yellow and red represent unusually low resistivity below Erebus (10 and 5 ohm meters, respectively). DGFZ = Discovery Graben fault zone; EFZ = Erebus fault zone. Credit: Hillet al., 2022.

    The picture below Erebus is “very glorious.” Areas with lower electrical resistivity indicate the material is hot and, to some extent, melted. The image shows a hot region that extends to at least 100 kilometers below Erebus. There is also a channel of melt going upward through the crust that feeds the volcano, the new research shows.

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    A languid plume rises from Mount Erebus’s lava lake in 1983. Credit: Bill Rose/Michigan Technological University, CC BY-NC-ND 4.0

    Using this method gave the researchers a much higher resolution: It gave them a continuous view from a few hundred meters to about 100 kilometers deep. “That’s an advantage over other geophysical methods, such as most seismology,” said Wannamaker. The resolution got fuzzier the deeper they looked, however.

    In the image, a lower-resistivity area, likely magma, shoots toward the surface. This magma feeds the lava lake.

    Clues from the Deep

    “This material has been lurking down there,” said Wannamaker. This image “gives us some picture of the longer-term volatile recycling of the mantle and the crust, in particular to CO2.”

    More commonly studied volcanoes like the Cascades are rich in water. Water is very volatile (it easily bubbles out of the magma like fizz in a soda), and as the pressure drops as it gets nearer to the surface, it can suddenly saturate the magma and cause an explosive event, like the 1980 eruption of Mount Saint Helens.

    Erebus is different. The magma’s birthplace in the upper mantle has little water, and the small amount of water it possesses disappears as the magma rises to the surface. The result is dry magma “reaching all the way to the very near surface, which is what we haven’t seen elsewhere.” The team published the results in Nature Communications last month.

    Another notable feature in the new Erebus image is the magma skewing eastward as it nears the surface. For more than 200 million years, Antarctica was splitting in two at the West Antarctic Rift. The separation stopped 11 million years ago, but local movements on Terror Rift, which underlies Mount Erebus and other volcanoes, continued.

    The magma reaches a choke point at the intersection of faults. There, magma and gas pressure build up in the lower middle crust. Occasionally, the magma and gas break through, carrying magma to the lake.

    “Accessible” Mount Erebus

    “This is a landmark study,” said Rick Aster, a professor at Colorado State University who was not involved in the new work. The latest findings address “one of the most remarkable features of Erebus volcano—that it has been able to sustain a convecting phonologic lava lake in its inner crater for at least many decades.”

    Although the new data are the most detailed yet, the researchers can’t see deeper into the mantle unless they take measurements over a larger footprint. A bigger footprint would require taking more measurements on sea ice and the ice shelf, like they did for about a dozen sites in the present study.

    Surprisingly, Erebus is “one of the more accessible systems in the world, if not the most accessible,” said Hill. Although it’s far away, “you have none of the other restrictions of forest cover and accessibility. You can pretty much go anywhere on Erebus to make your measurement.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    “Eos” is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 10:46 am on June 28, 2022 Permalink | Reply
    Tags: "Large-Scale Reforestation Efforts Could Dry Out Landscapes Across the World", A new study suggests that planting more trees around the world could decrease water availability in some regions., , , , , Eos, Forests tend to dry out their local regions but increase the amount of rainfall in other places., One reason it’s taken so long to understand how trees affect the water cycle: studies have tended to focus on either local hydrology or larger-scale atmospheric effects., One underappreciated impact of tree planting is that it changes the water cycle., Studies show that if you change the tree cover in the Amazon forest this impacts precipitation in East Asia and in Canada or in Europe., Trees suck up water through their roots which decreases the amount of water that’s available in the ground.   

    From “Eos” : “Large-Scale Reforestation Efforts Could Dry Out Landscapes Across the World” 

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    From “Eos”

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    24 June 2022
    Nathaniel Scharping

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    A new study suggests that planting more trees around the world could decrease water availability in some regions. Credit: Downtowngal/Wikimedia, CC BY SA 3.0.

    Here’s a riddle for you: How can we both increase rainfall around the world and simultaneously decrease the amount of water that’s available? The answer, it turns out, is to plant more trees.

    That counterintuitive finding comes thanks to a new analysis, published in Nature Geoscience, of how large swathes of trees affect the amount of water both in the ground and in the atmosphere. It’s a finding with implications for a growing movement seeking to plant trees on an unprecedented scale to combat climate change—a movement that has drawn criticism as unrefined and overly idealistic.

    Understanding Trees and Precipitation

    One underappreciated impact of tree planting is that it changes the water cycle, said Anne Hoek van Dijke, a postdoctoral researcher at the Max Planck Institute of Biogeochemistry in Germany and a study coauthor. “People that work in forestry aren’t necessarily aware of the effects it has on water availability.”

    In the new study, she and her coauthors looked at what would happen to global water availability should we reforest 900 million hectares of land—nearly all the land available for reforestation. The effects are complex, they found, but the main takeaway is that land would, on average, actually lose water.

    One reason it’s taken so long to understand how trees affect the water cycle is that studies of the issue have tended to focus on either local hydrology or larger-scale atmospheric effects but never both at the same time, said ​​Edouard Davin, a professor at the Wyss Academy for Nature at the University of Bern. Davin was not a part of the new study.

    Trees suck up water through their roots which decreases the amount of water that’s available in the ground. Studies have shown for years that planting trees leads to reliably lower water levels in nearby streams. But trees also release that water into the atmosphere in a process called transpiration, and the water eventually turns into rainfall—something other studies have pointed out [Nature Geoscience].

    The result is that forests tend to dry out their local regions but increase the amount of rainfall in other places. These effects can be extraordinarily far-reaching.

    “Studies show that if you change the tree cover in the Amazon forest this impacts precipitation in East Asia and in Canada or in Europe,” Hoek van Dijke said.

    Worldwide Water Effects

    In their paper, Hoek van Dijke and her colleagues combined insights from several new data sets [Restoration Ecology] to create worldwide maps of how large-scale reforestation would affect water availability. Water availability declined by 5.3 millimeters per year on average worldwide, they said, even as precipitation increased by 4.2 millimeters per year. That discrepancy is in large part thanks to the fact that around one third of the rain would fall into the ocean, not on land where it’s needed.

    But the changes in water availability would differ greatly from place to place on the basis of factors like the potential area available for tree planting as well as where the regional precipitation typically comes from. Some regions would see decreases of as much as 38%, whereas others would see increases of around 6%. Countries like the United Kingdom and Madagascar would stand to lose water, whereas lower-latitude regions and the Tibetan Plateau would probably see an increase in water, as increased rainfall there offsets the losses due to evaporation.

    Hoek van Dijke cautioned that the study didn’t take into account variables like the future effects of climate change, the impacts of planting different kinds of tree species, or the effects of trees on atmospheric circulation patterns.

    But the implications for global reforestation programs, like the World Economic Forum’s 1t.org initiative to plant 1 trillion trees by 2030, are clear, said Sofie te Wierik, a Ph.D. candidate working on green and atmospheric water governance at the University of Amsterdam who was not involved in the study.

    “Looking at trees as merely a way to capture carbon is not really doing justice to the way they actually interact with their landscape,” she said. “They have a huge hydrological impact.”

    Smarter Reforestation

    Hoek van Dijke said that the research shouldn’t be seen as a condemnation of reforestation, but rather a reminder that altering Earth’s ecology on a large scale requires thoughtful approaches. And with the right decisions, we might even be able to take advantage of things like an increase in precipitation caused by tree planting.

    “The message we want to give is that people are aware of this,” she said. “With smart planning of reforestation we could avoid losing too much water in dry regions, or we could increase the water availability in dry regions.”

    That planning could look like planting trees upwind of drought-plagued or agricultural regions, so the extra moisture provided by the forests rains out where it’s needed most. But more work is needed to understand the interactions between forests and the water cycle before that happens, Hoek van Dijke said. For example, some research indicates that large forests can increase local rainfall by increasing turbulence in the atmosphere, causing more clouds to form.

    We’ll likely have more data about reforestation and the water cycle soon, thanks in part to the glut of case studies being planted around the world, scientists said. As reforestation efforts proceed, Hoek van Dijke said she’s looking forward to the opportunities they’ll provide for real-world tests of their models.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    “Eos” is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 12:11 pm on June 21, 2022 Permalink | Reply
    Tags: "Habitat Climate Change Vulnerability Index", "Reevaluating Ecosystems on the Basis of Climate Change Vulnerability", , , Eos, One needs to think about climate vulnerability differently for an ecosystem than an individual species., The authors applied the index to 33 ecosystems in 10 discrete categories in the United States., The scientists characterized a climate baseline for each ecosystem type (category) using observed climate data from 1976 through 2005.   

    From “Eos” : “Reevaluating Ecosystems on the Basis of Climate Change Vulnerability” 

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    From “Eos”

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    17 June 2022
    Deepa Padmanaban

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    Hardwood forests, like this one in Minnesota, would be reclassified from vulnerable to endangered if climate vulnerability were factored into the ecosystem’s risk factor. Credit: Eli Sagor, CC BY-NC 2.0

    Ecosystems play a vital role in maintaining biodiversity and provide such services as water and air filtration, pollination, and erosion prevention. But globally, ecosystems are being degraded by such human impacts as land development and pollution.

    To assess the status of ecosystems and guide conservation policies, the International Union for Conservation of Nature (IUCN) established the Red List of Ecosystems (RLE) in 2014. Ecosystems are evaluated and categorized with terms borrowed from IUCN’s internationally recognized categories for endangered species: from least concern (the least severe) to collapsed (the most severe, akin to extinction).

    Risk factors used for RLE assessment [PLOS ONE] include rates of spatial decline, rates of abiotic degradation (such as erosion), and rates of disruption to biotic processes (such as epidemics).

    Now a study [MDPI] conducted by scientists from the U.S. Forest Service and NatureServe, a nonprofit organization working on wildlife conservation, factors in climate change vulnerability as a risk factor for the RLE.

    “It’s a good idea to include climate risk in the assessment to effectively conserve and manage ecosystems,” said Mahesh Sankaran, a professor of ecology at the National Centre for Biological Sciences in Bangalore, India, who was not involved in the study, because “climatic changes will impact the structure, composition, and functioning of ecosystems.”

    Developing a Vulnerability Index

    Researchers first developed a framework called the Habitat Climate Change Vulnerability Index (HCCVI). The index considered such factors as exposure (the extent to which the climate within an ecosystem is likely to change), sensitivity (the degree to which any ecosystem is likely to be affected by these changes), and resilience (the ability of the system to recover).

    Patrick Comer, chief ecologist at NatureServe and lead author of the new paper, said, “One needs to think about climate vulnerability differently for an ecosystem than an individual species, as we’re dealing with an assemblage of species in their environment and how they interact. That was our intent with this framework.”

    The authors applied the index to 33 ecosystems in 10 discrete categories in the United States, ranging from cool temperate subalpine woodlands (the Rocky Mountains) to warm temperate grasslands (tallgrass and shortgrass prairies in the Midwest).

    They characterized a climate baseline for each ecosystem type (category) using observed climate data from 1976 through 2005. Exposure measures were calculated on the basis of changes in 19 bioclimatic variables such as annual mean temperature, annual precipitation, and seasonal mean climate conditions. Measures of ecosystem resilience included landscape condition, the presence and activity of invasive species, and the vulnerability of keystone species.

    When the authors applied the HCCVI to the RLE, they found that 17 of the 33 ecosystem scores shifted to higher-risk categories, including endangered.

    NatureServe is currently helping various federal agencies in the United States, including the U.S. Fish and Wildlife Service and the Bureau of Land Management, to apply the HCCVI to land management practices.

    “The intent is to assess climate vulnerability of major habitats that people manage and help them think about appropriate adaptation responses. However, we’re still in early stages in terms of the actual application,” Comer added.

    Local Ecosystems

    Malcolm North, a research ecologist in the U.S. Forest Service who was not involved in the study, said that “the index is fairly simple and is a good first approach. But ecosystems are complex and their vulnerability to climate change is hard to accurately predict.”

    “I do think this would be useful for organizations like the Forest Service as an initial index,” North said, “but each national forest develops its own 20- to 30-year forest plan built on the knowledge of the local forest ecosystems and regional climate change projections.”

    Comer’s group recognized this and is starting to translate the output of the HCCVI into maps to help land managers understand the climate risk across the range of ecosystems.

    “For example, in the pinyon juniper woodland that occurs across the intermountain West in the United States, in some portions we could say your vulnerability is high. And other places it’s sort of moderate,” he explained. He added that the index can even pinpoint the nature of the climate stress—for instance, whether it’s getting hotter and drier or hotter and wetter.

    Sankaran said characterizing climate vulnerability will help land managers identify specific locations in ecosystems where exposure is likely to be high and allocate resources to such mitigation activities as restoration, establishing corridors to enhance connectivity and facilitate species movement, and fire and grazing management.

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    “Eos” is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 11:50 am on June 21, 2022 Permalink | Reply
    Tags: "Avulsion": a rare event where a river changes course., "Backwater length": A river’s flow responds to the flatness of the ocean or lake and starts slowing down., "Fans": Places where a river emerges from a canyon or a valley., "Why Do Rivers Jump Off the Beaten Path?", Avulsions occur because rivers transport and drop sediment., Avulsions occur in rivers with high sediment flows., , , Eos, , , Now a new study mines almost 50 years of satellite imagery to gain insights into where rivers lurch onto new paths., Slowing rivers deposit increasing amounts of sediment which can eventually choke the flow forcing the river to find a new path., The importance of the problem is huge because river jumping events have caused the deadliest floods in recorded human history., You can think of avulsions as being the earthquakes of river deltas.   

    From “Eos” : “Why Do Rivers Jump Off the Beaten Path?” 

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    From “Eos”

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    21 June 2022
    Carolyn Wilke

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    On deltas (like the Pemali here, emptying into the Java Sea in Indonesia), key factors, such as the sediment load, affect where river avulsions occur. Credit: Sam Brooke and Vamsi Ganti, 2022.

    In 2008, the Kosi River in India abruptly changed course during a rare event called an avulsion. Over a matter of days, the Kosi’s path shifted about 100 kilometers, killing more than 400 people and displacing millions.

    What determines where avulsions occur isn’t well known, as data on such river relocations are sparse. Researchers have built their understanding of avulsions mostly from lab-scale experiments, numerical modeling, and studies of the deposits of past avulsions. Now a new study mines almost 50 years of satellite imagery to gain insights into where rivers lurch onto new paths.

    “You can think of avulsions as being the earthquakes of river deltas,” said Vamsi Ganti, a geomorphologist at the University of California-Santa Barbara, who led the new work. Avulsions are tied to river deltas as earthquakes are tied to faults, he explained, and just like ground shakers, avulsions are abrupt and can be catastrophic. “The importance of the problem is huge because river jumping events have caused the deadliest floods in recorded human history.” Researchers have even linked the decline of early cities in Mesopotamia to avulsions on the Tigris and Euphrates Rivers.

    Changes on the Delta

    To root out where avulsions occurred, Ganti’s team tracked changes to rivers in satellite images between 1973 and 2020. Sam Brooke, a postdoctoral researcher working with Ganti at the time, curated much of that data into movies that he watched for hours on end to ensure that the events captured were actual avulsions—sudden shifts—rather than gradual migrations. Once the team built their data set of 113 avulsions, they set about characterizing them.

    “The work is beautiful,” said Douglas Jerolmack, a geophysicist at the University of Pennsylvania in Philadelphia. “It’s comprehensive in a way that is rare” because it’s challenging to integrate such measurements globally, he said. The study also validates some of the frameworks and hypotheses that have bubbled up over the past couple of decades.

    Avulsions occur because rivers transport and drop sediment. Slowing rivers deposit increasing amounts of sediment which can eventually choke the flow forcing the river to find a new path. From the analysis, three regimes of avulsions emerged on the basis of the landscape and physical properties of rivers, the team reported in Science.

    Of the 113 avulsions, 33 were on fans, places where a river emerges from a canyon or a valley. These avulsions happened where rivers lose their confinement (where sediment builds up). “That is what people have believed for a long time, but [the new research has] shown it,” Jerolmack said.

    For the other 80 observations on rivers meeting the shore of an ocean or lake, the team linked avulsion locations to properties of the rivers’ flows. For each river, the team determined what’s called the backwater length on the basis of the rivers’ slopes and depths. Over its backwater length, a river’s flow responds to the flatness of the ocean or lake and starts slowing down, Jerolmack explained. A river’s backwater can be far from the shore—the Mississippi’s backwater zone stretches some 500 kilometers inland.

    For 50 of these 80 avulsions, avulsions occurred within the backwater zone. These rivers tended to be large rivers with a shallow slope, like the Mississippi and the Brahmaputra. Avulsions in the backwater had been documented for such rivers in 2007, but it took time for researchers to understand the physics behind them, Ganti said.

    For the other 30 instances on river deltas, avulsions occurred much farther upstream than the backwater length. Ganti’s team had observed this in Madagascar in 2020, but they thought such avulsions were rare. “The data suggests that there is this new regime of avulsions on deltas, which we didn’t think existed except for this weird case of Madagascar,” Ganti said.

    Such avulsions occur in rivers with high sediment flows on tropical islands such as Papua New Guinea or in desert environments in countries such as Eritrea and Ethiopia. During floods on these rivers, erosion can travel far upstream, causing avulsions outside the backwater zone. “Communities that have never experienced any avulsion hazards could start to experience them in the future,” Ganti said.

    River Reactions to Human Actions

    More information is needed on what drives this newly found avulsion regime, Jerolmack said. Lab-scale studies could sweep from the backwater regime, with its low-slope and low-sediment rivers, to the high–sediment supply regime. Tracking how water and sand move along that spectrum could help untangle the physics behind what makes a river switch from one regime to another, he said.

    On the basis of the new work, it seems possible that a river’s avulsion regime can also change because of human impacts, Ganti said. For instance, higher sediment loads caused by deforestation could potentially shift a river from the backwater regime to the high–sediment supply regime. Climate change may also shift avulsions upstream too, with more intense flooding events and greater flood variability. And rising sea levels will cause river mouths to retreat, Ganti said, pushing the entire backwater length up the river.

    The information drawn from this analysis provides a framework that may allow scientists to predict where avulsions might happen, Ganti said. And that could help communities make engineering decisions about how to protect themselves from these catastrophic events.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    “Eos” is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 1:20 pm on June 17, 2022 Permalink | Reply
    Tags: "Massive Groundwater Systems Lie Beneath Antarctic Ice", Although ice streams cover a tiny percentage of Antarctica they are responsible for most ice flow from the continent’s interior to the ocean., , , Eos, , , Groundwater has potential to shape how the ice sheets evolve dramatically., It is this missing process that hasn’t been considered in conceptual models of how ice streams work., It’s not bedrock beneath the till. It’s actually sediments., On the basis of the salinity of the water at those varying depths researchers demonstrated an exchange between seawater and fresh meltwater from the ice stream., Our understanding of the properties of ice sheets and the ways ice streams transport fast flowing ice and sediment from ice sheets to ocean basins has been incomplete., Scientists are updating ice stream models to understand the ways in which deep groundwater systems affect ice flow., The Scripps Research Institute, There is groundwater within those sediments that can flow up and down so it’s like an aquifer., Water moving within the sediments can contribute to the ice base; help lubricate the ice flow or even slow ice flow by pulling water away from the base of the ice., Whillans Ice Stream moves ice about 2 meters per day. Other nearby streams which range from hundreds to thousands of kilometers in length are faster.   

    From “Eos” and Scripps Research Institute : “Massive Groundwater Systems Lie Beneath Antarctic Ice” 

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    The Scripps Research Institute

    13 June 2022
    Robin Donovan

    Scientists are updating ice stream models to understand the ways in which deep groundwater systems affect ice flow.

    1
    Magnetotelluric stations were able to detect sediments and groundwater beneath Whillans Ice Stream in Antarctica. Credit: Kerry Key.

    If we want to understand the impacts of a warming planet, we must first learn how its coldest regions are faring. Melting ice leads to sea level rise, but our understanding of the properties of ice sheets and the ways ice streams transport fast flowing ice and sediment from ice sheets to ocean basins has been incomplete.

    Now, researchers led by Chloe Gustafson, a geophysicist and postdoctoral researcher at the Scripps Institution of Oceanography, have confirmed scientific suspicions, uncovering significant groundwater amid sediment below ice sheets in Whillans Ice Stream in Antarctica.

    “It is this missing process that hasn’t been considered in our conceptual models of how ice streams work,” Gustafson said of the study, which was published in Science. Scientists aren’t yet sure how these groundwater systems will affect the ice sheet above them, but they represent a new and potentially weighty factor in modeling the behavior of ice sheets.

    The groundwater “has potential to shape how the ice sheets evolve dramatically,” said Stanford glaciologist Dustin Schroeder, who was not involved with the study. “If we want numbers we can be confident in…for sea level rise contributions from ice sheets, we have to get this component right.”

    Although ice streams [Geophysical Research Letters] cover a tiny percentage of Antarctica, they are responsible for most ice flow from the continent’s interior to the ocean. Whillans Ice Stream moves ice about 2 meters per day; other nearby streams which range from hundreds to thousands of kilometers in length are faster.

    Looking Deeper Beneath the Ice

    Gustafson and her collaborators observed groundwater and sediment using magnetotellurics (MT), a method that harnesses natural variations in Earth’s electromagnetic fields to map subsurface properties, similar to how an MRI (magnetic resonance imaging) details the inner workings of the human body. They also gathered passive seismic data to confirm and supplement MT findings.

    Past research focused on shallow hydrologic systems, using techniques such as drilling through the ice to sample sediments below it, right where ice meets earth. Current models that predict the flow of ice streams include a film of water just millimeters thick atop a much thicker layer of sediment, or till. In the past, modelers believed the till sat atop an impermeable layer of bedrock. This turned out to be untrue.

    “It’s not bedrock beneath the till, it’s actually sediments,” Gustafson said. “There is groundwater within those sediments that can flow up and down so it’s like an aquifer.” Water moving within the sediments can contribute to the ice base; help lubricate the ice flow or even slow ice flow by pulling water away from the base of the ice.

    “We can think about the sediments holding the water as a water-saturated sponge,” Gustafson added. Although they weren’t able to determine the volume of the groundwater, its depths ranged from 220 to 820 meters (up to about half a mile). Ice above the measured groundwater is similarly thick, and Antarctic ice elsewhere can be up to 4 kilometers (2.5 miles) thick.

    Groundwater’s Outsized Impact

    On the basis of the salinity of the water at those varying depths researchers demonstrated an exchange between seawater and fresh meltwater from the ice stream. This interplay confirms that deep groundwater systems could affect ice streaming, an important transport system that carries ice from the continent’s interior to the sea. Cumulative changes in ice mass in Antarctica and Greenland are climate change indicators, and warmer temperatures have sped ice flow [EPA] in recent years, according to the U.S. EPA.

    Geophysicists suspected there might be more and deeper groundwater than they’d observed in earlier research, but Gustafson and her team were the first to prove them right using MT and passive seismic data. It wasn’t an easy task.

    Antarctica’s Challenging Conditions

    For Gustafson, being one member of a four-person team camping on the ice sheet for 6 weeks meant labor-intensive days spent not only placing instruments and gathering data but also weathering heavy winds, regularly removing snow buildup from around her tent, and completing camp chores.

    “Ice sheets are pretty remote. It’s hard and expensive to get there,” said Schroeder. Researching groundwater systems on any continent is a challenge, he continued, “but piling between 1 and 4 kilometers of ice on top makes it even harder.”

    Despite those challenges, he expects groundwater to be incorporated into new models of ice streams for both Antarctica and Greenland as researchers seek to understand what Gustafson’s finding means for upcoming changes in ice mass in the face of climate change.

    “When you have this big reservoir of water beneath the surface that has the potential to interact with water at the base of the ice sheet, that water can have a lot to say about where the ice above it flows,” Schroeder said.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Scripps Research Institute, one of the world’s largest, private, non-profit research organizations, stands at the forefront of basic biomedical science, a vital segment of medical research that seeks to comprehend the most fundamental processes of life. Over the last decades, the institute has established a lengthy track record of major contributions to the betterment of health and the human condition.

    The institute — which is located on campuses in La Jolla, California, and Jupiter, Florida — has become internationally recognized for its research into immunology, molecular and cellular biology, chemistry, neurosciences, autoimmune diseases, cardiovascular diseases, virology, and synthetic vaccine development. Particularly significant is the institute’s study of the basic structure and design of biological molecules; in this arena TSRI is among a handful of the world’s leading centers.

    The institute’s educational programs are also first rate. TSRI’s Graduate Program is consistently ranked among the best in the nation in its fields of biology and chemistry.

    “Eos” is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 12:25 pm on June 17, 2022 Permalink | Reply
    Tags: "Newly Discovered Lake May Offer a Glimpse into Antarctica’s Past", , , , Eos, , , , Not tiny Lake Snow Eagle was easy to miss as it is buried 3.2 kilometers (2 miles) under ice in Princess Elizabeth Land nearly 500 kilometers (a few hundred miles) from Antarctica’s coast., , Researchers say sediments trapped beneath Lake Snow Eagle could reveal clues about a time when Antarctica had no ice at all., The Jackson School of Geosciences at University of Texas-Austin, Yan and the other researchers said that the first hint that the lake and its host canyon even existed emerged when scientists spotted a smooth depression on satellite images of the ice sheet.   

    From “Eos” and The Jackson School of Geosciences at University of Texas-Austin: “Newly Discovered Lake May Offer a Glimpse into Antarctica’s Past” 

    Eos news bloc

    From “Eos”

    AT

    AGU

    and

    The Jackson School of Geosciences at University of Texas-Austin

    9 June 2022
    Andrew J. Wight

    Scientists dive—metaphorically—into Lake Snow Eagle, only recently revealed through ice-penetrating radar.

    1
    Shuai Yan (fourth from the right) and the team that conducted an airborne geophysical survey over Lake Snow Eagle in front of one of the aircraft involved in the survey. Credit: Shuai Yan/UT Jackson School of Geosciences.

    Although it is not tiny Lake Snow Eagle was easy to miss. The lake is estimated to be 198 meters (650 feet) deep, 48 kilometers (30 miles) long, and 14 kilometers (9 miles) wide but is buried 3.2 kilometers (2 miles) under ice in Princess Elizabeth Land, nearly 500 kilometers (a few hundred miles) from Antarctica’s coast.

    A new study [Geology] reveals not only how an international team of scientists discovered the lake using aerial ice-penetrating radar but how the discovery may lead to a fuller understanding of the evolution of the East Antarctic Ice Sheet.

    Shuai Yan, a graduate research assistant at the University of Texas at Austin, said that although researchers previously had “decent” measurements of the surface of the ice sheet, they lacked similar information about the area below. “We simply didn’t have any data from this region until we went and did the field work,” he said.

    Yan and the other researchers said that the first hint that the lake and its host canyon even existed emerged when scientists spotted a smooth depression on satellite images of the ice sheet. The team then spent 3 years flying systematic surveys over the site with ice-penetrating radar and sensors that measure minute changes in Earth’s gravity and magnetic field.

    Yan was the one who spotted the lake itself during the ICECAP 2 (International Collaborative Exploration of Central East Antarctica through Airborne geophysical Profiling) field campaign, which was conducted in 2018–2019 with the logistical assistance of the Australian Antarctic Division and in partnership with other international collaborators.

    Yan made the discovery during an overnight data-processing session. “We fly in the daytime, and I wasn’t on that specific flight. I was the one who processed the data overnight to make sure the data was good and everything was working well,” he explained. “Around midnight, I was sitting in front of where the radargram is processed, and on the screen we saw this beautiful, bright reflection.”

    That reflection was the lake hidden below the ice.

    2
    Newly discovered Lake Snow Eagle is outlined in a black-and-white satellite image of the Antarctic Ice Sheet. Credit: RADARSAT/European Space Agency, CC BY-SA 2.0

    Next Steps

    Researchers say sediments trapped beneath Lake Snow Eagle could reveal clues about a time when Antarctica had no ice at all—a sparsely documented time period more than 34 million years ago—as well as glacial cycles since then.

    “There is a significant amount of sediment at the bottom of this lake, and we believe these sediments could be an archive of what Antarctica was like before it froze over, how it froze, and the evolution of the ice sheet during the glacial cycles since then,” Yan said.

    Martin Siegert, a coauthor, glaciologist, and professor at Imperial College London, agreed. “Our knowledge is based on sediments at the ice sheet margin or offshore,” he explained. “A lake record would be in situ (from beneath the ice sheet itself) and so would be definitive in its information, rather than just clues that need to be unraveled from existing records.”

    Tobias Staal, a research associate in Antarctic seismology working for the Australian Centre for Excellence in Antarctic Science who was not involved with the new research, said that the lake’s existence has been suggested for a while but there had been large uncertainties.

    “The paper presents one of the first detailed insights of any kind into the region,” Staal said. “Previously, we only had satellite-derived data and some rather uncertain extrapolations to map the interior of Princess Elizabeth Land.”

    Staal said airborne geophysics provides some significant insight into subglacial geothermal heat flow and erosion/deposition of sediments. However, there is still much more to investigate with denser flight lines, ground-based investigations using seismic surveys, and even, potentially, drilling.

    Yan said that the team’s future goal is to secure funding to extract sediment samples from the lake bed.

    “We believe this lake could be an ideal target for direct coring,” Yan said. “It would be really challenging to drill through two miles of ice and a few hundred meters of water, but it would be exciting and scientifically important to one day have a sample from that sediment.”

    Staal advised that such a program would also be very costly and must be discussed in the context of other data gaps.

    Adriana Ariza-Pardo, a geoscientist and Antarctic researcher at GMAS consultants in Colombia who was also not involved in the new research, attested to the challenges from her own experiences there but agreed that Antarctica is an important place to study.

    “Antarctica is experiencing several changes in its environment, the most notable being those related to the loss of mass of glaciers, the extent of sea ice, the collapse of ice shelves, the increase in air temperature, along with the consequences that these variations generate in the particular Antarctic ecosystems and the rest of the planet,” Ariza-Pardo said. “A method to understand these changes can be done through sediment provenance studies, among other geoscientific methods.”

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Jackson School of Geosciences at The University of Texas at Austin unites the Department of Geological Sciences with two research units, the Institute for Geophysics and the Bureau of Economic Geology.

    The Jackson School is both old and new. It traces its origins to a Department of Geology founded in 1888 but became a separate unit at the level of a college only on September 1, 2005. The school’s formation resulted from gifts by the late John A. and Katherine G. Jackson initially valued at $272 million. The school’s endowment as of December 31, 2015 is $442.3 million.

    The Department of Geological Sciences offers the following undergraduate degree programs: Bachelor of Arts, Bachelor of Science in General Geology, Bachelor of Science in Environmental Science, Bachelor of Science in Geophysics, Bachelor of Science in Hydrogeology/Environmental Geology, Bachelor of Science in Teaching, Bachelor of Science in Geosystems Engineering and Hydrogeology. There is also an undergraduate Geological Sciences Honors Program. In the 2006-2007 academic year, the department awarded 49 undergraduate degrees.

    The department offers the following graduate degree programs: Master of Science (with thesis), Master of Arts (with report), and Doctoral Degree. In the 2006-2007 academic year, the department awarded 52 graduate degrees.

    In 2018, U.S. News & World Report ranked the Jackson School of Geosciences No. 7 among U.S. earth science graduate programs. In addition to the overall ranking, the Jackson School earned top 10 rankings in two of four earth science specialty areas, placing No. 1 in geology and No. 7 in geophysics and seismology. Other areas in which the school is actively involved are paleontology, sedimentology, stratigraphy, hydrology, environmental geology, climate, petroleum exploration, petrology, geochemistry, structural geology and tectonics.

    Students may also graduate with an interdisciplinary Master of Arts Degree through the Energy & Earth Resources (EER) Graduate Program. The EER Graduate Program provides the opportunity for students to prepare themselves in management, finance, economics, law and policy leading to analytical and leadership positions in resource–related fields. Private sector and government organizations face a growing need for professionals that can plan, evaluate, and manage complex resource projects, commonly international in scope, which often include partners with a variety of professional backgrounds. This program is well suited for those looking towards 21st century careers in energy, mineral, water, and environmental resources. Dual degrees in Energy & Earth Resources and Public Affairs are also available through the Jackson School and the Lyndon B. Johnson School of Public Affairs.

    The Jackson School’s faculty and research scientists pursue 200 active research projects a year with annual funding of over $25 million. Research is often collaborative across the three scientific units and interdisciplinary with other departments at The University of Texas at Austin.

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 9:05 am on June 10, 2022 Permalink | Reply
    Tags: "FWI": Full-Waveform Inversion, "The Big Data Revolution Unlocks New Opportunities for Seismology", Advances in computing are allowing seismologists to apply data-hungry algorithms to big data experiments., , , , , , Eos, , In Seismology the volumes of data being acquired from individual experiments are now reaching hundreds of terabytes in passive seismology., , Parallel and distributed computing allow scientists to perform many computations simultaneously.   

    From Eos: “The Big Data Revolution Unlocks New Opportunities for Seismology” 

    Eos news bloc

    From Eos

    AT

    AGU

    9 June 2022

    Stephen J. Arrowsmith
    sarrowsmith@smu.edu
    Daniel T. Trugman

    Karianne Bergen
    Beatrice Magnani

    1
    A recent experiment that used over 50,000 seismic nodes achieved the densest seismic survey on land. These photographs show nodes being staged, transported by truck, and charged/harvested in racks. Credit: Ourabah and Crosby [2020]

    Scientists have been measuring earthquakes for hundreds of years. As instruments have advanced, so has our understanding of how and why the ground moves. A recent article published in Reviews of Geophysics describes how the “Big Data” revolution is now advancing the field of seismology. We asked some of the authors to explain how seismic waves are measured, how measurement techniques have changed over time, and how big data is being collected and used to advance science.

    In simple terms, what is seismology and why is it important?

    Seismology is a science that is based on vibrational waves (‘seismic waves’) that travel through the Earth. Seismic waves produce ground motions that are recorded by seismometers. Recorded ground motions can provide vital clues both about the sources of waves (e.g., earthquakes, volcanoes, explosions, etc.) and about the properties of the Earth the waves travel through. Seismology provides tools for understanding the physics of earthquakes, for monitoring natural hazards, and for revealing the internal structure of the Earth.

    How does a seismometer work and what important advancements in knowledge have been made since their development?

    It’s surprisingly hard to accurately measure the motion of the ground because any instrument that does so must also move with the ground (otherwise it would have to be in the air, where it couldn’t directly record ground motion). To deal with this challenge, seismometers contain a mass on a spring that remains stationary (an ‘inertial mass’), and they measure the motion of the instrument relative to that mass. Early seismometers were entirely mechanical, but it’s hard to design a mechanical system where the inertial mass stays still over a range of frequencies of ground motion.

    A key advancement was the use of electronics to keep the mass fixed and therefore record a much wider range of frequencies. An ideal seismometer can record accurately over a broad band of frequencies and a wide range of ground motion amplitudes without going off scale. This is easier said than done, but seismometers are improving every year.

    What is the difference between passive and exploration seismology?

    Passive seismology is about recording the seismic waves generated by natural or existing sources like earthquakes. Passive seismologists typically deploy instruments for a long time in order to gather the data they need from the spontaneous occurrence of natural sources of seismic waves. In contrast, exploration seismologists generate their own seismic waves using anthropogenic sources like explosions, air guns, or truck vibrations. Because they control the timing and location of the source of seismic waves, exploration seismologists typically work with large numbers of instruments that are deployed for a short time. Exploration seismology is most widely used in the oil industry but can also be used for more general scientific purposes when high resolution imaging is needed.

    How have advances in seismologic methods improved subsurface imaging?

    Developments in seismic imaging techniques are allowing seismologists to significantly improve the resolution of images of the subsurface. A particularly powerful technique for high resolution imaging is called Full-Waveform Inversion (FWI). FWI uses the full seismogram for imaging, trying to match data and model “wiggle for wiggle” rather than only using simplified measures like travel times, and can thus provide better image resolution. The method has become widely adopted by the exploration seismology community for this reason and is now becoming more common in the passive seismic community as well.

    Another important innovation in imaging uses persistent sources of ambient noise like ocean waves to image the subsurface. This is particularly useful for short-term deployments where there is often insufficient time to wait around for natural sources like earthquakes to occur.

    What is “Big Data” and how is it being used in seismology?

    “Big Data” is a relative term that defines data containing greater variety, with larger volumes or coming in at a faster rate, which requires different data analysis methods and technologies than “small data”. In seismology the volumes of data being acquired from individual experiments are now reaching hundreds of terabytes in passive seismology, and petabytes in exploration seismology. For perspective, a typical laptop has less than one terabyte of disk storage. The velocity of data is the rate at which it is acquired or analyzed. In seismology, a new measurement technique called Distributed Acoustic Sensing (DAS) can fill a 1 terabyte hard drive in approximately 14 hours. The variety of data being used for seismic investigations is also increasing, with complementary data types like GNSS, barometric pressure, and infrasound becoming more commonly combined with seismic data.

    What are the main drivers of Big Data Seismology?

    There are three main drivers. First, innovations in sensing systems are allowing seismologists to conduct ‘big data’ experiments. Second, new data-hungry algorithms such as machine learning and deep neural networks are enabling seismologists to scale up their data analysis and extract more meaning from massive seismic datasets. Third, advances in computing are allowing seismologists to apply data-hungry algorithms to big data experiments. Parallel and distributed computing allow scientists to perform many computations simultaneously, with calculations often split across multiple machines, and cloud computing services provide researchers with access to on-demand computing power.

    Moving forward, what are some of the challenges and opportunities that Big Data seismologists face?

    In terms of challenges, the first relates to handling large amounts of data. Most seismologists are accustomed to easily accessing and sharing data via web services, with most of their processing and analysis of the data done on their own computers. This workflow and the infrastructure that supports it doesn’t scale well for Big Data Seismology. Another challenge is obtaining the skills that it takes to do research with big seismic datasets, which requires expertise not only in seismology but also in statistics and computer science. Skills in statistics and computer science are not routinely part of most Earth Science curricula, but they’re becoming increasingly important in order to do research at the cutting edge of Big Data Seismology.

    The opportunities are wide-ranging, and our paper discusses many opportunities for fundamental science discovery in detail, but it’s also hard to anticipate all the discoveries that will be made possible. Our best guide is to look back at the history of seismology, where many major discoveries have been driven by advances in data. For instance, the discovery of the layers of Earth followed the development of seismometers that were sufficiently sensitive to measure teleseismic earthquakes. The discovery of the global pattern of seismicity – which played a key part in the development of the theory of plate tectonics – was preceded by the development of the first global seismic network. The first digital global seismic network was followed by our first images of the convecting mantle. If we take the past as our guide, we can anticipate that the era of Big Data Seismology will provide the foundation for creative seismologists to make new discoveries.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 2:15 pm on June 7, 2022 Permalink | Reply
    Tags: "Planting Wetlands Could Help Stave Off Climate Catastrophe", , , , , , Eos, Peatlands are particularly important carbon sinks., Plants suck carbon from the atmosphere and use it.   

    From Eos: “Planting Wetlands Could Help Stave Off Climate Catastrophe” 

    Eos news bloc

    From Eos

    AT

    AGU

    1 June 2022
    Jennifer Schmidt

    A shift in priority and approach to wetland restoration could reduce atmospheric carbon.

    1
    Credit: iStock.com/Ali Suliman.

    Repopulating forests, planting neighborhood trees, and stopping large-scale logging are popular strategies to offset or reduce carbon emissions. But forests pale in comparison to wetlands’ carbon sequestration potential. Peatlands, salt marshes, and other coastal and inland wetlands cover just 1% of Earth’s surface, yet they store 20% of our planet’s ecosystem carbon, according to new research.

    Restoring wetlands is a powerful additional tool to combat climate change, said Brian Silliman, an ecologist at Duke University and a coauthor of the study, published in Science.

    Wetland Plants Hoard Carbon

    Plants suck carbon from the atmosphere and use it to grow roots, leaves, and flowers. That carbon is released only when the plants decay and landscapes erode away.

    The intricate root systems of partially submerged mangrove stands, salt marshes, and seagrass meadows filter material washing downstream from inland landscapes. The tangled mash of sediments and plant matter becomes the muddy embankment on which more trees and plants grow. Around 50% of the carbon buried in these environments comes from this filtered organic matter, according to the study.

    Peatlands are particularly important carbon sinks. Peat moss—a primary ingredient in many boggy wetlands—grows as mats of spongy plant matter. Older peat is buried beneath newer sprouts, and in the submerged, low-oxygen environment, sluggish decay locks in thick mats of carbon for millennia.

    Wetlands may be a powerhouse of sequestration and storage, but their limited area means they store a fraction of the total carbon sequestered in oceans and forests—the world’s biggest sinks, owing to their sheer size. Nevertheless, a wetland’s greater carbon density means that removing a patch of it has a bigger impact on atmospheric carbon than removing a patch of forest.

    Around 1% of wetlands are lost each year to threats such as construction, farming, and sea level rise, according to the study. With the loss of these environments comes the release of their stored carbon—accounting for roughly 5% of annual total global carbon emissions. “It’s billowing out of these degraded wetlands,” Silliman said.

    Moving Beyond Just Planting Trees

    Although regulations to minimize wetland loss exist, “we haven’t been as aggressive as we could be in restoring them. And part of that is because we’ve underappreciated their importance in the climate crisis,” said Peter Kareiva, a conservation biologist and president and CEO of Aquarium of the Pacific, who was not involved in the study. Governments and environmental organizations have initiatives to reforest vast stretches of land, he said, but they haven’t had those initiatives at such scale for wetlands. But the recognition that wetlands are vastly more carbon rich than oceans or forests could change that.

    “Everybody’s wondering how to offset their carbon: Here you go, you plant a wetland. You get a huge bang for your buck.”

    “[The study] is a call to action to scale it up,” Kareiva said.

    Restoring, protecting, and rebuilding wetlands can be both a global and grassroots strategy. “That’s something that people can get involved with locally,” Silliman said. “Policymakers who have bigger levers need to think about stopping the degradation of wetlands in a big way,” he added.

    “Everybody’s wondering how to offset their carbon,” he said. “Here you go: You plant a wetland. You get a huge bang for your buck.”

    A Shift in Wetland Restoration

    The new study also suggests a change in the approach to wetland restoration efforts. Traditional conservation practices focus on limiting negative interactions among plants and their environment, Silliman said. People plant over small areas and maximize spacing between individual plants to avoid competition. But that’s the wrong approach, he said. Isolated plants have little protection from storm surges, and many are lost during planting efforts. Restoring a wetland in this way is also expensive.

    Emerging research suggests that mutually beneficial interactions among plants and their environments are crucial to their survival—and to maximizing their prospects as a carbon sink. Planting wetland grasses in clumps gives them a better chance to survive because they are more protected, Kareiva said. Restoration costs go down when success rate goes up.

    “If you’ve firmly established a bunch of patches, they sometimes just spread on their own,” he explained. “You don’t have to plant seedlings everywhere.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 10:23 pm on June 6, 2022 Permalink | Reply
    Tags: "Coronal Dimmings Shine Light on Stellar CMEs", , Coronal dimmings are lower-density regions in a star’s corona that occur after those areas are depleted of plasma following a CME., Coronal mass ejections from stars have eluded easy observation so scientists are looking at what’s left behind., Eos, Over the past 3 decades researchers have detected evidence of stellar CMEs from M-class stars., Pinpointing stellar CMEs could be important for finding habitable exoplanets., , Unlike solar dimming of a few percent stellar dimming decreased emissions by 56%.   

    From Eos: “Coronal Dimmings Shine Light on Stellar CMEs” 

    Eos news bloc

    From Eos

    AT

    AGU

    6 June 2022
    Jenessa Duncombe

    Coronal mass ejections from stars have eluded easy observation so scientists are looking at what’s left behind.

    1
    Credit: S. Wiessinger/GSFC/NASA, Public Domain.

    You could be forgiven for missing what comes after a coronal mass ejection (CME). Colossal outbursts of plasma hurtling into space at hundreds to thousands of kilometers per second, CMEs are a spectacle. Scientists have observed many CMEs from our Sun since the 1970s.

    But researchers are now turning their gaze away from a CME’s jettison to what’s been lost. After a CME, extreme ultraviolet light in the corona dims noticeably at the ejection site. Finding darkened spots could hold a key to observing elusive stellar CMEs.

    New research using coronal dimming to identify CME candidates in stars found 21 occurrences of coronal dimmings in 13 different stars.

    Before this research, scientists could “probably count ‘convincing detections’ with our hands,” said astrophysicist Julián David Alvarado-Gómez at the Leibniz Institute for Astrophysics Potsdam, who was not involved in the work. “And some scientists would probably remain skeptical about some of them.”

    Pinpointing stellar CMEs could be important for finding habitable exoplanets. Stellar flares could “totally blow away the atmosphere of an exoplanet,” said Astrid Veronig, the lead researcher of the latest work and chair of Solar and Heliospheric Physics at the Institute of Physics at the University of Graz in Austria.

    Coronal Dimming

    Over the past 3 decades researchers have detected evidence of stellar CMEs from M-class stars. And in a 2019 paper in Nature Astronomy, Costanza Argiroffi published a detailed account of a monstrous CME from a star 450 light-years from Earth.

    Veronig and her colleagues took a different approach: coronal dimming.

    Coronal dimmings are lower-density regions in a star’s corona that occur after those areas are depleted of plasma following a CME. If these dimmings indicate CMEs, the latest work represents the largest number of stellar CME detections reported.

    Veronig found certain stars that dimmed more than once, like the rapidly rotating AB Dor with five events, the young AU Mic with three events, and the nearby Proxima Centauri with two events.

    “Proxima Centauri is the most interesting because it’s our closest star and it’s known to have exoplanets,” said Veronig, who published the work in Nature Astronomy last year.

    Sun as Star

    2
    Credit: Solar Dynamics Observatory/NASA, Public Domain.

    To start, the researchers first considered coronal dimming on our Sun. Looking at the Sun as if it were a far-off star, they analyzed the extreme ultraviolet light curves from instruments on NASA’s Solar Dynamics Observatory (SDO). They compared fluctuations in the light curve with images of CMEs and coronal dimmings caught by spatially resolved instruments on SDO.

    The team found that CMEs from the Sun precede coronal dimmings that decrease broadband extreme ultraviolet emissions by a few percent. The probability that the signature they observed was related to a CME was 95%.

    Next, Veronig and her team looked for stellar dimmings. Combing through historical extreme ultraviolet data collected by the Extreme Ultraviolet Explorer from NASA, as well as soft X-ray wavelengths from ESA’s X-ray Multi-Mirror Mission and NASA’s Chandra X-ray Observatory, they found about 200 star candidates.

    The stars had to be Sun-like, known to flare, and measured for long enough periods (e.g., 10 hours) to qualify.

    Unlike solar dimming of a few percent stellar dimming decreased emissions by 56%. Stellar light curves are noisier than the Sun’s, so only big events came through.

    “Now we’ve shown it is possible, can [scientists] go further and extract more information from it?” Veronig said of the new technique. Satellite missions planned by NASA, like the proposed Extreme-ultraviolet Stellar Characterization for Atmospheric Physics and Evolution (ESCAPE) mission [SPIE], would make spotting stellar coronal dimmings easier.

    Building Momentum

    Alvarado-Gómez called the work a “crucial contribution” to understanding space weather around other stars but worried about an underlying assumption that other stars will behave like our Sun. “Dimmings alone are not sufficient to unequivocally find a CME event.”

    Assistant professor in physics and applied physics Ofer Cohen from the University of Massachusetts Lowell called the technique promising but warned that detecting coronal dimmings can’t tell us about a CME’s characteristics or spatial position on the stellar disk. Cohen did not participate in the research.

    The results support a simulation paper [Cambridge Core] by Meng Jin at the SETI Institute and the Lockheed Martin Solar and Astrophysics Laboratory. Digging deeper into these promising findings from the latest paper and advancing modeling, said Jin, “will provide a critical reference for further instrumentation and methodology to better detect stellar CMEs that significantly influence the habitability of explanatory systems.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 9:27 pm on June 3, 2022 Permalink | Reply
    Tags: "'Landslide Graveyard' Holds Clues to Long-Term Tsunami Trends", "Megablocks", 2018 eruption of Anak Krakatau in Indonesia, , , , , Eos, , How can we assess the modern potential for hazardous tsunamis based only on these ancient buried remnants?, Subduction zone processes and their associated seismic activity, The underwater Hunga Tonga Hunga Ha’apai volcano, These key questions and issues are currently being addressed by a trans-Tasman team of researchers- including us-from Australia and New Zealand under the “Silent Tsunami” project., Tsunami originating from Hunga Tonga–Hunga Ha’apai in early 2022., Underwater landslides,   

    From Eos: “‘Landslide Graveyard’ Holds Clues to Long-Term Tsunami Trends” 

    Eos news bloc

    From Eos

    AT

    AGU

    3 June 2022
    Suzanne Bull
    s.bull@gns.cri.nz

    Sally J. Watson
    Jess Hillman
    Hannah E. Power
    Lorna J. Strachan

    1
    The Sun rises over the Tasman Sea and Mount Taranaki (at left on the horizon), as seen from R/V Tangaroa during research voyage TAN2111 in October 2021 to map part of New Zealand’s northwestern continental margin. Credit: Jess Hillman.

    “Ka mua, ka muri.” We walk backward into the future, with our eyes on the past. This whakataukī (proverb) represents a New Zealand Māori perspective that has much in common with the way Earth scientists study natural hazards. Understanding and learning from historical events inform our preparedness for and increase resilience against future disasters. Studying past tsunami events, for example, is an important part of better understanding the diverse and complex mechanisms of tsunami generation and for improving natural hazard assessments.

    Tsunamis are dangerous natural hazards and are most often caused by earthquakes. Consequently, coseismic tsunamis have drawn most of the focus from researchers and hazard planners.

    2
    In September 2009, American Samoa felt the effects of a powerful magnitude 8.1 earthquake that originated in the Tonga Trench, some 240 kilometers away. Only 15 minutes after earthquake shaking stopped, a large tsunami hit the Samoan archipelago, inundating coastal communities (Pago is shown here), catching many islanders off guard, and killing 35 people. Credit: National Park of American Samoa (NPSA)

    However, several recent tsunamis have been attributed to other sources on which less research has been done, including underwater landslides, as in the case of the Palu, Indonesia, event in 2018, and volcanic eruptions in the case of the tsunami originating from Hunga Tonga–Hunga Ha’apai in early 2022.

    3
    The landslide and tsunami associated with the 2018 eruption of Anak Krakatau, Indonesia, were responsible for more than 400 deaths. Credit: ESA.

    4
    In this satellite photo taken by Planet Labs PBC, an island created by the underwater Hunga Tonga Hunga Ha’apai volcano is seen smoking Jan. 7, 2022. An undersea volcano erupted in spectacular fashion near the Pacific nation of Tonga on Saturday, Jan. 15, sending large tsunami waves crashing across the shore and people rushing to higher ground. A tsunami advisory was in effect for Hawaii, Alaska and the U.S. Pacific coast, with reports of waves pushing boats up in the docks in Hawaii. (Planet Labs PBC via AP)

    The Tasman Sea, located between Australia and New Zealand and known for its notorious storms amid the “roaring forties” latitudes, may have witnessed a series of devastating tsunamis during the past 5 million years (i.e., in the Pliocene and Pleistocene, or Plio-Pleistocene, epochs). These tsunamis likely originated near New Zealand’s western coast and traveled more than 2,000 kilometers to also affect Australia, yet intriguingly, there is little easily observable evidence of these events. This tumultuous history is surprising considering that western New Zealand is not especially exposed to subduction zone processes and their associated seismic activity; such exposure is often the main indicator of how vulnerable a coastline is to a tsunami. However, New Zealand is surrounded by steep and, in some cases, tectonically active submarine slopes, where landslides can occur.

    5
    The study area of the Silent Tsunami project is shown here, along with seafloor bathymetry and existing seismic reflection data. The outline of the most recent giant landslide from the Pleistocene is also shown and is overlain by the ship track from the TAN2111 voyage in October 2021.

    In the past few decades, evidence of six giant underwater landslides dating from the Plio-Pleistocene has been discovered beneath the modern seafloor in the eastern Tasman Sea (Figure 1). The most recent, thought to have occurred about 1 million years ago, is the largest documented landslide in New Zealand, covering more than 22,000 square kilometers—an area larger than Wales. With a volume of about 3,700 cubic kilometers, this landslide was bigger than the famous tsunamigenic Storegga Slide, which involved massive collapses of the continental shelf off the coast of Norway roughly 8,200 years ago.

    6
    Much of the Norwegian coastline was at-risk because of the Storegga slide.

    7
    https://www.lifeinnorway.net/wp-content/uploads/2021/06/uk-norway-satellite-map-illustration-768×641.jpg.webp

    Can scientists use these landslide deposits to derive credible indications of past tsunamis? If so, how can we assess the modern potential for hazardous tsunamis based only on these ancient, buried remnants? Underwater landslides are not comprehensively included as tsunami sources in New Zealand’s hazard assessments. This data gap exists largely because of a lack of research into underwater landslide return rates (a statistical measure of how often these events are likely to recur) and tsunamigenic mechanisms, as well as of uncertainties introduced by errors in available dating methods and the difficulty and expense of obtaining samples. These key questions and issues are currently being addressed by a trans-Tasman team of researchers, including us, from Australia and New Zealand under the Silent Tsunami project (officially named Assessing Risk of Silent Tsunami in the Tasman Sea/Te Tai-o-Rēhua), which began in 2021.

    Search Strategy for Landslide Evidence

    Throughout the Plio-Pleistocene, a vast volume of material was eroded from the rapidly uplifting Southern Alps, on New Zealand’s South Island, and delivered to the coast by river networks. Powerful ocean currents then transported the sediment north to the country’s northwestern continental margin. The ocean basin duly accommodated the relentless influx of material, and the margin rapidly prograded (built outward toward the sea) via a series of spectacular, steeply dipping depositional surfaces (up to 1,500 meters tall) called sigmoidal clinoforms, which are the building blocks of deltas and basin margins. The unstable sediment piles, perched precariously at the edge of the tectonically hyperactive interface between the Pacific and Australian plates, inevitably then collapsed in catastrophic fashion several times over.

    However, evidence of these Tasman Sea landslides cannot be readily observed, in part because of a lack of detailed seafloor mapping in the area but also because the slides were quickly buried under other sediment. Compounding the difficulty are the erosion and uplift of New Zealand’s dynamic coastline, which have erased potential land-based geological evidence in the form of tsunami deposits. Only past seismic reflection surveying in the area enabled the discovery of evidence for these events (Figure 1), with geologists documenting the landslide deposits while mapping New Zealand’s offshore sedimentary basins.

    The new project takes a three-pronged approach to carry earlier findings forward. First, we’re combining tools and techniques from the playbook used to analyze the formation and evolution of sedimentary basins, especially how the basin filling process interacts with tectonic processes. These methods include the conversion of time series seismic reflection data into depth measurements using seismic wave velocities measured from drill holes (meaning the depth for each data point is known) and virtually stripping away overlying sediments (back stripping) using computational models. This approach allows us to unearth accurate original volumes (areal extent and thickness) of the landslides before their burial and compaction.

    Second, we’re applying these new physical descriptions of landslides, along with knowledge of where they occurred, to inform computational models. The models, run using the cutting-edge fluid dynamics modeling tool Basilisk, simulate landslide motion, tsunami generation, and hazard metrics like inundation extents, wave amplitudes, wave arrival times, and current velocities.

    Third, during two research voyages, we have collected new geophysical data—multibeam bathymetry, subbottom profiles, and high-resolution multichannel seismic reflection profiles—and sediment samples from rock dredges and sediment cores from the site of the landslides. Data from the voyages are perhaps most critical to the outcomes of the project. The modeling builds a picture of the likely impacts of the Tasman Sea landslides, but probing the sites of their origin in the real world draws tangible ties between these ancient events and the present day.

    So what about the present day? During sea level highstands, when sea levels rise above the edge of a continental shelf, as is the case today, delivery of sediment to the deep ocean is thought to decrease. However, a paucity of information from the Tasman Sea region means that no one knows how much, how fast, and exactly where sediment is accumulating at present. It is not clear whether the conveyor belt of northward sediment delivery is still operating or what could trigger a future landslide event.

    Setting Sail

    In October 2021, on the first of the two research voyages, a small science party of five boarded the R/V Tangaroa for an 11-day voyage to map some 5,000 square kilometers of the Tasman Sea for the first time and to identify targets for a sampling campaign to be conducted during the second voyage (Figure 1). The preexisting seismic reflection data set for the region (Figure 2), comprising data gathered during numerous explorative surveys over several decades, appeared to show evidence of “megablocks” peeking up through the modern seabed from within the most recent Tasman Sea landslide deposit. These megablocks are large clasts or “rafts” of material that were transported within a landslide and that have remained mostly intact. Such blocks often form highly irregular seafloor topography in the immediate aftermath of an underwater landslide and can create localized sediment traps when normal sedimentation resumes. Heading into the voyage, it was uncertain whether these features would be visible or prominent on the seafloor or whether we could identify viable targets for sampling.

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    Fig. 2. Ancient landslide deposits beneath the modern seafloor are evident in this seismic reflection profile produced from data collected prior to the Silent Tsunami project.

    True to form for the Tasman Sea, after leaving the shelter of Wellington Harbour, a howling southerly wind and 8-meter swells pummeled our ship during the 20-hour transit. Once on site, however, about 100 kilometers off New Zealand’s North Island, above the continental shelf break and rise, conditions calmed, allowing the ship’s multibeam echo sounders to run—and map the seafloor at high resolution—uninterrupted.

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    Fig. 3. Perspective views from the newly acquired bathymetric data set show shelf-slope canyons, pockmarks, and evidence of small, recent slope failures (top), as well as the tops of megablocks from the most recent ancient landslide rising above the modern seafloor of the continental rise at water depths of 1,500–1,700 meters (bottom).

    As the data came in, we spent long hours poring over them in the bathymetry lab aboard the Tangaroa. The time was highly rewarding. First came images of canyons, numerous pockmarks, and evidence of recent small-scale slope failures as the ship passed over the shelf break and traversed the continental slope (Figure 3). Then we saw an astonishing area of deep seafloor littered with numerous angular, often elongated ridges and peaks up to 100 meters in relief, some with surrounding “moats” winnowed by the action of recent ocean currents. These ridges are the exposed tops of megablocks from the most recent Tasman Sea landslide, still making their mark on the seafloor roughly 1 million years later.

    We decided the megablocks, now that we’d observed them firsthand, were viable targets for rock dredging, offering the tantalizing possibility of sampling landslide material itself. If we could achieve it, this sampling could allow us to characterize the sedimentology and physical properties of the landslide and thus to refine our fluid dynamics models. In addition, areas between blocks would be good targets to sample covering sediments to help constrain the minimum age of the most recent and largest landslide and to determine the rate and patterns of modern sediment accumulation.

    We set off on the 3-week-long second voyage, again aboard the Tangaroa, on 15 March 2022. Taking advantage of a spell of calm weather, we deployed the ship’s brand-new 96-channel solid seismic streamer to collect reflection data, then waited anxiously for the first data. Our worry was unnecessary, as the data looked beautiful, with much-improved resolution compared with the preexisting data set.

    The biggest highlights from this voyage came as we turned our attention to sediment sampling and targeted several megablocks with the rock dredge. We recovered a lot of sticky mud thought to be the “mud drape” formed by the continuous rain of fine-grained sediment that accumulates normally over many years. We also recovered fist- to paving slab–sized clasts of more consolidated mud and fine sand, which we cautiously assumed to be landslide material.

    After deciding to target a flat-topped megablock at roughly 1,500 meters depth for coring, we again waited nervously to see what, if anything, we’d recover. To the team’s excitement, we indeed recovered a 4-meter core from the megablock. Does it contain landslide material, or is it all mud drape? Time will tell. Now back on dry land, we are awaiting the results of nondestructive preliminary scanning before we split and subsample the core to determine in detail what we recovered. In all, 79 meters of core were successfully recovered on the voyage, including from the areas between megablocks, which we are confident will enable us to characterize modern sediment deposition and properties.

    From Data to Knowledge to Application

    We expect our project to generate new knowledge that builds a picture of modern-day conditions at the site of the Tasman Sea landslides; to refine our understanding of the return rate of large, potentially tsunami-generating landslides; and to develop credible scenarios of the specific hazards related to them. Pathways to assessing the usefulness of the information gained and to guide its uptake in national hazard assessments involve working with a hazard scientists’ advisory group, territorial authorities, and civil defense agencies.

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    Fig. 4. This depiction of the New Zealand National Tsunami Hazard Model shows expected tsunami heights along the country’s coastline. Although formally published in 2013, the model is continually updated as more information becomes available.

    The most likely conduit to implementation in New Zealand is the Review of Tsunami Hazard in New Zealand, a probabilistic risk assessment that quantitively estimates maximum tsunami heights along the country’s coastlines (Figure 4). The model underpins more detailed site-specific hazard assessments and emergency management planning and is continually refined and updated with new information. In Australia, new information from this project could be incorporated into state-based hazard assessments and education programs led by the country’s Emergency Management authorities.

    An exciting prospect is the potential to apply the same approaches used in our project to other areas of New Zealand, Australia, and elsewhere. Many of the world’s continental margins have been imaged using seismic reflection surveying—often during exploration for offshore energy resources—creating a vast repository of information about the subsurface. Most of what is known about tsunamis generated by underwater landslides comes from computational models, with few observed examples of such slides to validate them. But existing data sets may hold a wealth of data related to numerous examples of ancient underwater landslides now buried beneath the seafloor.

    Translating knowledge from examples of subsurface landslides into information to support hazard assessment is rarely done because of a lack of information on the ages of the landslides and the complexities of assessing their size introduced by their burial, compaction, and incomplete preservation. We hope that results and learning from our early-stage research will help scientists better understand regional tsunami hazards. We also hope that these results will pave the way for future endeavors to develop constructive tools to support refined tsunami hazard assessment and emergency management planning, helping safeguard people around and beyond the Tasman Sea.

    Acknowledgments

    The project described above is funded by the New Zealand Ministry of Business, Innovation and Employment Endeavour Fund, with additional support from the New Zealand Strategic Science Investment Fund, the Tangaroa Reference Group, and the University of Newcastle, Australia.

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