I. Climate Change
1.Science at the Border Between Ice and Ocean
A suite of instruments, including drones, remotely operated boats, and multibeam sonar, is helping scientists understand a little-studied area at the front of a calving glacier.
https://eos.org/articles/science-at-the-border-between-ice-and-ocean
2.Major Federal Tropical Research Project to Cease 7 Years Early
The Department of Energy shutters a project aimed at improving climate models less than halfway through the expected decade-long run.
https://eos.org/articles/major-federal-tropical-research-project-to-cease-7-years-early
II. Geochemistry, Mineralogy, Volcanology
1.Probing the Grain-Scale Processes That Drive Plate Tectonics
New experimental data suggest that rock composition may play a critical role in forming and perpetuating shear zones.
https://eos.org/research-spotlights/probing-the-grain-scale-processes-that-drive-plate-tectonics
III. Hydrology, Cryosphere & Earth Surface
1.Nonflood Flow May Be Major Driver of Delta Growth
Plants and fluctuating river flow work together to balance vertical sediment buildup with sediment delivery to the delta’s edge.
https://eos.org/research-spotlights/nonflood-flow-may-be-major-driver-of-delta-growth
IV. Biogeosciences
1.Searching for Organic Carbon in the Dry Valleys of Antarctica
Researchers identify the first evidence of microbial respiration in desiccated Antarctic permafrost soils.
https://eos.org/research-spotlights/searching-for-organic-carbon-in-the-dry-valleys-of-antarctica
2.Thirty Years of GBC in a Changing World
The outgoing Editor in Chief of Global Biogeochemical Cyclesreflects on how research topics published in the journal have adapted and developed since its launch three decades ago.
https://eos.org/editors-vox/thirty-years-of-gbc-in-a-changing-world
V. Geology & Geophysics
1.Hurricanes Expose Vulnerabilities in Puerto Rico Seismic Network
Could overreliance on cell networks to transmit data leave instruments in the dark after the next storm hits?
https://eos.org/articles/hurricanes-expose-vulnerabilities-in-puerto-rico-seismic-network
2.Fossils Provide New Clues to Tibetan Plateau’s Evolution
The bones of ancient rhinos, elephants, and fish constrain when the Tibetan Plateau rose high enough to prevent migration, a move that forced animals to adapt to high-altitude conditions.
https://eos.org/articles/fossils-provide-new-clues-to-tibetan-plateaus-evolution
3.Dan Rather’s Vision for Scientists in an Era of “Fake News”
Scientists must embrace communication, and communicators must work harder to tell more nuanced and compelling science stories, the newsman said to an auditorium full of scientists.
https://eos.org/articles/dan-rathers-vision-for-scientists-in-an-era-of-fake-news
4.Researchers Explore Carbon Footprints of Superheroes
A tongue-in-cheek exercise about comic book heroes aims to inspire people to consider the amount of greenhouse gas emissions they themselves cause.
https://eos.org/articles/researchers-explore-carbon-footprints-of-superheroes
5.Enabling FAIR Data Across the Earth and Space Sciences
Data experts from publishers, repositories, and other organizations met last month to kick off a project to promote open and Findable, Accessible, Interoperable, and Reusable (FAIR) data principles.
https://eos.org/agu-news/enabling-fair-data-across-the-earth-and-space-sciences
6.Exciting Section and Focus Group News
The American Geophysical Union announces new engagement pilots, simplified naming structure, and new GeoHealth section.
https://eos.org/agu-news/exciting-section-and-focus-group-news
VI. Geophysical Research Letters
1. Translating Uncertain Sea Level Projections Into Infrastructure Impacts Using a Bayesian Framework
Climate change may affect ocean-driven coastal flooding regimes by both raising the mean sea level (msl) and altering ocean-atmosphere interactions. For reliable projections of coastal flood risk, information provided by different climate models must be considered in addition to associated uncertainties. In this paper, we propose a framework to project future coastal water levels and quantify the resulting flooding hazard to infrastructure. We use Bayesian Model Averaging to generate a weighted ensemble of storm surge predictions from eight climate models for two coastal counties in California. The resulting ensembles combined with msl projections, and predicted astronomical tides are then used to quantify changes in the likelihood of road flooding under representative concentration pathways 4.5 and 8.5 in the near-future (1998–2063) and mid-future (2018–2083). The results show that road flooding rates will be significantly higher in the near-future and mid-future compared to the recent past (1950–2015) if adaptation measures are not implemented.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL076116/full
2. Potential for Small Unmanned Aircraft Systems Applications for Identifying Groundwater-Surface Water Exchange in a Meandering River Reach
The exchange of groundwater and surface water (GW-SW), including dissolved constituents and energy, represents a critical yet challenging characterization problem for hydrogeologists and stream ecologists. Here we describe the use of a suite of high spatial resolution remote sensing techniques, collected using a small unmanned aircraft system (sUAS), to provide novel and complementary data to analyze GW-SW exchange. sUAS provided centimeter-scale resolution topography and water surface elevations, which are often drivers of exchange along the river corridor. Additionally, sUAS-based vegetation imagery, vegetation-top elevation, and normalized difference vegetation index mapping indicated GW-SW exchange patterns that are difficult to characterize from the land surface and may not be resolved from coarser satellite-based imagery. We combined these data with estimates of sediment hydraulic conductivity to provide a direct estimate of GW “shortcutting” through meander necks, which was corroborated by temperature data at the riverbed interface.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL075836/full
3. Supraglacial Ponds Regulate Runoff From Himalayan Debris-Covered Glaciers
Meltwater and runoff from glaciers in High Mountain Asia is a vital freshwater resource for one-fifth of the Earth's population. Between 13% and 36% of the region's glacierized areas exhibit surface debris cover and associated supraglacial ponds whose hydrological buffering roles remain unconstrained. We present a high-resolution meltwater hydrograph from the extensively debris-covered Khumbu Glacier, Nepal, spanning a 7 month period in 2014. Supraglacial ponds and accompanying debris cover modulate proglacial discharge by acting as transient and evolving reservoirs. Diurnally, the supraglacial pond system may store >23% of observed mean daily discharge, with mean recession constants ranging from 31 to 108 h. Given projections of increased debris cover and supraglacial pond extent across High Mountain Asia, we conclude that runoff regimes may become progressively buffered by the presence of supraglacial reservoirs. Incorporation of these processes is critical to improve predictions of the region's freshwater resource availability and cascading environmental effects downstream.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL075398/full
4. Natural and Human-Induced Variability in Barrier-Island Response to Sea Level Rise
Storm-driven sediment fluxes onto and behind barrier islands help coastal barrier systems keep pace with sea level rise (SLR). Understanding what controls cross-shore sediment flux magnitudes is critical for making accurate forecasts of barrier response to increased SLR rates. Here, using an existing morphodynamic model for barrier island evolution, observations are used to constrain model parameters and explore potential variability in future barrier behavior. Using modeled drowning outcomes as a proxy for vulnerability to SLR, 0%, 28%, and 100% of the barrier is vulnerable to SLR rates of 4, 7, and 10 mm/yr, respectively. When only overwash fluxes are increased in the model, drowning vulnerability increases for the same rates of SLR, suggesting that future increases in storminess may increase island vulnerability particularly where sediment resources are limited. Developed sites are more vulnerable to SLR, indicating that anthropogenic changes to overwash fluxes and estuary depths could profoundly affect future barrier response to SLR.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL074811/full
5. Exceptional Air Mass Transport and Dynamical Drivers of an Extreme Wintertime Arctic Warm Event
At the turn of the years 2015/2016, maximum surface temperature in the Arctic reached record-high values, exceeding the melting point, which led to a strong reduction of the Arctic sea ice extent in the middle of the cold season. Here we show, using a Lagrangian method, that a combination of very different airstreams contributed to this event: (i) warm low-level air of subtropical origin, (ii) initially cold low-level air of polar origin heated by surface fluxes, and (iii) strongly descending air heated by adiabatic compression. The poleward transport of these warm airstreams occurred along an intense low-level jet between a series of cyclones and a quasi-stationary anticyclone. The complex 3-D configuration that enabled this transport was facilitated by continuous warm conveyor belt ascent into the upper part of the anticyclone. This study emphasizes the combined role of multiple transport processes and transient synoptic-scale dynamics for establishing an extreme Arctic warm event.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL075841/full
VII. AGU Blogs
1.Ancient weakening of Earth’s crust explains unusual intraplate earthquakes
New research reveals that mysterious intraplate seismic zones underwent significant deformation hundreds of millions of years ago.
2.Scientists capture Earth’s “hum” on ocean floor
Researchers have successfully quantified Earth’s vibrational “hum” using seismic instruments on the bottom of the ocean. A new study determined at the ocean bottom the frequencies at which the Earth naturally vibrates, and confirmed the viability of using ocean instruments to study the phenomenon.
https://blogs.agu.org/geospace/2017/12/06/scientists-capture-earths-hum-on-ocean-floor/
3.Cartogram maps provide new view of climate change risk
Scientists have developed cartograms — maps that convey information by contorting areas — to visualize the risks of climate change in a novel way.
https://blogs.agu.org/geospace/2017/12/06/cartogram-maps-provide-new-view-of-climate-change-risk/
Scientists have shown for the first time that dark fiber – the vast network of unused fiber-optic cables installed throughout the country and the world – can be used as sensors for detecting earthquakes, the presence of groundwater, changes in permafrost conditions, and a variety of other subsurface activity.
