bluuebunny/crossref_metadata_2025 huggingface dataset:
Applied geoethics: CITI199’s essays from the Austral University of Chile
Authors: Mulsow Sandor , Barrales Beatriz , Espinoza Nicolas , Flandez Magdalena , Ledezma Leandro , Munzenmayer Esteban , Rivera-Murton Adriana , Salinas Pablo , Valenzuela Fernando , Valenzuela Rodolfo , Valle Marco
Published: March 2021

Geoethics is a term that describes the internal knowledge of values ​​which must be reflected in the interaction with other people and with the physical and biological environment that surrounds us.

When talking about ethics or specifically geoethics, exact definitions are sought which always seem to be short and very difficult to write in a sentence. One of the reasons may be is that it is about minimizing a life process to a noun, adjective or adverb. "It is a life process," is an awareness of the maximum expression of that part that we call human, internal, which maintains a balanced posture. This self-awareness is essential since it allows to relate to the environment (including peers) in the same way, tolerant, dignified, respectful humanly and environmentally speaking

In 2020, during the pandemic, we have undertaken a challenge at our University by teaching a course on Geoethics in Earth Sciences (CITI199). This course was designed following the general guidelines of IAPG. The adaptation to the Chilean reality was given by the same students. After assimilating the bases of ethics, values ​​and moral principles, through the interventions of anthropologists, sociologists, geographers and native peoples, we have generated 2 unpublished activities in Chile, a student survey on the state of knowledge of geoethics in the School of Geology and applied the geoethical foundations in the daily life of Chile.

In this series of presentations we report the results and analysis of the survey and recommendations to continue with the process of offering the university community the value of having an initial geoethical position in professional development. Later in the session, 4 situations in which society interacts with the environment from a geoethical perspective are evaluated and analyzed: 1) degradation and use of soils, 2) massive production of exotic salmon, 3) use of fresh water and 4 ) privatization of the common heritage of humanity in international waters.
A Multi-Use Case Scientific Sensor Node
Authors: Hamilton Valarie , Moores Andrew
Published: March 2021

Nanometrics' Pegasus digitizer is the basis for a scientific grade node and is the latest development in many years of designing and building reliable seismic instruments for the scientific and monitoring community. Coupled in a grab-and-go quick deploy package with a variety of sensors enables responses to many types of events and environmental measurements. These types of systems are not only for hazards, such as earthquakes and volcanoes, but can form the basis of better tools used for critical structure and microzonation studies using ambient noise.  Pegasus takes advantage of a complete ecosystem of software, making planning, deploying and data harvesting very simple and straightforward as well as providing a dataset that includes automatically generated metadata in the form of StationXML and standard miniSEED data files.  Pegasus design criteria was based on optimal SWaP (Size, Weight and Power) and makes it unique in short to long duration deployments without swapping of units in the field, while its broad sensor compatibility enables many types of measurements and is completely compatible with the advantages of Nanometrics smart sensors.
Characterising Dansgaard-Oeschger cycles: from MIS3 to today
Authors: Andres Heather , Tarasov Lev
Published: March 2021

One of the main contributors to palaeoclimate variability on millennial timescales is understood to be Dansgaard-Oeschger (D-O) cycles. Our awareness of these phenomena arises primarily from quasi-periodic, abrupt transitions of large magnitude detected in δ18O records from Greenland ice cores (e.g. Dansgaard et al, 1982; Johnsen et al, 1992), although there is evidence of similar variability in other archives and regions. D-O cycles have plenty to capture the imagination:

the strength and rapidity of climate changes over Greenland,

their regularity throughout MIS3 (~60 to 30 thousand years before present) and occurrence during the last deglaciation contrasting with their relative absence during the Last Glacial Maximum and Holocene,

their opposed characteristics in Greenland and Antarctica,

and that different models require different boundary conditions to reproduce this phenomena, if they can reproduce it at all.

 

This talk characterises D-Olike cycles in two different models: Planet Simulator (PlaSim, an Earth System Model with simplified atmospheric physics, thermodynamic sea ice, and simplified ocean dynamics), and COSMOS (a CMIP3-era ESM). We identify four phases to D-O cycles and commonalities and differences in their representations in these models. Finally, we examine which phases of this type of variability continue to contribute to climate variability today and what that looks like.
Reduced eastern tropical Atlantic sea surface temperature variability at the end of the Green Sahara
Authors: Rustic Gerald , Pausata Francesco SR , DeMenocal Peter
Published: March 2021

Mid-Holocene proxy evidence records profound climatic changes, including alteration of the West African Monsoon system and the end of the ‘Green Sahara’ period. Model simulations have related changes in the West African Monsoon system, which controls present-day seasonal hydroclimate over much of the African continent north of the equator, to alterations of the tropical Walker circulation. Here we investigate the change in tropical sea surface temperature variability in the eastern tropical Atlantic, where ocean-atmosphere coupling is robust. Through analysis of the distribution of oxygen isotopes from the tests of individual specimens of the surface-dwelling foraminifer Globigerinoides ruber, we find that SST variability is significantly decreased at the end of the Green Sahara period ~3.5-5kya. During the period of reduced variability we also observe changes in the background state of the tropical Atlantic as characterized by the east-west SST gradient, linking variability to background conditions. We compare our record to co-eval records of tropical Pacific variability that describe changes to the El Niño Southern Oscillation, as well as to records of hydroclimate change in Southeast Asia, and find similarities in these records, suggesting a common origin of these climate signals. Taken together, this evidence points toward an alteration of the tropical Walker circulation which may, in part, be related to changes in vegetation and dust loading occurring during the drying of the Sahara at mid-Holocene.
Post-fire infiltration modeling – some soil physical considerations
Authors: Berli Markus , Shillito Rose M. , Giovando Jeremy J. , Pradhan Nawa , Pak Jang H. (“Jay”) , Floyd Ian E. , Acharya Kumud
Published: March 2021

Wildfires can change watershed hydrologic processes and increase the risks for soil erosion, flooding and debris flow after a fire. While fire-induced changes to the soil have significant effects on infiltration and runoff, the physical mechanisms remain unclear. A growing body of research suggests these mechanisms include soil water repellency (SWR) and the alteration of soil structure. The objective of this study was to relate SWR, soil structure, soil moisture to infiltration using a process-based, soil physics approach to better model infiltration into fire-affected soil, The ultimate goal is to improve the prediction of post-fire runoff with process-based hydrology models. Our research shows the effects of SWR and soil structure on infiltration can be captured by the soil hydraulic parameters of sorptivity and hydraulic conductivity, respectively. SWR reduces sorptivity and controls the early stage of infiltration during a storm. Changes in soil structure affect hydraulic conductivity and later stages of infiltration. Additionally, results show SWR can have an effect on unsaturated hydraulic conductivity but does not significantly affect saturated hydraulic conductivity. The study also highlights the important role soil water content plays for post-fire infiltration since both sorptivity and unsaturated hydraulic conductivity are functions of soil water content.
The Integrated Multisector, Multiscale Modeling (IM3) Research Project
Authors: Rice Jennie ,   IM3 Author Team
Published: March 2021

The Integrated Multisector, Multiscale Modeling (IM3) foundational science research project, funded by the U.S. Department of Energy, focuses on developing flexible, open-source, integrated modeling capabilities that capture the structure, dynamic behavior, and emergent properties of the multiscale interactions within and between human and natural systems. IM3 uses these capabilities to study the evolution, vulnerability, and resilience of interacting human and natural systems and landscapes from local to continental scales within the U.S., including responses to the compounding effects of long-term influences and short-term shocks. A key objective is to understand the implications of uncertainty in data, observations, models, and model coupling approaches for projections of human-natural system dynamics. IM3’s first phase (2017-2020) focused on regional-scale energy-water dynamics, interactions between land use and land cover change and regional climate, and on generating 1-km2 population and urbanization projections consistent with the Shared Socioeconomic Pathways. Current research is projecting the compound influences of climate change, heat waves, drought, socioeconomics, population, and urbanization on the dynamic interactions between energy, water, land, and urban systems during the 21st century, while maintaining consistency with global socioeconomic conditions. Experimental objectives include understanding the key drivers and interactions affecting the evolution of urban heat, water scarcity, and electricity grid stress. Modeling scales include the continental U.S., major electricity interconnections, watersheds, and urban areas, and experiments investigate the fidelity implications of differential spatiotemporal and process resolutions across scales. IM3 is also coordinating (and invites participation in) an open Community of Practice to establish a conceptual framework for the field of multisector dynamics to accelerate progress across relevant projects and areas of research. This presentation will outline the scope and challenges of IM3 as a transdisciplinary project seeking to contribute new insights and modes of analysis across scales, sectors, and systems.
Implementing the Sparrow laboratory data system in multiple subdomains of geochronology and geochemistry
Authors: Quinn Daven , Linzmeier Benjamin , Sundell Kurt , Gehrels George , Goring Simon , Marcott Shaun , Meyers Stephen , Peters Shanan , Ross Jake , Schmitz Mark , Singer Bradley , Williams John
Published: March 2021

Data sharing between laboratories is critical for building repeatable, comparable, and robust geochronology and geochemistry workflows. Meanwhile, in the broader geosciences, there is an increasing need for standardized access to aggregated geochemical data tied to basic geological context. Such data can be used to enrich sample and geochemical data repositories (e.g., EarthChem, Geochron.org, publisher archives), align geochemical context with other datasets that capture global change (e.g., Neotoma, the Paleobiology Database), and calibrate digital Earth models (e.g., Macrostrat) against geochronology-driven assessments of geologic time.

A typical geochemical lab manages a large archive of interpreted data; standardizing and contributing data products to community-level archives entails significant manual work that is not usually undertaken. Furthermore, without widely accepted  interchange formats, this effort must be repeated for each intended destination.

Sparrow (https://sparrow-data.org), in development by a consortium of geochronology labs, is a standardized system designed to support labs’ efforts to manage, contextualize, and share their geochemical data. The system augments existing analytical workflows with tools to manage metadata (e.g., projects, sample context, embargo status) and software interfaces for automated data exchange with community facilities. It is extensible for a wide variety of geochemical methods and analytical processes.

In this update, we will report on the implementation of Sparrow in the Arizona Laserchron Center detrital zircon facility, and how that lab is using the system to capture geological context across its data archive. We will review similar integrations underway with U-Pb, 40Ar/39Ar, SIMS, optically stimulated luminescence, thermochronology, and cosmogenic nuclide dating. We will also discuss preliminary efforts to aggregate the output of multiple chronometers to refine age calibrations for the Macrostrat stratigraphic model.
Nowcasting and multifractal features of the seismicity in the subduction zone of Tehuantepec Isthmus, southern México
Authors: Ramírez-Rojas Alejandro , Flores-Márquez Elsa Leticia
Published: March 2021

After the M8.2 earthquake occurred on September 07, 2017 at Isthmus of Tehuantepec, notable spatial and temporal changes where
registered, the temporal rate of occurrence increased and the spatial seismicity distribution showed a clear clusterization along
the region of collision of the Tehuantepec Transform/Ridge with the Middle America Trench off Chiapas. Also, the b-value in the
Gutenberg-Richer law showed changes in time. On the basis of that behavior we studied the sequence of magnitudes of the
earthquakes occurred within the Isthmus of Tehuantepec at southern Mexico from 2010 to 2020, by using the nowcasting method
and the multifractal detrended fluctuation analysis. Our findings suggest the b-value could depend on time and after the main-shock
M8.2, the underlying dynamics in the Tehuantepec ridge has been changed, which is clearly described by our analyses based on
nowcasting method and in the multifractality estimated changes.
Crustal folds alter local stress fields as demonstrated by magma sheet – fold interactions in the Central Andes
Authors: Clunes Matías , Browning John , Cembrano José , Marquardt Carlos , Gudmundsson Agust
Published: March 2021

For magma chambers to form or volcanic eruptions to occur magma must propagate through the crust as dikes, inclined sheets and sills. The vast majority of models that investigate magma paths assume the crust to be either homogeneous or horizontally layered, often composed of rocks of contrasting mechanical properties. In subduction regions that have experienced orogenesis, like the Andes, the crust has been deformed over several million years, resulting in rock layers that are commonly folded and steeply dipping. The assumption of homogeneous properties or horizontal layering then does not capture all of the potential magma path crustal interactions. Here we tackle this problem by determining the effect of a crust made of steeply inclined layers in which sills and inclined sheets are emplaced. We combine field observations from a sill emplaced in the core of an anticlinal fold at El Juncal in the Chilean Central Andes, such as lithologies, sill and fold limbs attitude, sill length and layers and sill thickness, with a suite of finite element method models to explore the mechanical interactions between inclined layers and magma paths. Our results demonstrate that the properties of the host rock layers as well as the contacts between the layers and the crustal geometry all play an important role on magma propagation and emplacement at shallow levels. Sill propagation and emplacement through heterogeneous and anisotropic crustal segments changes the crustal stress field promoting sill arrest, deflection or propagation. Specifically, sills are more likely to be deflected when encountering shallow dipping layers rather than steeply dipping layers of a fold. Mechanically weak contacts encourage sill deflection due to the related rotation of the maximum principal compressive stress and this effect is attenuated when the fold layers are more steeply dipping. This processes may change the amount and style of surface deformation recorded, with significant implications for monitoring of active volcanoes.
Impact of Winter Soil Processes on Nutrient Leaching in Cold Region Agroecosystems
Authors: Krogstad Konrad , Jensen Grant , Gharasoo Mehdi , Hug Laura , Rudolph David , Van Cappellen Philippe , Rezanezhad Fereidoun
Published: March 2021

High-latitude cold regions are warming more than twice as fast as the rest of the planet, with the greatest warming occurring during the winter. Warmer winters are associated with shorter periods of snow cover, resulting in more frequent and extensive soil freezing and thawing. Freeze-thaw cycles influence soil chemical, biological, and physical properties and any changes to winter soil processes may impact carbon and nutrients export from affected soils, possibly altering soil health and nearby water quality. These impacts are relevant for agricultural soils and practices in cold regions as they are critical in governing water flows and quality within agroecosystems. In this study, a soil column experiment was conducted to assess the leaching of nutrients from fertilized agricultural soil during the non-growing season. Four soil columns were exposed to a non-growing season temperature and precipitation model and fertilizer amendments were made to two of the columns to determine the efficacy of fall-applied fertilizers and compared to other two unfertilized control columns. Leachates from the soil columns were collected and analyzed for cations and anions. The experiment results showed that a transition from a freeze period to a thaw period resulted in significant loss of chloride (Cl-), sulfate (SO42-) and nitrate (NO3-). Even with low NO3- concentrations in the applied artificial rainwater and fertilizer, high NO3- concentrations (~150 mg l-1) were observed in fertilized column leachates. Simple plug flow reactor model results indicate the high NO3- leachates are found to be due to active nitrification occurring in the upper oxidized portion of the soil columns mimicking overwinter NO3- losses via nitrification in agricultural fields. The low NO3- leachates in unfertilized columns suggest that freeze-thaw cycling had little effect on N mineralization in soil. Findings from this study will ultimately be used to bolster winter soil biogeochemical models by elucidating nutrient fluxes over changing winter conditions to refine best management practices for fertilizer application.
First look at the urban carbon flux inversion system for Megacity CO2-Seoul
Authors: Oh Eunsil , Jeong Sujong , Kim Yeonsu , Park Hoonyoung , Park Charin , Park Hayoung , Sim Sojeong , Yoon Jeongmin , Kwack Taeye
Published: March 2021

To verify the urban fossil fuel carbon dioxide (FFCO2) flux over the Seoul Capital Area (SCA), we initiated the “Megacity CO2-Seoul” project in the year 2018. For the project, our research group established CO2 and XCO2 ground measurement stations deploying Seoul National University CO2 Measurement instruments (SNUCO2M) and EM27/SUN. We also produced 1x1km urban biospheric flux with the CArbon Simulator from Space (CASS) and 1x1km FFCO2 carbon emission inventory by employing machine learning techniques. The project comprises inverse modeling system using WRF-STILT. Under the Bayesian inverse model framework, we assess FFCO2 inventory of Seoul, which are generated by the bottom-up approach, by paring the ground CO2 measurement constraints. This is the first look at the verification of self-developed FFCO2 inventory of Seoul. We are currently working on the improvement of the WRF-STILT inverse modeling system. In this presentation, we report verification of FFCO2 emissions in SCA on February 2018. Our estimate reflects that our prior FFCO2 inventory was overestimated in the comparison with results of the inverse model. Detailed results will be presented at the webinar. This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korean government (MSIT) (No. NRF-2019R1A2C3002868).
Exploring links between geodynamics and climate change
Authors: Hoggard Mark , Richards Fred
Published: March 2021

Combating global climate change remains one of the greatest challenges facing humanity in the coming decades. Whilst oceanographers, ice sheet dynamicists, and atmospheric modellers all have an obvious role to play in leading efforts to tackle this problem, there remain many aspects that require careful consideration and cross-disciplinary interaction in other areas of the geosciences. In this talk, I will use selected examples to illustrate important links between geodynamics and climate change, including improving our understanding of its potential impacts and mitigation. The first concerns the role of mantle convection in influencing palaeo sea-level records and ice sheet dynamics. For example, Pliocene interglacial periods are commonly invoked as potential climatic analogues for the near-future conditions expected in our warming world, but there is considerable uncertainty over the extent to which important sea-level indicator sites have been perturbed, post-deposition, by convection-induced dynamic topography. The second link involves the growing shortage of metals that are key to the manufacture of technologies for low-carbon energy generation and storage. Tackling this shortfall requires an improvement in our ability to locate new, high-grade metal deposits, particularly those buried beneath shallow sedimentary cover. Novel geodynamical insights into the geological processes responsible for ore genesis will form a core component of narrowing the exploration search-space, and we have recently demonstrated this approach for sediment-hosted metal deposits. Through these case studies, I will show that it is primarily through developing an environment of cross-disciplinary discussion and financial support that our community is most likely to progress in understanding the potential impacts of climate change and how we may mitigate against them. Although one of the least well-studied components, the solid Earth is increasingly being recognised as a critical part of the climate system. Researchers working in topics as diverse as rock mechanics, seismology, convection modelling, and geochemistry all have a crucial role to play.
Speleothems of South American and Asian Monsoons Influenced by a Green Sahara
Authors: Tabor Clay , Otto-Bliesner Bette , Liu Zhengyu
Published: March 2021

Compared to preindustrial, the mid-Holocene (6 ka) had significantly greater Northern Hemisphere summer insolation, slightly warmer global surface temperature, and slightly lower CO2 concentration. Vegetation was also different during the mid-Holocene. Possibly most prominent was the growth of temperate vegetation in the now barren Sahara. This Saharan vegetation response was related to intensification of the African Monsoon associated with the mid-Holocene orbital configuration. Hydroclimate of the Asian Monsoon and South American Monsoon also responded to mid-Holocene forcings, with general wetting and drying, respectively.

The mid-Holocene is frequently used for model-proxy comparison studies. However, climate models often struggle to replicate the proxy signals of this period. Here, we attempt to reduce these model-proxy discrepancies by exploring the significance of a vegetated Sahara during the mid-Holocene. Using the water isotopologue tracer enabled version of the Community Earth System Model (iCESM1), we perform mid-Holocene simulations that include and exclude temperate vegetation in the Sahara. We compare our model results with δ18O values from mid-Holocene speleothem records in the Asian and South American Monsoon regions.

We find that inclusion of vegetated Sahara during the mid-Holocene leads to global warming, alters the hemispheric distribution of energy, and generally amplifies the δ18O of precipitation responses in the South American and Asian Monsoon regions; these feedbacks improve the δ18O agreement between model outputs and speleothem records of the mid-Holocene. Our results highlight the importance of regional vegetation alteration for accurate simulation of past climate, even when the region of study is far from the source of vegetation change.
Rx TimeMachine: A global pseudoprospective earthquake forecast database for training and ranking predictive algorithms
Authors: Kamer Yavor , Nandan Shyam , Hiemer Stefan , Ouillon Guy , Sornette Didier
Published: March 2021

Recent advances in machine learning and pattern recognition methods have propagated into various applications in seismology. Phase picking, earthquake location, anomaly detection and classification applications have benefited also from the increased availability of cloud computing and open-source software libraries. However, applications of these new techniques to the problems of earthquake forecasting and prediction have remained relatively stagnant.

The main challenges in this regard have been the testing and validation of the proposed methods. While there are established metrics to quantify the performance of algorithms in common pattern recognition and classification problems, the earthquake prediction problem requires a properly defined reference (null) model to establish the information gain of a proposed algorithm. This complicates the development of new methods, as researchers are required to develop not only a novel algorithm but also a sufficiently robust null model to test it against.

We propose a solution to this problem. We have recently introduced a global real-time earthquake forecasting model that can provide occurrence probabilities for a user defined time-space-magnitude window anywhere on the globe (Nandan et al. 2020). In addition, we have proposed the Information Ratio (IR) metric that can rank algorithms producing alarm based deterministic predictions as well as those producing probabilistic forecasts (Kamer et al. 2020). To provide the community with a retrospective benchmark, we have run our model in a pseudoprospective fashion for the last 30 years (1990-2020). We have calculated and stored the earthquake occurrence probabilities for each day, for the whole globe (at ~40km resolution) for various time-space windows (7 to 30 days, 75 to 300 km). These can be queried programmatically via an Application Programmable Interface (API) allowing model developers to train and test their algorithms retrospectively. Here we shall present how the Rx TimeMachine API is used for the training of a simple pattern recognition algorithm and show the algorithm's prospective predictive performance.

Nandan, S., Kamer, Y., Ouillon, G., Hiemer, S., Sornette, D. (2020). Global models for short-term earthquake forecasting and predictive skill assessment. European Physical Journal ST. doi: 10.1140/epjst/e2020-000259-3 
Kamer, Y., Nandan, S., Ouillon, G., Hiemer, S., Sornette, D. (2020). Democratizing earthquake predictability research: introducing the RichterX platform. European Physical Journal ST. doi: 10.1140/epjst/e2020-000260-2 
Eruptive frequency of the Bora-Baricha-Tullu Moye (BBTM) volcanic system in the Central Main Ethiopian Rift
Authors: Tadesse Amdemichael Zafu , Fontijn Karen , Melaku Abate Assen , Gebru Ermias Filfilu , Smith Victoria , Tomlinson Emma , Barfod Dan , Gopon Phillip , Ayalew Dereje , Yirgu Gezahegn , Gudbrandson Snorri
Published: March 2021

The Main Ethiopian Rift (MER) is the northern portion of the East African Rift System and separates the Eastern and Western plateaus of Ethiopia. The recent volcanic and tectonic activity is largely focused within the rift basin along a 20 km wide zone on the rift floor. Large silicic volcanic complexes are aligned along this central rift axis but their eruptive histories are not well constrained.

The Bora-Baricha-Tullu Moye (BBTM) volcanic field is situated in the central Main Ethiopian Rift and has a different appearance than the other MER volcanic systems. The BBTM constitutes several late Quaternary edifices, the major ones are: Tullu Moye, Bora and Baricha. In addition, there are multiple smaller eruptive vents (e.g. Oda and Dima), cones, and domes across the ca. 20 X 20 km wide area. Currently, there is very little information on the frequency and magnitude of past volcanic eruptions. We present a new dataset of field observations, componentry, petrography, geochronology (40Ar/39Ar), and glass major and trace element chemistry. The data are assessed as potential fingerprints to assign diagnostic features and correlate units across the area, and establish a tephrostratigraphic framework for the BBTM volcanic field.

Two large-volume and presumably caldera-forming eruptions are identified, the younger of which took place at 100 ka. The volcanic products exposed in the BBTM area show that the volcanic field has undergone at least 20 explosive eruptions since then. The post-caldera eruptions have comenditic (Tullu Moye) and pantelleretic (Bora and Baricha) magma compositions. Other smaller edifices such as Oda and Dima also erupted pantelleritic magmas, and only differ slightly in composition than tephra of Bora and Baricha. Tullu Moye had two distinct explosive eruptions that dispersed tephra up to 14 km away and on to the eastern plateau. Bora and Baricha together had at least 8 explosive eruptions. Their deposits can be distinguished by their light grey color and unique lithic components. Oda had 7 eruptions, the most recent of which generated a pyroclastic density current that travelled up to 10 km away from the vent. Dima experienced at least 3 eruptions, generating tephra with a bluish-grey colour.

This mapping and compositional analysis of the deposits from the BBTM in the MER indicates that the region has been more active in the last 100 ka than previously thought, which has implications for hazards assessments for the region.
Requiem for the Regolith Hypothesis: Sea-Level and Temperature Reconstructions Provide a New Template for the Middle Pleistocene Transition
Authors: Clark Peter U. , Shakun Jeremy , Rosenthal Yair , Köhler Peter , Schrag Dan , Pollard Dave , Liu Zhengyu , Bartlein Pat
Published: March 2021

The Middle Pleistocene Transition (MPT) has been characterized as the transition in temperature and sea level from low-amplitude, 41-kyr variability to high-amplitude, quasi-100-kyr variability in the absence of any orbital forcing between 1.2 and 0.7 Ma. The regolith hypothesis is one of a class of hypotheses developed to explain the MPT in sea level, which has been largely inferred from d18Obenthic records. Here we use a global array of 130 sea-surface temperature (SST) records based on Mg/Ca, alkenone, and faunal proxies to reconstruct global and regional SST change over the last 4.5 Myr. Average global temperature cooled by ~6.5oC since ~3.5 Ma, with the MPT represented by a significant increase in the rate of cooling between ~1.4 and 0.8 Ma, and a change from dominant 41-kyr to dominant quasi-100-kyr frequencies at ~1.2 Ma that are well correlated with CO2 over the last 800 ka (r2=0.6). Temperature terminations after 1.2 Ma correspond to skipped obliquity beats and, for the last 800 ka, large increases in CO2. We use our global SST reconstruction to remove the temperature signal from the Ahn17 d18Obenthic stack to derive d18Oseawater. Accounting for the influence of changing temperature on the isotopic composition of ice sheets, we use the d18Oseawater record to reconstruct global sea level for the last 4.5 Myr. These results suggest sea-level minima equivalent to or lower than the LGM sea-level low stand (130 m) throughout the Pleistocene. Since inception of Northern Hemisphere glaciation ~3 Ma, sea level varied linearly with obliquity until ~1.2 Ma, when sea-level began to vary nonlinearly with obliquity, with the largest terminations occurring at the same time as temperature terminations that correspond to increasing obliquity and CO2. These results suggest that the MPT is largely a temperature phenomenon likely associated with CO2. The regolith hypothesis other hypotheses developed to explain a transition from low- to high-amplitude sea level variability during the MPT are no longer required, with the MPT change in sea-level response to obliquity likely due to modulation by CO2.
Different energetics of global monsoon over land and ocean
Authors: Chakraborty Arindam , Jalihal Chetankumar , Srinivasan Jayaraman
Published: March 2021

Monsoons were traditionally considered to be land-based systems. Recent definitions of monsoons based on either the seasonal reversal of winds or the local summer precipitation accounting for more than 50% of the annual precipitation suggests that monsoon domains extend over oceanic regions as well. The concept of global monsoon combines all the monsoon domains into a single entity. Modern observations show that the variations in precipitation are nearly coherent across all the individual monsoon domains on decadal timescales. Using a transient simulation of the global climate over the last 22,000 years as well as reanalysis data of the modern climate, we have shown that tropical precipitation has different characteristics over land and ocean grids. This is due to the differences in the energetics of monsoon over land and ocean grids. With a lower thermal heat capacity, the net surface energy flux over land is negligible, whereas it is quite large over the ocean. In fact, the orbital scale variability of net energy flux into the atmosphere over the ocean is controlled by the surface energy flux. Another major difference between land and ocean grids of the global monsoon is in the vertical profile of the vertical pressure velocity. It is bottom-heavy over land and top-heavy over the ocean. This results in smaller vertical transport of moist static energy (which has a minimum in the lower troposphere) over land, and a larger vertical transport over the ocean. These differences between the land and ocean, suggest that the land and ocean grids should not be combined as is traditionally done. Global monsoon-land and global monsoon-ocean should be studied separately.
Modern warming exceeds sea surface temperatures of the Holocene Thermal Maximum in Kongsfjorden, Svalbard
Authors: Guruvayoorappan Harikrishnan , Miettinen Arto , Divine Dmitry , Mohan Rahul
Published: March 2021

Certain past climatic events act as an analogue for future climatic conditions. The Holocene epoch featured a number of climatic variations of which Holocene Thermal Maximum (HTM) stands out as a recognizable phenomenon, especially in the North Atlantic and the Arctic. Similar to modern warming, HTM in Svalbard recorded extreme warmth along with intense deglaciation and sea ice retreat. Therefore, predictions of future climate using HTM depends on understanding the changes in interactions between ocean, sea ice, and atmospheric conditions. While many studies exist on this period, only few have reconstructed ocean surface conditions in the Arctic at high resolution. Here we present the first diatom-based high-resolution quantitative reconstruction of sea surface conditions from Kongsfjorden, Svalbard covering the period of ca. 10.5 to 7.5 cal. kyr BP. Our reconstructions of sea surface temperature (SST) and sea ice conditions are based on diatom microfossil records from a 454 cm long marine sediment core from Kongsfjorden, Svalbard. The section from 454 to 300 cm was used for reconstructions owing to the lack of availability of diatom microfossils. Owing to their high sensitivity towards SST and sea ice, diatoms act as excellent proxies of these environmental conditions in the past. The SST record from Kongsfjorden reveals moderately warm open water conditions and highly variable sea ice conditions during the HTM. The SST achieves maximum values during the early Holocene insolation maxima ca. 10.5 to 7.5 cal. kyr BP, followed by a slow cooling trend simultaneously with the decreasing insolation intensity. Our results emphasize the regional heterogeneity observed in ocean surfaces during the HTM and how modern warming in the study area has already reached sea surface temperatures comparable to the HTM. 
Asynchronous effects of vegetation protection on landform evolution
Authors: Quijano Baron Juan , Saco Patricia , Rodriguez Jose
Published: March 2021

Vegetation protects soil against erosion by intercepting rain, increasing flow resistance, promoting soil infiltration and improving soil strength. However, the representation of vegetation dynamics in Landform Evolution Models (LEMs) is very simplified, which could result in over/under estimations of erosion rates. Here we use a new model framework to study the differences in erosion rates when considering different processes associated with vegetation protection. We analysed the changes in erosion rates by considering: (1) the effect of root biomass on soil erodibility, (2) the effect of leaf cover on soil diffusivity, (3) the effect of litter on flow resistance, and (4) the effect of soil carbon on soil infiltration. We implemented the model in an open-forest savannah catchment situated in Howard Springs (Northern Territory, Australia) and ran simulations using daily time step for 100 years. The modelling framework comprises a coupled Landform Evolution Model (LEM) with dynamic biochemical vegetation and biomass pools dynamics. Our results show that bare soil conditions generate a 100% increase in erosion compared to those using the full dynamic vegetation (that include protection from all carbon pools). We find that the effects from vegetation protection and rainfall are asynchronous, with substantial vegetation growth typically lagging behind substantial rainfall events. This means that rainfall events at the beginning of the rainy season contribute heavily to erosion. For the specific case of Howard Springs, leaves and roots are the most important factors that control erosion except when they are not fully recovered after the dry season. At this time the effect of the litter, and to a lesser extent the soil carbon, turn out to be determinant. Overall, this study highlights the importance of including dynamic vegetation and the effects of the biomass pools on controlling erosion in order to estimate erosion rates.
Can land subsidence be monitored with ambient seismic auto-correlations?
Authors: Ermert Laura , Denolle Marine , Cabral Cano Enrique , Chaussard Estelle , Solano Rojas Dario
Published: March 2021

Mexico City has been undergoing rapid subsidence for more than 100 years due to groundwater extraction. During the 2010s, rates surpassing 30 centimeters/year were observed by satellite geodetic measurements. Not only does this subsidence pose grave challenges for buildings, urban infrastructure, and water management, but it also changes the seismic response of the affected subsurface layers and thereby alters the seismic hazard in the metropolis that has seen devastating site effects both in the 1985 Michoacan and 2017 Puebla earthquake. We use data and numerical modeling of ambient noise auto-correlations to gain a better insight into the subsidence process through ambient noise techniques.

We establish a baseline for the long-term and seasonal variations of seismic velocity near the basin from long-term recordings of the Geoscope station UNM, located at the Universidad Nacional Autónoma de México in the geotechnical hill zone. We further study temporary recordings from the MASE array (MASE (2007): Meso America Subduction Experiment. Caltech. Dataset. doi:10.7909/C3RN35SP) to see how subsidence and other factors may influence seismic velocity in the geotechnical hill, transition, and lake zones.

We find that seasonal oscillations and a strong, rapid velocity drop coincident with the 2017 Puebla earthquake overlay a multi-year increasing trend in seismic velocity. We cautiously interpret the multi-year increase as a long-term effect of subsidence. We further study the temporal correlations of seismic velocity changes with other environmental time series like precipitation, and model auto-correlations in order to improve our understanding of their composition and sensitivity.
Assessing the impact of climate and land-use change on the hydrological response of the upper Betwa River basin
Authors: Kumar Amit , Gaurav Kumar
Published: March 2021

Climate and land-use change have altered the regional hydrological cycle. As a result, the mean summer monsoon rainfall has decreased by 10 % over central India during 1950-2015. This study evaluates the combined effect of climate and land-use change on the hydrological response of the upper Betwa River basin in Central India. We use Landsat satellite images from 1990 to 2018 to compute the changes in various land-use types; waterbody, built-up, forest, agriculture, and open land. In the past two decades, we found that the water body, built-up, and cropland have increased by 63 %, 65 %, and 3 %, respectively. However, forest and open land have decreased by 16 % and 23 %. Further, we observed a significant increase in annual average temperature and a decrease in the mean rainfall in the study area during 1980-2018.

We then coupled the land-use change with weather parameters (precipitation, temperature, wind speed, solar radiation, and relative humidity) and setup the SWAT (Soil and water assessment tool) model to simulate the hydrological responses in the catchment. We have run this model for two different time steps, 1980-2000 and 1998-2018, using the land-use of 1990 and 2018. Calibration and validation are performed for (1991-1994, 2000-2004) and (1995-1998, 2005-2008) respectively using SUFI-2 method. Our results show that the surface runoff and percolation decreased by -21 and -9 %, whereas evapotranspiration increased by 3 % in the upper Betwa River basin during 2001-2018. A decrease in rainfall, runoff, and percolation will have considerable implications on regional water security.
Coastal wetland substrate elevation is dynamically related to accommodation space and influenced by sea-level rise
Authors: Rogers Kerrylee , Saintilan Neil
Published: March 2021

The resilience of coastal wetlands in the fate of sea-level rise is proposed to be related to the combined influence of changes in substrate organic matter volume, mineral sediment volume, auto-compaction of accumulating material and deep subsidence; however, relatively few studies have measured all of these variables. In addition, there is ongoing debate about the suitability of this data for modelling the behaviour of coastal wetlands under anticipated sea-level rise projections as temporal discrepancies in the elevation response of coastal wetlands derived from observational and stratigraphic records exist. To resolve these issues, data derived from a range of techniques sensitive to changes occurring at annual, decadal and century timescales, is presented in the context of available accommodation space, that is, the space in which tidally-borne material can accumulate. Focussing on an embayment in Victoria, Australia, analyses confirm that at annual-decadal timescales, organic matter behaves like a sponge, compressing as the overburden of material accumulates, resulting in auto-compaction that modulates the degree of surface elevation change that occurs as tidally-borne material accumulates. These processes operate concurrently and are influenced by sediment availability, yet vary on the basis of available accommodation space. At longer timescales, the influence of auto-compaction diminishes as organic matter has undergone significant compression and decomposition, yet accumulated material remains proportional to available accommodation space. These analyses confirm that temporal discrepancies in rates of substrate elevation change can be resolved by accounting for the timescale over which processes operate and the influence of sea-level rise on available accommodation space. Accordingly, models should dynamically consider rates of surface elevation change relative to available accommodation space.
Landslide Detection of Hyperspectral Remote Sensing Data Based on Deep Learning With Constrains
Authors: Li Yao
Published: March 2021

There is a growing demand for constructing a complete and accurate landslide maps and inventories in a wide range, which leading explosive growth in extraction algorithm study based on remote sensing images. To the best of our knowledge, no study focused on deep learning-based methods for landslide detection on hyperspectral images.We proposes a deep learning frameworkwith constraints to detect landslides on hyperspectral image. The framework consists of two steps. First, a deep belief network is employed to extract the spectral–spatial features of a landslide. Second, we insert the high-level features and constraints into a logistic regression classifier for verifying the landslide. Experimental results demonstrated that the framework can achieve higher overall accuracy when compared to traditional hyperspectral image classification methods. The precision of the landslide detection on the whole image, obtained by the proposed method, can reach 97.91%, whereas the precision of the linear support vector machine, spectral information divergence, and spectral angle match are 94.36%, 84.50%, and 86.44%, respectively. Also, this article reveals that the high-level feature extraction system has a significant potential for landslide detection, especially in multi-source remote sensing.
Zoning of probability of contagion of COVID 19 and common respiratory diseases aggravated by climatic, environmental and social factors.
Authors: Morales André , Yépez Rincón Fabiola Doracely , Delgado Granados Hugo , Velasco Herrera Victor Manuel Naumovich , Ramírez Serrato Nelly Lucero
Published: March 2021

Worldwide, there has been an unusual epidemiological phenomenon with the SARS -COV2 virus, which has had important repercussions at the social and economic level and has left the country in a vulnerable situation. From the beginning, various epidemiological mathematical models have been presented that simulate the behavior of the contagion over time, however, these do not contemplate climatic and spatial variables. It is well known that respiratory problems are associated mainly with environmental pollution, sudden changes in temperature or low temperatures, and high humidity content in the environment. Therefore, it is necessary to carry out a quantitative projection of the behavior of the virus in environmental matrices of strategic importance for human health. For this project, a multicriteria analysis was carried out that consists of the conjugation of the different thematic maps related in a categorized way by the level of affectation, divided into five classes, from very low to very high, considering the repercussions and relationship of each of these factors. With respect to the mitigation or spread of respiratory diseases, respectively. For this, 3 scenarios were carried out from a weighted linear sum of the projected levels of affectation under 3 considerations: Climate susceptibility: minimum temperatures, average temperatures, height, and humidity; Environmental susceptibility: with urban mobility, industrial activity, and Social exposure: Population density and marginalization. The result will allow us to obtain a zoning map for the Probability of contagion due to environmental and social conditions at the national level that highlights the population that needs greater mitigation efforts and that can be used freely by the corresponding authorities.