The Brine Availability Test in Salt (BATS) is a field heater test being conducted in the bedded salt formation at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, NM. BATS is focused on exploring brine availability as part of a wider investigation into the disposal of heat-generating radioactive waste in salt. Brine has the potential to transport radionuclides, corrode waste forms and packages, reduce criticality, and pressurize porosity to resist closure through salt creep. In BATS, two identical arrays of horizontal boreholes were constructed in an experimental drift, 650 m below ground at WIPP. In each array, 13 observational boreholes were installed around a central borehole. One of the two array was heated, and the other array was left at ambient temperature. During the first heating phase (January to March 2020), the 750 W heater ran for 4 weeks. The central boreholes included dry nitrogen gas circulation behind a packer. The gas stream removed moisture which flowed into the boreholes. The gas stream was analyzed in-drift for stable water isotopes using a cavity ringdown spectrometer and gas composition using a quadrupole mass spectrometer. The satellite boreholes in each array included numerous thermocouples, electrical resistivity tomography (ERT) electrodes, acoustic emissions (AE) piezoelectric transducers, distributed temperature and strain fiber optics, and a cement seal exposure tests (both sorel and fly-ash base concretes). Cores from the boreholes were X-ray CT imaged for mineralogical and fracture distribution. We present an overview of the first phase of the test, and illustrate key data collected during the first heating cycle. Follow-on tests in the same boreholes will include gas and liquid tracer tests and additional packer-based gas permeability testing. New boreholes for the next round of BATS in 2021 are being planned.

Is it possible for a rocky planet to have too much internal heating to maintain a habitable surface environment? In the Solar System, the best example of a world with high internal heating is Jupiter’s moon Io, which has a heat flux of approximately 2 W m-2 compared to the Earth’s 90 mW m-2. The ultimate upper limit to internal heating rates is the Tidal Venus Limit, where the geothermal heat flux exceeds the Runaway Greenhouse Limit of 300 W m-2 for an Earth-mass planet. Between Io and a Tidal Venus there is a wide range of internal heating rates whose effects on planetary habitability remain unexplored. We investigate the habitability of these worlds, referred to as Ignan Earth’s. We demonstrate how the mantle will remain largely solid despite high internal heating, allowing for the formation of a convectively buoyant and stable crust. In addition, we model the long-term climate of Ignan Earth’s by simulating the carbonate-silicate cycle in a vertical tectonic regime (known as heat-pipe tectonics, expected to dominate on such worlds) at varying amounts of internal heating. We find that Earth-mass planets with internal heating fluxes below 30 W m-2 produce average surface temperatures that Earth has experienced in its past (below 30 oC), and worlds with higher heat fluxes still result in surface temperatures far below that of 100 oC, indicating a wide range of internal heating rates may be conducive with habitability.

Following the Hunga Tonga–Hunga Ha’apai (HTHH) eruption in January 2022, stratospheric ozone depletion was observed in the Southern Hemisphere mid-latitudes and Antarctica during the 2022 austral wintertime and springtime. This eruption injected sulfur dioxide and unprecedented amounts of water vapor into the stratosphere. This work examines and quantifies the chemistry contribution of the volcanic materials to the ozone depletion using chemistry-climate model simulations with nudged meteorology. Simulated 2022 ozone and nitrogen oxides (NOx) anomalies show a good agreement with satellite observations. We find that chemistry only contributes up to 6% and 20% ozone destruction at mid-latitudes wintertime and Antarctic springtime respectively. The majority of the ozone depletion is attributed to the internal variability and dynamical changes forced by the eruption. Both the simulation and observations show a significant NOx reduction associated with the HTHH aerosol plume, indicating the enhanced dinitrogen pentoxide hydrolysis on sulfate aerosol.

There is large uncertainty in the future sea level change at regional scales under anthropogenic global warming. This study uses a novel design of ocean-only general circulation model (OGCM) experiments to investigate the ocean’s response to surface buoyancy and momentum flux perturbations, as part of the Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP), and compares with results from coupled, atmosphere-ocean GCM (AOGCM) experiments. Much of the inter-model spread is driven by the response to surface heat flux perturbations. In a multi-model ensemble of OGCMs forced with identical surface heat flux perturbations, regional sea level and ocean heat content changes demonstrate considerable disagreement, especially in the North Atlantic. Spread in both residual mean advection and diapycnal diffusion changes contribute to much of the multi-model disagreement over regional heat content change. Residual mean advection changes are related to the large spread in simulated Atlantic meridional overturning circulation (AMOC) weakening (20-50%). We find approximately 10% more AMOC weakening in response to surface heat flux perturbations in AOGCMs relative to OGCMs with consistent ocean models. This enhanced AMOC weakening is driven by an atmosphere-ocean feedback which amplifies the surface heat flux perturbation. In the North Pacific, there is little agreement amongst the ensemble over which processes lead to ocean warming, with varying contributions from residual mean advection and diapycnal diffusion. For the Pacific basin, the atmosphere-ocean feedback reduces sea surface temperature (SST) warming by 0.5°C. In the Southern Ocean, the atmosphere-ocean feedback is not generally important for buoyancy and momentum flux perturbations.

The burgeoning field of socio-hydrology aims to understand the dynamics of coupled human-water systems in order to inform sustainable water management. However, socio-hydrological methods have traditionally relied on the quantification of qualitative social data, which runs into significant epistemological challenges between the positivist paradigm of hydrology and the interpretivist paradigm of much of social science. This article builds on recent literature that advocates for a pluralistic approach, retaining the methodological and epistemological differences inherent to social sciences and hydrology, and thereby revealing a more complete understanding of situated human-water relationships. In this vein, we propose rapid ethnography as a tool to complement hydrological modeling. We demonstrate the utility of this technique with a case study on hydrological entanglements of rural livelihoods in Andes, Antioquia, Colombia–a region dominated by agriculture, but with the presence of artisanal and small-scale gold mining (ASGM). Our ethnographic study builds on previous hydrological models and quantitative social studies of the region by exploring a myriad of local risk perceptions of hydrological systems, in particular, 1) climate change, 2) water contamination, and 3) hydrological erosion and landslides. We explore how these risk perceptions informed livelihood decisions that paradoxically threatened the very hydrological resources that the livelihoods depended on; yet, this cycle was difficult to interrupt given prevailing economic and political constraints. Ultimately, we seek to advocate for pluralistic approaches in socio-hydrology to help understand complex human-water relationships and ultimately identify critical points of intervention for sustainable water resource management, model-based or otherwise.

The Antarctic Ice Sheet (AIS) response to past warming consistent with the 1.5–2°C ‘safe limit’ of the United Nations Paris Agreement is currently not well known. Empirical evidence from the most recent comparable period, the Last Interglaciation, is sparse, and transient ice-sheet experiments are few and inconsistent. Here we present new, transient, GCM-forced ice-sheet simulations validated against proxy reconstructions. This is the first time such an evaluation has been attempted. Our empirically-constrained simulations indicate that the AIS contributed 4 m to global mean sea level by 126 ka BP, with ice lost primarily from the Amundsen, but not Ross or Weddell Sea, sectors. We resolve conflict between previous work and show that the AIS thinned in the Wilkes Subglacial Basin but did not retreat. We also find that the West Antarctic Ice Sheet may be predisposed to future collapse even in the absence of further environmental change, consistent with previous studies.

A document by Gabrielle Tepp. Click on the document to view its contents.

The severity and frequency of wildfires have risen dramatically in recent years, drawing attention to the term ‘wildland-urban interface’ (WUI), the region where man-made constructions meet flammable vegetation. Herein, we mapped a finer-scale, novel linear WUI for California (CA) based on the intersection of boundaries of wildland vegetation and building footprint. The direct intersection is referred to as a direct WUI, whereas the intersection at 100-m is known as an indirect WUI. More fires were ignited closer to direct WUI than indirect WUI due to their proximity to communities. However, the overlap of past fire perimeters with indirect WUI is greater than that with direct WUI which shows that more areas were burned in the indirect WUI due to embers transported by strong wind gusts during large wildfires. The study’s findings will help land managers and policymakers in controlling fire dangers, land-use planning, and reducing threats to fire-prone communities.

The monthly mean sunspot number has been larger in June-July 2023 than the double peak of solar cycle 24 (146 in February 2014 and 139 in November 2011) and brings us back to the sunspot level of solar cycle 23. However, the number of rocket launches, satellites in orbit and private space companies has increased dramatically in the past 20 years. Additionally, there is a growing interest for space exploration beyond Earth’s orbit, to the Moon and beyond, which comes with higher risk of being affected by space weather. Here, we discuss some of these trends and the role of the journal to improve awareness of space weather impacts.

A document by Lukas Pilz. Click on the document to view its contents.

Tropical cyclones dominate the disturbance regime experienced by forest ecosystems in many parts of the world. Interactions between cyclone disturbance regimes and nutrient availability strongly influence forest ecosystem dynamics. However, uncertainty exists over the importance of soil fertility properties (i.e., total soil phosphorus-P concentration) in mediating forest resistance and recovery from cyclone disturbance. We hypothesized that forests on soils with low total P (e.g., developed on limited-P parent material) have a higher resistance to but a slower recovery from cyclone disturbance than forests on high P soils. We investigated cyclone impacts on litterfall, an essential conduit for nutrient recycling in forest ecosystems. We compiled site-level forest litterfall data from 53 studies and datasets associated with 15 naturally-occurring one simulated tropical cyclone in 23 sites within five regions (Taiwan, Australia, Mexico, Hawaii, and the Caribbean)and four cyclone basins. We calculated the effect sizes of cyclone disturbance on the litterfall mass and nutrient (P and nitrogen-N) concentrations and fluxes during the first (< five) years post-disturbance across a total soil P gradient. We also assessed the effect of 20 covariates on the degree of cyclone impact on litterfall. Total litterfall mass flux increased by 4820%following cyclone disturbance. Such an initial increase in litterfall mass reflects the magnitude of cyclone-derived plant material input to the forest floor, which was highest in the Caribbean and lowest in Taiwan. Among 20 covariates, soil P and region were the best predictors of cyclone effects on total litterfall mass, explaining 80% of the variance. The effect sizes increased linearly with soil P and region, from significantly lower in Taiwan (low-P) to largest in the Caribbean (high-P). Total litterfall P and N fluxes increased significantly post-cyclone, whereas the increase in leaf P flux was twice as that in Nflux. Results highlight the importance of understanding the interactions between disturbance and nutrient gradients in forest ecosystems to understand forest responses to altered cyclone regimes expected under climate change.

N2O and CH4 soil flux studies traditionally consider certain time periods and certain ecosystems to be of low importance due to very small or negligible expected flux rates. Periods of such “negligible” fluxes are rarely reported because small fluxes are hard to resolve, measurements are costly, time-consuming, and often take a lot of power. “Negligible” flux sites are also rarely studied because small fluxes are hard to resolve, measurements are time-consuming and costly, and it is hard to get funding to measure something when the error bars cross zero. However, such fluxes may not be negligible in time when multiplied by long time duration, for example, 340 out of 365 days per year. Similarly, these may not be negligible in space when multiplied by a large area. When GHG budgets are of interest, very small fluxes multiplied by hundreds of days or square kilometers, or both, could easily exceed large fluxes multiplied by few days or square kilometers. The new OF-CAES technology [1-7] has very low minimum detectable flux which may help make more of such measurements valuable and valid in both time and space. The presentation will demonstrate the field data on the N2O and CH4 soil flux performance of this new technology. Conceptual simulations will demonstrate the significant advantages of using the technology when measuring small N2O and CH4 fluxes over time and space. References: [1] Burba, 2021. Eddy Covariance Method for Scientific, Regulatory, and Commercial Applications. LI-COR Biosciences, 660 pp (under review) [2] Burba, 2021. Atmospheric Flux Measurements. In Advances in Spectroscopic Monitoring of the Atmosphere. Elsevier Science, 618 pp [3] Koulikov and Kachanov, 2014. Laser-based cavity-enhanced optical absorption gas analyzer with laser feedback optimization. US Patent 8659758 [4] Leggett et al, 2019. Development of Trace CH4 and CO2 Analyzers: Performance Evaluation Studies, GCWerks Integration, and Field Results. AGUFM [5] Minish et al, 2019. New High-Precision Low-Power CO2 and CH4 Analyzers for Multiple Applications. Geophysical Research Abstracts, Vol. 21 [6] Romanini et al, 2014. Introduction to cavity-enhanced absorption spectroscopy. In Cavity-Enhanced Spectroscopy and Sensing. Springer, 546 pp [7] Xu et al, 2020. How do soil temperature and moisture regulate N2O flux from an urban lawn? AGUFM

Cyanobacterial blooms present challenges for water treatment, especially in regions like the Canadian prairies where poor water quality intensifies water treatment issues. Buoyant cyanobacteria that resist sedimentation present a challenge as water treatment operators attempt to balance pre-treatment and toxic disinfection by-products. Here, we used microscopy to identify and describe the succession of cyanobacterial species in Buffalo Pound Lake, a key drinking water supply. We used indicator species analysis to identify temporal grouping structures throughout two sampling seasons from May to October 2018 and 2019. Our findings highlight two key cyanobacterial bloom phases – a mid-summer diazotrophic bloom of Dolichospermum spp. and an autumn Planktothrix agardhii bloom. Dolichospermum crassa and Woronchinia compacta served as indicators of the mid-summer and autumn bloom phases, respectively. Different cyanobacterial metabolites were associated with the distinct bloom phases in both years: toxic microcystins were associated with the mid-summer Dolichospermum bloom and some newly monitored cyanopeptides (anabaenopeptin A and B) with the autumn Planktothrix bloom. Despite forming a significant proportion of the autumn phytoplankton biomass (greater than 60%), the Planktothrix bloom had previously not been detected by sensor or laboratory-derived chlorophyll-a. Our results demonstrate the power of targeted taxonomic identification of key species as a tool for managers of bloom-prone systems. Moreover, we describe an autumn Planktothrix agardhii bloom that has the potential to disrupt water treatment due to its evasion of detection. Our findings highlight the importance of identifying this autumn bloom given the expectation that warmer temperatures and a longer ice-free season will become the norm.

Forest management can enhance forest resiliency against natural disturbances such as fire, drought, or disease. Mechanical thinning, followed by a prescribed burn, is a useful technique to achieve a desired forest structure, usually maximizing large tree basal area or decreasing fuel loads, meant to protect against wildfire or reduce water stress in the western US. Changing forest structure can alter ecosystem function by reducing competition and exposing soil, modifying microclimates and creating suitable conditions for shrubs and grasses to encroach. Typically, forest treatments are expected to make the remaining trees more productive through competitive release, and an open canopy helps the understory to thrive. This enhanced plant water use often contradicts the expected result of increased streamflow following thinning. In mountainous terrain, water yield is further complicated by hillslope-scale processes of subsurface lateral flow and groundwater recharge. This research seeks to understand how management-derived forest structure influences hillslope-scale forest regrowth and water yield. We apply a spatially-distributed ecohydrologic model (RHESSys) to an experimental hillslope in the Sierra Nevada, CA. We incorporate multi-temporal Lidar observations and U.S. Forest Service Forest Inventory & Analysis (FIA) survey data to estimate post-thinning regrowth in treated plots in the watershed, which is used to verify RHESSys accuracy of vegetation regrowth. Then, we run long-term virtual thinning experiments to understand how the combination of thinning and prescribed burns in upslope and riparian sites separately and concurrently influences regrowth and water fluxes in these sites. We expect that an intermediate forest density will yield the most co-benefits in terms of carbon sequestration and water yield. However, these patterns will likely be modified along a hillslope, such that riparian forest stands will be less sensitive to the competitive release that thinning provides, whereas dense upslope forests will be highly sensitive to treatment since they are more water-limited. Water yield is likely to be confounded by multiple factors, including topography, whether a burn follows thinning to remove understory fluxes, and interactions between upslope thinning and processes of lateral flow and groundwater recharge when increased riparian water use compensates for additional upslope subsidies.

We examined data from the American Geophysical Union (AGU), the world’s largest earth and space science society, to characterize cohort demographics of multiple milestones in a biogeoscientists’ career. Geoscientists of color and White women make up a smaller proportion of those participating in activities critical to transitioning from student to professional (submitting manuscripts, getting published, and being asked to review) in comparison to White men. However, gender parity for biogeoscientists appears within reach at earlier career stages, with 37% AGU Biogeosciences members and 41% of Biogeosciences attendees at the Fall Meeting identifying as women in 2020. Unfortunately, data is lacking to make the same assessment for geoscientists of color. A large proportion of manuscripts are submitted by men (73%), many of which have no co-authors that identify as women or non-binary geoscientists, which likely points to inequitable resources and a greater service burden for scientists from historically excluded groups. Further, our communities’ bias of who we suggest as reviewers results in 85% of the reviewer invites going to White geoscientists and 63% going to men. Thus, while representation of diverse communities has improved in some areas, barriers to publishing results in journals not reflecting society: 25% and 22% of manuscripts were led by or included non-White geoscientists, respectively, and fewer than 5% and 7% were led by or included non-White, women geoscientists, respectively. Therefore, in sectors like academia where publishing remains critical for advancement, this process represents a significant obstacle for biogeoscientists not already part of the majority.

The Barents Sea is one of the main pathways for warm and saline Atlantic Water (AW) entering the Arctic Ocean. It is an important region for water mass transformation and dense-water production that contribute to the Atlantic meridional overturning circulation. Here, we present data from three cruises and nine glider missions conducted between 2019 and 2022 in the western Barents Sea, and compare with historical data collected from 1950 to 2009. We present circulation pathways, hydrography, heat content and volume fluxes of Atlantic- and Arctic-origin waters. Our observations show that 0.9±0.1 Sv (1 Sv = 106 m3 s-1) of Atlantic-origin water reaches the Polar Front (PF) region before splitting into several branches and eventually subducting beneath Polar Water (PW). The observed increased heat content in the AW inflow over the past decades can be traced under the Polar front. The amount of heat stored in the basin north of the PF is determined by the density difference between AW and PW, and reached a maximum in the 90s when PW was particularly fresh. The inflow of Atlantic Water (AW) into the Barents Sea during the period from 2019 to 2022 exhibits a decrease in salinity of up to 0.1 g kg-1 compared to previous decades. Consequently, this leads to a reduction in the production of dense water, an increased temperature gradient across the PF, and a reduced poleward transport of warm water.

Survey evidence has indicated that a significant percentage of the population does not fully embrace the scientific consensus regarding climate change. This paper assesses whether the hourly temperature data support this denial. The analysis examines the relationship between hourly CO2 concentration levels and temperature using hourly data from the NOAA-operated Barrow observatory in Alaska. At this observatory, the average annual temperature over the 2015-2020 period was about 3.37 oC higher than in 1985–1990. A time-series model to explain hourly temperature is formulated using the following explanatory variables: the hourly level of total downward solar irradiance, the CO2 value lagged by one hour, proxies for the diurnal variation in temperature, proxies for the seasonal temperature variation, and proxies for possible non-anthropomorphic drivers of temperature. The purpose of the time-series approach is to capture the data’s heteroskedastic and autoregressive nature, which would otherwise “mask” CO2’s “signal” in the data. The model is estimated using hourly data from 1985 through 2015. The results are consistent with the hypothesis that increases in CO2 concentration levels have nontrivial consequences for hourly temperature. The estimated annual contributions of factors exclusive of CO2 and downward total solar irradiance are very small. The model was evaluated using out-of-sample hourly data from 1 Jan 2016 through 31 Aug 2017. The model’s out-of-sample hourly temperature predictions are highly accurate, but this accuracy is significantly degraded if the estimated CO2 effects are ignored. In short, the results are consistent with the scientific consensus on climate change.

Cenozoic growth of the Andes has been strongly influenced by subduction dynamics, reactivation of inherited crustal heterogeneities, and the superposed effects of climate. Subduction of the submarine Carnegie Ridge has fundamentally impacted late Cenozoic magmatism and tectonic activity in the northern Andes. Time-temperature inverse modeling of new thermochronological data from the Western Cordillera of Ecuador reveals two phases of cooling separated by isothermal conditions. The first cooling phase immediately postdates early and middle Miocene magmatism in the Western Cordillera and is attributed to post-magmatic thermal relaxation. The second cooling phase started after 6 Ma, which we infer to record the exhumation in the Western Cordillera, coeval with the last cooling phase in the Eastern Cordillera. Based on these findings we posit that the onset of subduction of the Carnegie Ridge at ~6-5 Ma increased plate coupling at the subduction interface and promoted shortening and regional rock uplift in the northern Andes. Overall, our results highlight the essential role of bathymetric anomalies in driving regional upper-plate deformation at non-collisional convergent plate margins.