Distinct stores and the routing of water in the deep critical zone of a snow-dominated volcanic catchment Hydrology and Earth System Sciences DOI 10.5194/hess-23-4661-2019 3 December 2019 This paper examines the influence of the subsurface structure on water routing, water residence times, and the hydrologic response of distinct groundwater stores and further investigates their contribution to streamflow. We conclude that deep groundwater from the fractured aquifer system, rather than shallow groundwater, is the dominant source of streamflow, which highlights the need to better characterize the deep subsurface of mountain systems using interdisciplinary studies such as this one. Read more
Meeting climate targets by direct CO2 injections: what price would the ocean have to pay? Earth System Dynamics DOI 10.5194/esd-10-711-2019 22 November 2019 This modeling study is the first one to look at the suitability and collateral effects of direct CO2injection into the deep ocean as a means to bridge the gap between CO2emissions and climate impacts of an intermediate CO2emission scenario and a temperature target on a millennium timescale, such as the 1.5 °C climate target of the Paris Agreement. Read more
Geo-locate project: a novel approach to resolving meteorological station location issues with the assistance of undergraduate students Geoscience Communication DOI 10.5194/gc-2-157-2019 22 November 2019 The Global Land and Marine Observations Database aims to produce a comprehensive land-based meteorological data archive and inventory. Data sources contained stations in incorrect locations; therefore, we developed the Geo-locate project, enlisting the help of undergraduate geography students. The project has resolved 1926 station issues so far. Due to the success of the Geo-locate project, we encourage other organizations to engage university students to help resolve similar data issues. Read more
New Last Glacial Maximum ice thickness constraints for the Weddell Sea Embayment, Antarctica The Cryosphere DOI 10.5194/tc-13-2935-2019 22 November 2019 We studied the history of ice masses at three locations in the Weddell Sea Embayment, Antarctica. We measured rare isotopes in material sourced from mountains overlooking the Slessor Glacier, Foundation Ice Stream, and smaller glaciers on the Lassiter Coast. We show that ice masses were between 385 and 800 m thicker during the last glacial cycle than they are at present. The ice masses were both hundreds of metres thicker and remained thicker closer to the present than was previously thought. Read more
Evaluating climate emulation: fundamental impulse testing of simple climate models Earth System Dynamics DOI 10.5194/esd-10-729-2019 22 November 2019 Simple climate models (SCMs) underlie many important scientific and decision-making endeavors. This illustrates the need for their use to be rooted in a clear understanding of their fundamental responses. In this study, we provide a comprehensive assessment of model performance by evaluating the fundamental responses of several SCMs. We find biases in some responses, which have implications for decision science. We conclude by recommending a standard set of validation tests for any SCM. Read more
Melt at grounding line controls observed and future retreat of Smith, Pope, and Kohler glaciers The Cryosphere DOI 10.5194/tc-13-2817-2019 15 November 2019 We used a number of computer simulations to understand the recent retreat of a rapidly changing group of glaciers in West Antarctica. We found that significant melt underneath the floating extensions of the glaciers, driven by relatively warm ocean water at depth, was likely needed to cause the large retreat that has been observed. If melt continues around current rates, retreat is likely to continue through the coming century and extend beyond the present-day drainage area of these glaciers. Read more
The first version of the Pan-European Indoor Radon Map Natural Hazards and Earth System Sciences DOI 10.5194/nhess-19-2451-2019 15 November 2019 The first version of the Pan-European Indoor Radon Map is presented in this article. The map has been developed using summary statistics estimated from 1.2 million samples. It represents an average radon concentration per 10 km x 10 km grid cell under the assumption that there are dwellings in the grid cell. It is a major contribution to the understanding of the exposure to ionizing radiation of Europeans and a first step towards a European radon exposure and, in the future, radon dose map. Read more
Seismic location and tracking of snow avalanches and slush flows on Mt. Fuji, Japan Earth Surface Dynamics DOI 10.5194/esurf-7-989-2019 15 November 2019 Avalanches and slush flows from Mt. Fuji are a major natural hazard as they may attain run-out distances of up to 4 km and destroy parts of the forest and infrastructure. We located and tracked them for the first time using seismic data. Numerical simulations were conducted to assess the precision of the seismic tracking. We also inferred dynamical properties characterizing these hazardous mass movements. This information is indispensable for assessing avalanche risk in the Mt. Fuji region. Read more
Calving cycle of the Brunt Ice Shelf, Antarctica, driven by changes in ice shelf geometry The Cryosphere DOI 10.5194/tc-13-2771-2019 15 November 2019 Two large icebergs are about to break off from the Brunt Ice Shelf in Antarctica. Rifting started several years ago and is now approaching its final phase. Satellite data and computer simulations show that over the past 2 decades, growth of the ice shelf has caused a build-up of forces within the ice, which culminated in its fracture. These natural changes in geometry coincided with large variations in flow speed, a process that is thought to be relevant for all Antarctic ice shelf margins. Read more
Effects of land use and anthropogenic aerosol emissions in the Roman Empire Climate of the Past DOI 10.5194/cp-15-1885-2019 8 November 2019 Using the global aerosol–climate model ECHAM-HAM-SALSA, the effect of humans on European climate in the Roman Empire was quantified. Both land use and novel estimates of anthropogenic aerosol emissions were considered. We conducted simulations with fixed sea-surface temperatures to gain a first impression about the anthropogenic impact. While land use effects induced a regional warming for one of the reconstructions, aerosol emissions led to a cooling associated with aerosol–cloud interactions. Read more
Electron pairing in mirror modes: surpassing the quasi-linear limit Annales Geophysicae DOI 10.5194/angeo-37-971-2019 8 November 2019 The mirror mode starts as a zero-frequency ion fluid instability and saturates quasi-linearly at very low magnetic level, while forming extended magnetic bubbles. These trap the adiabatically bouncing electron component which forms pairs near the mirror points. The large pair anisotropy causes further growth beyond quasilinear level. Including pressure equilibrium gives and estimate of the required pair density. Read more
Microbial community composition and abundance after millennia of submarine permafrost warming Biogeosciences DOI 10.5194/bg-16-3941-2019 8 November 2019 Permafrost temperatures increased substantially at a global scale, potentially altering microbial assemblages involved in carbon mobilization before permafrost thaws. We used Arctic Shelf submarine permafrost as a natural laboratory to investigate the microbial response to long-term permafrost warming. Our work shows that millennia after permafrost warming by > 10 °C, microbial community composition and population size reflect the paleoenvironment rather than a direct effect through warming. Read more
The biophysics, ecology, and biogeochemistry of functionally diverse, vertically and horizontally heterogeneous ecosystems: the Ecosystem Demography model, version 2.2 – Part 1: Model description Geoscientific Model Development DOI 10.5194/gmd-12-4309-2019 8 November 2019 Our paper describes the Ecosystem Demography model. This computer program calculates how plants and ground exchange heat, water, and carbon with the air, and how plants grow, reproduce and die in different climates. Most models simplify forests to an average big tree. We consider that tall, deep-rooted trees get more light and water than small plants, and that some plants can with shade and drought. This diversity helps us to better explain how plants live and interact with the atmosphere. Read more
The biophysics, ecology, and biogeochemistry of functionally diverse, vertically and horizontally heterogeneous ecosystems: the Ecosystem Demography model, version 2.2 – Part 2: Model evaluation for tropical South America Geoscientific Model Development DOI 10.5194/gmd-12-4347-2019 29 October 2019 The Ecosystem Demography model calculates the fluxes of heat, water, and carbon between plants and ground and the air, and the life cycle of plants in different climates. To test if our calculations were reasonable, we compared our results with field and satellite measurements. Our model predicts well the extent of the Amazon forest, how much light forests absorb, and how much water forests release to the air. However, it must improve the tree growth rates and how fast dead plants decompose. Read more
Modeling forest plantations for carbon uptake with the LPJmL dynamic global vegetation model Earth System Dynamics DOI 10.5194/esd-10-617-2019 29 October 2019 We developed a computer model that simulates forests plantations at global scale and how fast such forests can take up CO2from the atmosphere. Using this new model, we performed simulations for a scenario in which a large fraction (14 %) of global croplands and pastures are either converted to planted forests or natural forests. We find that planted forests take up CO2substantially faster than natural forests and are therefore a viable strategy for reducing climate change. Read more
Contrasting thinning patterns between lake- and land-terminating glaciers in the Bhutanese Himalaya The Cryosphere DOI 10.5194/tc-13-2733-2019 29 October 2019 We investigate thickness change of Bhutanese glaciers during 2004–2011 using repeat GPS surveys and satellite-based observations. The thinning rate of Lugge Glacier (LG) is > 3 times that of Thorthormi Glacier (TG). Numerical simulations of ice dynamics and surface mass balance (SMB) demonstrate that the rapid thinning of LG is driven by both negative SMB and dynamic thinning, while the thinning of TG is minimised by a longitudinally compressive flow regime. Read more
Ensemble models from machine learning: an example of wave runup and coastal dune erosion Natural Hazards and Earth System Sciences DOI 10.5194/nhess-19-2295-2019 29 October 2019 Wave runup is important for characterizing coastal vulnerability to wave action; however, it is complex and uncertain to predict. We use machine learning with a high-resolution dataset of wave runup to develop an accurate runup predictor that includes prediction uncertainty. We show how uncertainty in wave runup predictions can be used practically in a model of dune erosion to make ensemble predictions that provide more information and greater predictive skill than a single deterministic model. Read more
Geologic and geomorphic controls on rockfall hazard: how well do past rockfalls predict future distributions? Natural Hazards and Earth System Sciences DOI 10.5194/nhess-19-2249-2019 11 October 2019 Here we evaluate geologic, geomorphic, and anthropogenic controls on rockfall hazard and highlight the complexity of interpreting future rockfall hazard based on former boulder distributions. To evaluate how past rockfall deposits relate to contemporary rockfall hazard, we mapped then compared the locations, physical characteristics, and lithologies of rockfall boulders deposited during the 2010–2011 Canterbury earthquake sequence (n= 185) with their prehistoric counterparts (n= 1093). Read more
Relative impact of aerosol, soil moisture, and orography perturbations on deep convection Atmospheric Chemistry and Physics DOI 10.5194/acp-19-12343-2019 7 October 2019 This study addresses the relative impact of orography, soil moisture, and aerosols on precipitation over Germany in different weather regimes. We find that the impact of these perturbations is higher for weak than for strong large-scale forcing. Furthermore, aerosols and soil moisture are both of similar importance for precipitation forecasting, which indicates that their inclusion in operational ensemble forecasting should be assessed in the future. Read more
Mapping landscape connectivity as a driver of species richness under tectonic and climatic forcing Earth Surface Dynamics DOI 10.5194/esurf-7-895-2019 1 October 2019 Mountainous landscapes have long been recognized as potential drivers for genetic drift, speciation, and ecological resilience. We present a novel approach that can be used to assess and quantify drivers of biodiversity, speciation, and endemism over geological time. Using coupled climate–landscape models, we show that biodiversity under tectonic and climatic forcing relates to landscape dynamics and that landscape complexity drives species richness through orogenic history. Read more