Timing of exotic, far-traveled boulder emplacement and paleo-outburstflooding in the central Himalayas Earth Surface Dynamics DOI 10.5194/esurf-8-769-2020 27 October 2020 Large boulders found in two Himalayan valleys show signs of long fluvial transport (>10 km). Paleo-discharges required to mobilize these boulders exceed typical monsoon discharges. Exposure dating shows that a cluster of these boulders was emplaced ca. 5 kyr ago. This period is coeval with a weakening of the Indian monsoon and glacier retreat in the area. We, therefore, suggest that glacier lake outburst floods are likely mechanisms that can explain these exceptional transport processes. Read more
An improved mechanistic model for ammonia volatilization in Earth system models: Flow of Agricultural Nitrogen version 2 (FANv2) Geoscientific Model Development DOI 10.5194/gmd-13-4459-2020 27 October 2020 Mostly emitted by the agricultural sector, ammonia has an important role in atmospheric chemistry. We developed a model to simulate how ammonia emissions respond to changes in temperature and soil moisture, and we evaluated agricultural ammonia emissions globally. The simulated emissions agree with earlier estimates over many regions, but the results highlight the variability of ammonia emissions and suggest that emissions in warm climates may be higher than previously thought. Read more
The Ekman spiral for piecewise-uniform viscosity Ocean Science DOI 10.5194/os-16-1089-2020 22 October 2020 Ekman’s (1905) solution for how wind affects ocean surface currents is revisited and extended analytically for a piecewise-constant profile of vertical diffusion. This allows a comprehensive understanding of how the surface current deflection angle relative to the wind direction varies with the profile of vertical diffusion. Read more
Impact of an educational program on earthquake awareness and preparedness in Nepal Geoscience Communication DOI 10.5194/gc-3-279-2020 22 October 2020 We study the impact of an educational seismology program on earthquake awareness and preparedness in Nepal. We see that educational activities implemented in schools are effective at raising awareness levels and in improving adaptive capacities and preparedness for future earthquakes. Knowledge also reached the broader community though social learning, leading to broadscale awareness. The result observed in this study is encouraging for the continuation and expansion of the program. Read more
ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21st century The Cryosphere DOI 10.5194/tc-14-3033-2020 20 October 2020 The Antarctic ice sheet has been losing mass over at least the past 3 decades in response to changes in atmospheric and oceanic conditions. This study presents an ensemble of model simulations of the Antarctic evolution over the 2015–2100 period based on various ice sheet models, climate forcings and emission scenarios. Results suggest that the West Antarctic ice sheet will continue losing a large amount of ice, while the East Antarctic ice sheet could experience increased snow accumulation. Read more
A protocol for calculating basal melt rates in the ISMIP6 Antarctic ice sheet projections The Cryosphere DOI 10.5194/tc-14-3111-2020 20 October 2020 To predict the future Antarctic contribution to sea level rise, we need to use ice sheet models. The Ice Sheet Model Intercomparison Project for AR6 (ISMIP6) builds an ensemble of ice sheet projections constrained by atmosphere and ocean projections from the 6th Coupled Model Intercomparison Project (CMIP6). In this work, we present and assess a method to derive ice shelf basal melting in ISMIP6 from the CMIP6 ocean outputs, and we give examples of projected melt rates. Read more
The making of the New European Wind Atlas – Part 1: Model sensitivity Geoscientific Model Development DOI 10.5194/gmd-13-5053-2020 16 October 2020 Wind energy resource assessment routinely uses numerical weather prediction model output. We describe the evaluation procedures used for picking the suitable blend of model setup and parameterizations for simulating European wind climatology with the WRF model. We assess the simulated winds against tall mast measurements using a suite of metrics, including the Earth Mover’s Distance, which diagnoses the performance of each ensemble member using the full wind speed and direction distribution. Read more
Review article: Hilbert problems for the climate sciences in the 21st century – 20 years later Nonlinear Processes in Geophysics DOI 10.5194/npg-27-429-2020 15 October 2020 The scientific questions posed by the climate sciences are central to socioeconomic concerns today. This paper revisits several crucial questions, starting with What can we predict beyond 1 week, for how long, and by what methods?, and ending with Can we achieve enlightened climate control of our planet by the end of the century? We review the progress in dealing with the nonlinearity and stochasticity of the Earth system and emphasize major strides in coupled climate–economy modeling. Read more
The future sea-level contribution of the Greenland ice sheet: a multi-model ensemble study of ISMIP6 The Cryosphere DOI 10.5194/tc-14-3071-2020 15 October 2020 In this paper we use a large ensemble of Greenland ice sheet models forced by six different global climate models to project ice sheet changes and sea-level rise contributions over the 21st century. The results for two different greenhouse gas concentration scenarios indicate that the Greenland ice sheet will continue to lose mass until 2100, with contributions to sea-level rise of 90 ± 50 mm and 32 ± 17 mm for the high (RCP8.5) and low (RCP2.6) scenario, respectively. Read more
In situ measurements of soil and plant water isotopes: a review of approaches, practical considerations and a vision for the future Hydrology and Earth System Sciences DOI 10.5194/hess-24-4413-2020 13 October 2020 Water isotopes are a scientific tool that can be used to identify sources of water and answer questions such as From which soil depths do plants take up water?, which are highly relevant under changing climatic conditions. In the past, the measurement of water isotopes required tremendous effort. In the last decade methods have advanced and can now be applied in the field. Herein, we review the current status of direct field measurements of water isotopes and discuss future applications. Read more