A discontinuous Galerkin finite-element model for fast channelized lava flows v1.0 Geoscientific Model Development DOI 10.5194/gmd-14-3553-2021 23 July 2021 Lava flows present a natural hazard to communities around volcanoes and are usually slow-moving (< 1-5 cm/s). Lava flows during the 2018 eruption of Kilauea volcano, Hawai’i, however, reached speeds as high as 11 m/s. To investigate these dynamics we develop a new lava flow computer model that incorporates a nonlinear expression for the fluid viscosity. Model results indicate that the lava flows at Site 8 of the eruption displayed shear thickening behavior due to the flow’s high bubble content. Read more
Fracking bad language – hydraulic fracturing and earthquake risks Geoscience Communication DOI 10.5194/gc-4-303-2021 21 July 2021 The potential for hydraulic fracturing (fracking) to induce seismicity is a topic of widespread interest. We find that terms used to describe induced seismicity are poorly defined and ambiguous and do not translate into everyday language. Such bad language has led to challenges in understanding, perceiving, and communicating risks around seismicity and fracking. Our findings and recommendations are relevant to other geoenergy topics that are potentially associated with induced seismicity. Read more
Microbial and geo-archaeological records reveal the growth rate, origin and composition of desert rock surface communities Biogeosciences DOI 10.5194/bg-18-3331-2021 19 July 2021 Biological rock crusts (BRCs) are common microbial-based assemblages covering rocks in drylands. BRCs play a crucial role in arid environments because of the limited activity of plants and soil. Nevertheless, BRC development rates have never been dated. Here we integrated archaeological, microbiological and geological methods to provide a first estimation of the growth rate of BRCs under natural conditions. This can serve as an affordable dating tool in archaeological sites in arid regions. Read more
Faster decline and higher variability in the sea ice thickness of the marginal Arctic seas when accounting for dynamic snow cover The Cryosphere DOI 10.5194/tc-15-2429-2021 16 July 2021 We re-estimate pan-Arctic sea ice thickness (SIT) values by combining data from the Envisat and CryoSat-2 missions with data from a new, reanalysis-driven snow model. Because a decreasing amount of ice is being hidden below the waterline by the weight of overlying snow, we argue that SIT may be declining faster than previously calculated in some regions. Because the snow product varies from year to year, our new SIT calculations also display much more year-to-year variability. Read more
Oxygen isotope exchange between water and carbon dioxide in soils is controlled by pH, nitrate and microbial biomass through links to carbonic anhydrase activity SOIL DOI 10.5194/soil-7-145-2021 14 July 2021 Understanding how the rate of oxygen isotope exchange between water and CO2 varies in soils is key for using the oxygen isotope composition of atmospheric CO2 as a tracer of biosphere CO2 fluxes at large scales. Across 44 diverse soils the rate of this exchange responded to pH, nitrate and microbial biomass, which are hypothesised to alter activity of the enzyme carbonic anhydrase in soils. Using these three soil traits, it is now possible to predict how this isotopic exchange varies spatially. Read more
Interactions between deforestation, landscape rejuvenation, and shallow landslides in the North Tanganyika–Kivu rift region, Africa Earth Surface Dynamics DOI 10.5194/esurf-9-445-2021 12 July 2021 We investigated how shallow landslide occurrence is impacted by deforestation and rifting in the North Tanganyika–Kivu rift region (Africa). We developed a new approach to calculate landslide erosion rates based on an inventory compiled in biased © Google Earth imagery. We find that deforestation increases landslide erosion by a factor of 2–8 and for a period of roughly 15 years. However, the exact impact of deforestation depends on the geomorphic context of the landscape (rejuvenated/relict). Read more
FaIRv2.0.0: a generalized impulse response model for climate uncertainty and future scenario exploration Geoscientific Model Development DOI 10.5194/gmd-14-3007-2021 9 July 2021 This paper presents an update of the FaIR simple climate model, which can estimate the impact of anthropogenic greenhouse gas and aerosol emissions on the global climate. This update aims to significantly increase the structural simplicity of the model, making it more understandable and transparent. This simplicity allows it to be implemented in a wide range of environments, including Excel. We suggest that it could be used widely in academia, corporate research, and education. Read more
VAHCOLI, a new concept for lidars: technical setup, science applications, and first measurements Atmospheric Measurement Techniques DOI 10.5194/amt-14-3815-2021 7 July 2021 We present a new concept for a cluster of lidars that allows us to measure time-resolved profiles of temperatures, winds, and aerosols in the entire middle atmosphere for the first time, also covering regional horizontal scales (“four-dimensional coverage”). Measurements are performed during day and night. The essential component is a newly developed laser with unprecedented performance. We present the first measurements. New observational capabilities in atmospheric physics are established. VAHCOLI, a new concept for lidars: technical setup, science applications, and first measurements">Read more
Comment on “Exceptionally high heat flux needed to sustain the Northeast Greenland Ice Stream” by Smith-Johnsen et al. (2020) The Cryosphere DOI 10.5194/tc-15-2251-2021 5 July 2021 The modelling of Smith-Johnson et al. (The Cryosphere, 14, 841–854, 2020) suggests that a very large heat flux of more than 10 times the usual geothermal heat flux is required to have initiated or to control the huge Northeast Greenland Ice Stream. Our comparison with known hotspots, such as Iceland and Yellowstone, shows that such an exceptional heat flux would be unique in the world and is incompatible with known geological processes that can raise the heat flux. Read more
Deoxygenation dynamics on the western Nile deep-sea fan during sapropel S1 from seasonal to millennial timescales Climate of the Past DOI 10.5194/cp-17-1025-2021 2 July 2021 The Mediterranean Sea turned repeatedly into an oxygen-deprived basin during the geological past, as evidenced by distinct sediment layers called sapropels. We use here records of the last sapropel S1 retrieved in front of the Nile River to explore the relationships between riverine input and seawater oxygenation. We decipher the seasonal cycle of fluvial input and seawater chemistry as well as the decisive influence of primary productivity on deoxygenation at millennial timescales. Read more
