Additional carbon inputs to reach a 4 per 1000 objective in Europe: feasibility and projected impacts of climate change based on Century simulations of long-term arable experiments Biogeosciences DOI 10.5194/bg-18-3981-2021 16 August 2021 Increasing soil organic carbon (SOC) stocks is beneficial for climate change mitigation and food security. One way to enhance SOC stocks is to increase carbon input to the soil. We estimate the amount of carbon input required to reach a 4 % annual increase in SOC stocks in 14 long-term agricultural experiments around Europe. We found that annual carbon input should increase by 43 % under current temperature conditions, by 54 % for a 1 °C warming scenario and by 120 % for a 5 °C warming scenario. Read more
Tropical deoxygenation sites revisited to investigate oxygen and nutrient trends Ocean Science DOI 10.5194/os-17-833-2021 13 August 2021 Six tropical areas in the Pacific, Atlantic and Indian oceans were investigated for trends for the years since 1950 for temperature, salinity, oxygen and nutrients at 50 to 300 m and 300 to 700 m depth. Generally, temperature increases, oxygen decreases and nutrients often increase. Overlain variability on the trends seem to be related to climate modes. Different trends indicate that oxygen and nutrient trends cannot by completely explained by local warming. Read more
Disparities in particulate matter (PM10) origins and oxidative potential at a city scale (Grenoble, France) – Part 2. Atmospheric Chemistry and Physics DOI 10.5194/acp-21-9719-2021 11 August 2021 With an enhanced source apportionment obtained in a companion paper, this paper acquires more understanding of the spatiotemporal associations of the sources of PM to oxidative potential (OP), an emerging health-based metric. Multilayer perceptron neural network analysis was used to apportion OP from PM sources. Results showed that such a methodology is as robust as the linear classical inversion and permits an improvement in the OP prediction when local features or non-linear effects occur. Read more
Continental-scale controls on soil organic carbon across sub-Saharan Africa SOIL DOI 10.5194/soil-7-305-2021 9 August 2021 We investigated various soil and climate properties that influence soil organic carbon (SOC) concentrations in sub-Saharan Africa. Our findings indicate that climate and geochemistry are equally important for explaining SOC variations. The key SOC-controlling factors are broadly similar to those for temperate regions, despite differences in soil development history between the two regions. Read more
Investigations on the anthropogenic reversal of the natural ozone gradient between northern and southern midlatitudes Atmospheric Chemistry and Physics DOI 10.5194/acp-21-9669-2021 6 August 2021 The few ozone measurements made before the 1980s indicate that industrial development increased ozone concentrations by a factor of ~ 2 at northern midlatitudes, which are now larger than at southern midlatitudes. This difference was much smaller, and likely reversed, in the pre-industrial atmosphere. Earth system models find similar increases, but not higher pre-industrial ozone in the south. This disagreement may indicate that modeled natural ozone sources and/or deposition loss are inadequate. Read more
Evaluation of ocean dimethylsulfide concentration and emission in CMIP6 models Biogeosciences DOI 10.5194/bg-18-3823-2021 4 August 2021 In this study we analyse surface ocean dimethylsulfide (DMS) concentration and flux to the atmosphere from four CMIP6 Earth system models over the historical and ssp585 simulations. Our analysis of contemporary (1980–2009) climatologies shows that models better reproduce observations in mid to high latitudes. The models disagree on the sign of the trend of the global DMS flux from 1980 onwards. The models agree on a positive trend of DMS over polar latitudes following sea-ice retreat dynamics. Read more
Committed and projected future changes in global peatlands – continued transient model simulations since the Last Glacial Maximum Biogeosciences DOI 10.5194/bg-18-3657-2021 2 August 2021 We present long-term projections of global peatland area and carbon with a continuous transient history since the Last Glacial Maximum. Our novel results show that large parts of today’s northern peatlands are at risk from past and future climate change, with larger emissions clearly connected to larger risks. The study includes comparisons between different emission and land-use scenarios, driver attribution through factorial simulations, and assessments of uncertainty from climate forcing. Read more
Rarefied particle motions on hillslopes – Part 1: Theory Earth Surface Dynamics DOI 10.5194/esurf-9-539-2021 30 July 2021 Sediment particles skitter down steep hillslopes on Earth and Mars. Particles gain speed in going downhill but are slowed down and sometimes stop due to collisions with the rough surface. The likelihood of stopping depends on the energetics of speeding up (heating) versus slowing down (cooling). Statistical physics predicts that particle travel distances are described by a generalized Pareto distribution whose form varies with the Kirkby number – the ratio of heating to cooling. Read more
SoilGrids 2.0: producing soil information for the globe with quantified spatial uncertainty SOIL DOI 10.5194/soil-7-217-2021 28 July 2021 This paper focuses on the production of global maps of soil properties with quantified spatial uncertainty, as implemented in the SoilGrids version 2.0 product using DSM practices and adapting them for global digital soil mapping with legacy data. The quantitative evaluation showed metrics in line with previous studies. The qualitative evaluation showed that coarse-scale patterns are well reproduced. The spatial uncertainty at global scale highlighted the need for more soil observations. Read more
Mapping the aerodynamic roughness of the Greenland Ice Sheet surface using ICESat-2: evaluation over the K-transect The Cryosphere DOI 10.5194/tc-15-2601-2021 26 July 2021 We developed a method to estimate the aerodynamic properties of the Greenland Ice Sheet surface using either UAV or ICESat-2 elevation data. We show that this new method is able to reproduce the important spatiotemporal variability in surface aerodynamic roughness, measured by the field observations. The new maps of surface roughness can be used in atmospheric models to improve simulations of surface turbulent heat fluxes and therefore surface energy and mass balance over rough ice worldwide. ICESat-2: evaluation over the K-transect">Read more
