Predicting soil moisture conditions across a heterogeneous boreal catchment using terrain indices Hydrology and Earth System Sciences DOI 10.5194/hess-26-4837-2022 19 December 2022 Terrain indices constitute a good candidate for modelling the spatial variation of soil moisture conditions in many landscapes. In this study, we evaluate nine terrain indices on varying DEM resolution and user-defined thresholds with validation using an extensive field soil moisture class inventory. We demonstrate the importance of field validation for selecting the appropriate DEM resolution and user-defined thresholds and that failing to do so can result in ambiguous and incorrect results. Read more
GC Insights: Diversifying the geosciences in higher education: a manifesto for change Geoscience Communication DOI 10.5194/gc-5-275-2022 16 December 2022 In this manifesto, we offer six points of reflection that higher education geoscience educators can act upon to recognise and unlearn their biases and diversify the geosciences in higher education, complementing current calls for institutional and organisational change. This serves as a starting point to gather momentum to establish community-built opportunities for implementing and strengthening diversity, equity, inclusion, and justice holistically in geoscience education. Read more
Cloud adjustments from large-scale smoke–circulation interactions strongly modulate the southeastern Atlantic stratocumulus-to-cumulus transition Atmospheric Chemistry and Physics DOI 10.5194/acp-22-12113-2022 14 December 2022 Smoke from southern Africa blankets the southeast Atlantic from June-October, overlying a major transition region between overcast and scattered clouds. The smoke affects Earth’s radiation budget by absorbing sunlight and changing cloud properties. We investigate these effects in regional climate and large eddy simulation models based on international field campaigns. We find that large-scale circulation changes more strongly affect cloud transitions than smoke microphysical effects in our case. Read more
Progress and challenges in glacial lake outburst flood research (2017–2021): a research community perspective Natural Hazards and Earth System Sciences DOI 10.5194/nhess-22-3041-2022 12 December 2022 Glacial lake outburst floods (GLOFs) have attracted increased research attention recently. In this work, we review GLOF research papers published between 2017 and 2021 and complement the analysis with research community insights gained from the 2021 GLOF conference we organized. The transdisciplinary character of the conference together with broad geographical coverage allowed us to identify progress, trends and challenges in GLOF research and outline future research needs and directions. Read more
Observation-constrained estimates of the global ocean carbon sink from Earth system models Biogeosciences DOI 10.5194/bg-19-4431-2022 9 December 2022 Estimates of the ocean sink of anthropogenic carbon vary across various approaches. We show that the global ocean carbon sink can be estimated by three parameters, two of which approximate the ocean ventilation in the Southern Ocean and the North Atlantic, and one of which approximates the chemical capacity of the ocean to take up carbon. With observations of these parameters, we estimate that the global ocean carbon sink is 10% larger than previously assumed, and we cut uncertainties in half. Read more
Hydrography, circulation, and response to atmospheric forcing in the vicinity of the central Getz Ice Shelf, Amundsen Sea, Antarctica Ocean Science DOI 10.5194/os-18-1339-2022 7 December 2022 Ice shelves in the Amundsen Sea are thinning rapidly as ocean currents bring warm water into cavities beneath the floating ice. We use 2-year-long mooring records and 16-year-long model simulations to describe the hydrography and circulation near the ice front between Siple and Carney Islands. We find that temperatures here are lower than at neighbouring ice fronts and that the transport of heat toward the cavity is governed by wind stress over the Amundsen Sea continental shelf. Read more
Shallow marine carbonates as recorders of orbitally induced past climate changes – example from the Oxfordian of the Swiss Jura Mountains Climate of the Past DOI 10.5194/cp-18-2117-2022 5 December 2022 Some 155 million years ago, sediments were deposited in a shallow subtropical sea. Coral reefs formed in a warm and arid climate during high sea level, and clays were washed into the ocean at low sea level and when it rained. Climate and sea level changes were induced by cyclical insolation changes. Analysing the sedimentary record, it appears that sea level rise today (as a result of global warming) is more than 10 times faster than the fastest rise reconstructed from the geologic past. Read more
Contrasting drought legacy effects on gross primary productivity in a mixed versus pure beech forest Biogeosciences DOI 10.5194/bg-19-4315-2022 2 December 2022 Identifying drought legacy effects is challenging because they are superimposed on variability driven by climate conditions in the recovery period. We develop a residual-based approach to quantify legacies on gross primary productivity (GPP) from eddy covariance data. The GPP reduction due to legacy effects is comparable to the concurrent effects at two sites in Germany, which reveals the importance of legacy effects. Our novel methodology can be used to quantify drought legacies elsewhere. Read more
Recession or resilience? Long-range socioeconomic consequences of the 17th century volcanic eruptions in northern Fennoscandia Climate of the Past DOI 10.5194/cp-18-2077-2022 30 November 2022 Tree-ring data and written sources from northern Fennoscandia reveal that large 17th century eruptions had considerable climatic, agricultural, and socioeconomic impacts far away from the eruption locations. Yet, micro-regional investigation shows that the human consequences were commonly indirect, as various factors, like agro-ecosystems, resource availability, institutions, and personal networks, dictated how the volcanic cold pulses and related crop failures materialized on a societal level. Read more
HORAYZON v1.2: an efficient and flexible ray-tracing algorithm to compute horizon and sky view factor Geoscientific Model Development DOI 10.5194/gmd-15-6817-2022 28 November 2022 Terrain horizon and sky view factor are crucial quantities for many geoscientific applications; e.g. they are used to account for effects of terrain on surface radiation in climate and land surface models. Because typical terrain horizon algorithms are inefficient for high-resolution (< 30 m) elevation data, we developed a new algorithm based on a ray-tracing library. A comparison with two conventional methods revealed both its high performance and its accuracy for complex terrain. Read more
Reliability of flood marks and practical relevance for flood hazard assessment in southwestern Germany Natural Hazards and Earth System Sciences DOI 10.5194/nhess-22-2963-2022 25 November 2022 Encouraging a systematic use of flood marks for more comprehensive flood risk management, we collected a large number of marks along the Kinzig, southwestern Germany, and tested them for plausibility and temporal continuance. Despite uncertainty, the marks appeared to be an overall consistent and practical source that may also increase flood risk awareness. A wide agreement between the current flood hazard maps and the collected flood marks moreover indicated a robust local hazard assessment. Read more
South American Summer Monsoon variability over the last millennium in paleoclimate records and isotope-enabled climate models Climate of the Past DOI 10.5194/cp-18-2045-2022 23 November 2022 We evaluated the South American Summer Monsoon over the last millennium and dynamically interpreted the principal modes of variability. We find the spatial patterns of the monsoon are an intrinsic feature of the climate modulated by external forcings. Multi-centennial mean state departures during the Medieval Climate Anomaly and Little Ice Age show regionally coherent patterns of hydroclimatic change in both a multi-archive network of oxygen isotope records and isotope-enabled climate models. Read more
Ice core evidence for major volcanic eruptions at the onset of Dansgaard–Oeschger warming events Climate of the Past DOI 10.5194/cp-18-2021-2022 21 November 2022 Major volcanic eruptions are known to cause considerable short-term impacts on the global climate. Their influence on long-term climate variability and regime shifts is less well-understood. Here we show that very large, bipolar eruptions occurred more frequently than expected by chance just before abrupt climate change events in the last glacial period (Dansgaard–Oeschger events). Thus, such large eruptions may in some cases act as short-term triggers for abrupt regime shifts of the climate. Read more
Comprehensive space–time hydrometeorological simulations for estimating very rare floods at multiple sites in a large river basin Natural Hazards and Earth System Sciences DOI 10.5194/nhess-22-2891-2022 18 November 2022 Estimating the magnitude of rare to very rare floods is a challenging task due to a lack of sufficiently long observations. The challenge is even greater in large river basins, where precipitation patterns and amounts differ considerably between individual events and floods from different parts of the basin coincide. We show that a hydrometeorological model chain can provide plausible estimates in this setting and can thus inform flood risk and safety assessments for critical infrastructure. Read more
Bayesian assessment of chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC) and halon banks suggest large reservoirs still present in old equipment Atmospheric Chemistry and Physics DOI 10.5194/acp-22-11125-2022 16 November 2022 Halocarbons contained in equipment continue to be emitted after production has ceased. These “banks” must be carefully accounted for in evaluating compliance with the Montreal Protocol. We extend a Bayesian model to the suite of regulated chemicals subject to banking. We find that banks are substantially larger than previous estimates, and we identify banks by chemical and equipment type whose future emissions will contribute to global warming and delay ozone-hole recovery if left unrecovered. Read more
The impact of climate oscillations on the surface energy budget over the Greenland Ice Sheet in a changing climate The Cryosphere DOI 10.5194/tc-16-3375-2022 14 November 2022 To overcome internal climate variability, this study uses k-means clustering to combine NAO, GBI and IWV over the Greenland Ice Sheet (GrIS) and names the approach as the North Atlantic influence on Greenland (NAG). With the support of a polar-adapted RCM, spatio-temporal changes on SEB components within NAG phases are investigated. We report atmospheric warming and moistening across all NAG phases as well as large-scale and regional-scale contributions to GrIS mass loss and their interactions. Read more
Invited perspectives: Views of 350 natural hazard community members on key challenges in natural hazards research and the Sustainable Development Goals Natural Hazards and Earth System Sciences DOI 10.5194/nhess-22-2771-2022 11 November 2022 Here we present survey responses of 350 natural hazard community members to key challenges in natural hazards research and step changes to achieve the Sustainable Development Goals. Challenges identified range from technical (e.g. model development, early warning) to governance (e.g. co-production with community members). Step changes needed are equally broad; however, the majority of answers showed a need for wider stakeholder engagement, increased risk management and interdisciplinary work. Read more
Effects of orbital forcing, greenhouse gases and ice sheets on Saharan greening in past and future multi-millennia Climate of the Past DOI 10.5194/cp-18-1897-2022 9 November 2022 Using an Earth system model of intermediate complexity, we quantify contributions of the Earth’s orbit, greenhouse gases (GHGs) and ice sheets to the strength of Saharan greening during late Quaternary African humid periods (AHPs). Orbital forcing is found as the dominant factor, having a critical threshold and accounting for most of the changes in the vegetation response. However, results suggest that GHGs may influence the orbital threshold and thus may play a pivotal role for future AHPs. Read more
TermPicks: a century of Greenland glacier terminus data for use in scientific and machine learning applications The Cryosphere DOI 10.5194/tc-16-3215-2022 7 November 2022 Terminus traces have been used to understand how Greenland’s glaciers have changed over time; however, manual digitization is time-intensive, and a lack of coordination leads to duplication of efforts. We have compiled a dataset of over 39 000 terminus traces for 278 glaciers for scientific and machine learning applications. We also provide an overview of an updated version of the Google Earth Engine Digitization Tool (GEEDiT), which has been developed specifically for the Greenland Ice Sheet. Read more
Bedrock depth influences spatial patterns of summer baseflow, temperature and flow disconnection for mountainous headwater streams Hydrology and Earth System Sciences DOI 10.5194/hess-26-3989-2022 4 November 2022 The geologic structure of mountain watersheds may control how groundwater and streamwater exchange, influencing where streams dry. We measured bedrock depth at 191 locations along eight headwater streams paired with stream temperature records, baseflow separation and observations of channel dewatering. The data indicated a prevalence of shallow bedrock generally less than 3 m depth, and local variation in that depth can drive stream dewatering but also influence stream baseflow supply. Read more