Highlight articles

This page features highlight articles from EGU's open access journals Biogeosciences, Geoscientific Model Development and SOIL. These articles of particular interest are selected by journal editors.

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In-depth characterization of diazotroph activity across the western tropical South Pacific hotspot of N₂ fixation (OUTPACE cruise)

Here we report N₂ fixation rates from a ∼ 4000 km transect in the western and central tropical South Pacific, a particularly undersampled region in the world ocean.

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20th century

Oxygen deficiency is a major environmental problem deteriorating seafloor habitats especially in the coastal ocean with large human impact. Here we apply a wide set of chemical and physical analyses to a 1500-year long sediment record and show that, although long-term climate variability has modulated seafloor oxygenation in the coastal northern Baltic Sea, the oxygen loss over the 20th century is unprecedentedly severe, emphasizing the need to reduce anthropogenic nutrient input in the future.

Transfer of diazotroph-derived nitrogen to the planktonic food web across gradients of N₂ fixation activity and diversity in the western tropical South Pacific Ocean

Biological dinitrogen (N₂) fixation provides the major source of new nitrogen (N) to the open ocean, contributing more than atmospheric deposition and riverine inputs to the N supply. Yet the fate of the diazotroph-derived N (DDN) in the planktonic food web is poorly understood. The main goals of this study were (i) to quantify how much of DDN is released to the dissolved pool during N₂ fixation and how much is transferred to bacteria, phytoplankton and zooplankton, and (ii) to compare the DDN release and transfer efficiencies under contrasting N₂ fixation activity and diversity in the oligotrophic waters of the western tropical South Pacific Ocean.

Reviews and syntheses: Carbonyl sulfide as a multi-scale tracer for carbon and water cycles

Measurements of the trace gas carbonyl sulfide (OCS) are helpful in quantifying photosynthesis at previously unknowable temporal and spatial scales. While CO₂ is both consumed and produced within ecosystems, OCS is mostly produced in the oceans or from specific industries, and destroyed in plant leaves in proportion to CO₂. This review summarizes the advancements we have made in the understanding of OCS exchange and applications to vital ecosystem water and carbon cycle questions.

Field-warmed soil carbon changes imply high 21st-century modeling uncertainty

The temperature sensitivity of soil carbon loss is a critical parameter for projecting future CO₂. Isolating soil temperature response in the field is challenging due to difficulties isolating root and microbial respiration. We use a database of direct-warming soil carbon changes to generate a new global temperature sensitivity. Incorporating this into Earth system models reduces projected soil carbon. But it also shows that variation due to this parameter is as high as all other causes.

Crossing the chasm: how to develop weather and climate models for next generation computers?

Weather and climate models consist of complex software evolving in response to both scientific requirements and changing computing hardware. After years of relatively stable hardware, more diversity is arriving. It is possible that this hardware diversity and the pace of change may lead to an inability for modelling groups to manage their software development. This “chasm” between aspiration and reality may need to be bridged by large community efforts rather than traditional “in-house” efforts.

Mercury distribution and transport in the North Atlantic Ocean along the Geotraces-GA01 transect

We first report the mercury distribution in the water section across the subpolar and subtropical gyres of the North Atlantic Ocean (GEOTRACES-GA01 transect). It allows the characterisation of various seawater types in terms of mercury content and the quantification of mercury transport associated with the Atlantic Meridional Overturning Circulation. It shows the nutrient-like biogeochemical behaviour of mercury in this ocean.

Interannual drivers of the seasonal cycle of CO₂ in the Southern Ocean

The Southern Ocean accounts for a large portion of the variability in oceanic CO₂ uptake. However, the drivers of these changes are not understood due to a lack of observations. In this study, we used an ensemble of gap-filling methods to estimate surface CO₂. We found that winter was a more important driver of longer-term variability driven by changes in wind stress. Summer variability of CO₂ was driven primarily by increases in primary production.

A protocol for the intercomparison of marine fishery and ecosystem models: Fish-MIP v1.0

Model intercomparison studies in the climate and Earth sciences communities have been crucial for strengthening future projections. Given the speed and magnitude of anthropogenic change in the marine environment, the time is ripe for similar comparisons among models of fisheries and marine ecosystems. We describe the Fisheries and Marine Ecosystem Model Intercomparison Project, which brings together the marine ecosystem modelling community to inform long-term projections of marine ecosystems.

Intercomparison of Antarctic ice-shelf, ocean, and sea-ice interactions simulated by MetROMS-iceshelf and FESOM 1.4

MetROMS and FESOM are two ocean/sea-ice models which resolve Antarctic ice-shelf cavities and consider thermodynamics at the ice-shelf base. We simulate the period 1992–2016 with both models, and with two options for resolution in FESOM, and compare output from the three simulations. Ice-shelf melt rates, sub-ice-shelf circulation, continental shelf water masses, and sea-ice processes are compared and evaluated against available observations.

BG Biogeosciences Highlight articles