The Levantine Basin in the eastern Mediterranean Sea is one of the most nutrient-poor marine regions on Earth. Using a detailed model and observations, we studied how oxygen changes from 2013 to 2020. We found that winter cooling draws oxygen into the sea and moves it to deeper waters, while warmer months release some back. Overall, the basin absorbs more oxygen than it releases, and winter heat loss and circulation patterns strongly control how oxygen is stored and transported.

We developed PeatDepth-ML, a machine learning model predicting peat depth worldwide to help estimate carbon stocks in these climate-critical ecosystems. Our model predicts median depths of 134 cm in peatlands. Using bootstrapping, we rigorously assessed how sampling bias affects predictions. This revealed predictor selection and regional accuracy can vary greatly with different data subsets, demonstrating model reliability fundamentally depends on training data quality and geographic coverage.

Climate change has increased droughts in recent years, damaging forests worldwide. To better understand which forests are most at risk, we analysed data of dead trees across Luxembourg during the 2018-2020 droughts. We found that tree death was strongly linked to nearby dying trees, especially in conifer forests, suggesting the spread of bark beetles, and that taller forests were more vulnerable. These findings can help guide forest management and make forests more resilient to a drier future.

We investigate accumulation rates, stocks, provenance and lability of sedimentary organic carbon in fjords around Stavanger, Norway. We find that all measured parameters show high variability and spatial heterogeneity over short spatial scales. Our results call into question assumptions that are made when upscaling local studies for global assessments. We propose steps to better account for spatial heterogeneity when upscaling to higher levels.

Our research shows that animals such as birds and mammals shaping the bacteria community structure found in Arctic snow. By analyzing snow samples from coastal Spitsbergen, we found that microbes linked to animal waste were common and influenced the types of bacteria present. This suggests that wildlife, not just wind or air, helps bring microbes into snow. Understanding this helps us better predict how Arctic ecosystems respond to environmental change and how life adapts in extreme conditions.

The composition of particulate Fe (pFe) influences the fate of Fe in the upper ocean. Using Fe uptake experiments and living biomass estimates, we show that over half of chemically labile pFe in the surface ocean is stored in living cells. The rest appears to be driven by contributions from dust, detritus, and/or in situ mineral precipitation onto dust particles. The large biotic component here compared to the North Atlantic supports previously reported high biotic Fe recycling at Station ALOHA.

Evidence is growing that bio-optical relationships in the Southern Ocean differ from what they are elsewhere. Uncertainties about these properties are far from been resolved. However, our study adds a new piece to this puzzle by examining the bio-optical properties of the absorption coefficient of colored dissolved organic matter, which is the least documented property in oceanic waters. As for the methodology, this is the first time that Biogeochemical-Argo float data are used to quantify it.

We used a multi-proxy approach combining peat, tree ring, climate, and historical records to reconstruct > 2300 years of peatland dynamics in a Central European region. Results show a human-induced shift from alder to pine forest due to land use change and acidification, stressing the importance of long-term records for peatland conservation.

Our results provide biogeochemical and seafloor habitat context to cold-water corals, contributing to the understanding of potential influence of methane seepage on corals off northern Norway. Furthermore, the produced seafloor orthomosaics and habitat maps will facilitate the monitoring of habitat changes in response to future climate-driven environmental disturbances. 

We developed an approach to quantify how molecules accumulate at the ocean surface on a nanometer scale. By combining laser spectroscopy with an electrochemical technique, we determined how densely these molecular films cover the water surface. Such single-molecule-thick layers can strongly affect gas transfer between the ocean and the atmosphere. Comparing our measurements with existing datasets allowed us to generate an initial global estimate of surfactant surface coverage potential.

We use five different versions of a biogeochemical model to show that how phytoplankton growth processes are represented strongly shapes projections of future ocean productivity and carbon export. Added model complexity does not have a uniform global effect as some new processes mainly influence specific ocean regions, while others, such as an additional small phytoplankton type, lead to large intramodel differences in future trends and latitudinal patterns of productivity and carbon export.

Reef-building corals create their skeletons in two steps: first by adjusting their internal fluid chemistry, then by precipitating the solid mineral. Our results show that calcium and strontium uptake is actively regulated by corals and responds to sea surface temperature, while barium flows in passively. Understanding these patterns explains seasonal variations in coral geochemistry and improves the accuracy of using coral records to reconstruct past climate.

This study examines the spatiotemporal variability of soil CH₄, N₂O and CO₂ fluxes based on measurements across 56 spatial sites in an urban park. Our results show that soils in urban greenspaces function as sources of N₂O and weak sinks of CH₄. We developed random forest models to predict the probability of hot and cold spots of gas fluxes. Our study offers valuable insights into scaling gas fluxes in urban greenspaces, enabling a better assessment of how urbanization affects landscape fluxes.

Carbonyl sulphide (COS) is a trace gas that can be used to estimate plant CO₂ uptake. For this, the ratio of deposition velocities of COS and CO₂ (leaf relative uptake - LRU) is relevant. We use a soil – canopy – atmospheric mixed layer model to simulate COS and CO₂ plant uptake in needleleaf ecosystems, and derive LRU. We find significant in-canopy variability of LRU, and develop a regression model for canopy-scale LRU. The results can contribute to improving COS-based ecosystem plant CO₂ uptake estimates in needleleaf forests.

Element cycles in oxygen-depleted areas such as upwelling areas inform future deoxygenation scenarios. The Benguela upwelling system shows strong decoupling of nitrogen and phosphorus cycling due to seasonal shelf anoxia. Anaerobic processes result in pelagic nitrogen loss as N₂. At the same time, sediments are rich in fish-derived and bacterial phosphorus, with high fluxes of excess phosphate, altering deep-water nitrogen:phosphorus ratios. Such alterations can affect ocean functioning.

Ocean alkalinity enhancement is viewed as a promising option for carbon dioxide removal. When alkalinity is added in the open ocean through mineral powders, carbon uptake from the atmosphere is decreased when mineral particles sink before fully dissolving. Here we prescribe vertical alkalinity release profiles to an Earth system model. We show that carbon uptake may initially decrease by more than 75% when grain size doubles and that full uptake is delayed by centuries and spatially dispersed.