The representation of light propagation in seawater is critical for modelling marine biogeochemistry. We analyse results from a radiative transfer model that accounts for the absorption and scattering of light in the ocean with their respective uncertainties. We compare these results with in situ and remote-sensed data. Our analysis highlights the benefits of accounting for model uncertainties while using advanced representations of light in modelling frameworks.

Nitrate is a crucial nutrient in oceans, whose excess can trigger uncontrolled algae growth that damages marine ecosystems. We used machine learning to generate skilled, gap-free, bi-decadal surface nitrate data from sparse observations, revealing areas on the North-West European Shelf that are more vulnerable to excess algae growth if nutrient pollution occurs. We also looked at bi-decadal trends in coastal nitrate and the impact of winter nitrate on spring phytoplankton blooms.

To investigate if greenhouse gases (GHG) emissions from ponds vary among clear-water ponds with macrophytes and turbid-water ponds with phytoplankton, we measured CO₂, CH₄, and N₂O concentrations and emissions in two clear- and two turbid-water urban ponds in the city of Brussels from June 2021 to December 2023. Differences in  CH₄ ebullitive emissions were observed between clear- and turbid-water ponds but none for CO₂ and N₂O emissions.

Treeline ecotones are exposed to pronounced differences in irradiation and nutrient availability in complex mountain relief. We compared growth phenology and growth rate of Picea abies on north- and south-facing slopes at sites differing in nutrient availability at the lower part of the treeline ecotone. Our results suggest that temperature alone governs growth phenology, but nutrient availability modulates the growth rate in the peak season when temperature no longer limits cambial activity.

Climate warming speeds up lake eutrophication, creating “dead zones” where aquatic life suffocates due to oxygen depletion. The sediments of Amsoldingersee, a Swiss lake, revealed how climate shifts impacted the lake around 10 000–18 000 years ago. (1) Algal composition differed between both cold and warm periods. (2) Nutrient additions from dust controlled algal growth more than temperature. (3) Cold periods with ice cover led to oxygen depletion. (4) Algal communities recovered after anoxic phases.