To improve the accuracy of spatial carbon exchange estimates, we evaluated simple linear models for net ecosystem exchange (NEE) and gross primary productivity (GPP) and how they can be used to upscale the CO₂ exchange of agricultural fields. The models are solely driven by Sentinel-2-derived vegetation indices (VIs). Evaluations show that different VIs have variable power to estimate NEE and GPP of crops in different years. The overall performance is as good as results from complex crop models.

The European Arctic is experiencing rapid regional warming, causing glaciers that terminate in the sea to retreat onto land. Due to this process, the area of a well-studied fjord, Hornsund, has increased by around 100 km² (40%) since 1976. Combining satellite and in situ data with a mathematical model, we estimated that, despite some negative consequences of glacial meltwater release, such emerging coastal waters could mitigate climate change by increasing carbon uptake and storage by sediments.

Greenhouse gases are produced and consumed via a number of pathways. Quantifying these pathways helps reduce the climate and environmental footprint of anthropogenic activities. The contribution of the pathways can be estimated from the isotopic composition, which acts as a fingerprint for these pathways. We have developed the Time-resolved FRactionation And Mixing Evaluation (TimeFRAME) model to simplify interpretation and estimate the contribution of different pathways and their uncertainty.

Ocean alkalinity enhancement (OAE) is an emerging marine CO₂ removal method, but its environmental effects are insufficiently understood. The OAE Pelagic Impact Intercomparison Project (OAEPIIP) provides funding for a standardized and globally replicated microcosm experiment to study the effects of OAE on plankton communities. Here, we provide a detailed manual for the OAEPIIP experiment. We expect OAEPIIP to help build scientific consensus on the effects of OAE on plankton.

The addition of alkaline minerals into the ocean might reduce excessive anthropogenic CO₂ emissions. Magnesium hydroxide can be added in large amounts because of its low seawater solubility without reaching harmful pH levels. The toxicity effect results of magnesium hydroxide, by simulating the expected concentrations from a ship's dispersion scenario, demonstrated low impacts on both sensitive and local assemblages of marine microalgae when compared to calcium hydroxide.

We used the DayCent model to assess the potential impact of integrated soil fertility management (ISFM) on maize production, soil fertility, and greenhouse gas emission in Kenya. After adjustments, DayCent represented measured mean yields and soil carbon stock changes well and N₂O emissions acceptably. Our results showed that soil fertility losses could be reduced but not completely eliminated with ISFM and that, while N₂O emissions increased with ISFM, emissions per kilogram yield decreased.

High frequency pCO₂ measurements reveal net neutral CO₂ flux in a mesohaline reach of the Chesapeake Bay. Net off-gassing to the atmosphere begins in June when water temperatures rise above ~26ºC, continuing through November when temperatures fall below ~10ºC. Dissolved CO₂ concentrations follow day–night cycles and are especially pronounced in warm waters. From December through May, the river is largely an uninterrupted sink for CO₂ (i.e. CO₂ is drawn out of the atmosphere into the river).

Ecosystem carbonyl sulfide (COS) fluxes were employed to optimize GPP estimation across ecosystems with the Biosphere-atmosphere Exchange Process Simulator (BEPS), which was developed for simulating the canopy COS uptake under its state-of-the-art two-leaf modeling framework. Our results showcased the efficacy of COS in improving model prediction and reducing prediction uncertainty of GPP and enhanced insights into the sensitivity, identifiability, and interactions of parameters related to COS.

During cold seasons, methane release from northern wetlands is important but often underestimated. We studied a boreal bog to understand methane emissions in spring and fall. At cold temperatures, methane release decreases due to lower production rates, but efficient methane transport through plant structures, decaying plants, and the release of methane stored in the pore water keep emissions ongoing. Understanding these seasonal processes can improve models for methane release in cold climates.

We used a soil model to replicate two litterbag decomposition experiments to examine the implications of climate, litter quality, and soil microclimate representation. We found that macroclimate was more important than litter quality for modeled mass loss. By comparing different representations of soil temperature and moisture we found that using observed data did not improve model results. We discuss causes for this and suggest possible improvements to both the model and experimental design.

Methane (CH₄) is an important greenhouse gas and contributes to climate warming. However, the input of CH₄ from coastal areas to the atmosphere is not well defined. Dissolved and atmospheric CH₄ was determined at high spatial resolution in or above the North Sea. The atmospheric CH₄ concentration was mainly influenced by wind direction. With our detailed study on the spatial distribution of CH₄ fluxes we were able to provide a detailed and more realistic estimation of coastal CH₄ fluxes.

We calculate the amount of anthropogenic carbon (C_ant) in the Atlantic for the years 1990, 2000, 2010 and 2020. C_ant is the carbon that is taken up by the ocean as a result of humanmade CO₂ emissions. To determine the amount of C_ant, we apply a technique that is based on the observations of other humanmade gases (e.g., chlorofluorocarbons). Regionally, changes in ocean ventilation have an impact on the storage of C_ant. Overall, the increase in C_ant is driven by the rising CO₂ in the atmosphere.

Seven million years ago, the marine gateway connecting the Mediterranean Sea with the Atlantic Ocean started to close, and, as a result, water circulation ceased. To find out how this phenomenon affected the fish living in the Mediterranean Sea, we examined the changes in the isotopic composition of otoliths of two common fish species. Although the species living at the surface fared pretty well, the bottom-water fish starved and eventually became extinct in the Mediterranean.