Our study presents a time series of methane emissions in a high-Arctic-tundra landscape over 14 summers, which shows large variations between years. The methane emissions from the valley are expected to more than double in the late 21st century. This warming increases permafrost thaw, which could increase surface erosion in the valley. Increased erosion could offset some of the rise in methane fluxes from the valley, but this would require large-scale impacts on vegetated surfaces.

A theoretical model of grey seal seasonal abundance on Sable Island (SI) coupled with chlorophyll-a concentration [chl-a] measured by satellite revealed the impact of seal nitrogen fertilization on the surrounding waters of SI, Canada. The increase in seals from about 100 000 in 2003 to about 360 000 in 2018 during the breeding season is consistent with an increase in [chl-a] leeward of SI. The increase in seal abundance explains 8 % of the [chl-a] increase.

We examined if sea-level rise and plant genotype interact to affect soil microbial functioning in a mesocosm experiment using two genotypes of a dominant salt-marsh grass characterized by differences in flooding sensitivity. Larger variability in microbial community structure, enzyme activity, and litter breakdown in soils with the more sensitive genotype supports our hypothesis that effects of climate change on soil microbial functioning can be controlled by plant intraspecific adaptations.

During summer, maxima of phytoplankton chlorophyll concentration (DCM) occur in the subsurface of the Mediterranean Sea and can play a relevant role in carbon sequestration into the ocean interior. A numerical model based on in situ and satellite observations provides insights into the range of DCM conditions across the relatively small Mediterranean Sea and shows a western DCM that is 25 % shallower and with a higher phytoplankton chlorophyll concentration than in the eastern Mediterranean.

The shallow shelf seas play a large role in the global cycling of CO₂ and also support large fisheries. We use an autonomous underwater vehicle in the central North Sea to measure the rates of change in oxygen and nutrients. Using these data we determine the amount of carbon dioxide taken out of the atmosphere by the sea and measure how productive the region is. These observations will be useful for improving our predictive models and help us predict and adapt to a changing ocean.

Here we present a new modelling framework specifically designed to simulate alluvial peat growth, taking into account the river dynamics. The results indicate that alluvial peat growth is strongly determined by the number, spacing and movement of the river channels in the floodplain, rather than by environmental changes or peat properties. As such, the amount of peat that can develop in a floodplain is strongly determined by the characteristics and dynamics of the local river network.

Dense blooms of cyanobacteria occur every summer in the Baltic Proper and can add to eutrophication by their ability to turn nitrogen gas into dissolved inorganic nitrogen. Being able to correctly estimate the size of this nitrogen fixation is important for management purposes. In this work, we find that the life cycle of cyanobacteria plays an important role in capturing the seasonality of the blooms as well as the size of nitrogen fixation in our ocean model.

Savanna fires play a key role in the global carbon cycle because they release methane. Although it burns the most, there are few studies from West Africa. We conducted 36 experimental fires according to local practice to collect smoke samples. We found that fires set early in the season had higher methane emissions than those set later, and head fires had double the emissions of backfires. We conclude policies to reduce emissions will not have the desired effects if fire type is not considered.

This study incorporated moss into an extant biogeochemistry model to simulate the role of moss in carbon dynamics in the Arctic. The interactions between higher plants and mosses and their competition for energy, water, and nutrients are considered in our study. We found that, compared with the previous model without moss, the new model estimated a much higher carbon accumulation in the region during the last century and this century.

Using a regional model of the northwestern North Atlantic shelves in combination with a surface water time series and repeat transect observations, we investigate surface CO₂ variability on the Scotian Shelf. The study highlights a strong seasonal cycle in shelf-wide pCO₂ and spatial variability throughout the summer months driven by physical events. The simulated net flux of CO₂ on the Scotian Shelf is out of the ocean, deviating from the global air–sea CO₂ flux trend in continental shelves.

Anthropogenic CO₂ is chronically acidifying aquatic ecosystems. We aimed to determine the impact of future freshwater acidification on the physiology and behaviour of an important aquaculture crustacean, Chinese mitten crabs. We report that elevated freshwater CO₂ levels lead to impairment of calcification, locomotor behaviour, and survival and reduced metabolism in this species. Results suggest that present-day calcifying invertebrates could be heavily affected by freshwater acidification.

We investigate the factors controlling the soil organic carbon (SOC) stability and temperature sensitivity of abandoned prehistoric agricultural terrace soils. Results suggest that the burial of former topsoil due to terracing provided an SOC stabilization mechanism. Both the soil C : N ratio and SOC mineral protection regulate soil SOC temperature sensitivity. However, which mechanism predominantly controls SOC temperature sensitivity depends on the age of the buried terrace soils.

Mercury is a problematic metal in the environment. It is crucial to understand the Hg circulation in ecosystems. We explored the mercury concentration in foliage from a diverse set of plants, locations and sampling periods to study the accumulation of Hg in leaves–needles over time. Mercury was always higher in older tissue: in broadleaved trees, conifers and wheat. Specific leaf area, the leaf area per unit leaf mass, turned out to be critical for Hg accumulation in leaves–needles.

We performed model simulations of vegetation change for a historic period and a range of climate change scenarios at a high spatial resolution. Projected treeline advance continued at the same or increased rates compared to our historic simulation. Temperature isotherms advanced faster than treelines, revealing a lag in potential vegetation shifts that was modulated by nitrogen availability. At the year 2100 projected treelines had advanced by 45–195 elevational metres depending on the scenario.

We show that for an unperturbed cold western Antarctic Peninsula fjord, the seasonality of iron and manganese is linked to the dispersal of metal-rich meltwater sources. Geochemical measurements of trace metals in meltwaters, porewaters, and seawater, collected during two expeditions, showed a seasonal cycle of distinct sources. Finally, model results revealed that the dispersal of surface meltwater and meltwater plumes originating from under the glacier is sensitive to katabatic wind events.