A chemical kinetics theory is proposed to explain the non-monotonic relationship between temperature and biochemical rates. It incorporates the observed thermally reversible enzyme denaturation that is ensured by the ceaseless thermal motion of molecules and ions in an enzyme solution and three well-established theories: (1) law of mass action, (2) diffusion-limited chemical reaction theory, and (3) transition state theory.

Knowledge of ancient ocean N cycling can help illuminate past climate change. Using field and lab studies, this work ground-truths a promising proxy for marine N cycling, the N isotope composition of cold-water coral (CWC) skeletons. Our results estimate N turnover in CWC tissue; quantify the isotope effects between CWC tissue, diet, and skeleton; and suggest that CWCs possibly feed mainly on metazoan zooplankton, suggesting that the marine N proxy may be sensitive to the food web structure.

The Fennoscandian boreal and mountain regions harbour a wide range of ecosystems sensitive to climate change. A new, highly resolved high-emission climate scenario enabled modelling of the vegetation development in this region at high resolution for the 21st century. The results show dramatic south to north and low- to high-altitude shifts of vegetation zones, especially for the open tundra environments, which will have large implications for nature conservation, reindeer husbandry and forestry.

This study investigates whether northeastern North Pacific oxygen changes may be caused by surface density changes in the northwest as water moves along density horizons from the surface into the subsurface ocean. A correlation is found with a lag that about matches the travel time of water from the northwest to the northeast. Salinity is the main driver causing decadal changes in surface density, whereas salinity and temperature contribute about equally to long-term declining density trends.

Arctic marine ecosystems are highly susceptible to impacts of climate change and ocean acidification. We present pH and pCO₂ time series (2016–2020) from the Chukchi Ecosystem Observatory and analyze the drivers of the current conditions to get a better understanding of how climate change and ocean acidification could affect the ecological niches of organisms.

Knowledge of carbon isotope fractionation is important for the assessment of the pathways involved in the degradation of organic matter. Formate is an important intermediate during this process. It was mainly converted to carbon dioxide and acetate both in the presence and absence of sulfate. Methane was only a minor product and was mainly formed from the acetate. The acetate was depleted in the heavy carbon atom relative to formate, while the carbon dioxide was enriched.

Higher evaporation has been predicted in peatlands due to climatic drying. We determined whether the water-conservative vegetation at a Southern Hemisphere bog could cause a different response to dryness compared to a "typical" Northern Hemisphere bog, using decades-long evaporation datasets from each site. At the southern bog, evaporation increased at a much lower rate with increasing dryness, suggesting that this peatland type may be more resilient to climate warming than northern bogs.

The marine CO₂ system can be measured independently and continuously by BGC-Argo floats since numerous pH sensors have been developed to suit these autonomous measurements platforms. By applying the Argo correction routines to float pH data acquired in the subpolar North Atlantic Ocean, we report the uncertainty and lack of objective criteria associated with the choice of the reference method as well the reference depth for the pH correction.

This study uses novel techniques to look at the microstructure of planktonic foraminifera (single-celled marine organisms) fossils, to further our understanding of how they form their hard exterior shells and how the microstructure and chemistry of these shells can change as a result of processes that occur after deposition on the seafloor. Understanding these processes is of critical importance for using planktonic foraminifera for robust climate and environmental reconstructions of the past.

The coastal ocean in the northeastern USA provides many services, including fisheries and habitats for threatened species. In summer 2019, a bloom occurred of a large unusual phytoplankton, the diatom Hemiaulus, with nitrogen-fixing symbionts. This led to vast changes in productivity and grazing rates in the ecosystem. This work shows that the emergence of one species can have profound effects on ecosystem function. Such changes may become more prevalent as the ocean warms due to climate change.

We show that F_yieldLIF was not correlated with SIF_y at the diurnal timescale, and the diurnal patterns in SIF and PAR did not match under clear-sky conditions due to canopy structure. Φ_k was sensitive to canopy structure. RF models show that Φ_k can be predicted using reflectance in different bands. RF models also show that F_yieldLIF was more sensitive to reflectance and radiation than SIF and SIF_y, indicating that the combined effect of reflectance bands could hide the SIF physiological trait.

Soil organic matter stability depends on future temperature and precipitation scenarios. We used radiocarbon (¹⁴C) data and model predictions to understand how the transit time of carbon varies under environmental change in grasslands and peatlands. Soil moisture affected the Δ¹⁴C of peatlands, while temperature did not have any influence. Our models show the correspondence between Δ¹⁴C and transit time and could allow understanding future interactions between terrestrial and atmospheric carbon

Landscapes are often assumed to be homogeneous when using eddy covariance fluxes, which can lead to biases when calculating carbon budgets. In this study we report eddy covariance carbon fluxes from heterogeneous tundra. We used the footprints of each flux observation to unmix the fluxes coming from components of the landscape. We identified and quantified hot spots of carbon emissions in the landscape. Accurately scaling with landscape heterogeneity yielded half as much regional carbon uptake.

Shellfish aquaculture operates in nearshore areas where data on ocean acidification parameters are limited. We show daily and seasonal variability in pH and saturation states of calcium carbonate at nearshore aquaculture sites in British Columbia, Canada, and determine the contributing drivers of this variability. We find that nearshore locations have greater variability than open waters and that the uptake of carbon by phytoplankton is the major driver of pH and saturation state variability.

Late-spring frost (LSF), critically low temperatures when trees have already flushed their leaves, results in freezing damage leaving trees with reduced ability to perform photosynthesis. Forests with a high proportion of susceptible species like European beech are particularly vulnerable. However, this process is rarely included in dynamic vegetation models (DVMs). We show that the effect on simulated productivity and biomass is substantial, warranting more widespread inclusion of LSF in DVMs.

For 8 years we sampled a temperate rainforest and a peatland in Chile to estimate their efficiency to capture carbon per unit of water lost. The efficiency is more related to the water lost than to the carbon captured and is mainly driven by evaporation instead of transpiration. This is the first report from southern South America and highlights that ecosystems might behave differently in this area, likely explained by the high annual precipitation (~ 2100 mm) and light-limited conditions.