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Tidal salt marsh soil emits greenhouse gases, as well as sulfur-based gases, which play roles in global climate but are not well studied as they are difficult to measure. Traditional methods of measuring these gases worked relatively well for carbon dioxide, but less so for methane, nitrous oxide, carbon disulfide, and dimethylsulfide. High variability of trace gases complicates the ability to accurately calculate gas budgets and new approaches are needed for monitoring protocols.

The unique microbial eukaryotic community structure and lower diversity have been demonstrated in five freshwater lakes of the Fildes Peninsula, Antarctica. Stochastic processes and biotic co-occurrence patterns were shown to be important in shaping microbial eukaryotic communities in the area. Our study provides a better understanding of the dynamic patterns and ecological assembly processes of microbial eukaryotic communities in Antarctic oligotrophic lakes (Fildes Peninsula).

Seagrasses are marine plants with the capacity to act as carbon sinks due to their high primary productivity, using carbon for growth. This capacity can play a key role in climate change mitigation. We compiled and published data showing that two Mediterranean seagrass species have different metabolic rates, while the study method influences the rates of the measurements. Most communities act as carbon sinks, while the western basin might be more productive than the eastern Mediterranean.

We adopt a high-resolution carbon model for the Gulf of Mexico (GoM) and calculate the decadal trends of important carbon system variables in the GoM from 2001 to 2019. The GoM surface CO₂ values experienced a steady increase over the past 2 decades, and the ocean surface pH is declining. Although carbonate saturation rates remain supersaturated with aragonite, they show a slightly decreasing trend. The northern GoM is a stronger carbon sink than we thought.

Pools are common features of peatlands. We documented dissolved organic matter (DOM) composition in pools and peat of an ombrotrophic boreal peatland to understand its origin and potential role in the peatland carbon budget. The survey reveals that DOM composition differs between pools and peat, although it is derived from the peat vegetation. We investigated which processes are involved and estimated that the contribution of carbon emissions from DOM processing in pools could be substantial.

Bacteriophages comprise one of the factors that may influence mineralization processes. The number of bacteriophages in the environment usually exceeds the number of bacteria by an order of magnitude. One of the more interesting processes is the formation of framboidal pyrite, and it is not entirely clear what processes determine its formation. Our studies indicate that some bacterial viruses may influence the formation of framboid-like or spherical structures.

The greenhouse gas methane (CH₄) drives climate change. Microorganisms in river sediments produce CH₄ when degrading organic matter, but the contribution of rivers to atmospheric CH₄ concentrations is uncertain. To better understand riverine CH₄ cycling, we measured concentration profiles of CH₄ and relevant reactants that might influence the CH₄ cycle. We found substantial CH₄ production, especially in fine, organic-rich sediments during summer and signs of microbial CH₄ consumption.

Investigating the effect of the presence of plateau pikas on ecosystem services of alpine meadows is helpful to understand the role of the presence of small mammalian herbivores in grasslands. The results of this study showed that the presence of plateau pikas led to higher biodiversity conservation, soil nitrogen and phosphorus maintenance, and carbon sequestration of alpine meadows, whereas it led to lower forage available to livestock and water conservation of alpine meadows.

Coastal hypoxia is a major environmental problem of increasing severity. The 21st-century projections analyzed indicate global coastal waters will warm and experience rapid declines in oxygen. The forecasted median coastal trends for increasing sea surface temperature and decreasing oxygen capacity are 48 % and 18 % faster than the rates observed over the last 4 decades. Existing hypoxic areas are expected to worsen, and new hypoxic areas likely will emerge under these warming-related pressures.

This study provides new equations that can be used to estimate aboveground tree biomass in larch-dominated forests of northeast Siberia. Applying these equations to 53 forest stands in the Republic of Sakha (Russia) resulted in significantly larger biomass stocks than when using existing equations. The data presented in this work can help refine biomass estimates in Siberian boreal forests. This is essential to assess changes in boreal vegetation and carbon dynamics.

We demonstrate the TEX86 (TetraEther indeX of 86 carbon atoms) paleoclimate proxy can become heavily impacted by the ocean floor archaeal community. The impact results from source inputs, their diagenetic and catagenetic alteration, and further overprint by the additions of lipids from the ocean floor sedimentary archaeal community. We then present a method to correct the overprints by using IPLs (intact polar lipids) extracted from both water column and subsurface archaeal communities.

Estimates of the ocean sink of anthropogenic carbon vary across various approaches. We show that the global ocean carbon sink can be estimated by three parameters, two of which approximate the ocean ventilation in the Southern Ocean and the North Atlantic, and one of which approximates the chemical capacity of the ocean to take up carbon. With observations of these parameters, we estimate that the global ocean carbon sink is 10 % larger than previously assumed, and we cut uncertainties in half.

The functioning of ecosystems involves numerous biophysical processes which interact with each other. Land surface models (LSMs) are used to describe these processes and form an essential component of climate models. In this paper, we evaluate the performance of three LSMs and their interactions with soil moisture and vegetation. Though we found room for improvement in the simulation of soil moisture and drought stress, the main cause of errors was related to the simulated growth of vegetation.

Increasing atmospheric carbon dioxide (CO₂) causes leaves to close their stomata (through which water evaporates) but also promotes leaf growth. Even if individual leaves save water, how much will be consumed by a whole plant with possibly more leaves? Using different mathematical models, we show that plant stands that are not very dense and can grow more leaves will benefit from higher CO₂ by photosynthesizing more while adjusting their stomata to consume similar amounts of water.

The study uses the stable isotope ¹³C of carbon in methane to investigate the origins of spatial and temporal variation in methane emitted by a temperate wetland ecosystem. The results indicate that methane production is more important for spatial variation than methane consumption by micro-organisms. Temporal variation on a seasonal timescale is most likely affected by more than one driver simultaneously.

The dramatical increase in SO₄^2- concentration up to 100 mg L^-1 in eutrophic lakes has aroused great attention. It enhanced the sulfate reduction to release a large amount of ΣS^2- during cyanobacteria decomposition. The Fe²⁺ released from the iron reduction process is captured by ΣS^2-, and finally the combination of iron and P was reduced, promoting the release of endogenous P. Therefore, increasing sulfate concentrations are shown to be a hidden promoter of eutrophication in shallow lakes.

Spruce and larch trees are effective archiving species for historical atmospheric mercury using growth rings of bole wood. Mercury stable isotope analysis proved an effective tool to characterise industrial mercury signals and assess mercury uptake pathways (leaf uptake for both wood and bark) and mercury cycling within the trees. These data detail important information for understanding the mercury biogeochemical cycle particularly in forest systems.

Identifying drought legacy effects is challenging because they are superimposed on variability driven by climate conditions in the recovery period. We develop a residual-based approach to quantify legacies on gross primary productivity (GPP) from eddy covariance data. The GPP reduction due to legacy effects is comparable to the concurrent effects at two sites in Germany, which reveals the importance of legacy effects. Our novel methodology can be used to quantify drought legacies elsewhere.

The impact of anthropogenic climate change on the biological production of phytoplankton in the ocean is a cause for concern because its evolution could affect the response of marine ecosystems to climate change. Here, we identify biological N fixation and its response to future climate change as a key process in shaping the future evolution of marine phytoplankton production. Our results show that further study of how this nitrogen fixation responds to environmental change is essential.

Soils account for the largest share of carbon found in terrestrial ecosystems, and accurate depiction of soil carbon decomposition is essential in understanding how permanent these carbon storages are. We present a straightforward way to include carbon isotope concentrations into soil decomposition and carbon storages for the Yasso model, which enables the model to use ¹³C as a natural tracer to track changes in the underlying soil organic matter decomposition.

This study explores the seasonal, inter-annual, and multi-year drivers of the South Atlantic air–sea CO₂ flux. Our analysis showed seasonal sea surface temperatures dominate in the subtropics, and the subpolar regions correlated with biological processes. Inter-annually, the El Niño–Southern Oscillation correlated with the CO₂ flux by modifying sea surface temperatures and biological activity. Long-term trends indicated an important biological contribution to changes in the air–sea CO₂ flux.

Inland waters play an important role in the global carbon cycle by storing, transforming and transporting carbon from land to sea. Comparatively little is known about carbon dynamics at the river–estuarine transition. A study of tributaries of Chesapeake Bay showed that biological processes exerted a strong effect on carbon transformations. Peak carbon retention occurred during periods of elevated river discharge and was associated with trapping of particulate matter.

Tree canopies are strong moderators of understory climatic conditions. In tropical areas, trees cool down the microclimates. Using remote sensing and field measurements we show how even intermediate canopy cover and agroforestry trees contributed to buffering the hottest temperatures in Kenya. The cooling effect was the greatest during hot days and in lowland areas, where the ambient temperatures were high. Adopting agroforestry practices in the area could assist in mitigating climate change.

To remain within the Paris climate agreement, there is an increasing need to develop and implement carbon capture and sequestration techniques. The global climate benefits of implementing negative emission technologies over the next century are assessed using an Earth system model covering a wide range of plausible climate states. In some model realisations, there is continued warming after emissions cease. This continued warming is avoided if negative emissions are incorporated.

Excess radiation and low temperatures exacerbate drought impacts on canopy conductance (G_s) among transects. The primary determinant of drought stress on G_s was soil moisture on the Loess Plateau (LP) and the Mongolian Plateau (MP), whereas it was the vapor pressure deficit on the Tibetan Plateau (TP). Radiation exhibited a negative effect on G_s via drought stress within transects, while temperature had negative effects on stomatal conductance on the TP but no effect on the LP and MP.

Based on observing system simulation experiments using a mesoscale-resolving model, we found that to significantly improve uncertainties and biases in carbon dioxide (CO₂) mapping in the Southern Ocean, it is essential to resolve the seasonal cycle (SC) of the meridional gradient of CO₂ through high frequency (at least daily) observations that also span the region's meridional axis. We also showed that the estimated SC anomaly and mean annual CO₂ are highly sensitive to seasonal sampling biases.

This study shows that livestock grazing and grass cutting can determine whether a grassland is adding (source) or removing (sink) carbon (C) to/from the atmosphere. The annual C balance of 1855 managed grassland fields in Great Britain was quantified for 2017–2018 using process modelling and earth observation data. The examined fields were, on average, small C sinks, but the summer drought of 2018 led to a 9-fold increase in the number of fields that became C sources in 2018 compared to 2017.

Understanding how plants decompose is important for understanding where the atmospheric CO₂ they absorb ends up after they die. In forests, decomposition is controlled by rain but not in deserts. We performed a 2.5-year study in one of the driest places on earth (the Namib desert in southern Africa) and found that fog and dew, not rainfall, closely controlled how quickly plants decompose. We also created a model to help predict decomposition in drylands with lots of fog and/or dew.

The distinct carbon isotopic values of C₃ and C₄ plants are widely used to reconstruct past hydroclimate, where more C₃ plants reflect wetter and C₄ plants drier conditions. Here we examine the impact of regional hydroclimatic conditions on plant isotopic values in the Godavari River basin, India. We find that it is crucial to identify regional plant isotopic values and consider drought stress, which introduces a bias in C₃ / C₄ plant estimates and associated hydroclimate reconstructions.

Quantifying the feedback from the decomposition of thawing permafrost soils is crucial to establish adequate climate warming mitigation scenarios. Past efforts have focused on abiotic and to some extent microbial drivers of decomposition but not biotic drivers such as soil fauna. We added soil fauna (Collembola Folsomia candida) to permafrost, which introduced bacterial taxa without affecting bacterial communities as a whole but increased CO₂ production (+12 %), presumably due to priming.

Future projections under the RCP8.5 and RCP4.5 emission scenarios of the Mediterranean Sea biogeochemistry at the end of the 21st century show different levels of decline in nutrients, oxygen and biomasses and an acidification of the water column. The signal intensity is stronger under RCP8.5 and in the eastern Mediterranean. Under RCP4.5, after the second half of the 21st century, biogeochemical variables show a recovery of the values observed at the beginning of the investigated period.

We reply to Lars Björn's critique of our article concerning the importance of photon dissipation to the origin and evolution of the biosphere. Björn doubts our assertion that organic pigments, ecosystems, and the biosphere arose out of a non-equilibrium thermodynamic imperative to increase global photon dissipation. He shows that the albedo of some non-living material is less than that of living material. We point out, however, that photon dissipation involves other factors besides albedo.

Four different methods for quantifying photosynthesis (GPP) at ecosystem scale were tested, of which two are based on carbon dioxide (CO₂) and two on carbonyl sulfide (COS) flux measurements. CO₂-based methods are traditional partitioning, and a new method uses machine learning. We introduce a novel method for calculating GPP from COS fluxes, with potentially better applicability than the former methods. Both COS-based methods gave on average higher GPP estimates than the CO₂-based estimates.

Soils will likely become warmer in the future, and this can increase the release of carbon dioxide (CO₂) into the atmosphere. As microbes can take up soil CO₂ and prevent further escape into the atmosphere, this study compares the rate of uptake and release of CO₂ at two different temperatures. With warming, the rate of CO₂ uptake increases less than the rate of release, indicating that the capacity to modulate soil CO₂ release into the atmosphere will decrease under future warming.

Soil organic carbon (SOC) that is transferred to the ocean by rivers forms a long-term sink of atmospheric CO₂ upon burial on the ocean floor. We here test if certain bacterial membrane lipids can be used to trace SOC through the monsoon-fed Godavari River basin in India. We find that these lipids trace the mobilisation and transport of SOC in the wet season but that these lipids are not transferred far into the sea. This suggests that the burial of SOC on the sea floor is limited here.