Interest in the value of natural environments' carbon sequestration services has steadily increased over the past two decades. Consequently, there has been a surge in carbon science research, particularly in aquatic environments such as freshwater bodies, wetlands, and marine coastal zones, driven by their efficient removal of atmospheric carbon dioxide (CO2) and decadal-scale carbon burial. However, conditions that promote carbon storage (anoxia and organic loading) can favour processes that produce methane (CH4) and nitrous oxide (N2O). Despite their lower concentrations and shorter atmospheric lifespan for CH4, CH4 and N2O have significant global warming potentials and thus are among the most potent greenhouse gases, following CO2. The contribution of CH4 from aquatic and wetland environments represents approximately half of global CH4 emissions. That of N2O is still unquantified.

For the development of accurate nature-based carbon crediting schemes and nationally determined contributions, the inclusion of greenhouse gas flux estimations in the Anthropocene are vital. Yet in recent years, it has become clear that fundamental knowledge gaps remain regarding the contribution of greenhouse gas emissions from natural habitats. Climate warming and anthropogenic environmental pressures also threaten the delicate balance of carbon sink and source habitats. Changes in precipitation patterns result in fluctuations in groundwater levels and altered hydrological connectivity, periodically exposing or inundating soils and sediments, which can shift ecosystems between net sources and sinks of CO₂, CH₄, and N₂O. Rising temperatures can promote methanogenesis, the microbial process that produces CH4, leading to greater carbon offsets through increased CH4 emissions. Nutrient pollution considerably increases the availability of environmental nitrate and ammonium, stimulating the production of N2O via incomplete denitrification. As our natural habitats become increasingly subject to these anthropogenic pressures, our understanding of how the environment may contribute needs to be addressed. Thus, we aim to expand the availability of greenhouse gas data and identify several gaps in the understanding of greenhouse gas dynamics in freshwater bodies, wetlands, and marine coastal zones within this Research Topic.

We invite studies focusing on greenhouse gas fluxes in freshwater, wetlands, and marine coastal systems, with particular interest in the drivers of GHG fluxes, the impacts of anthropogenic pressures, and investigations that incorporate spatiotemporal dynamics (e.g. seasonal monitoring). Submitted works should be in the form of original studies, as outlined above, and updated reviews covering large-scale GHG dynamics across aquatic and wetland ecosystems.

Specific themes could focus on the following:

- Presentation of greenhouse gas fluxes from freshwater, wetland, and/or coastal environments, with a particular interest in those with a seasonal aspect and/or with the inclusion of N2O fluxes to fill current data and knowledge gaps.

- Impacts of anthropogenic environmental pressure, including land use, nutrient loading, pollution, and climate feedbacks, on greenhouse gas dynamics in freshwater bodies, wetlands, and marine coastal zones.

- ‘Land to sea’-scape research exploring habitat connectivity and its relation to greenhouse gas dynamics

- Management and restoration strategies that influence greenhouse gas emissions, including rewetting, conservation, and nature-based solutions.

- Advances in modelling and methodological developments of CO₂, CH₄, and N₂O fluxes across spatial and temporal scales in freshwater, wetland, and coastal systems.

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Greenhouse Gas Dynamics in Freshwater, Wetland, and Coastal Systems in the Anthropocene