The ocean plays a key role in the global carbon cycle and its carbon sink strength is critical for removing atmospheric carbon dioxide and stabilizing global climate. This oceanic carbon sink strength is difficult to measure and models provide estimates that differ from one another. Terhaar combines multiple modeling approaches using composite model-based averages and fully coupled Earth System Models to take advantages of the benefits of both, and in doing so derives a similar sink strength to existing estimates but with reduced uncertainty.

Ecosystems are, in many ways, changing more rapidly than they have in the past. Rapid past ecological changes can provide critical insight into how to best understand ecosystem function to improve ecological restoration, but a historic focus on community composition in the paleoecological literature can obscure the causes of these changes, making mechanisms unclear. The authors demonstrate a path forward using pollen and diatom records from a lake in the Italian Alps to construct a narrative of terrestrial and aquatic ecosystem changes that combines well-established vegetation changes with rapid changes to water management changes to explore how rapidly the ecosystem responds to perturbations, and how aquatic function has been restored after pollution events. Doing so provides new insight into how to use the paleoecological record to understand restoration success and the time scales upon which ecosystem changes occur.

Intensifying wildfire regimes in many parts of the world are increasing the production of pyrogenic organic matter (PyOM), with potential implications for water supplies that are critical for domestic, industrial, agricultural, and ecological needs. This study provides a novel assessment of the influence of PyOM on aquatic ecosystems and showed that PyOM can be actively transformed in aquatic ecosystems and may be an increasing source of C emissions to the atmosphere as the prevalence of wildfires increases.

Application for BG Letter format accepted.

This laboratory and protein database research by Fabisik and co-workers demonstrates that the widespread freshwater cyanobacterium Microcystis aeruginosa is capable of producing nitrous oxide, a very potent greenhouse gas, from nitrite. This discovery poses the important question about the relevance of these organisms for global nitrous oxide emissions into the atmosphere and their response to environmental change.

Tropical cyclones are typically assumed to be associated with ecosystem damage. This study challenges this assumption and suggests that instead of reducing plant biomass, cyclones in East Asia may increase biomass production by alleviating water stress.

The authors adopted a new and attractive approach, based on the use of thermal springs appearing at different times, to study the short-term and long-term (> 50 years) effect of warming on the soil C stock under subarctic grasslands. This new approach allows to take a new look at the question of a positive feedback between temperature and soils that can amplify global warming. Indeed, most studies on this subject are based on warming experiments conducted over the short term (some years) or on questionable correlative approaches where the temperature co-varies with many other factors (e.g., study of soil C stocks along latitudinal temperature gradients). Their study challenges the current dominant view on the effect of warming on the dynamics of SOM. Indeed, results suggest that soil C losses in the subarctic grasslands studied cease after 5 years of warming. These observations corroborate those obtained in the rare ecosystem warming experiments maintained beyond 10 years. In addition, results suggest that the C stocks present in the deep soil horizons, where plant roots are not or hardly present, are not affected by warming. These unexpected discoveries, together with other recent observations, show the glaring lack of knowledge on the fundamental mechanisms of the effect of temperature on catalytic processes, which seriously compromises our ability to predict the soil-climate feedback.