Ideas and perspectives: Sea-level change, anaerobic methane oxidation, and the glacial–interglacial phosphorus cycle Biogeosciences DOI 10.5194/bg-19-1421-2022 30 May 2022 A glacial–interglacial methane-fuelled redistribution of reactive phosphorus between the oceanic and sedimentary phosphorus reservoirs can occur in the ocean when falling sea level lowers the pressure on the seafloor, destabilizes methane hydrates, and triggers the dissolution of P-bearing iron oxides. The mass of phosphate potentially mobilizable from the sediment is similar to the size of the current oceanic reservoir. Hence, this process may play a major role in the marine phosphorus cycle. Read more
Bacterial and eukaryotic intact polar lipids point to in situ production as a key source of labile organic matter in hadal surface sediment of the Atacama Trench Biogeosciences DOI 10.5194/bg-19-1395-2022 27 May 2022 In this study, we investigate the chemical diversity and abundance of microbial lipids as markers of organic matter sources in the deepest points of the Atacama Trench sediments and compare them to similar lipid stocks in shallower surface sediments and in the overlying water column. We evaluate possible organic matter provenance and some potential chemical adaptations of the in situ microbial community to the extreme conditions of high hydrostatic pressure in hadal realm. Read more
Acidification of the Nordic Seas Biogeosciences DOI 10.5194/bg-19-979-2022 4 May 2022 Ocean acidification, a direct consequence of the CO2 release by human activities, is a serious threat to marine ecosystems. In this study, we conduct a detailed investigation of the acidification of the Nordic Seas, from 1850 to 2100, by using a large set of samples taken during research cruises together with numerical model simulations. We estimate the effects of changes in different environmental factors on the rate of acidification and its potential effects on cold-water corals. Read more
Late Neogene evolution of modern deep-dwelling plankton Biogeosciences DOI 10.5194/bg-19-743-2022 25 April 2022 Deep-living organisms are a major yet poorly known component of ocean biomass. Here we reconstruct the evolution of deep-living zooplankton and phytoplankton. Deep-dwelling zooplankton and phytoplankton did not occur 15 Myr ago, when the ocean was several degrees warmer than today. Deep-dwelling species first evolve around 7.5 Myr ago, following global climate cooling. Their evolution was driven by colder ocean temperatures allowing more food, oxygen, and light at depth. Read more
Representativeness assessment of the pan-Arctic eddy covariance site network and optimized future enhancements Biogeosciences DOI 10.5194/bg-19-559-2022 18 April 2022 Thawing of Arctic permafrost soils could trigger the release of vast amounts of carbon to the atmosphere, thus enhancing climate change. Our study investigated how well the current network of eddy covariance sites to monitor greenhouse gas exchange at local scales captures pan-Arctic flux patterns. We identified large coverage gaps, e.g., in Siberia, but also demonstrated that a targeted addition of relatively few sites can significantly improve network performance. Read more
Not all biodiversity rich spots are climate refugia Biogeosciences DOI 10.5194/bg-18-6567-2021 1 April 2022 Biodiversity is under threat from the effects of global warming, and assessing the effects of climate change on areas of high species richness is of prime importance to conservation. Terrestrial and freshwater rich spots have been and will be less affected by climate change than other areas. However, marine rich spots of biodiversity are expected to experience more pronounced warming. Read more
Photosynthetic activity in Devonian Foraminifera Biogeosciences DOI 10.5194/bg-18-5719-2021 17 January 2022 Benthic foraminifera play a significant role in modern reefal ecosystems mainly due to their symbiosis with photosynthetic microorganisms. Foraminifera were also components of Devonian stromatoporoid coral reefs; however, whether they could have harbored symbionts has remained unclear. We show that Devonian foraminifera may have stayed photosynthetically active, which likely had an impact on their evolutionary radiation and possibly also on the functioning of Paleozoic shallow marine ecosystems. Read more
Assessing the representation of the Australian carbon cycle in global vegetation models Biogeosciences DOI 10.5194/bg-18-5639-2021 7 January 2022 The Australian continent is included in global assessments of the carbon cycle such as the global carbon budget, yet the performance of dynamic global vegetation models (DGVMs) over Australia has rarely been evaluated. We assessed simulations by an ensemble of dynamic global vegetation models over Australia and highlighted a number of key areas that lead to model divergence on both short (inter-annual) and long (decadal) timescales. Read more
Modeling the marine chromium cycle: new constraints on global-scale processes Biogeosciences DOI 10.5194/bg-18-5447-2021 10 December 2021 Chromium (Cr) is a redox-sensitive element that holds promise as a tracer of ocean oxygenation and biological activity. We here implemented the oxidation states Cr(III) and Cr(VI) in the Bern3D model to investigate the processes that shape the global Cr distribution. We find a Cr ocean residence time of 5–8 kyr and that the benthic source dominates the tracer budget. Further, regional model–data mismatches suggest strong Cr removal in oxygen minimum zones and a spatially variable benthic source. Read more
Persistent impacts of the 2018 drought on forest disturbance regimes in Europe Biogeosciences DOI 10.5194/bg-18-5223-2021 22 November 2021 Europe was affected by an extreme drought in 2018. We show that this drought has increased forest disturbances across Europe, especially central and eastern Europe. Disturbance levels observed 2018–2020 were the highest on record for 30 years. Increased forest disturbances were correlated with low moisture and high atmospheric water demand. The unprecedented impacts of the 2018 drought on forest disturbances demonstrate an urgent need to adapt Europe’s forests to a hotter and drier future. Read more