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After 'Zero CO2': Tracing uncertainties in the Zero Emissions Commitment (ZEC) signal
No full textCan we constrain ZEC using observable metrics?:
One of the defining challenges of our century is to limit global warming. Reducing anthropogenic carbon dioxide emissions to net zero has been understood to be a central measure in achieving this climate goal. Still, after achieving net zero CO2 emissions, the climate system could show a delayed temperature response. This temperature response is called Zero Emissions Commitment (ZEC) and has been estimated to be approximately 0±0.3 K in the ZECMIP multi-model mean (Jones et al., 2019; MacDougall et al., 2020). Understanding and constraining ZEC remains relevant, especially when considering the remaining carbon budget for reaching ambitious climate targets. However, individual climate models show a high level of uncertainty in the ZEC response.
ZEC is closely related to the carbon cycle, the planetary heat uptake and their respective distance to their equilibrium states at the point of net zero. Therefore, we investigate how the pre-industrial state and responsiveness of these processes to anthropogenic climate change relate to their ZEC response in Earth system models simulating the ZECMIP experiments. We aim to characterise the models' ZEC response as a function of the chosen, observable climate variables (e.g., overturning strength at 26° N, global carbon project (Friedlingstein et al., 2023) carbon fluxes, or ocean heat content of the upper 700 m), that will then later serve as basis for observationally constrained ZEC estimates. We will show first preliminary results and invite feedback on the study design
Large-scale larval connectivity analysis of the keystone species Ostrea edulis across the North Sea
No full textOstrea edulis is a biogenic reef-forming marine species that was once widespread along European coastlines. Over the past two centuries, popula.ons have drama.cally declined and fragmented into small, isolated groups, primarily due to overexploitation. In response, restoration efforts across Europe have intensified, creating an increasing demand for diverse data to support effective and sustainable conservation strategies. Dispersal capacity and population connectivity are key to understanding metapopulation dynamics in patchily fragmented marine populations, providing a necessary basis for informed restoration site selection within conservation management. However, despite this recognized importance, knowledge of O. edulis connectivity remains unresolved for the fragmented populations in the North Sea. To address this gap, a biophysical modeling approach was employed, combining larval dispersal simulations with a high-resolution hydrodynamic circulation model. Oceanographically-driven connectivity among 14 North Sea subpopulations along the Scandinavian coast and Wadden Sea was predicted and interpreted in the light of genetic population structure and historical distribution data. Results revealed a well-connected metapopulation of 12 Scandinavian subpopulations, clearly separated from two isolated populations in the Wadden Sea, as confirmed by genetic data. Two subpopulations within the Scandinavian metapopulation were identified as persistent source populations linking the Danish-Swedish and Norwegian populations, highlighting their critical role in metapopulation stability and resilience, and thus the priority of their conservation. Restoring at known historical sites of O. edulis along the Dutch and German coasts of the Wadden Sea could enable their reconnection to the Scandinavian metapopulation by creating stepping-stone habitats. These findings provide insights to guide effective conservation strategies to restore wild wild O. edulis populations
A Bridge Between Geological, Mining and Archaeological Heritage: The Monreal Marble Quarry (Salamanca, Spain)
No full textNatural stone has been utilised in the southeastern region of Salamanca province (Spain) since the Chalcolithic period, with the Monreal quarry and its Cream Monreal Marble forming part of this legacy. This study aims to revaluate the Monreal quarry, which is included in the Spanish Inventory of Sites of Geological Interest (IELIG) and currently shows signs of neglect and vandalism. The quarry was operational until recently and remnants of the extraction methods can still be found. The research primarily focuses on the geological and mining educational potential of the site, highlighting its exceptional palaeontological significance and its connections to the area’s archaeological heritage. The Monreal quarry contains the highest concentration of archaeocyaths from the Upper Ovetian (Cambrian Series 2 Stage 3) of the Iberian Peninsula and, hence, Western Europe. This makes it the best outcrop for observing these fossils and understanding these hypercalcified marine animals that inhabited the region about 515 Ma ago. This study reveals for the first time that the Cream Monreal Marble and a Visigothic religious sculpture housed in the Museum of Salamanca are identical in mesoscale, mineralogical composition and isotopic C and O, thereby establishing a significant link between the quarry and the historical heritage of the region. Additionally, a georoute between the Monreal quarry, the Granite Theme Park of Los Santos, and the Iter ab Emerita Asturicam Roman road (UNESCO World Heritage Site) is suggested to facilitate the preservation of the quarry and enhance its geological, palaeontological, mining and cultural values
The chromosomal genome sequence of Aplysina aerophoba (Nardo, 1833) and its associated microbial metagenome sequences
No full textWe present a genome assembly from an individual Aplysina aerophoba (gold sponge; Porifera; Demospongiae; Verongiida; Aplysinidae). The genome sequence is 158.8 megabases in span. Most of the assembly is scaffolded into 22 chromosomal pseudomolecules. The mitochondrial genome has also been assembled and is 19.62 kilobases in length. Several symbiotic bacterial genomes were assembled as MAGs, including Candidatus Poribacteria species. Gene annotation of this assembly on Ensembl identified 27,086 protein coding genes
Monitoring marine carbon dioxide removal: quantitative analysis of indicators for carbon removed and environmental side-effects.
No full textMarine Carbon Dioxide Removal (mCDR) implementations can potentially remove 1–15 Gt CO2 yr-1, which encompasses the minimum requirement removal of CDR in 2050 to limit warming below 2°C by 2100. Despite their potential, mCDR represents only a tiny fraction of currently deployed CDR methods. Their implementations require not only a comprehensive understanding of the marine processes involved, but also a robust monitoring for their effectiveness and potential environmental impacts. In this work, we surveyed the mCDR scientific literature to identify measurable indicators for quantitative information across different ecosystems and methods used for monitoring the carbon removed and environmental side-effects, and explore the main common challenges. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis protocol PRISMA: the search queries were established, and the literature search and criteria for inclusion/exclusion were transparently defined. Our results reveal the lack of a direct linkage from the mCDR-induced rates of chemical and biological changes to the amount of carbon removed from the atmosphere and the magnitude of associated environmental impacts. The heterogeneity of marine biogeochemical and ecological processes in time and space together with the propagation of biogeochemical signals in an open system represent the most common challenge reported for the monitoring approaches. Our results show that we are in need of indicators that provide reliable quantification of CO2 removal rates and information on environmental impacts. Finally, based on our gap analysis, we provide monitoring recommendations such as the use of common metrics and the baseline establishment. Currently, the lack of standardized indicators and monitoring procedures inhibits the verification, and hence, creates risks for further investment and prevents the entering of mCDRs in existing carbon certificate trading systems, hindering the long term growth of this sector
Kritik des Geomar-Instituts: Fangquoten in Nord- und Ostsee zu hoch
No full textDas Kieler Meeresforschungsinstitut Geomar (Schleswig-Holstein) kritisiert in einer neuen Studie die EU und ihre Fangquoten. Die Rede ist von systematischem Versagen in der Fischereipolitik. Die EU gehe von viel zu hohen Fischbeständen in Nord- und Ostsee aus. Die aktuellen Fangquoten führten nach Angaben des Geomars zu einer stetigen Überfischung und so zum Abbau der Fischbestände
Making waves in Kiel: high-level roundtable calls for urgent action to restore the Baltic Sea
No full textAhead of the start of The Ocean Race Europe in Kiel, leaders from science, politics, and civil society came together for a high-level roundtable to discuss the escalating crisis in one of the world’s most imperiled marine ecosystems: the Baltic Sea.
The event, Making Waves – the Baltic Edition, is the third in a series of roundtables focused on coastal health. It builds on previous gatherings in Alicante (November 2024) and during the UN Ocean Conference in Nice (June 2025), and aims to bring the winning mentality of offshore sailing to the urgent race to restore our oceans
From the 8.2 ka event to the Little Ice Age: Holocene cold periods and human impact recorded in alpine glaciofluvial peatlands (Silvretta Mountains, Switzerland)
No full textHigh alpine peatlands are naturally impacted by extreme climatic conditions and heterogeneous topography. In the Alps, humans have been influencing their development for millennia, and accelerating climate change puts them under additional pressure. In the Swiss part of the Fimba Valley (or Val Fenga; > 2350 m a.s.l. (metres above sea level)), small-scale peatlands have been investigated to gain knowledge on climatic and anthropogenic impacts on alpine landscapes using quantitative and semi-quantitative geochemical parameters derived from inter-calibrated portable X-ray fluorescence spectrometry (pXRF) and XRF core scanning, sedimentology, and radiocarbon dating. The onset of peat formation, after the retreat of the Fimba Valley glacier, has been dated to a time window between 10 450 and 9000 cal BP at the lower (northern) end and to 6600 cal BP at the upper (southern) end of a 470 m long transect. Holocene cold episodes appear to have increased erosive glacial activity in the western side of the valley, resulting in high minerogenic sediment loads being deposited on the peatlands by a meltwater channel, interrupting peat accumulation repeatedly. In the early Holocene, distinct minerogenic layers suggest glacier growth and cold and potentially wet conditions around 9200, 8200, and 6300 cal BP. With the impact and extent of the 8.2 ka cold event still being under discussion for this region of the Alps, a coarse gravel layer is strong evidence for a marked glacial response in the Silvretta Mountains to a particularly cold and wet episode. Cooler climate conditions seem to have prevailed around 5400, 5000, 4500, and 3600 cal BP. Afterwards, the proportion of anthropogenic forcing in erosional processes and other disturbances increased. During and since the Middle Ages, soil or sediment erosion and decreasing peat accumulation were and have continued to be consequences of at least one of the following factors: deforestation; livestock grazing and traffic (trade, tourism); and, temporarily, the Little Ice Age. These impacts and their potential effects on carbon accumulation and flood risk mitigation in the valley should be considered in land management practice. Despite their strong minerotrophic character and a likely post-depositional release due to erosion and decomposition in recent layers, the peatlands have preserved clear signals of atmospheric lead (Pb) pollution: one correlated with the Roman period and another around 1450 cal BP. Rapidly changing sedimentation and hydrology in small mountain peatlands are a challenge for radiocarbon chronologies, high-resolution sampling, and the detection of atmospheric geochemical signals. Yet, our study demonstrates that dynamic glaciofluvial stream-bank mires are valuable for the reconstruction of the impact of climate and humans on alpine environments – from prehistory to the present
Observations of tracer ventilation in the Cape Basin, Agulhas Current Retroflection
No full textThe Cape Basin is a highly dynamic region, strongly influenced by the Agulhas Retroflection and its associated ring shedding. The region is characterized by high eddy kinetic energy, amplified mixing and water mass transformation. While model studies have shown that meso- to submesoscale features enhance water mass formation and tracer stirring, there has been limited observations made at the required spatiotemporal scales to capture such stirring and mixing processes. This study integrates high-resolution glider observations with satellite data to indicate the presence of shear-driven instabilities occurring at submesoscale fronts that enhance vertical diapycnal transport, leading to low apparent oxygen utilization and high levels of particulate organic carbon in the deeper ocean. These tracers are then distributed within the ocean interior via mesoscale advection and stirring along isopycnals, providing observational evidence for the role of the meso- to submesoscale strain field in surface to ocean interior water mass transformation and their broader implications on ocean circulation
Hypoxia adaptation shapes genomic architecture and vertical niche transitions in copepods
No full textOxygen Minimum Zone (OMZ) expansion is a major challenge to marine ecosystems and associated zooplankton. Calanoid copepods include lineages that tolerate hypoxia and exhibit functional traits such as diel vertical migrations to, or dormancy within, hypoxic mesopelagic zones. However, the evolutionary origins and molecular drivers of these traits remain unclear. Herein, we integrate a time-calibrated phylotranscriptomic tree of 50 copepod species with ancestral trait reconstruction, gene family copy number variation, and palaeoceanographic data to infer the evolutionary timing and ecological drivers of hypoxia adaptation. Our results support that post-embryonic dormancy originated in calanoid ancestors, accompanied by widespread gene expansions primarily involving hypoxia-response pathways as well as lipid and amino acid metabolism. Mesopelagic colonisation by calanoid lineages likely occurred during the Ordovician deep-sea oxygenation event. This was followed, during the Carboniferous deep-sea deoxygenation, by a secondary habitat shift toward shallower waters and embryonic dormancy, and gene contractions in the superfamily Diaptomoidea. We further analysed the hypoxia-induced transcriptomic response of Eucalanus hyalinus from the Benguela upwelling OMZ, and identified a coordinated response involving extracellular matrix remodelling, amino acid recycling for anaerobic energy and antioxidant production as well as triglycerides to wax ester conversion. Gene family expansions upstream (proteolysis, transport) and downstream (antioxidant biosynthesis) of core metabolic pathways suggest purifying selection on dosage-sensitive nodes. Together, these results link palaeoclimate change to lineage-specific genome evolution patterns supporting copepod adaptation to oxygen limitation