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Carbon-climate feedbacks to spatial aerosol model implementation variations
No full textAerosols have played an important role in defining climate development over the historical period, due to their cooling impact in the atmosphere. However, as their emissions are expected to decrease in the upcoming decades, and therefore also their cooling effect, they will likely be associated with the future warming of the planet. Despite their importance, and the high uncertainty of their radiative forcing, aerosols inclusion or consideration in, for example, simple climate models, integrated assessment models and carbon metrics requires extensive simplifications and assumptions. Typically, interactions between physical and biogeochemical processes, as well as triggered feedbacks, are disregarded by such models and metrics, which is a potential further source of uncertainty in the aerosols’ led responses in a changing climate. By varying the spatial implementation of aerosols in an intermediate complexity model, we explore the variability in Earth system responses under a highly ambitious mitigation scenario due to a change in aerosols forcing. When spatial heterogeneities in forcing are disregarded, surface air temperature development can differ by almost 0.1°C, which would correspond to an approximate uncertainty of 200 GtCO2 in estimates of remaining carbon budgets. The warming and cooling contributions of different Earth system processes, such as land carbon uptake or ocean heat uptake, are also seen to vary strongly depending on the spatial distribution of aerosols in the atmosphere. The main processes driving these responses are found to be land surface temperature and its impact on soil respiration, as well as ocean ventilation processes and sea ice cover changes. These findings highlight that the spatial distribution of aerosols is capable of triggering important climate feedbacks, which should not be disregarded when assessing climate development and simulated Earth system responses. These feedbacks will be instrumental in defining potential pathways for temperature stabilisation and evaluating, for example, remaining carbon budgets
Assessment of Plankton Size Structure From CMIP6 Earth System Models With a Novel Pelagic Size Structure Database
No full textPlankton community structure influences biogeochemical and ecosystem processes, such as sequestration of atmospheric CO 2 , carbon export to the ocean floor, and the productivity of higher trophic levels. One means of analyzing community structure is through the distribution of biovolume across size classes (the size spectrum), since size is a proxy for plankton functional traits. To understand how climate forcing affects plankton communities, we assessed the size spectra in the historical simulations of seven Earth System Models (ESMs) included in the 6th Coupled Model Intercomparison Project and analyzed projected changes under a high emissions scenario (SSP5‐8.5). We compared historical estimates with the Pelagic Size Structure database (PSSdb), a novel size structure dataset from imaging systems. The median slope from models ranged from −1.66 to −1.07, with shallower slopes from this range approximating both the theoretical expectation and PSSdb observations (−1.05), with variations around the median representing differences in the total biovolume distribution across plankton functional groups. Consistent with the observations, most ESMs show steeper slopes and lower biovolume in oligotrophic subtropical gyres compared with productive ocean regions. Historical versus climate change simulations reveal increases in slope and biovolume at high latitudes, associated with greater biomass and productivity, and decreases at lower latitudes, consistent with nutrient limitation from stronger stratification. We emphasize the need for expanded observational data. Despite ESMs not being designed to simulate size, the plankton size spectra from models provide insights on large‐scale ecological and biogeochemical processes, and how climate change could affect these dynamics in the future.
Key Points
Earth System Models with more than three plankton size classes can represent a similar biomass stock across increasing size classes
Models agreed on size spectra slope steepening under a high‐emission scenario, consistent with an overall reduction in plankton size
Model‐data comparisons highlight the need for better modeled size representation and expanded coverage of plankton size dat
esting Solid Earth - Climate Connections and Generation of Crust at the Fast-Spreading Southeast Pacific Rise using time series, Cruise No. SO314, 13th August 2025 - 5th October 2025, Pepeete (French Polynesia) - Antofagasta (Chile), T-SECTOR SEPR
No full textCruise SO314 took place at the Southeastern Pacific Rise (SEPR) in late summer of 2025 in the
frame of the EU-funded ERC Synergy Project "T-SECTOR". Its main goal was to provide
evidence for direct links between climate (continental ice sheets and sea level) and solid Earth
processes (amount and composition of newly formed oceanic crust at mid ocean ridges). Models
have predicted that differences in hydrostatic pressure on the ocean crust as a consequence of
glacial/interglacial sea level variability resulted in thicker newly formed oceanic crust, changes in
its geochemical signature and elevated hydrothermal activity during glacials and vice versa.
To achieve the goals of the cruise, 77 closely spaced gravity cores were taken along a 75
nm section across the SEPR, of which 44 reached the basaltic basement and contain basaltic
glasses and hydrothermally influenced sediments in their lowermost meter directly above the
basement. These cores reflect changes in the elemental and isotopic composition of the crust over
time. They will form a continuous composite time series of volcanic and hydrothermal activity of
the SEPR of the past 1 million years. Sampling was complemented by wax coring and dredging in
areas without significant sediment coverage.
To determine changes in crustal thickness over time, seismic measurements were carried
out at highest resolution consisting of the multi-day deployment of Ocean Bottom Seismometers
(3 x 47 OBS) and subsequent multi-channel seismic and refraction seismic profiling along the
same 75 nm section as occupied for the sediment coring
Jenseits des Lichts
No full textTief unter der spiegelglatten See vor Mayotte stößt ein deutsches Forschungsteam auf eine verborgene Welt: Kaltwasserkorallen, die im Dunkeln gedeihen. Eine Reise in die Finsternis des Indischen Ozean
A Systems Perspective: How Social–Ecological Networks Can Improve Our Understanding and Management of Biological Invasions
No full textReversing biodiversity loss and the sustainability crisis requires approaches that explicitly consider human-nature interdependencies. Social-ecological networks, which incorporate social and ecological actors and entities, as well as their interactions, provide such an approach. Social-ecological networks have been applied to a range of complex issues, including sustainable resource use, management of ecosystem services and disservices, and collective action. However, the application of social-ecological networks to invasion science remains limited so far, despite their clear potential for studying human contributions to introduction pathways of nonnative species, invasion success, direct and indirect impacts, and their management. In the present article, we review past applications of social-ecological networks to biological invasions, provide guidance on how to construct and analyze such networks, with an illustrative example, and outline future opportunities of social-ecological networks in invasion science. We aim to inform and inspire the applications of social-ecological networks to improve our ability to meet the diverse challenges facing invasion science
NN-TOC v1: global prediction of total organic carbon in marine sediments using deep neural networks
No full textSpatial predictions of total organic carbon (TOC) concentrations and stocks are crucial for understanding marine sediments’ role as a significant carbon sink in the global carbon cycle. In this study, we present a geospatial prediction of TOC concentrations and stocks at a 5 x 5 arc minute grid scale, using a deep learning model — a novel machine learning approach based on a new compilation of over 22,000 global TOC measurements and a new set of predictors, such as seafloor lithologies, grain size distribution, and an alpha-chlorophyll satellite data. In our study, we compared the predictions and discuss the limitations from various machine learning methods. Our findings reveal that the neural network approach outperforms methods such as k Nearest Neighbors and random forests, which tend to overfit to the training data, especially in highly heterogeneous and complex geological settings. We provide estimates of mean TOC concentrations and total carbon stock in both continental shelves and deep sea settings across various marine regions and oceans. Our model suggests that the upper 10 cm of oceanic sediments harbors approximately 171 Pg of TOC stock and has a mean TOC concentration of 0.68 %. Furthermore, we introduce a standardized methodology for quantifying predictive uncertainty using Monte Carlo dropout and present a map of information gain, that measures the expected increase in model knowledge achieved through in-situ sampling at specific locations which is pivotal for sampling strategy planning
Simulated surface normalised relative vorticity in INALT60
No full textVisualisation of daily averaged surface normalised relative vorticity as simulated on the highest resolution grid in INALT60.L120-KRS0020 for the period 2015/01/01 to 2017/12/31. Background image on the African continent: Blue Marble with Topography and Bathymetr
Asynchronous Poleward Migration of the Atlantic Subtropical Gyres Over the Past 22,000 years
No full textBy exchanging huge amounts of heat between the tropics and high latitudes, subtropical gyres significantly impact Earth's energy balance. Yet, their dynamical changes during the last deglaciation remain poorly understood. Here, nine records of the planktonic foraminiferal species Globorotalia truncatulinoides, that inhabits the permanent deep thermocline of subtropical gyres, are used to explore the meridional migration of both the North and South Atlantic subtropical gyres (NASG and SASG, respectively) in the past 22,000 years. We find that both gyres migrated poleward, with the SASG migration 1,500 years earlier than the NASG. Records from the North Atlantic Ocean indicate that the NASG's northern boundary has shifted over 6°. Climate model simulations suggest that these migrations are coupled with shifts in meridional temperature gradients. The poleward migration of the Atlantic subtropical gyres was crucial for sustaining a milder modern high-latitude climate in comparison with that of the last ice age.
Key Points:
- Atlantic subtropical gyres have asynchronously migrated poleward over the last 22,000 years
- Poleward migration of the Atlantic subtropical gyres started ∼1,500 years earlier in the Southern Hemisphere
- The northern boundary of North Atlantic subtropical gyre likely moved poleward at least 6
Fluke-less pygmy killer whale spotted on the central Atlantic
No full textThe increase in fluke-less whale reports raises concerns about the negative impacts of fishing activities and shipping routes on cetaceans. In addition to natural causes, the main reason for tail mutilation is ship strikes and entanglements in fishing gear (Urbán J. et al. 2004; Zimmer 2018; Jahoda 2020; Kim et al. 2022).
Gray whales (Eschrichtius robustus) and bottlenose dolphins (Tursiops aduncus) have been reported to survive these injuries by adapting their peduncle movement to match their group’s speed, participating in social activities, and reproducing (Urbán J. et al. 2004; Kim et al. 2022). Here, we report the sighting of a fluke-less pygmy killer whale (Feresa attenuata Gray, 1874), a rarely observed species of oceanic dolphin (McSweeney et al. 2009), in the central Atlantic.
The injured pygmy killer whale was spotted on 01 November 2024 during RV METEOR expedition M205 at position 10° 32′ 15.96″ N, 26° 42′ 51.68″ W in the central Atlantic, ca. 540 km SW of the Cabo Verde Islands, as a member of a group of three animals. When diving, the fluke-less whale occasionally lifted the terminal end of its caudal peduncle above the water surface (Fig. 1). It was remarkable to see that it was keeping up relatively effortlessly with the group surrounding stationary RV METEOR in a loose formation for about 15 min before setting on again together with the group. Photos and video footage (Fig. 1a–l) revealed that the tail stump of the fluke-less individual seemed to be well healed. However, while the two other individuals showed much more reciprocal interaction in parallel swimming patterns, joint surfing, and small jumps, the amputated individual remained nearby but outside the cluster for most of these activities. While wild individuals can manage and survive the partial loss of body parts, complete fin amputation is usually life-threatening (Wells et al. 2008; Kim et al. 2022). The more remarkable it is that this pygmy killer whale used the same propulsion method observed for fluke-amputated gray whales and dolphins (Urbán J. et al. 2004; Kim et al. 2022). This indicates that the observed means of propulsion — moving the flat peduncle in lateral side-to-side movements (relative to the dorsal midline), partially turning its whole body to the side — is a shared strategy for dolphins and other whales that lost their flukes and survived the injury
Sources and fate of particulate organic matter along the river-estuary-coastal ocean continuum: Constraints from amino acid and amino sugar carbon isotopes
No full textEstuaries represent hotspots for organic matter cycling. Understanding the sources and fate of organic matter in estuaries is crucial for quantifying the transport of terrestrial organic carbon to the coastal ocean and air-sea carbon dioxide fluxes. Here we report the abundance and carbon isotopic signatures of bulk particulate organic matter (POM) as well as particulate amino sugars and amino acids in surface suspended particles along the salinity gradient in the Changjiang Estuary and adjacent coastal ocean. Our data show that bulk δ13C values are directly related to the δ13C values of essential amino acids, suggesting a control by primary production on bulk δ13C values. A large degree of fractionation (−26‰) between phytoplankton δ13C and dissolved inorganic carbon δ13C values was observed in regions with salinities greater than 28, leading to a decline in bulk δ13C values. Examining the δ13C patterns of individual amino sugars and amino acids reveals that terrestrial amino sugars are produced by mixed sources of bacteria, fungi, and algae, while terrestrial amino acids originate from vascular plants and bacteria. Along the salinity gradient, the source of amino sugars shifted to bacteria, whereas amino acids transitioned to algae. Moreover, the low carbon- and nitrogen-normalized yields of amino acids (∼10% and ∼22%, respectively) observed in the Changjiang River suggest an advanced diagenetic state of terrestrial POM. In contrast, elevated POM reactivity in moderate to high salinity zones indicates contributions from phytoplankton production. Using the bacterial biomarker muramic acid, we found that a substantial portion (∼19%) of terrestrial POM is of bacterial origin. Combining the distinct excursions in bulk, amino sugar, and amino acid δ13C values in low salinity (<20) regions of the estuary indicates that terrestrial organic matter is extensively removed in the estuarine regions. Together, these findings underscore significant alterations in the sources and properties of organic matter along the river-estuary-coastal ocean continuum, with bacterial reworking playing an important role