ALBERT

Description: Global population projections foresee the biggest increase to occur in Africa with most of the available uncultivated land to ensure food security remaining on the continent. Simultaneously, greenhouse gas emissions are expected to rise due to ongoing land use change, industrialisation, and transport amongst other reasons with Africa becoming a major emitter of greenhouse gases globally. However, distinct knowledge on greenhouse gas emissions sources and sinks as well as their variability remains largely unknown caused by its vast size and diversity and an according lack of observations across the continent. Thus, an environmental research infrastructure—as being setup in other regions—is more needed than ever. Here, we present the results of a design study that developed a blueprint for establishing such an environmental research infrastructure in Africa. The blueprint comprises an inventory of already existing observations, the spatial disaggregation of locations that will enable to reduce the uncertainty in climate forcing’s in Africa and globally as well as an overall estimated cost for such an endeavour of about 550 M€ over the next 30 years. We further highlight the importance of the development of an e-infrastructure, the necessity for capacity development and the inclusion of all stakeholders to ensure African ownership.

Description: The Black Sea has undergone several limnic and marine stages due to fluctuations in the global sea level. The exchange of saline water from the Mediterranean Sea to the Black Sea through the Bosporus Strait was interrupted when the sea level dropped below the Bosporus sill. This induced limnic conditions, while marine conditions were established after the reconnection to saline Mediterranean seawater. Extended river fan systems developed during sea level low-stands, providing large amounts of organic material being buried by rapid sedimentation on the slopes of the Black Sea margins. The biogenic degradation of this material produces most of the methane gas expelled into the anoxic water column today. This largely happens by ubiquitous cold vents at ~700 m water depth (i.e. at the stability boundary of methane hydrates) and by mud volcanoes in ~2000 m water depth. A significant amount of gas is expected to accumulate in the sediment within the methane hydrate stability zone. However, bottom-simulating reflectors, the seismic indicator for gas hydrates, are not found everywhere along the margin. Recent analyses of the Danube and Dniepr fans have revealed a discontinuous gas hydrate formation in an area with no active seeps, while areas of active seepage located in the vicinity of BSR reflections held no gas hydrates. In addition, the ongoing diffusion of salt into the uppermost Black Sea sediment pore space since the last glacial maximum further reduces the volume of the gas hydrate stability zone. Estimates of the total amount of gas stored in gas hydrates therefore require a detailed structural analysis prior to regional- or basin-scale modelling attempts.

Description: Deep sea mining for poly-metallic nodules impacts the environment in many ways. A key potential hazard is the creation of a sediment plume from resuspending sediment during seabed mining. The resuspended matter disperses with currents but eventually resettles on the seabed. Resettling causes a blanketing of the seafloor environment, potentially causing harm to in-, epi- and hyperbenthic communities with possible cascading effects into food webs of deep sea habitats. Mapping the extent of such blanketing is thus an important factor in quantifying potential impacts of deep-sea mining.One technology that can assess seabed blanketing is optical imaging with cameras at square-kilometre scale. To efficiently analyse the resulting Terabytes of image data with minimized bias, automated image analysis is required. Moreover, effective quantitative monitoring of the blanketing requires ground truthing of the image data. Here, we present results from a camera-based monitoring of a deep-sea mining simulation combined with automated image analysis using the CoMoNoD method and low-cost seabed sediment traps for quantification of the blanketing thickness. We found that the impacted area was about 50 percent larger than previously determined by manual image annotation.

Description: It is a good method to utilize the grain size distribution curves and cumulative frequency curves of marine or river sediments to estimate the hydrodynamic conditions, transportation processes and sedimentary environment. However, researchers can only rely on Excel or Grapher to plot the curves one by one at the present day. The manual plotting procedures are complicated, and calculating the truncation points is time-consuming. To solve the aforementioned problems, we have developed a software tool to plot cumulative frequency curves and calculate the values of truncation points automatically. The software has the ability to plot curves of hundreds of samples accurately and rapidly, promoting researchers to analyze transport mechanisms and hydrodynamic environments. And it is convenient to apply the software to compare the processes of transportation and deposition between different samples.

Description: Intense bottom-ice algal blooms, often dominated by diatoms, are an important source of food for grazers, organic matter for export during sea ice melt, and dissolved organic carbon. Sea-ice diatoms have a number of adaptations, including accumulation of compatible solutes, that allows them to inhabit this highly variable environment characterized by extremes in temperature, salinity, and light. In addition to protecting them from extreme conditions, these compounds present a labile, nutrient-rich source of organic matter, and include precursors to climate active compounds (e.g., dimethyl sulfide [DMS]), which are likely regulated with environmental change. Here, intracellular concentrations of 45 metabolites were quantified in three sea-ice diatom species and were compared to two temperate diatom species, with a focus on compatible solutes and free amino acid pools. There was a large diversity of metabolite concentrations between diatoms with no clear pattern identifiable for sea-ice species. Concentrations of some compatible solutes (isethionic acid, homarine) approached 1 M in the sea-ice diatoms, Fragilariopsis cylindrus and Navicula cf. perminuta, but not in the larger sea-ice diatom, Nitzschia lecointei or in the temperate diatom species. The differential use of compatible solutes in sea-ice diatoms suggests different adaptive strategies and highlights which small organic compounds may be important in polar biogeochemical cycles.

Description: This report summarizes the first WP6 consultation on ocean liming, which focused on the life-cycle assessment (LCA) of lime produced within existing industrial processes for carbon dioxide removal through ocean alkalinity enhancement (see Deliverable 6.2 for further details on the LCA).

Description: This document is the first of three periodic reports on available data.

Description: This report provides an overview on the cooperation activities with relevant EU projects and other initiatives on negative emission technologies in the first phase of the OceanNETs project (01.07.2020 – 31.12.2021).

Description: This report provides an overview of OceanNETs engagement with relevant stakeholders and the OceanNETs stakeholder reference group in the first 18 month of the project (01.07.2020 – 31.12.2021).

Description: Marine electromagnetic methods provide useful and independent measures for the identification and quantification of submarine gas hydrates. The resistivity of seafloor sediments, drawn from area-wide electromagnetic data, mainly depends on the sediment porosity and the nature of the pore fluid. Gas hydrates and free gas are both electrically resistive. The replacement of saline water, thus conductive pore water with resistive gas hydrate or free gas, increases the sediment resistivity and can be used to provide accurate saturation estimates if the background lithology is known. While seismic methods are predominantly used to study the distribution of submarine gas hydrates, a growing number of global field studies have demonstrated that the joint interpretation of marine seismic and electromagnetic methods improves the evaluation of submarine gas hydrate targets. This article discusses the relationship between resistivity and free gas/gas hydrate saturation levels, how the resistivity of the sediment may be measured and summarizes the status and results of current and past field studies.

Description: In times of accelerating climate change, species are challenged to respond to rapidly shifting environmental settings. Yet, faunal distribution and composition are still scarcely known for remote and little explored seas, where observations are limited in number and mostly refer to local scales. Here, we present the first comprehensive study on Eurasian-Arctic macrobenthos that aims to unravel the relative influence of distinct spatial scales and environmental factors in determining their large-scale distribution and composition patterns. To consider the spatial structure of benthic distribution patterns in response to environmental forcing, we applied Moran’s eigenvector mapping (MEM) on a large dataset of 341 samples from the Barents, Kara and Laptev Seas taken between 1991 and 2014, with a total of 403 macrobenthic taxa (species or genera) that were present in ≥ 10 samples. MEM analysis revealed three spatial scales describing patterns within or beyond single seas (broad: ≥ 400 km, meso: 100–400 km, and small: ≤ 100 km). Each scale is associated with a characteristic benthic fauna and environmental drivers (broad: apparent oxygen utilization and phosphate, meso: distance-to-shoreline and temperature, small: organic carbon flux and distance-to-shoreline). Our results suggest that different environmental factors determine the variation of Eurasian-Arctic benthic community composition within the spatial scales considered and highlight the importance of considering the diverse spatial structure of species communities in marine ecosystems. This multiple-scale approach facilitates an enhanced understanding of the impact of climate-driven environmental changes that is necessary for developing appropriate management strategies for the conservation and sustainable utilization of Arctic marine systems.

Description: Every year, vast quantities of plastic debris arrive at the ocean surface. Nevertheless, our understanding of plastic movements is largely incomplete and many of the processes involved with the horizontal and vertical displacement of plastics in the ocean are still basically unknown. In this chapter we review the dynamics associated with the transport of plastics and other pollutants at oceanic fronts. Fronts had been historically defined as simple barriers to exchange, but here we show that the role of these structures in influencing the transport of plastics is more complex. The tools used to investigate the occurrence of frontal structures at various spatial scales are reviewed in detail, with a particular focus on their potential applications to the study of plastic pollution. Three selected case studies are presented to better describe the role of fronts in favoring or preventing plastic exchanges: the large-scale Antarctic Circumpolar Current, a Mediterranean mesoscale front, and the submesoscale fronts in the Gulf of Mexico. Lastly, some aspects related to the vertical subduction of plastic particles at oceanic fronts are discussed as one of the most promising frontiers for future research. The accumulation of floating debris at the sea surface is mainly affected by the horizontal components of frontal dynamics. At the same time, vertical components can be relevant for the export of neutrally buoyant particles from the surface into the deep sea. Based on these evidences, we propose that submesoscale processes can provide a fast and efficient route of plastic transport within the mixed layer, while mesoscale instabilities and associated vertical velocities might be the dominant mechanism to penetrate the deeper ocean on slower but broader scales. We conclude that given the ubiquitous presence of fronts in the world’s ocean, their contribution to the global plastic cycle is probably not negligible and the role of these processes in vertically displacing neutrally buoyant microplastics should be investigated in more detail.

Description: The Barents Sea, located close to the Arctic Ocean, is a petroleum province featuring an extensive occurrence of gas hydrates and shallow gas in compacted sediments. Glacial erosion and uplift have contributed to the migration of gas originating from deeper rocks to the shallow sediments of this region, resulting in hydrates with higher-order hydrocarbons in addition to methane. This article documents reported gas hydrate indications and major controls on hydrate stability in the Barents Sea.

Description: Since global navigation satellite systems (GNSS) for determining the absolute geolocation do not reach into the ocean, underwater robots typically obtain a GNSS position at the water surface and then use a combination of different sensors for estimating their pose while diving, including inertial navigation, acoustic doppler velocity logs, ultra short baseline localization systems and pressure sensors. When re-navigating to the same seafloor location after several days, months or years, e.g. for coastal monitoring, the absolute uncertainty of such systems can be in the range of meters for shallow water, and tens of meters for deeper waters in practice. To enable absolute relocalization in marine data science applications that require absolute seafloor positions in the range of centimeter precision, in this contribution we suggest to equip the monitoring area with visual markers that can be detected reliably even in case they are partially overgrown or partially buried by sediment, which can happen quickly in coastal waters. Inspired by patterns successful in camera calibration, we create robust markers that exhibit features at different scales, in order to allow detection, identification and pose estimation from different cameras and various altitudes as visibility (and therefore the maximum possible survey altitude) in coastal waters can vary significantly across seasons, tides and weather. The low frequency content of the marker resembles a human-readable digit, in order to allow easy identification by scientists. We present early results including promising initial tests in coastal waters.

Description: While offshore groundwater has been utilized by coastal communities as far back as 1000 BC, only in the past 10 years has the global volume of fresh-to-brackish water hosted in offshore aquifers been truly appreciated. There are vast quantities (~300–500 × 103 km3) of offshore freshened groundwater sequestered in continental shelf sediments under water depths of less than 60 m within 110 km of the coastline. New marine geophysical methods now make it possible to map and quantify low salinity offshore groundwater bodies. To date, these offshore resources have not been developed. Offshore freshened groundwater could be produced if wells are located close to the shoreline and coastal desalination plants.

Description: Research undertaken in Task 2.2 identified a range of governance challenges to ocean-based NETs related to the global ocean governance framework, e.g., linked to the transboundary nature of the ocean, potential effects of ocean-based NETs on the ocean’s condition and marine ecosystem services, as well as the many unknowns and uncertainties linked to NET-deployment. The fragmented approaches and frameworks in place to govern the global ocean further complicate comprehensive governance of these emerging technologies. This deliverable presents results from a workshop that explored how oceanbased NETs should be governed to best confront these challenges and integrate international climate targets as well as global goals for ocean and biodiversity conservation, in addition to global ambitions towards sustainable development. The workshop is part of research undertaken by Task 2.2 to assess how ocean-based NETs are addressed by the current global ocean governance framework and develop governance scenarios and recommendations to policy makers for a “good governance” of NETs in the ocean.

Description: This working paper presents first insights on lay public perceptions of marine carbon dioxide removal (CDR) approaches. In seven focus groups, three in Germany and four in Norway (including one pilot) the researchers asked members of the lay public to share their views of the ocean and the effects of climate change, four CDR approaches, as well as their reflections on responsible research and innovation (RRI) of marine CDR. The four CDR methods were ocean iron fertilization, ocean alkalinity enhancement, artificial upwelling, and blue carbon management through restoration of coastal and marine ecosystems. In addition, respondents were asked to compare the four approaches. Our findings indicate that the public will be very supportive of blue carbon management irrespective of its actual carbon sequestration potential, due in part to the perceived bad state of marine ecosystems worldwide. Participants were skeptical whether any of the CDR approaches could have relevant effect on carbon sequestration and long-term storage; they reasoned about issues such as the ability to scale up treatments in time and space, unforeseen or unforeseeable effects on ecosystems in time and space, and the role of industry in the implementation process. They argued that despite the potential availability of marine CDR, industry and the general public should stop polluting behaviors and practices. Nevertheless, the participants universally agreed that further research on all four CDR methods should be pursued to better understand effects on climate, ecosystems, local communities, and the economy.

Description: This is the stylized description of our ocean liming case study, which we are using the introduce our life-cycle assessment to stakeholders in our consultation process

Description: Any integration of extra carbon dioxide removal (CDR) via terrestrial or marine sink enhancement into climate policies requires accounting for their effectiveness in reducing atmospheric carbon concentration and translating this information into the amount of carbon credits (to be used in official and voluntary emission trading schemes). Here, we assess accounting schemes in their appropriateness of assigning carbon credits. We discuss the role of temporary carbon storage and present the various ccounting methods for carbon credit assignment. We explain how we have implemented the methods numerically and analyse carbon assignments across the different accounting schemes, using stylized, model-based ocean sink enhancement experiments.

Description: This report summarizes OceanNETs stakeholder engagement activities in the Canary Islands, prior and during the mesocosm study in ocean alkalinity enhancement carried out on the island of Gran Canaria in September-October 2021. It also presents ideas for future stakeholder engagement in the islands.

Description: Realistic alkalinization scenarios, under the global context, are proposed and examined, which can be extent to include spatial considerations and specific technical and regulatory constraints. Results provide a set of stylistic projections of total mineral (carbonate and silicate) addition, with its temporal timeframe spanning from as early as 2025 up to 2100). Among others, these estimates can be used to constrain model simulations that will be carried out in Work Package 4.

Description: We applied a 1-D plankton ecosystem-biogeochemical model to assess the impacts of ocean alkalinity enhancement (OAE) on seasonal changes in biogeochemistry and plankton dynamics. Depending on deployment scenarios, OAE should theoretically have variable effects on pH and seawater pCO2, which might in turn affect (a) plankton growth conditions and (b) the efficiency of carbon dioxide removal (CDR) via OAE. Thus, a major focus of our work is how different magnitudes and temporal frequencies of OAE might affect seasonal response patterns of net primary productivity (NPP), ecosystem functioning and biogeochemical cycling. With our study we aimed at identifying a parameterization of how magnitude and frequency of OAE affect net growth rates, so that these effects could be employed for Earth System Modell applications. So far we learned that a meaningful response parameterization has to resolve positive and negative anomalies that covary with temporal shifts. As to the intricacy of the response patterns, the derivation of such parameterization is work in progress. However, our study readily provides valuable insights to how OAE can alter plankton dynamics and biogeochemistry. Our modelling study first focuses at a local site where time series data are available (European Station for Time series in the Ocean Canary Islands ESTOC), including measurements of pH, concentrations of total alkalinity, dissolved inorganic carbon (DIC), chlorophyll-a and dissolved inorganic nitrogen (DIN). These observational data were made available by Andres Cianca (personal communication, PLOCAN, Spain), Melchor Gonzalez and Magdalena Santana Casiano (personal communication, Universidad de Las Palmas de Gran Canaria). The choice of this location was underpinned by the fact that the first OAE mesocosm experiment was conducted on the Canary Island Gran Canaria, which will facilitate synthesizing our modelling approach with experimental findings. For our simulations at the ESTOC site in the Subtropical North Atlantic we found distinct, non-linear responses of NPP to different temporal modes of alkalinity deployment. In particular, phytoplankton bloom patterns displayed pronounced temporal phase shifts and changes in their amplitude. Notably, our simulations suggest that OAE can have a slightly stimulating effect on NPP, which is however variable, depending on the magnitude of OAE and the temporal mode of alkalinity addition. Furthermore, we find that increasing alkalinity perturbations can lead to a shift in phytoplankton community composition (towards coccolithophores), which even persists after OAE has stopped. In terms of CDR, we found that a decrease in efficiency with increasing magnitude of alkalinity addition, as well as substantial differences related to the timing of addition. Altogether, our results suggest that annual OAE during the right season (i.e. physical and biological conditions), could be a reasonable compromise in terms of logistical feasibility, efficiency of CDR and side-effects on marine biota. With respect to transferability to global models, the complex, non-linear responses of biological processes to OAE identified in our simulations do not allow for simple parameterizations that can easily adapted. Dedicated future work is required to transfer the observed responses at small spatiotemporal scales to the coarser resolution of global models.

Description: Underwater images are challenging for correspondence search algorithms, which are traditionally designed based on images captured in air and under uniform illumination. In water however, medium interactions have a much higher impact on the light propagation. Absorption and scattering cause wavelength- and distance-dependent color distortion, blurring and contrast reductions. For deeper or turbid waters, artificial illumination is required that usually moves rigidly with the camera and thus increases the appearance differences of the same seafloor spot in different images. Correspondence search, e.g. using image features, is however a core task in underwater visual navigation employed in seafloor surveys and is also required for 3D reconstruction, image retrieval and object detection. For underwater images, it has to be robust against the challenging imaging conditions to avoid decreased accuracy or even failure of computer vision algorithms. However, explicitly taking underwater nuisances into account during the feature extraction and matching process is challenging. On the other hand, learned feature extraction models achieved high performance in many in-air problems in recent years. Hence we investigate, how such a learned robust feature model, D2Net, can be applied to the underwater environment and particularly look into the issue of cross domain transfer learning as a strategy to deal with the lack of annotated underwater training data.

Description: Fish food is an inevitable item in human consumption with healthy sourceof good quality proteins and fat. Aqua industry can help to improve food security,livelihoods for the poorest and to meet the world’s food demands. But producingmore seafood that is at affordable cost with rich nutrition is challenging for aquaindustry. Many factors affect the productivity of aqua industry; one such an impor-tant constraint is bacterial diseases. Hence, Aqua industry, a booming businesssector, immensely requires continued research with scientific and technical devel-opments, and innovations. Study of bacterialfish disease is one such thrust areawhich requires intense research to understand the causes and control bacterialdiseases infish. The appearance and development of afish disease is the result ofthe interaction among pathogen, host and environment. An insight into bacterialfishdiseases, clinical symptoms and treatment may help to manage the bacterial diseasesand so can make aqua industry a more profitablefield. This chapter deals withdifferent aspects of the most threatening bacterial diseases, occurring in farmedfishes and also in wildfishes, which are results infish loss and economic lossworldwide. A wide range of gram positive and gram-negative bacteria causingbacterial diseases, clinical symptoms, diagnosis, treatment, vaccines and the natureof water habitat are also discussed in this chapter.

Description: The Digital Earth project aimed for the integration of data science and Earth science. Here, we reflect on the main lessons learned that include the need for interdisciplinary collaboration, thinking out of the box, the concept of ‘thinking in workflows’ and models for the sustainable implementation of scientific software, data infrastructure and policies.

Description: Digital Earth is a project funded by the German Helmholtz Association with all centers of the research field Earth and Environment involved. The main goal of the Digital Earth project is to develop and bundle data science methods in extendable and maintainable scientific workflows that enable natural scientists in collaboration with data scientists to achieve a deeper understanding of the Earth system. This has been achieved by developing solutions for data analysis and exploration with visual and computational approaches with data obtained in a SMART monitoring approach and modeling studies, accompanied by a continuous evaluation of the collaboration processes. In this chapter, the history, setup, and focus of the Digital Earth project are described.

Description: The Digital Earth project aims at a strong interrelation between Data and Earth Science and a step-change in implementing data science methods within Earth science research. During the project, the progress of interdisciplinary collaboration and adoption of data science methods has been measured and assessed with the goal to trace the success of the project. This chapter provides the set-up of this evaluation and the results from two online questionnaires that were held after the start and before the end of the project.

Description: Diversity within marine microbiomes spans the three domains of life: microbial eukaryotes (i.e., protists), bacteria, and archaea. Although protists were the first microbes observed by microscopy, it took the advent of molecular techniques to begin to resolve their complex and reticulate evolutionary history. Symbioses between microbial entities have been key in this journey, and such interactions continue to shape the ecology of marine microbiomes. Nowadays, photosynthetic marine protists are appreciated for their activities as primary producers, rivalling land plant contributions in the global carbon cycle. Predatory protists are known for consuming prokaryotes and other protists, with some combining metabolisms into a mixotrophic lifestyle. Still, much must be learned about specific interactions and lifestyles, especially for uncultured groups recognized just by environmental sequences. With respect to the fate of protists in food webs, there are many paths to consider. Despite being in early stages of identifying interactions, whether mutualistic or death-inducing infections by parasites and viruses, knowledge is advancing rapidly via methods for interrogation in nature without culturing. Here, we review marine protists, their evolutionary histories, diversity, ecological roles, and lifestyles in all layers of the ocean, with reference to how views have shifted over time through extensive investigation.

Description: Net-zero climate policies foresee deployment of atmospheric carbon dioxide removal wit geological, terrestrial, or marine carbon storage. While terrestrial and geological storage would be governed under the framework of national property rights, marine storage implies that carbon is transferred from one global common, the atmosphere, to another global common, the ocean, in particular if storage exceeds beyond coastal applications. This paper investigates the option of carbon dioxide removal (CDR) and storage in different (marine) reservoir types in an analytic climate-economy model, and derives implications for optimal mitigation efforts and CDR deployment. We show that the introduction of CDR lowers net energy input and net emissions over the entire time path. Furthermore, CDR affects the Social Cost of Carbon (SCC) via changes in total economic output but leaves the analytic structure of the SCC unchanged. In the first years after CDR becomes available the SCC is lower and in later years it is higher compared to a standard climate-economy model. Carbon dioxide emissions are first higher and then lower relative to a world without CDR. The paper provides the basis for the analysis of decentralized and potentially non-cooperative CDR policies.

Description: This study uses an existing perturbed parameter ensemble (PPE) of simulated ocean CO2 removal (CDR) to better determine sustainable pathways of ocean-based NET deployment and to provide information to constrain the design of subsequent modelling experiments. The results show that ocean alkalinity enhancement (OAE) can only help meet SDG13 (Climate Action) when other ambitious mitigation efforts are taken. This reinforces that OAE is not a substitute for emissions reduction, but could contribute to meeting our climate goals (if other factors suggest OAE is worth doing). For SDG14 (Life Below Water), the results suggest OEA can contribute to limiting or even reversing ocean acidification. Meeting many other SDG14 objectives is closely linked to also meeting SDG13. A key recommendation is therefore, that subsequent simulations in OceanNETs should only use SDG13 compatible baseline scenarios, unless there is some specific need for process understanding at higher levels of climate change. The analysis has also determined that the idealized CDR in the PPE is not suitable for determining many socio-economic constraints and the implications that these have for meeting the SDGs. Another key recommendation is therefore, that subsequent simulations within OceanNETs should use more realistic scenarios of CDR deployment.

Description: In part one of this deliverable, an ensemble of 14 CMIP6 Earth System Models is evaluated regarding their performance in simulating alkalinity and related parameters. The majority of the models and the multi-model-mean underestimate surface alkalinity compared to climatological observations. Alkalinity biases stemming from the parametrization of calcium carbonate formation and dissolution can be as big as biases stemming from model physics. In part two, we test the sensitivity of parametrizations concerning the carbonate chemistry in the FESOM2.1-REcoM3 and give recommendations for addressing alkalinity biases.

Description: This is the data management plan for the research project OceanNETs. It compiles OceanNETs research data output and describes the data handling during and after the projects duration with the aim to make OceanNETs research data FAIR – sustainably available for the scientific community. This data management plan is a living document; it will be continuously developed in close cooperation with the consortium members throughout the project duration. Version 2

Description: The potential biogeochemical and ecological impacts of ocean alkalinity enhancement were tested in a 5-weeks mesocosm experiment conducted in the subtropical, oligotrophic waters off Gran Canaria in September/October 2021. In the nine mesocosms, each with a volume of about 10 m3 inhabiting a natural plankton community, alkalinity enhancement was achieved through addition of a mix of sodium bicarbonate and sodium carbonate, simulating CO2-equilibrated alkalinization in a gradient from control up to twice the natural alkalinity. The response of the enclosed plankton community to the alkalinity addition was monitored in over 50 parameters which were sampled or measured in situ daily or every second day. In addition to the mesocosm experiment, a series of side experiments were conducted, focusing on individual aspects of mineral dissolution, secondary precipitation and biological responses at the primary producer level. This campaign, in which 47 scientists from 6 nations participated, generated the most comprehensive data set collected so far on the ecological and biogeochemical impacts of ocean alkalinity enhancement.

Description: Marine protists abound, but are challenging to study, and their interactions with other microbes in nature remain largely unknown. We captured wild predatory protists (choanoflagellates) and discovered a divergent, obligately co-associated bacterial group that lives by extracting resources from these predators.

Description: Emissions trading systems (ETS) and markets usually do not allow for the inclusion of carbon dioxide removal (CDR) activities and if they do, removal activities are primarily restricted to afforestation. The New Zealand emission trading system (NZ ETS), for examples, integrates afforestation, and the California Low-Fuel Standard, the Quebec ETS and the Chinese ETS permit the restricted inclusion of afforestation offsets. Furthermore, the California Low-Carbon Fuel Standard System allows for the inclusion of removal via Direct Air Capture. In combination with the 45Q tax credit program, the largest incentives for CDR via Negative Emissions Technologies (NETs) are currently provided in the US. However, both do not yet allow for the inclusion of ocean-based carbon removal. Hence, we provide first a brief overview about the NZ ETS and its inclusion of afforestation, pointing out that the concept will likely not be applicable to ocean-based CDR with the potential exemption of blue carbon projects. Second, we discuss the 45Q tax credit program, the California Low-Fuel Standard System, and the California Compliance Offset Scheme. Third, we provide an overview about the company database related to ocean-based carbon removal. Fourth, we briefly look at the voluntary carbon market, providing some insights for carbon removal accounting.

Description: This deliverable synthesizes the results on public perceptions of marine CDR methods from the first two years of OceanNETs. The purpose is to inform the other work packages in OceanNETs and stakeholders about our results in a timely and brief manner about the ways members of the public view marine CDR specifically but also in the broader context of net-zero targets and climate policy. The deliverable summarises results of two studies: (1) focus groups held in Germany and Norway that covered ocean fertilization, ocean alkalinity enhancement, artificial upwelling and blue carbon management and (2) a deliberative survey in Norway that covered ocean alkalinity enhancement, macroalgae farming with BECCS or biomass sinking and land-based BECCS and enhanced weathering as terrestrial approaches for comparison. Participants in both studies emphasise the importance of reducing emissions and changing consumptions patterns. They hardly discuss the need to remove CO2 from the atmosphere to reach the Paris climate goal and the concept of negative emissions seems difficult for them to engage with. Among the methods, participants prefer ecosystem-based approaches like mangrove or seagrass restoration over other methods like alkalinity enhancement or ocean fertilization. Participants are concerned about the actual feasibility of deployment at a relevant removal scale and for a longer period. Connected to this are concerns about the controllability of the deployment and the methods’ impact, like difficulties to control negative environmental effects from biomass sinking at the seafloor. They also question the buildup of additional infrastructure or additional interventions into nature on top of already existing human interference. The opportunity to deliberate the methods increases participants’ certainty about their assessment but only slightly changes the direction of the assessment.

Description: The Indo-Pacific Warm Pool (IPWP) exerts a dominant role in global climate by releasing huge amounts of water vapour and latent heat to the atmosphere and modulating upper ocean heat content (OHC), which has been implicated in modern climate change1. The long-term variations of IPWP OHC and their effect on monsoonal hydroclimate are, however, not fully explored. Here, by combining geochemical proxies and transient climate simulations, we show that changes of IPWP upper (0–200 m) OHC over the past 360,000 years exhibit dominant precession and weaker obliquity cycles and follow changes in meridional insolation gradients, and that only 30%–40% of the deglacial increases are related to changes in ice volume. On the precessional band, higher upper OHC correlates with oxygen isotope enrichments in IPWP surface water and concomitant depletion in East Asian precipitation as recorded in Chinese speleothems. Using an isotope-enabled air–sea coupled model, we suggest that on precessional timescales, variations in IPWP upper OHC, more than surface temperature, act to amplify the ocean–continent hydrological cycle via the convergence of moisture and latent heat. From an energetic viewpoint, the coupling of upper OHC and monsoon variations, both coordinated by insolation changes on orbital timescales, is critical for regulating the global hydroclimate.

Description: Data-driven science has turned into a fourth fundamental paradigm of performing research. Earth System Science, following a holistic approach in unraveling the complex network of processes and interactions shaping system Earth, particularly profits from embracing data-driven approaches next to observation and modeling. At the end, increasing digitalization of Earth sciences will lead to cultural transformation towards a Digital Earth Culture.

Description: A comprehensive study of the Earth system and its related processes requires a holistic examination and understanding of multidimensional data acquired with a large number of different sensors or produced by various models. To this end, the Digital Earth project developed a set of software solutions to study environmental data sets using visual approaches. In the following chapter, we present three data visualization products developed to deal with the challenges of the analysis and exploration of environmental data.

Description: Reliable data are the base of all scientific analyses, interpretations and conclusions. Evaluating data in a smart way speeds up the process of interpretation and conclusion and highlights where, when and how additionally acquired data in the field will support knowledge gain. An extended SMART monitoring concept is introduced which includes SMART sensors, DataFlows, MetaData and Sampling approaches and tools. In the course of the Digital Earth project, the meaning of SMART monitoring has significantly evolved. It stands for a combination of hard- and software tools enhancing the traditional monitoring approach where a SMART monitoring DataFlow is processed and analyzed sequentially on the way from the sensor to a repository into an integrated analysis approach. The measured values itself, its metadata, and the status of the sensor, and additional auxiliary data can be made available in real time and analyzed to enhance the sensor output concerning accuracy and precision. Although several parts of the four tools are known, technically feasible and sometimes applied in Earth science studies, there is a large discrepancy between knowledge and our derived ambitions and what is feasible and commonly done in the reality and in the field.