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  • 1
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    Assessment of Global Ocean Biogeochemistry Models for Ocean Carbon Sink Estimates in RECCAP2 and Recommendations for Future Studies (2024)
    American Geophysical Union (AGU)
    In:  EPIC3Journal of Advances in Modeling Earth Systems, American Geophysical Union (AGU), 16(3), ISSN: 1942-2466
    Details
    Publication Date: 2024-06-11
    Description: The ocean is a major carbon sink and takes up 25%–30% of the anthropogenically emitted CO2. A state-of-the-art method to quantify this sink are global ocean biogeochemistry models (GOBMs), but their simulated CO2 uptake differs between models and is systematically lower than estimates based on statistical methods using surface ocean pCO2 and interior ocean measurements. Here, we provide an in-depth evaluation of ocean carbon sink estimates from 1980 to 2018 from a GOBM ensemble. As sources of inter-model differences and ensemble-mean biases our study identifies (a) the model setup, such as the length of the spin-up, the starting date of the simulation, and carbon fluxes from rivers and into sediments, (b) the simulated ocean circulation, such as Atlantic Meridional Overturning Circulation and Southern Ocean mode and intermediate water formation, and (c) the simulated oceanic buffer capacity. Our analysis suggests that a late starting date and biases in the ocean circulation cause a too low anthropogenic CO2 uptake across the GOBM ensemble. Surface ocean biogeochemistry biases might also cause simulated anthropogenic fluxes to be too low, but the current setup prevents a robust assessment. For simulations of the ocean carbon sink, we recommend in the short-term to (a) start simulations at a common date before the industrialization and the associated atmospheric CO2 increase, (b) conduct a sufficiently long spin-up such that the GOBMs reach steady-state, and (c) provide key metrics for circulation, biogeochemistry, and the land-ocean interface. In the long-term, we recommend improving the representation of these metrics in the GOBMs.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 2
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    Moisture Sources and Pathways Determine Stable Isotope Signature of Himalayan Waters in Nepal (2023)
    American Geophysical Union (AGU)
    In:  EPIC3AGU Advances, American Geophysical Union (AGU), 4(1), ISSN: 2576-604X
    Details
    Publication Date: 2024-05-08
    Description: The Himalayan mountain range produces one of the steepest and largest rainfall gradients on Earth, with 〉3 m/yr rainfall difference over a ∼100 km distance. The Indian Summer Monsoon (ISM) contributes more than 80% to the annual precipitation budget of the central Himalayas. The remaining 20% falls mainly during pre-ISM season. Understanding the seasonal cycle and the transfer pathways of moisture from precipitation to the rivers is crucial for constraining water availability in a warming climate. However, the partitioning of moisture into the different storage systems such as snow, glacier, and groundwater and their relative contribution to river discharge throughout the year remains under-constrained. Here, we present novel field data from the Kali Gandaki, a trans-Himalayan river, and use 4-year time series of river and rain water stable isotope composition (δ18O and δ2H values) as well as river discharge, satellite Global Precipitation Measurement amounts, and moisture source trajectories to constrain hydrological variability. We find that rainfall before the onset of the ISM is isotopically distinct and that ISM rain and groundwater have similar isotopic values. Our study lays the groundwork for using isotopic measurements to track changes in precipitation sources during the pre-ISM to ISM transition in this key region of orographic precipitation. Specifically, we highlight the role of pre-ISM precipitation, derived from the Gangetic plain, to define the seasonal river isotopic variability across the central Himalayas. Lastly, isotopic values across the catchment document the importance of a large well-mixed groundwater reservoir supplying river discharge, especially during the non-ISM season.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 3
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    Anthropogenic Perturbations Change the Quality and Quantity of Terrestrial Carbon Flux to the Coastal Ocean (2023)
    American Geophysical Union (AGU)
    In:  EPIC3Journal of Geophysical Research Biogeosciences, American Geophysical Union (AGU), 128(10), ISSN: 2169-8953
    Details
    Publication Date: 2024-04-11
    Description: Human activities have increasingly changed terrestrial particulate organic carbon (POC) export to the coastal ocean since the Industrial Age (19th century). However, the influence of human perturbations on the composition and flux of terrestrial biospheric and petrogenic POC sub-pools remains poorly constrained. Here, we examined 13C and 14C compositions of bulk POC and source-specific biomarkers (fatty acids, FA) from two nearshore sediment cores collected in the Pearl River-derived mudbelt, to determine the impacts of human perturbations of the Pearl River watershed on the burial of terrestrial POC in the coastal ocean over the last century. Our results show that although agricultural practices and deforestation during the 1930s–1950s increased C4 plant coverage in the watershed, the export fluxes of terrestrial biospheric and petrogenic POC remained rather unchanged; however, added perturbations since 1974, including increasing coal consumption, embankment and dam constructions caused massive export of both petrogenic POC and relatively fresh terrestrial biospheric POC from the river delta. Our data reveal that human activities substantially enhance the transfer of petrogenic POC and fresh biospheric POC to the coastal ocean after ca. 1974, with the latter process acting as an important sink for anthropogenic CO2.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 4
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    Process‐Based Intercomparison of Water Isotope‐Enabled Models and Reanalysis Nudging Effects (2024)
    American Geophysical Union (AGU)
    In:  EPIC3Journal of Geophysical Research: Atmospheres, American Geophysical Union (AGU), 129(1), ISSN: 2169-897X
    Details
    Publication Date: 2024-05-21
    Description: The products from the Stable Water Isotope Intercomparison Group, Phase 2, are currently used for numerous studies, allowing water isotope model-data comparisons with various isotope-enabled atmospheric general circulation model (AGCMs) outputs. However, the simulations under this framework were performed using different parameterizations and forcings. Therefore, a uniform experimental design with state-of-the-art AGCMs is required to interpret isotope observations rigorously. Here, we evaluate the outputs from three isotope-enabled numerical models nudged by three different reanalysis products and investigate the ability of the isotope-enabled AGCMs to reproduce the spatial and temporal patterns of water isotopic composition observed at the surface and in the atmospheric airborne water. Through correlation analyses at various spatial and temporal scales, we found that the model's performance depends on the model or reanalysis we use, the observations we compare, and the vertical levels we select. Moreover, we employed the stable isotope mass balance method to conduct decomposition analyses on the ratio of isotopic changes in the atmosphere. Our goal was to elucidate the spread in simulated atmospheric column δ18O, which is influenced by factors such as evaporation, precipitation, and horizontal moisture flux. Satisfying the law of conservation of water isotopes, this budget method is expected to explain various fractionation phenomena in atmospheric meteorological and climatic events. It also aims to highlight the spreads in modeled isotope results among different experiments using multiple models and reanalyses, which are primarily dominated by uncertainties in moisture flux and precipitation, respectively.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
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    Samudra Report No.88, December 2022 (2023)
    International Collective in Support of Fishworkers (ICSF) | India
    Details
    Publication Date: 2023-04-07
    Description: The International Collective in Support of Fishworkers (ICSF) has released the latest edition of its popular fisheries publication – SAMUDRA Report, its triannual journal on fisheries, communities and livelihoods. SAMUDRA Report No. 88, dated December 2022, has a special focus on the International Year of Artisanal Fisheries and Aquaculture (IYAFA 2022), with reports from several regions of how the year was celebrated as well as the ICSF Statements made at the IYAFA 2022 Asia Workshop. The editorial Comment points to how the abiding message of IYAFA 2022 should be that the social pillar of sustainable development ought to be strengthened to protect the future of lives and livelihoods in the small-scale fisheries subsector. A report from the United Nations Oceans Conference 2022 details how representatives of small-scale fishing communities – the most numerous ocean users –launched a Call to Action in a conerence that brought together two main protagonists: those clamouring for reforms in ocean governance to ‘Save Our Ocean’, and those clamouring for reforms to open up the ‘Blue Economy’. The article from Taiwan says that securing the rights of migrant workers in the nation’s fisheries is an ongoing and evolving process... SAMUDRA Report No. 88 can be accessed at https://www.icsf.net/samudra-articles.php?id=9537
    Description: Published
    Description: Refereed
    Keywords: ICSF ; Samudra Report ; IYAFA ; SSF Guidelines ; Small-scale Fisheries ; Sustainable Development ; Asia ; COFI ; Nigeria ; Taiwan ; Forced Labour ; Migrant workers ; Livelihoods ; Tamil Nadu ; Shrimp ; India ; Aquaculture ; Bangladesh ; Hilsa ; IPC ; Lake Victoria ; MPA ; Conservation ; Obituary ; Film Festival ; France ; Fishing Communities ; Small-scale Fisheries
    Repository Name: AquaDocs
    Type: Book/Monograph/Conference Proceedings
    Format: 68pp.
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  • 6
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    Permafrost Carbon: Progress on Understanding Stocks and Fluxes Across Northern Terrestrial Ecosystems (2024)
    American Geophysical Union (AGU)
    In:  EPIC3Journal of Geophysical Research: Biogeosciences, American Geophysical Union (AGU), 129(3), ISSN: 2169-8953
    Details
    Publication Date: 2024-02-27
    Description: Significant progress in permafrost carbon science made over the past decades include the identification of vast permafrost carbon stocks, the development of new pan‐Arctic permafrost maps, an increase in terrestrial measurement sites for CO〈jats:sub〉2〈/jats:sub〉 and methane fluxes, and important factors affecting carbon cycling, including vegetation changes, periods of soil freezing and thawing, wildfire, and other disturbance events. Process‐based modeling studies now include key elements of permafrost carbon cycling and advances in statistical modeling and inverse modeling enhance understanding of permafrost region C budgets. By combining existing data syntheses and model outputs, the permafrost region is likely a wetland methane source and small terrestrial ecosystem CO〈jats:sub〉2〈/jats:sub〉 sink with lower net CO〈jats:sub〉2〈/jats:sub〉 uptake toward higher latitudes, excluding wildfire emissions. For 2002–2014, the strongest CO〈jats:sub〉2〈/jats:sub〉 sink was located in western Canada (median: −52 g C m〈jats:sup〉−2〈/jats:sup〉 y〈jats:sup〉−1〈/jats:sup〉) and smallest sinks in Alaska, Canadian tundra, and Siberian tundra (medians: −5 to −9 g C m〈jats:sup〉−2〈/jats:sup〉 y〈jats:sup〉−1〈/jats:sup〉). Eurasian regions had the largest median wetland methane fluxes (16–18 g CH〈jats:sub〉4〈/jats:sub〉 m〈jats:sup〉−2〈/jats:sup〉 y〈jats:sup〉−1〈/jats:sup〉). Quantifying the regional scale carbon balance remains challenging because of high spatial and temporal variability and relatively low density of observations. More accurate permafrost region carbon fluxes require: (a) the development of better maps characterizing wetlands and dynamics of vegetation and disturbances, including abrupt permafrost thaw; (b) the establishment of new year‐round CO〈jats:sub〉2〈/jats:sub〉 and methane flux sites in underrepresented areas; and (c) improved models that better represent important permafrost carbon cycle dynamics, including non‐growing season emissions and disturbance effects.〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 7
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    Baffling shades of blue: Addressing the impacts of the blue economy on small-scale fisheries in Latin America (2024)
    International Collective in Support of Fishworkers (ICSF) | India
    Details
    Publication Date: 2024-01-08
    Description: The incessant noise over ‘Blue Economy’ and ‘Blue Growth’ leaves artisanal and small-scale fishers dazed and confused. This report works through that confusion. It draws on scholarship from the trenches and the research centres across ten Latin American countries. From extensive interviews, policy reviews, analyses of finances and online datasets. In granular detail, it examines how Blue Growth affects artisanal fishers and their need for equity and justice. Through the baffling shades of blue—conflicts, priorities, the politics of managing our coasts and seas—this report finds clear light. It lays down the agenda for fishworkers and organizations working for them.
    Description: Published
    Description: Refereed
    Keywords: Latin America ; Small-scale Fisheries ; Coastal States ; Artisanal Fisheries ; Equity ; Fishworkers ; Brazil ; Chile ; Peru ; Ecuador ; Colombia ; Panama ; Costa Rica ; Nicaragua ; Honduras ; Guatemala ; ICSF ; Small-scale Fisheries
    Repository Name: AquaDocs
    Type: Book/Monograph/Conference Proceedings
    Format: 125p.
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  • 8
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    Baffling Shades of Blue Addressing the impacts of the Blue Economy on small-scale fisheries in Latin America (2022)
    International Collective in Support of Fishworkers (ICSF)
    In:  EPIC3International Collective in Support of Fishworkers (ICSF)
    Details
    Publication Date: 2024-02-07
    Repository Name: EPIC Alfred Wegener Institut
    Type: Other , notRev
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