About

About Ocean Carbon for Climate

Ocean carbon is one of only two observational constraints within global carbon assessments. The OC4C project aims to initiate preliminary activities towards the long-term generation of ocean carbon Climate Data Records (CDRs) which will provide and use multiple Essential Climate Variables (ECVs).

Our objectives are to improve, advance and further constrain current estimates of the uptake of atmospheric carbon dioxide (CO2) and its exchange with the ocean (air-sea CO2 fluxes), and to fully characterise and reduce the uncertainties of these estimates. Within this, we will generate a global climate quality time series dataset of ocean carbon air-sea CO2 fluxes which will provide an estimate of the ocean carbon sink from 1980 to present day. This effort involves a diverse group of internationally recognised ocean carbon scientists from across the community

Project Aims & Objectives 

The aim of the OC4C project is to improve our understanding of the physical and biogeochemical aspects inherent to the ocean carbon uptake, and how they are related to the climate change, both on a global and regional basis. To achieve this, the work on this project sets out to address eight key objectives. These are to: 

  1. Improve and upgrade the state-of-the-art Earth observation (EO)-based estimation of carbon fluxes through the assessment of different reference SST (at their related ocean depths), and refine the ocean carbon fluxes uncertainty estimates. 
  2. Improve and upgrade the state-of-the-art EO-based estimation of carbon fluxes through the assessment of the relevance of marine biology, and refine the ocean carbon fluxes uncertainty estimates. 
  3. Begin to reconcile/recalibrate the currently diverging Global carbon Budget (GCB) model estimates with these upgraded EO Carbon sink datasets. 
  4. Explore carbon sink variability in relation to climate indexes (e.g., ENSO) occurrence and phasing. 
  5. Assess carbon sink variability at different temporal scales (seasonal, inter-annual) and in challenging ocean basins (e.g. the Arctic Ocean) 
  6. Perform a model versus EO sampling sensitivity analysis to assess the inherent sampling-driven differences. 
  7. Provide both global and regional estimates; for the latter, assess the options for regionalization (extrapolation, downscaling, etc.) and the guidance provided by biogeochemical provinces and biomes. 
  8. Draft a scientific roadmap for channelling the relevant upgraded EO carbon fluxes estimates for the future wider context of Global Stocktake reporting for the Paris Agreement. 

Project Background

Observation-based estimates of the annual ocean carbon uptake (sink) have now become a key component within global carbon budget assessments used to guide policy. Ocean and atmosphere observations form the two key observational pillars and constraints within these annual carbon budget assessments, with their uncertainties directly impacting the closure of the total budget. The policy relevance of these annual carbon assessments cannot be underestimated; they provide information about the impact of mitigation policies and they also enable updates on the so called “remaining carbon budget”, which identifies how much CO2 can be emitted in the coming decades without overshooting specific climate targets. Thus, efforts to increase understanding of, as well as improve the quantification of the ocean carbon sink, will strengthen its constraint on the remaining components of the budget within annual assessments, and increase the strength of any resulting policy guidance.

Project Plans 

Professor Jamie Shutler (university of Exeter) is responsible for guiding the project’s scientific and technical activity. Project Manager Ruth Wilson (Space ConneXions Ltd) is responsible for the management and execution of the work to be performed, and for the coordination of the consortium’s work. The project draws on the scientific expertise of the partners, UoE, PML, VLIZ, AWI, LSCE and UC (see image ‘Team Roles’). 

The project work is split into 6 Tasks (see image ‘work breakdown’). These are: 

Task 1: Requirement Baseline

  • Identify all the available satellite, in-situ and model datasets that serve the scope
    of the project, altogether with plans and procedures to acquire them.
  • Assess the best candidate test sites to be used for the development of the
    regional experimental products.
  • Consolidate the list of recent and ongoing international initiatives/projects related
    to the investigated theme, with a clear description of the added value of the proposed work with respect to existing activities and identification of potential areas for collaboration.

Task 2: Algorithm Development

  • Identify an adequate reference SST data source and perform reanalysis to a
    common depth.
  • Assess the most adequate land/ocean/ice masks.
  • Assess multiple CO2 interpolation schemes.
  • Incorporate biological modulation and control on pCO2 and also consider incorporating observation-based alkalinity.
  • Update the gas transfer velocity coefficient (Ks) with the latest advancements on
    its geophysical dependencies (wind speed, whitecaps, etc.).
  • Update and use dedicated EO tools (e.g. FluxEngine) for the routine provision of
    harmonised and consistent ocean carbon flux data.
  • Embed the generated high quality, global, multi-mission, consistent time-series
    of relevant ocean carbon datasets within an experimental data package for further
  • exploitation and reference by the user community.

Task 3: Validation

  • Generate validation metrics and compare them with the accuracy, precision and
    stability requirements specified earlier in the development cycle in the RB.
  • Characterize and report products uncertainties, through direct or indirect
    methods, paying also attention to the spatial and temporal representation errors.

Task 4: Impact Assessment & Model Intercomparison

  • Assess the differences existing between observation-based and model-based
    CO2 fluxes estimates, once the upgraded estimates developed in Task-2 are considered.
  • Evaluate to which extent the two estimates come any closer, when
    uncertainties/error bars upon the observation-based estimates are included.
  • Assess if and to which extent the ocean carbon sinks are correlated to major
    climate indexes (such as ENSO) and identify any temporal lags.
  • Sample the modelled pCO2 data at the same locations in space and time as the
    in-situ data underpinning the EO-based approaches. Evaluate EO-model spatial and temporal consistencies or discrepancies, once devoid of the sampling effect.
  • Upscale GOBMs models at EO spatial and temporal resolution and assess
    statistics evolution, once devoid of the representation error.

Task 5: Scientific Roadmap

  • Provide a Scientific Roadmap that shall summarize the major achievements and related shortcoming/bottlenecks of the project for future ocean carbon climatic perspectives.
  • Organize and hold a community workshop and summarize the related outcomes
    in the Scientific Roadmap.

Task 6: User Engagement & Outreach

  • Ensure that the entire project work shall be aware and complementary with additional ongoing related activities, both within and outside ESA.