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Actively demonstrating the value and importance of estimating the ocean carbon sink

Actively demonstrating the value and importance of estimating the ocean carbon sink

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Jamie D. Shutler, Professor of Earth observation and climate, University of Exeter, UK, Visit: June 2023

The last 15 or so years have seen an exponential increase in the use of satellite Earth observations for studying surface ocean carbon which have included the use of observations of sea surface temperature, salinity, sea state and ocean biology.   Consequently, satellite Earth observations are now a fundamental component for assessing ocean carbon. These ocean carbon assessments, which use a synergy of in situ data and satellite observations, form one of only two observational constraints within global carbon budget assessments used to guide international policy (e.g., Friedlingstein et al., 2023). And so strangely ocean carbon data are a key constraint on land carbon assessments. Despite their important role, their critical nature and heavy reliance on satellite observations is often invisible or opaque to policy (Shutler et al., 2024) and few studies have actively demonstrated or exploited this constraint. During Prof Shutler’s visit at the ESRIN Science Hub he aimed to identify approaches to actively demonstrate the power of these satellite observation-based ocean carbon assessments and part of this effort included designing a digital twin approach (figure 1). Prof Shutler identified that all components of this approach are already being routinely used by international groups in a pre-operational, ad-hoc, or distributed manner.  Combining them in a single digital twin could be used to identify where scientific community effort is best focussed to improve assessments, used to assess the scientific and policy advice impact of major national funding decisions to infrastructure. For example, the power of the approach in figure 1 could be demonstrated under a range of ‘what if’ scenarios including: what happens to the ocean carbon sink estimate and global budget closure if we include ocean eddies, ocean biology, or novel in situ data types within the analyses (e.g., Argo floats)?  And what happens to the global carbon budget closure if the uncertainties within the ocean observational constraint or the river to ocean carbon flow are reduced?  Or what happens to the strength of any resultant policy advice if key satellite or in situ observation networks are funded, versus not funded? 

This work is now published within Shutler et al., (2024).

Figure 1: The digital twin component structure or an observing system simulation experiment approach to identify the strength of the observation-based carbon sink estimates. The logos within each module element give typical agency and community data providers. Boxes in blue are where satellite Earth observation data are exploited within global assessments (e.g., Friedlingstein et al., 2023). Techniques typically used for the boxes in green and red are beginning to use satellite observations through new carbon emissions focussed satellite missions, and this exploitation is expected to continue increasing. This figure now appears within Shutler et al., (2024).
References

Friedlingstein, P., et al., 2023. Global carbon budget 2023. Earth System Science Data, 15(12), pp.5301-5369, https://doi.org/10.5194/essd-15-5301-2023

Shutler, J.D., et al., 2024. The increasing importance of satellite observations to assess the ocean carbon sink and ocean acidification. Earth-Science Reviews, 250, p. 104682, https://doi.org/10.1016/j.earscirev.2024.104682

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