On April 23, 2021, the Intergovernmental Oceanographic Commission of UNESCO ("IOC") released "Integrated Ocean Carbon Research: Overview of Ocean Carbon Research and Outlook for Ocean Carbon Research and Observation in the Next Ten Years" (Integrated Ocean Carbon Research: A Summ

On April 23, 2021, the Intergovernmental Oceanographic Commission of UNESCO ("IOC") released "Integrated Ocean Carbon Research: Overview of Ocean Carbon Research and Outlook for Ocean Carbon Research and Observation in the Next Ten Years" (Integrated Ocean Carbon Research: A Summary of Ocean Carbon Research, and Vision of Coordinated Ocean Carbon Research and Observations for the Next Decade) report introduces the current understanding of the role of the ocean in the carbon cycle and points out future development directions. The report aims to provide policymakers with the knowledge they need to develop policies to mitigate and adapt to climate change over the next decade.

1 Comprehensive overview of the ocean carbon cycle

The ocean plays a key role in regulating climate warming by absorbing large amounts of CO2 and heat emitted by humans. As the amount of CO2 in the atmosphere has continued to increase since the industrial era, the ocean has absorbed a large amount of carbon, equivalent to 41 ± 15% of CO2 emissions from fossil fuels and 28% of anthropogenic CO2 emissions caused by fossil fuels and land use changes. . The total global carbon budget as of 2007 reflects the importance of the ocean in long-term carbon sequestration. In order to understand and predict future carbon sinks, it is necessary to improve our understanding of the processes and combinations of each link in the carbon cycle. At present, the assessment method of ocean carbon sink is based on the observation results formed by three-dimensional ocean models and ocean surface pCO2 data, and is carried out on a monthly time scale. The

ocean carbon sink assessment is benchmarked through internal observations, which can quantify the total amount of anthropogenic CO2 in the ocean on an interdecadal scale. Models can more accurately represent ocean processes at spatial and temporal scales and provide a basis for future predictions. Combining data and models, improving data acquisition and processing, enhancing the representation of biological processes in models, and operating across spatial and temporal scales will help improve understanding and quantification of the evolving ocean carbon sink, and improve observation and Accuracy of ocean model results. Future ocean responses to stress changes will largely depend on CO2 emission scenarios. If emissions remain high, the amount of CO2 in the atmosphere will continue to increase through this century. Therefore, the thermodynamic forces that drive some CO2 into the ocean will also persist. In this case, constraints on ocean carbon sinks would manifest as reduced buffering capacity, while the marine biological pump may change. As emissions decrease, the thermodynamic forces driving ocean CO2 will decrease, but a deeper understanding of possible changes in ocean carbon sinks must be developed and allowable emissions must be modified. This requires more model-based studies and a deeper assessment of recent interannual and decadal changes using observations and model results. The

model, including observing system simulation experiments, is an effective tool for evaluating when and where supplementary sampling can minimize uncertainty in observational products. Modeling and data merging using data assimilation can help advance scientific understanding by making fuller use of information from observations. It is necessary to adopt a standardized framework to generate complete uncertainty reports for observations to facilitate their full utilization in data assimilation. For predictive models where data assimilation cannot be directly employed, such studies should consider various future emission scenarios. Marine carbon sinks are likely to respond asymmetrically to emissions trajectories, and the physical, biogeochemical and biological responses that accompany this process will require detailed assessment.

The progress made in recent years in combining model and observational studies to understand abiotic processes in marine anthropogenic carbon sinks should be extended to the study of marine biological processes that regulate natural carbon cycles. The extent to which biofeedback alters the natural carbon cycle needs to be studied. To fully understand the socioeconomic benefits of the ocean, as well as the potential socioeconomic impacts of future feedbacks, a comprehensive and integrated research program is necessary.

2 Basic questions and emerging research questions The

report raised the following four basic questions and emerging research questions: ① Will the absorption of anthropogenic CO2 by the ocean continue to become a major abiotic process? ②What role does biology play in the ocean carbon cycle? How does its effect change? ③How does carbon exchange between land-ocean-ice occur? How does this exchange change over time? ④ How do humans change the ocean’s carbon cycle and its feedback, including how to specifically remove CO2 from the atmosphere?

3 Methods to carry out comprehensive ocean carbon research

The report proposes to carry out comprehensive ocean carbon research from the following eight aspects: ① Strengthen continued financial support for the observation network; ② Strengthen and coordinate the existing carbon observation and comprehensive project portfolio; ③ Regional priorities; ④ New process research and experiments; ⑤ New technologies that help enhance autonomous observation and analysis; ⑥ Combining models and observations; ⑦ Consideration of solutions: mitigation means; ⑧ Management of comprehensive carbon research plans.

4 Research questions and recommendations in integrated ocean carbon research

The vision for integrated ocean carbon research revolves around several levels related to climate and social issues, such as the United Nations Decade of Ocean Science for Sustainable Development and the Ocean Decade Challenge. issues involved. Although these issues are not specifically addressed in the vision document, they can directly promote the implementation of comprehensive ocean carbon research. These questions are aligned with the vision for integrated ocean carbon research and are categorized by scope and scale. It is important that integrated studies of ocean carbon not only focus on global-level issues, but also recognize the importance of regional and local levels, as in some cases regional-level processes can have a direct impact on carbon processes and ecological impacts on local populations. Great impact, which requires dedicated research efforts.

4.1 Social and policy-relevant research questions

(1) Will the ocean continue to serve as a carbon sink proportional to carbon emissions from human activities?

(2) What is the impact of increased CO2 levels on the ocean? What capabilities and needs exist to curb rising CO2 levels?

(3) Can the ocean’s carbon sequestration be enhanced safely?

4.2 Global Research Questions

(1) What are the key natural and anthropogenic factors that influence biological carbon cycles and ocean health?

(2) Is the food web changing in the twilight zone, and what impact will this have on the evolution of the ocean carbon cycle?

(3) Will the changing division between particulate inorganic carbon (PIC) and particulate organic carbon (POC) affect inorganic carbon cycling, transport and flux?

(4) As the amount of anthropogenic CO2 emissions decreases, how will global ocean carbon absorption change in the future?

(5) Are dissolved organic carbon pools changing, and what are the implications for climate and environmental change?

(6) How does carbon storage change in key land-ocean reservoirs?

(7) In the context of climate change, will the formation of deep water and meridional overturning circulation change, and what impact will this have on ocean carbon absorption?

(8) How to incorporate multiple stressors on the ocean carbon system when evaluating observations and simulation results?

(9) What impact does deoxygenation have on the ocean carbon cycle?

4.3 Regional Research Questions

(1) What impact does (changing) sea ice have on the ocean carbon cycle?

(2) What are the historical and future impacts of the changing Southern Ocean on the global carbon cycle/budget?

(3) How to improve the regional balance of carbon sources and carbon sinks within the ecosystem?

(4) What are the trends in ocean acidification in the polar regions?

(5) What are the causes of spatiotemporal changes in the Southern Ocean carbon sink and what is its intensity?

(6) What impact does ocean acidification have on high-latitude biota? How will this impact ripple out to other global biogeochemical cycles and higher trophic levels?

(7) What role does the tropical ocean edge play in the carbon budget, and has this role changed?

(8) What impact has acidification had on the marine ecosystems of the Eastern Edge Upwelling System (EBUS)?

(9) What role does the western marginal system play as a poleward carbon conveyor, including in mesoscale changes (eddies)?

(10) How do sewage and runoff from coastal large cities affect horizontal organic and inorganic carbon inputs and the resulting coastal sea-to-air carbon flux?

(11) How do the carbon cycle of the continental shelf and the amount of carbon entering the ocean change in the horizontal direction?

(12) What are the combined socioeconomic impacts of climate change driven by changes in ocean carbon chemistry, ocean warming, and sea level rise?

(13) How can marine carbon management strategies in estuaries and shelf seas be improved to serve fisheries, aquaculture, tourism, carbon sequestration and other marine activities?

4.4 General recommendations for integrated ocean carbon research

(1) Maintaining and enhancing uninterrupted high-quality ocean carbon observations is critical to quantifying the strength and change of ocean carbon sinks.

(2) Collaboratively co-design, appropriately fund and operate carbon observing systems through the engagement of agencies and entities, including the private sector.

(3) Further use remote sensing to conduct a comprehensive survey of the ocean carbon cycle.

(4) Strengthen the development and utilization of new technologies in terms of sensors and platforms.

(5) supports best practices in measurement, data sharing, and quantifying uncertainty in the carbon budget.

(6) Accelerate the application of artificial intelligence in quantifying processes, patterns and exchanges in the carbon cycle.

(7) Strengthening the link between biogeochemistry and ecology in the ocean carbon cycle.

(8) More comprehensive land-ocean integration into global carbon cycle assessments and Earth system models.

(9) uses laboratory and field studies, including appropriate geoengineering studies, to bridge critical gaps in understanding, elucidate mechanisms and advance model parameterization.

(10) Create a comprehensive and reliable ocean carbon and biogeochemistry prediction system through activities such as improved integrated products, modeling and model data fusion.

(11) Advancing data assimilation in ocean carbon studies.

Please indicate the source and author when reprinting this article: "Resources and Environment Dynamic Monitoring Express" 2021, Issue 10, 2021, Lanzhou Documentation and Information Center, Chinese Academy of Sciences, compiled by Xue Mingliang .