Theme 1: Greenhouse Gases and the Oceans

Carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) are the most significant long-lived greenhouse gases (GHGs) after water vapour. Physical and biogeochemical processes in the surface ocean play an important role in controlling the ocean-atmosphere GHG fluxes. Understanding the sensitivity of these processes to climate and environmental change is of critical importance for the mitigation of climate change.

Theme 1 team


Team leaders

Karin Kvale (New Zealand,
Zouhair Lachkar (United Arab Emirates,

Team members

Damian Arévalo-Martínez (The Netherlands,
Dorothee Bakker (United Kingdom,
Tom Bell (United Kingdom,
Marcela Cornejo D'Ottone (Chile,
Sam Dupont (Sweden,
Arne Körtzinger (Germany,
Kitack Lee (Korea,
Iole B. M. Orselli (Brasil,
Parvadha Suntharalingam (United Kingdom,
Sam Wilson (United States,
Lisan Yu (United States,
Guiling Zhang (China,

Processes and impacts/stressors associated with long-lived greenhouse gases.

Processes and impacts/stressors associated with long-lived greenhouse gases.

Research questions

Key questions to be addressed within this theme are:

  • Which surface ocean processes control GHG cycling at regional to global scales?
  • What are the main feedback mechanisms between climate change and oceanic GHG emissions?
  • How can we assess future oceanic fluxes of GHGs in a changing ocean and atmosphere?
  • What is the role of natural vs. anthropogenically forced variability in ocean greenhouse gas fluxes?



Expand observational capabilities and regional coverage
To better quantify oceanic GHG budgets and air-sea fluxes and improve understanding of associated processes, we highly recommend detailed analyses of GHG fluxes and processes in key regions. These include the eastern boundary upwelling systems (EBUS), western boundary current systems, Southern Ocean, Artic Ocean land-ocean continuum, oceanic Oxygen Minimum Zones (OMZs). Recommended approaches include (i) higher resolution numerical models and artificial intelligence (e.g., machine learning), (ii) novel observing tools and methods (e.g., remote sensing technology, in situ biogeochemical sensors, isotope, and tracer methods), (iii) diverse platforms, including ships, autonomous platforms (e.g., Argo floats, gliders), moorings, and Saildrones. Sustained time-series observations at fixed sites are also necessary to characterize the seasonal and interannual variability and long-term trends in regional GHG fluxes.
Development of new analysis tools and extension of existing methodologies to quantify GHG fluxes
Improved quantification of ocean-atmosphere CO2 fluxes has been achieved by combining surface-ocean carbon measurements with a range of mapping methods including spatial interpolation, multi-variate regression, and neural network analyses. These methods are valuable tools and should be applied to ocean measurements of N2O and CH4 to provide improved quantification of other GHG fluxes.
Future changes in ocean GHG fluxes
Significant questions remain in predicting how future oceanic GHG fluxes will evolve in response to the combined impacts of multiple environmental stressors (e.g., ocean warming, deoxygenation, and acidification) and the reduction in CO2 emissions. Successful prediction of future GHG evolution requires the development of ocean biogeochemical models able to represent the key physical, chemical, and ecosystem processes and their interactions, in order to reliably estimate the impacts of anthropogenic pressures and environmental changes on the ocean GHG fluxes. Relevant biogeochemical and ecosystem component models should also be incorporated into Earth System Models (ESMs) employed for climate prediction to enable accurate quantification of the important GHG-climate feedbacks.




Planned activities

Research programmes on regional ocean-atmosphere GHG fluxes

Current national and international programmes investigating ocean CO2 uptake in the Southern Ocean include the US National Science Foundation’s “Southern Ocean Carbon and Climate Observations and Modeling” (SOCCOM) project, the European Union’s "Integrated Carbon Observation System "(ICOS), the UK National Environmental Research Council funded projects “Role of the Southern Ocean in the Earth System” (RoSES), and “Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports” (ORCHESTRA), and the European H2020 project “Southern Ocean Carbon and Heat Impact on Climate” (SO-CHIC). Further programmes investigating the ocean GHG fluxes include the “Atlantic Meridional Transect Ocean Flux from Satellite Campaign” (AMT4oceanSatFlux), “Role of Eddies in the Carbon Pump of Eastern Boundary Upwelling Systems” (REEBUS), "Biogeochemical processes and Air–sea exchange in the Sea-Surface microlayer" (BASS), "Exchange fluxes of climate-relevant trace gases off the Western Antarctic Peninsula" (EWARP), the Horizon Europe project Greenfeedback and the Boknis Eck time series station. Information on planned observational programmes and workshops can be found via the respective programme websites:

Surface Ocean CO2 Atlas

The community-led Surface Ocean CO2 Atlas ( is used for quantification of ocean CO2 uptake and ocean acidification and for evaluation of climate models and sensor data. SOCAT has an annual release of quality-controlled in situ surface ocean fCO2 (fugacity of CO2) measurements for the global ocean and coastal seas from 1957 onwards. The value chain based on in situ inorganic carbon measurements of the ocean, of which SOCAT is part, provides policy makers with vital information in climate negotiations.

Integrated Ocean Carbon Research (IOC-R) Group

Following on the successes of the previous SOLAS/IMBER Carbon group (SIC), a new Integrated Ocean Carbon Research Group has been formed. This initiative is jointly sponsored by IOC, IMBER, SOLAS, IOCCP, GCP, CLIVAR, and WCRP. The group will identify the key research needs for ocean carbon science for the next decade, develop strategies to address these needs, and address the links to societal and policy applications. An initial expert group workshop was held at the International Oceanographic Commission, Paris, in October 2019; The group has published the report: “Integrated ocean carbon research: a summary of ocean carbon research, and vision of coordinated ocean carbon research and observations for the next decade” in 2021.