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

Marcela Cornejo D'Ottone (Chile, marcela.cornejo@pucv.cl)
Guiling Zhang (China, guilingzhang@ouc.edu.cn)
 

Team members

Damian Arévalo-Martínez (The Netherlands, d.arevalomartinez@science.ru.nl)
Dorothee Bakker (United Kingdom, d.bakker@uea.ac.uk)
Tom Bell (United Kingdom, tbe@pml.ac.uk)
Arne Körtzinger (Germany, akoertzinger@geomar.de)
Siv Kari Lauvset (Norway, siv.lauvset@norceresearch.no)
Kitack Lee (Korea, ktl@postech.ac.kr)
Iole B. M. Orselli (Brasil, iole.orselli@furg.br)
Parvadha Suntharalingam (United Kingdom, p.suntharalingam@uea.ac.uk)
Sam Wilson (United States, stwilson@hawaii.edu)
 

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?

 

Priorities

Detailed regional analyses
To better quantify and predict the evolution of oceanic GHG budgets and air-sea fluxes, we highly recommend detailed analyses of GHG fluxes in key regions. These include the Southern Ocean, coastal and marginal seas, and oceanic Oxygen Minimum Zones (OMZs). Recommended approaches include (i) higher resolution numerical models, which represent the coupling of key processes for circulation, ecosystems and relevant biogeochemistry, and (ii) detailed biogeographical sampling of marine ecosystems across gradients to characterise the variations in environmental drivers and GHG fluxes responses. A coordinated synthesis of these approaches is also required to enable accurate quantification and prediction of GHG fluxes from these regions.
Increased density of observations
In order to reliably assess the spatial and temporal variation of air-sea GHG fluxes, significant increases in the coverage of current observations are required; these include measurements from ships, autonomous platforms (e.g., Argo floats, gliders), and moorings. 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. Satellite observations of relevant marine ecosystem and oceanic properties should also be exploited and linked systematically to in-situ oceanic measurements.
Development of new analysis tools and extension of existing methodologies
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). 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.
Links to Ocean Obs’19

 

 

 

Planned activities

See SOLAS Activities 2020-2021 table here

Research programs 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 programs investigating the ocean 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), and the Boknis Eck time series station. Information on planned observational programs and workshops can be found via the respective program websites:

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 development of the Integrated Ocean Carbon Research Plan is now in progress and will most likely be presented in 2020.

 

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