• shareshare
  • link
  • cite
  • add
auto_awesome_motion View all 2 versions
Other research product . 2019

Sensitivity of atmospheric CO2 to regional variability in particulate organic matter remineralization depths

Wilson, Jamie D.; Barker, Stephen; Edwards, Neil R.; Holden, Philip B.; Ridgwell, Andy;
Open Access
Published: 31 Jul 2019

The concentration of CO2 in the atmosphere is sensitive to changes in the depth at which sinking particulate organic matter is remineralized: often described as a change in the exponent “b” of the Martin curve. Sediment trap observations from deep and intermediate depths suggest there is a spatially heterogeneous pattern of b, particularly varying with latitude, but disagree over the exact spatial patterns. Here we use a biogeochemical model of the phosphorus cycle coupled with a steady-state representation of ocean circulation to explore the sensitivity of preformed phosphate and atmospheric CO2 to spatial variability in remineralization depths. A Latin hypercube sampling method is used to simultaneously vary the Martin curve independently within 15 different regions, as a basis for a regression-based analysis used to derive a quantitative measure of sensitivity. Approximately 30 % of the sensitivity of atmospheric CO2 to changes in remineralization depths is driven by changes in the subantarctic region (36 to 60∘ S) similar in magnitude to the Pacific basin despite the much smaller area and lower export production. Overall, the absolute magnitude of sensitivity is controlled by export production, but the relative spatial patterns in sensitivity are predominantly constrained by ocean circulation pathways. The high sensitivity in the subantarctic regions is driven by a combination of high export production and the high connectivity of these regions to regions important for the export of preformed nutrients such as the Southern Ocean and North Atlantic. Overall, regionally varying remineralization depths contribute to variability in CO2 of between around 5 and 15 ppm, relative to a global mean change in remineralization depth. Future changes in the environmental and ecological drivers of remineralization, such as temperature and ocean acidification, are expected to be most significant in the high latitudes where CO2 sensitivity to remineralization is also highest. The importance of ocean circulation pathways to the high sensitivity in subantarctic regions also has significance for past climates given the importance of circulation changes in the Southern Ocean.

53 references, page 1 of 6

Boyd, P. W.: Toward quantifying the response of the oceans' biological pump to climate change, Front. Mar. Sci., 2, 77,, 2015.

Cael, B. B. and Bisson, K.: Particle Flux Parameterizations: Quantitative and Mechanistic Similarities and Differences, Front. Mar. Sci., 5, 395,, 2018. [OpenAIRE]

Cao, L. and Zhang, H.: The role of biological rates in the simulated warming effect on oceanic CO2 uptake, J. Geophys. Res.-Biogeo., 122, 1098-1106,, 2017.

Chikamoto, M. O., Abe-Ouchi, A., Oka, A., and Smith, S. L.: Temperature-induced marine export production during glacial period, Geophys. Res. Lett., 39, L21601,, 2012.

Cram, J. A., Weber, T., Leung, S. W., McDonnell, A. M. P., Liang, J.-H., and Deutsch, C.: The Role of Particle Size, Ballast, Temperature, and Oxygen in the Sinking Flux to the Deep Sea, Global Biogeochem. Cy., 32, 858-876,, 2018.

DeVries, T., Primeau, F., and Deutsch, C.: The sequestration efficiency of the biological pump, Geophys. Res. Lett., 39, l13601,, 2012. [OpenAIRE]

DeVries, T., Liang, J.-H., and Deutsch, C.: A mechanistic particle flux model applied to the oceanic phosphorus cycle, Biogeosciences, 11, 5381-5398, 2014, 2014.

Duteil, O., Koeve, W., Oschlies, A., Bianchi, D., Galbraith, E., Kriest, I., and Matear, R.: A novel estimate of ocean oxygen utilisation points to a reduced rate of respiration in the ocean interior, Biogeosciences, 10, 7723-7738, 7723-2013, 2013.

Eggleston, S. and Galbraith, E. D.: The devil's in the disequilibrium: multi-component analysis of dissolved carbon and oxygen changes under a broad range of forcings in a general circulation model, Biogeosciences, 15, 3761-3777,, 2018. [OpenAIRE]

Fay, A. R. and McKinley, G. A.: Global open-ocean biomes: mean and temporal variability, Earth Syst. Sci. Data, 6, 273-284,, 2014.

Funded by
UKRI| CO2-CarbonCycle-Climate-Interactions (C4I)
  • Funder: UK Research and Innovation (UKRI)
  • Project Code: NE/H017240/1
  • Funding stream: NERC
PAst Links in the Evolution of Ocean’s Global ENvIronment and Ecology
  • Funder: European Commission (EC)
  • Project Code: 617313
  • Funding stream: FP7 | SP2 | ERC
Related to Research communities
European Marine Science Marine Environmental Science : PAst Links in the Evolution of Ocean’s Global ENvIronment and Ecology