Blog Archive

Wednesday, October 31, 2018

Quantification of ocean heat uptake from changes in atmospheric O2 and CO2 composit

Nature, 563 (31 October 2018) 105-108

Quantification of ocean heat uptake from changes in atmospheric O2 and COcomposit


The ocean is the main source of thermal inertia in the climate system1. During recent decades, ocean heat uptake has been quantified by using hydrographic temperature measurements and data from the Argo float program, which expanded its coverage after 20072,3. However, these estimates all use the same imperfect ocean dataset and share additional uncertainties resulting from sparse coverage, especially before 20074,5. Here we provide an independent estimate by using measurements of atmospheric oxygen (O2) and carbon dioxide (CO2)—levels of which increase as the ocean warms and releases gases—as a whole-ocean thermometer. We show that the ocean gained 1.33 ± 0.20  × 1022 joules of heat per year between 1991 and 2016, equivalent to a planetary energy imbalance of 0.83 ± 0.11 watts per square metre of Earth’s surface. We also find that the ocean-warming effect that led to the outgassing of O2 and CO2 can be isolated from the direct effects of anthropogenic emissions and CO2 sinks. Our result—which relies on high-precision O2 measurements dating back to 19916—suggests that ocean warming is at the high end of previous estimates, with implications for policy-relevant measurements of the Earth response to climate change, such as climate sensitivity to greenhouse gases7 and the thermal component of sea-level rise8.


  1. 1.
    IPCC. Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) (Cambridge Univ. Press, Cambridge, 2013).
  2. 2.
    Abraham, J. P. et al. A review of global ocean temperature observations: implications for ocean heat content estimates and climate change. Rev. Geophys51, 450–483 (2013).
  3. 3.
    Riser, S. C. et al. Fifteen years of ocean observations with the global Argo array. Nat. Clim. Chang e 6, 145–153 (2016).
  4. 4.
    Boyer, T. et al. Sensitivity of global upper-ocean heat content estimates to mapping methods, XBT bias corrections, and baseline climatologies. J. Clim29, 4817–4842 (2016).
  5. 5.
    Cheng, L. et al. XBT science: assessment of instrumental biases and errors. Bull. Am. Meteorol. Soc97, 924–933 (2016).
  6. 6.
    Keeling, R. F. & Manning, A. C. in Treatise on Geochemistry 385–404 (Elsevier, Oxford, 2014).
  7. 7.
    Forster, P. M. Inference of climate sensitivity from analysis of Earth’s energy budget. Annu. Rev. Earth Planet. Sci44, 85–106 (2016).
  8. 8.
    Church, J. A. et al. in Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) 1137–1216 (IPCC, Cambridge Univ. Press, Cambridge, 2013).
  9. 9.
    Ishii, M. et al. Accuracy of global upper ocean heat content estimation expected from present observational data sets. Sci. Online Lett. Atmos13, 163–167 (2017).
  10. 10.
    Johnson, G. C. et al. Ocean heat content. Am. Meteorol. Soc. Bull98, S66–S68 (2017).
  11. 11.
    Desbruyères, D. G., Purkey, S. G., McDonagh, E. L., Johnson, G. C. & King, B. A. Deep and abyssal ocean warming from 35 years of repeat hydrography. Geophys. Res. Lett43, 10356–10365 (2016).
  12. 12.
    Cheng, L. et al. Improved estimates of ocean heat content from 1960 to 2015. Sci. Adv3, e1601545 (2017).
  13. 13.
    Allan, R. P. et al. Changes in global net radiative imbalance 1985–2012. Geophys. Res. Lett41, 5588–5597 (2014).
  14. 14.
    Palmer, M. D. Reconciling estimates of ocean heating and Earth’s radiation budget. Curr. Clim. Change Rep3, 78–86 (2017).
  15. 15.
    Loeb, N. G. et al. Observed changes in top-of-the-atmosphere radiation and upper-ocean heating consistent within uncertainty. Nat. Geosci5, 110–113 (2012).
  16. 16.
    Battle, M. et al. Measurements and models of the atmospheric Ar/N2 ratio. Geophys. Res. Lett30, 1786 (2003).
  17. 17.
    Ritz, S. P., Stocker, T. F. & Severinghaus, J. P. Noble gases as proxies of mean ocean temperature: sensitivity studies using a climate model of reduced complexity. Quat. Sci. Rev30, 3728–3741 (2011).
  18. 18.
    Resplandy, L. et al. Constraints on oceanic meridional heat transport from combined measurements of oxygen and carbon. Clim. Dyn47, 3335–3357 (2016); erratum 49, 4317 (2017).
  19. 19.
    Stephens, B. B. et al. Testing global ocean carbon cycle models using measurements of atmospheric O2 and CO2 concentration. Glob. Biogeochem. Cycles12, 213–230 (1998).
  20. 20.
    Le Quéré, C. et al. Global carbon budget 2016. Earth Syst. Sci. Data 8, 605–649 (2016).
  21. 21.
    DeVries, T. The oceanic anthropogenic CO2 sink: storage, air-sea fluxes, and transports over the industrial era. Glob. Biogeochem. Cycles 28, 631–647 (2014).
  22. 22.
    Wang, R. et al. Influence of anthropogenic aerosol deposition on the relationship between oceanic productivity and warming. Geophys. Res. Lett42, 10745–10754 (2015).
  23. 23.
    Rietbroek, R., Brunnabend, S.-E., Kusche, J., Schröter, J. & Dahle, C. Revisiting the contemporary sea-level budget on global and regional scales. Proc. Natl Acad. Sci. USA 113, 1504–1509 (2016).
  24. 24.
    IPCC. Climate Change 2007: Synthesis Report (eds Core Writing Team, Pachauri, R. K. & Reisinger, A.) (IPCC, Geneva, 2008).
  25. 25.
    Keeling, R. F. & Severinghaus, J. P. in The Carbon Cycle (eds Wigley, T. M. L. & Schimel, D.) 134–140 (Cambridge Univ. Press, New York, 2000).
  26. 26.
    Resplandy, L., Séférian, R. & Bopp, L. Natural variability of CO2 and O2 fluxes: what can we learn from centuries-long climate models simulations? J. Geophys. Res. Oceans 120, 384–404 (2015).
  27. 27.
    Eddebbar, Y. A. et al. Impacts of ENSO on air-sea oxygen exchange: observations and mechanisms. Glob. Biogeochem. Cycles 31, 2017GB005630 (2017).
  28. 28.
    Keeling, R. F. & Garcia, H. E. The change in oceanic O2 inventory associated with recent global warming. Proc. Natl Acad. Sci. USA 99, 7848–7853 (2002).
  29. 29.
    Bopp, L., Le Quéré, C., Heimann, M., Manning, A. C. & Monfray, P. Climate-induced oceanic oxygen fluxes: implications for the contemporary carbon budget. Glob. Biogeochem. Cycles 16, 1022 (2002).
  30. 30.
    Keeling, C. D., Piper, S. C., Whorf, T. P. & Keeling, R. F. Evolution of natural and anthropogenic fluxes of atmospheric CO2 from 1957 to 2003. Tellus B Chem. Phys. Meterol63, 1–22 (2011).
  31. 31.
    Levitus, S. et al. World ocean heat content and thermosteric sea level change (0–2000 m), 1955–2010. Geophys. Res. Lett39, L10603 (2012).
  32. 32.
    Olsen, A. et al. The Global Ocean Data Analysis Project version 2 (GLODAPv2)—an internally consistent data product for the world ocean. Earth Syst. Sci. Data 8, 297–323 (2016).
  33. 33.
    Severinghaus, J. P. Studies of the Terrestrial O 2 and Carbon Cycles in Sand Dune Gases and in Biosphere. PhD Thesis, Columbia Univ. (1995).
  34. 34.
    Hamme, R. C. & Keeling, R. F. Ocean ventilation as a driver of interannual variability in atmospheric potential oxygen. Tellus B Chem. Phys. Meterol60, 706–717 (2008).
  35. 35.
    Andres, R. J., Boden, T. A. & Higdon, D. A new evaluation of the uncertainty associated with CDIAC estimates of fossil fuel carbon dioxide emission. Tellus B Chem. Phys. Meterol66, 23616 (2014).
  36. 36.
    Keeling, R. F., Manning, A. C., Paplawsky, W. J. & Cox, A. C. On the long-term stability of reference gases for atmospheric O2/N2 and CO2 measurements. Tellus B Chem. Phys. Meterol59, 3–14 (2007).
  37. 37.
    Ballantyne, A. P. et al. Audit of the global carbon budget: estimate errors and their impact on uptake uncertainty. Biogeosciences 12, 2565–2584 (2015).
  38. 38.
    Bronselaer, B., Winton, M., Russell, J., Sabine, C. L. & Khatiwala, S. Agreement of CMIP5 simulated and observed ocean anthropogenic CO2 uptake. Geophys. Res. Lett44, 12298–12305 (2017).
  39. 39.
    Oeschger, H., Siegenthaler, U., Schotterer, U. & Gugelmann, A. A box diffusion model to study the carbon dioxide exchange in nature. Tellus 27, 168–192 (1975).
  40. 40.
    MacFarling Meure, C. et al. Law Dome CO2, CH4 and N2O ice core records extended to 2000 years BP. Geophys. Res. Lett33, L14810 (2006).
  41. 41.
    Wang, D., Gouhier, T. C., Menge, B. A. & Ganguly, A. R. Intensification and spatial homogenization of coastal upwelling under climate change. Nature 518, 390–394 (2015).
  42. 42.
    Ito, T., Nenes, A., Johnson, M. S., Meskhidze, N. & Deutsch, C. Acceleration of oxygen decline in the tropical Pacific over the past decades by aerosol pollutants. Nat. Geosci9, 443–447 (2016).
  43. 43.
    Jickells, T. D. et al. A reevaluation of the magnitude and impacts of anthropogenic atmospheric nitrogen inputs on the ocean. Glob. Biogeochem. Cycles 31, 289–305 (2017).
  44. 44.
    Somes, C. J., Landolfi, A., Koeve, W. & Oschlies, A. Limited impact of atmospheric nitrogen deposition on marine productivity due to biogeochemical feedbacks in a global ocean model. Geophys. Res. Lett43, 4500–4509 (2016).
  45. 45.
    Aumont, O., Ethé, C., Tagliabue, A., Bopp, L. & Gehlen, M. PISCES-v2: an ocean biogeochemical model for carbon and ecosystem studies. Geosci. Model Dev8, 2465–2513 (2015).
  46. 46.
    Talley, L. D. et al. Changes in ocean heat, carbon content, and ventilation: a review of the first decade of GO-SHIP global repeat hydrography. Annu. Rev. Marine Sci8, 185–215 (2016).
  47. 47.
    Sarmiento, J. L. & Gruber, N. Sinks for anthropogenic carbon. Phys. Today 55, 30–36 (2002).
  48. 48.
    Garcia, H. E. & Gordon, L. I. Oxygen solubility in seawater: better fitting equations. Limnol. Oceanogr37, 1307–1312 (1992).
  49. 49.
    Gruber, N., Sarmiento, J. L. & Stocker, T. F. An improved method for detecting anthropogenic CO2in the oceans. Glob. Biogeochem. Cycles 10, 809–837 (1996).
  50. 50.
    Dunne, J. P. et al. GFDL’s ESM2 global coupled climate–carbon Earth system models. Part I: physical formulation and baseline simulation characteristics. J. Clim25, 6646–6665 (2012).
  51. 51.
    Dunne, J. P. et al. GFDL’s ESM2 global coupled climate–carbon Earth system models. Part II: carbon system formulation and baseline simulation characteristics. J. Clim26, 2247–2267 (2013).
  52. 52.
    Séférian, R., Iudicone, D., Bopp, L., Roy, T. & Madec, G. Water mass analysis of effect of climate change on air–sea CO2 fluxes: the Southern Ocean. J. Clim25, 3894–3908 (2012).
  53. 53.
    Kay, J. E. et al. The Community Earth System Model (CESM) large ensemble project: a community resource for studying climate change in the presence of internal climate variability. Bull. Am. Meteorol. Soc96, 1333–1349 (2015).
  54. 54.
    Keller, D. P., Oschlies, A. & Eby, M. A new marine ecosystem model for the University of Victoria Earth System Climate Model. Geosci. Model Dev5, 1195–1220 (2012).
  55. 55.
    Bopp, L. et al. Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models. Biogeosciences 10, 6225–6245 (2013).
  56. 56.
    Keller, D. P., Kriest, I., Koeve, W. & Oschlies, A. Southern Ocean biological impacts on global ocean oxygen. Geophys. Res. Lett43, 6469–6477 (2016).
  57. 57.
    Long, M. C., Deutsch, C. & Ito, T. Finding forced trends in oceanic oxygen. Glob. Biogeochem. Cycles30, 381–397 (2016).
  58. 58.
    Taylor, K. E., Stouffer, R. J. & Meehl, G. A. An overview of CMIP5 and the experiment design. Bull. Am. Meteorol. Soc93, 485–498 (2012).
  59. 59.
    Moore, J. K., Lindsay, K., Doney, S. C., Long, M. C. & Misumi, K. Marine ecosystem dynamics and biogeochemical cycling in the Community Earth System Model [CESM1(BGC)]: comparison of the 1990s with the 2090s under the RCP4.5 and RCP8.5 scenarios. J. Clim26, 9291–9312 (2013).
  60. 60.
    Rödenbeck, C., Le Quéré, C., Heimann, M. & Keeling, R. F. Interannual variability in oceanic biogeochemical processes inferred by inversion of atmospheric O2/N2 and CO2 data. Tellus B Chem. Phys. Meterol60, 685–705 (2008).
  61. 61.
    Hamme, R. C. Mechanisms controlling the global oceanic distribution of the inert gases argon, nitrogen and neon. Geophys. Res. Lett29, 35-1–35-4 (2002).
  62. 62.
    Trenberth, K. E., Fasullo, J. T., von Schuckmann, K. & Cheng, L. Insights into Earth’s energy imbalance from multiple sources. J. Clim29, 7495–7505 (2016).
  63. 63.
    WCRP Global Sea Level Budget Group. Global sea level budget 1993–present. Earth Syst. Sci. Data 10, 1551–1590 (2018).
  64. 64.
    Morice, C. P., Kennedy, J. J., Rayner, N. A. & Jones, P. D. Quantifying uncertainties in global and regional temperature change using an ensemble of observational estimates: the HadCRUT4 data set. J. Geophys. Res. Atmos117, D08101 (2012).
  65. 65.
    Hansen, J., Ruedy, R., Sato, M. & Lo, K. Global surface temperature change. Rev. Geophys48, RG4004 (2010).
  66. 66.
    Vose, R. S. et al. NOAA’s merged land–ocean surface temperature analysis. Bull. Am. Meteorol. Soc93, 1677–1685 (2012).
  67. 67.
    Keeling, R. F., Körtzinger, A. & Gruber, N. Ocean deoxygenation in a warming world. Annu. Rev. Mar. Sci2, 199–229 (2010).
  68. 70.
    Schmidtko, S., Stramma, L. & Visbeck, M. Decline in global oceanic oxygen content during the past five decades. Nature 542, 335–339 (2017).
  69. 68.
    Helm, K. P., Bindoff, N. L. & Church, J. A. Observed decreases in oxygen content of the global ocean. Geophys. Res. Lett38, L23602 (2011).
  70. 69.
    Ito, T., Minobe, S., Long, M. C. & Deutsch, C. Upper ocean O2 trends: 1958–2015. Geophys. Res. Lett44, 4214–4223 (2017).

No comments: