THIS POST IS A CRITICAL REVIEW OF A PNAS PAPER BY TIM DEVRIES OF THE UNIVERSITY OF CALIFORNIA SANTA BARBARA

CITATION: Decadal trends in the ocean carbon sink, Tim DeVries et al, Proceedings of the National Academy of Sciences 2019, 116 (24) 11646-11651; DOI: 10.1073/pnas.1900371116  [LINK]

ABSTRACT:  Measurements show large decadal variability in the rate of CO2 accumulation in the atmosphere that is not driven by CO2 emissions. The decade of the 1990s experienced enhanced carbon accumulation in the atmosphere relative to emissions, while in the 2000s, the atmospheric growth rate slowed, even though emissions grew rapidly. These variations are driven by natural sources and sinks of CO2 due to the ocean and the terrestrial biosphere. In this study, we compare three independent methods for estimating oceanic CO2 uptake and find that the ocean carbon sink could be responsible for up to 40% of the observed decadal variability in atmospheric CO2 accumulation. Data-based estimates of the ocean carbon sink from pCO2 mapping methods and decadal ocean inverse models generally agree on the magnitude and sign of decadal variability in the ocean CO2 sink at both global and regional scales. Simulations with ocean biogeochemical models confirm that climate variability drove the observed decadal trends in ocean CO2 uptake, but also demonstrate that the sensitivity of ocean CO2 uptake to climate variability may be too weak in models. Furthermore, all estimates point toward coherent decadal variability in the oceanic and terrestrial CO2 sinks, and this variability is not well-matched by current global vegetation models. Reconciling these differences will help to constrain the sensitivity of oceanic and terrestrial CO2 uptake to climate variability and lead to improved climate projections and decadal climate predictions.

TRANSLATION: Measurements show that atmospheric composition is not responsive to fossil fuel emissions confirming a finding to that effect in this denier blog [LINK] . The decade of the 1990s experienced enhanced carbon accumulation in the atmosphere relative to emissions, while in the 2000s, the atmospheric growth rate slowed, even though emissions grew rapidly. Therefore these variations must be driven by nature’s carbon cycle as claimed by in the denier blogs: [LINK]

THE INTERPRETATION OF THESE DATA BY THE AUTHORS: The authors use these data to propose a decadal variability in ocean-atmosphere CO2 flux. Then use the same data to test this hypothesis. This kind of hypothesis test suffers from circular reasoning. It is not possible to test a hypothesis with the same data used to construct the hypothesis. In a related post we show that it is not possible detect the impact of fossil fuel emissions on the carbon cycle because carbon cycle flows are an order of magnitude larger and with large uncertainties because these flows cannot be directly measured and must be inferred. [LINK] [LINK] [LINK] .

WHAT DOES THE MASS BALANCE SHOW?  The data show that changes in oceanic CO2 attributed to fossil fuel emissions are not possible because of a mass balance deficit. There is not enough fossil fuel emissions to explain observed annual changes in oceanic CO2. These changes are likely best understood in terms of geological carbon flows in the ocean as for example the CO2 bubbles just off the coast from the University of California Santa Barbara. The relative insignificance of the atmosphere in this respect is discussed in a related post [LINK] .

CONCLUSION: The evidence does not support the claim that fossil fuel emissions can explain changes in atmospheric and oceanic CO2 concentration. There is no evidence that either atmospheric composition or ocean acidification are responsive to fossil fuel emissions at an annual time scale. The climate science dependence on the atmosphere to explain all observed changes ignores much larger geological flows of carbon. [LINK] [LINK] [LINK] [LINK] [LINK]   

POSTSCRIPT: The total mass of the ocean and atmosphere taken together is 1.36E18 metric tonnes of which the atmosphere is 0.38% and the ocean 99.62%. The insistence of climate science that the atmosphere tail wags the ocean dog in terms of heat and carbon dioxide content is not credible in many different ways.