ABSTRACT: Detrended correlation analysis of annual fossil fuel emissions and mean annual changes in ocean CO2 concentration in the sample period 1958-2014 shows no evidence that the two series are causally related. The finding is inconsistent with the claim that fossil fuel emissions have a measurable impact on the CO2 concentration of the oceans at a lag and time scale of one 1 year. The results are presented with the disclaimer that the CO2 data time series is discontinuous.

Environmentalists and climate scientists have for long struggled with the issue of fossil fuel emissions because this source of carbon appears to be external and unnatural and foreign to the surface biota, the natural carbon cycle, and to a fragile climate and environmental equilibrium that nurtures life on earth. It is thought that the “extra” CO2 collects in the planet’s CO2 inventories either in the atmosphere where its accumulation can cause dangerous climate change by way of the greenhouse effect and global warming (Callendar, 1938) (Hansen, 1984) (IPCC, 2014), or in the oceans where its unnatural excess can have harmful effects on marine life by way of ocean acidification (Caldeira K. , 2003) (Doney, 2004) (McNeil, 2006). In both cases the time scale of these effects, that is the time from emission to a measurable change in accumulation, is thought to be annual (NOAA-1, 2015) (Scripps, 2013) (IPCC, 2007) (IPCC, 2014). In previous works we looked at the carbon flow accounting methodology that leads to the accumulation hypothesis (Munshi, Uncertain flow accounting, 2015) and presented a critical evaluation of the link between fossil fuel emissions and changes in atmospheric composition (Munshi, Responsiveness of Atmospheric CH4, 2015) (Munshi, Responsiveness of atmospheric CO2, 2015). In this short note we look at empirical evidence that could support a causal link between fossil fuel emissions and ocean acidification.

The oceans form the largest known reservoir of inorganic CO2 on the surface of the planet. As such it plays an important role in the natural carbon cycle and in the ‘carbon budget’ of the surface-atmosphere climate system (IPCC, 2014). According to the IPCC, the inorganic dissolved CO2 content of the oceans, not including the ocean floor, was 38,000 GTC (gigatons of carbon equivalent) in 2009 (IPCC, 2014). Using a figure of 1.35×10 21 liters as the volume of the oceans, the equivalent CO2 concentration of the oceans is 2.345 mmol/L (millimoles per liter) in close agreement with more than 124,000 measurements made by oceanic research vessels since 1958 that show an average of 2.244 mmol/L. This work adds to the rich and growing body of investigation into the impact of fossil fuel emissions on ocean acidification by presenting this data in relation to fossil fuel emissions as an empirical study to complement prior works that relied mostly on climate models and laboratory experiments (Cornwall, 2015) (Caldeira K. , 2003) (McNeil, 2006) (Flynn, 2015) (Munday, 2011).

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