Editing IPCC:AR6/WGI/Chapter-4 (section)

==== 4.3.2.5 Surface Ocean pH ====

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The AR5 assessed from CMIP5 simulations that it is ''virtually certain'' that increasing storage of carbon by the ocean under all four RCPs through to 2100 will increase ocean acidification in the future ( [[#Ciais--2013|Ciais et al., 2013]] ). Specifically, AR5 reported that CMIP5 models project increased ocean acidification globally to 2100 under all RCPs, and that the corresponding model mean and model spread in the decrease in surface ocean pH from 1986–2005 to 2081–2100 would be 0.065 (0.06–0.07) for RCP2.6, 0.145 (0.14–0.15) for RCP4.5, 0.203 (0.20–0.21) for RCP6.0 and 0.31 (0.30–0.32) for RCP8.5.

Based on results from the CMIP6 models we conclude that, except for the lower-emissions scenarios SSP1-1.9 and SSP1-2.6, ocean surface pH decreases monotonically through the 21st century ( ''high confidence'' ) (Figure 4.8).

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[[File:c3df335bb75a1ec547422e0caa92442f IPCC_AR6_WGI_Figure_4_8.png]]

'''Figure''' '''4.8 |''' '''Global average surface ocean pH.''' The shadings around the SSP1-2.6 and SSP5-7.0 curves are the 5–95% ranges across those ensembles. The numbers inside each panel are the number of model simulations. Results are from concentration-driven simulations. Further details on data sources and processing are available in the chapter data table (Table 4.SM.1).

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