Ocean acidification at 450ppm

Southern Ocean acidification: A tipping point at 450-ppm atmospheric CO2 — PNAS

I don't think I have quoted before from this paper which came out last year. It predicts aragonite undersaturation in the Southern Oceans by 2038 (assuming we hit CO2 of 450 ppm by 2030), which is earlier than previously thought, and the consequences of that are set out pretty well in this paragraph:

Early aragonite undersaturation is of particular concern for the zooplankton species comprising Pteropods, which form aragonite shells. Southern Ocean Pteropods comprise up to one-quarter of total zooplankton biomass in the Ross Sea (13), Weddell Sea (14), and East Antarctica (15), can sometimes displace krill as the dominant zooplankton (16), and dominate carbonate export fluxes south of the Antarctic Polar Front (17), and even organic carbon export (18). Pteropods in Southern Ocean sediment traps show partial dissolution and “frosted” appearance of shells just below the aragonite saturation horizon (17, 19), indicating vulnerability to low carbonate ion concentrations. The most dominant Southern Ocean Pteropod species is Limacina helicina, with Limacina retroversa and others playing a smaller role (20). The dominant species, L. helicina, is known to have a life cycle of 1–2 years with important veliger larval development during winter months (20–22), which will be adversely impacted by early wintertime aragonite undersaturation. Given their multiyear life cycles, our results imply that Pteropods in the Southern Ocean will need to withstand aragonite undersaturation far sooner than previously predicted with possible significant effects throughout the Southern Ocean marine food web.

Just thought you should know. Politicians seem so shy of mentioning the effect of CO2 on oceans, though.