Ocean acidification is not going away

Ocean acidification only pops its head up occasionally in the media now as a dire threat from increasing CO2 in the atmosphere:  probably because it is such an incremental change that it doesn't have the ring of immediate alarm about climate change as do heat waves, floods or fires. 

But it's not going away, even if it is pretty difficult to study.    (Replicating the effect in laboratory settings turned out to be a lot trickier than initially realised.)

There's a new study out on how it affects ocean areas with naturally venting CO2.  I'm sure we've seen similar studies in other places, but it confirms that the future of the coastal areas under high CO2 is more likely green and slimy with less biodiversity:

To assess the likely ecological effects of ocean acidification we compared intertidal and subtidal marine communities at increasing levels of pCO₂ at recently discovered volcanic seeps off the Pacific coast of Japan (34° N). This study region is of particular interest for ocean acidification research as it has naturally low levels of surface seawater pCO₂ (280–320 µatm) and is located at a transition zone between temperate and sub-tropical communities. We provide the first assessment of ocean acidification effects at a biogeographic boundary. Marine communities exposed to mean levels of pCO₂ predicted by 2050 experienced periods of low aragonite saturation and high dissolved inorganic carbon. These two factors combined to cause marked community shifts and a major decline in biodiversity, including the loss of key habitat-forming species, with even more extreme community changes expected by 2100. Our results provide empirical evidence that near-future levels of pCO₂ shift sub-tropical ecosystems from carbonate to fleshy algal dominated systems, accompanied by biodiversity loss and major simplification of the ecosystem.

 A report on the study explains:

They found that while a few plant species benefitted from the changing conditions, they tended to be smaller weeds and algae that blanket the seabed, choking corals and lowering overall marine diversity.

These species, and some smaller marine animals, are thriving because they are more tolerant to the stress posed by rising levels of CO₂.

Jason Hall-Spencer, Professor of Marine Biology at the University of Plymouth, said: "Our research site is like a time machine. In areas with pre-Industrial levels of CO₂ the coast has an impressive amount of calcified organisms such as corals and oysters. But in areas with present-day average levels of surface seawater CO₂ we found far fewer corals and other calcified life, and so there was less biodiversity. It shows the extensive damage caused by humans due to CO₂ emissions over the past 300 years and unless we can get a grip on reducing CO₂ emissions we will undoubtedly see major degradation of coastal systems worldwide."