Is there a link to the study being referenced? I couldn't find any citations. Ocean acidification is worth talking about, but this article is sensational as heck. Constant use of dire language ("safe limit ... exceeded", "crucial threshold ... breached", "safe boundaries ... crossed", "sustainable levels ... exceeded", "close to the danger limit") with no values explained or interpreted for the reader and only vague references to imminent catastrophe.
Maybe it's talking about this new NOAA dashboard, it's hard to tell, but I think this was a much better read: