The oceans have a remarkably stable PH of 8.2-8.3.  That's alkaline, not acidic.

What idiot is recommending lower levels of CO2?  We're coming off dangerously low levels during the Maunder Minimum.  Life ceases to exist at levels below 150 ppm, and thrives at levels well above 1200 ppm.  The Earth has experiences levels of around 10,000 ppm during about half a dozen cycles as life was developing.  "Normal" is between 1200 and 2000 ppm.