Ocean Acidification    (SciAm article)
¥Currently ~1/3 of CO2 released by burning fossil fuels ends up in the ocean.
¥Absorbed CO2 forms carbonic acid in seawater, lowering the slightly alkaline pH level, changing the balance of carbonate & bicarbonate ions.
¥Shift toward acidity & ensuing changes in ocean chemistry, make it more difficult for creatures to build hard parts out of calcium carbonate.
¥Decline in pH thus threatens a variety of organisms, including corals, which provide one of the richest habitats on earth.
¥Within a century, Southern Ocean surface will be corrosive to shells of tiny snails key in the marine food chain within this highly productive zone.