acidifying oceans
If carbon dioxide emissions keep rising, surface waters could become more acidic than they have been for 300 million years - except perhaps during global catastrophes. And this warning follows a report that the biological productivity of the oceans has fallen by six per cent since the 1980s.

"We are changing the chemistry of the ocean and we don't know what it's going to do," says Ken Caldeira, a climate specialist at Lawrence Livermore National Laboratory in California.
�Jeff Hecht/New Scientist 09.25 .03