About 55 million years ago, in the Eocene, volcanic activity
spewed enormous amounts of carbon dioxide into the air. The
earth warmed by 4-5 degrees Centigrade. All surface ice melted,
and every place on earth became tropical, even Antarctica. Sea
levels rose a great deal and a significant amount of land was
lost to the sea. It is estimated that sea levels rise some 10 to
20 meters (yards) for every 1 degree C increase in the average
surface temperature, over the long term. But along with all that
dramatic change came something else. The seas absorbed a lot of
the new carbon dioxide, creating carbonic acid. About 50% of
some sorts of sea creatures did not survive the change. The
earth is repeating the experiment today, with human beings
spewing out enormous amounts of carbon dioxide. And faster. Much
faster indeed than in the Eocene. Because of acidification and
over-fishing, the world could lose a large number of ocean
species just in the next 40 years or so.