According to www.reuters.com, CO2 emissions could be the cause of coral reefs dying off.

Here is what the article had to say:

"Increasingly acidic oceans and warming water temperatures due to carbon dioxide emissions could kill off the world's ocean reefs by the end of this century, scientists warned on Monday.  The experts told a meeting in London the predicted pace of emissions means a level of 450 parts per million of carbon dioxide (CO2) in the atmosphere will be reached by 2050, putting corals on a path to extinction in the following decades."

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