A microscopic marine alga is thriving in the North Atlantic to an extent that defies scientific predictions, suggesting swift environmental change as a result of increased carbon dioxide in the ocean, a study led a by Johns Hopkins University scientist has found.What these findings mean remains to be seen, as does whether the rapid growth in the tiny plankton's population is good or bad news for the planet.Published today in the journal Science, the study details a tenfold increase in the abundance of single-cell coccolithophores between 1965 and 2010, and a particularly sharp spike since the late 1990s in the population of these pale-shelled floating phytoplankton.