Ocean acidification rate may be unprecedented

The world's oceans may be turning acidic faster today from human carbon emissions than they did during four major extinctions in the last 300 million years, when natural pulses of carbon sent global temperatures soaring, according to a study to be published on Friday in journal Science. In a review of hundreds of paleoceanographic studies, a team of researchers from five countries assessed in detail a number of climate change events in the planet's history, including the asteroid impact that made the dinosaurs go extinct and the Permian mass-extinction which wiped out around 95 percent of all life on Earth. They found that current rates of ocean acidification are unparalleled in Earth's history. "The geological record suggests that the current acidification is potentially unparalleled in at least the last 300 million years of Earth history, and raises the possibility that we are entering an unknown territory of marine ecosystem change," said Andy Ridgwell, a University of Bristol professor, in a statement. Oceans are currently absorbing about a quarter of the CO2 released into the atmosphere, lowering the pH of the surface ocean. As atmospheric CO2 increases, so does the rate at which it will dissolve in seawater, forcing surface ocean pH lower and lower -- a process called ocean acidification. Laboratory experiments suggest that if the pH continues to fall, we may start to see impacts on marine organisms such as slower growth, fewer offspring, muscle wastage, dwarfism, reduced activity and the dissolution of their carbonate shells -- with knock-on effects throughout the marine ecosystem.