The warming climate may earn carbon dioxide all the headlines (including ones about senators who can’t tell the difference between a couple blizzards and a 130-year climate record), but the gas is having another effect that’s less familiar but no less devastating. Some of the carbon dioxide we pump into the air gets sucked into the ocean, where it lowers the pH of seawater. We’ve already dropped the pH of the ocean measurably, and as we burn more fossil fuels we will drop it more. Ocean acidification has the potential to wreak world-wide havoc on marine life.

Today in Yale Environment 360, I write about scientists comparing today’s ocean acidification to the last time something comparable happened–55 million years ago.