We know that average sea levels have risen over the past century, and that global warming is to blame. But what is climate change doing to the saltiness, or salinity, of our oceans? This is an important question because big shifts in salinity could be a warning that more severe droughts and floods are on their way, or even that global warming is speeding up. Now, new research coming out of the United Kingdom (U.K.) suggests that the amount of salt in seawater is varying in direct response to man-made climate change.