Tropical ocean waters have become dramatically saltier over the past 40 years, while oceans closer to Earth's poles have become fresher, scientists reported today in the journal Nature. Earth's warming surface may be intensifying evaporation over oceans in the low latitudes -- raising salinity concentrations there -- and transporting more fresh water vapor via the atmosphere toward Earth's poles. These large-scale, relatively rapid oceanic changes suggest that recent climate changes, including global warming, may be altering the fundamental planetary system that regulates evaporation and precipitation and cycles fresh water around the globe. The study was conducted by Ruth Curry, a...