Over the last 50 years, the satly parts of the oceans have become saltier and the fresh reigons have become fresher, and the percentage of change is greater than scientists can possibly explain.
Many oceanographers have a hunch about what is going on: climate change. Ray Schmitt, a senior scientist at Woods Hole Oceanographic Institution, said "Climate is changing all the time, and some of that change is due to natrual variation. The 50-year trend we are talking about, most of us believe is really due to global warming."
This is really important because the ocean is the heart of the planets water cycle. 86% of global evaporation and 79% of global precipitation occur over the ocean. More evaporation, as compared to precipitaion, translates into saltier water. All the while, in regions where precipitation is favored, water is fresher.
How this works is: Compared to fresh water, salt water is heavier, so its more prone to sinking. Temperature has simular effect, with warmth causing the water to rise. Differences in salinity and temperature turn a slow-moving conveyor belt of ocean currents that encircles the planet.
It may work out that higher xalinity in some reigons counterbalances fresher waters in others, Schmitt said: "It is a delicate balance and what we think it is now is not too likely, the conveyor belt is going to shut down anytime soon."
http://news.yahoo.com/mysterious-changes-ocean-salt-spur-nasa-expedition-155938671.html
PS. I know its not a United Stated Event but I thought it was really interesting.
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