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2013-02-07. With a grain of salt -- Ocean surface layer captures influence of human activity.

posted Mar 20, 2013, 11:02 AM by Alan Gould
| Rachel Berkowitz, Physics Today. Relevant to GSS Climate Change chapter 7. Excerpt:  ...In a warming world, increased temperature means that the atmosphere can hold and transport more water vapor—a 7% increase in atmospheric moisture content for every degree Celsius of warming in Earth's lower troposphere. This affinity for moisture affects the entire water cycle, throughout the global climate system. Change is especially reflected in increased patterns of evaporation and precipitation, and a corresponding increase in ocean surface salinity, since surface salinity patterns respond to water cycle changes. ...In the past 50 years, salinity differences—the marker of the oceanic water cycle—have intensified in the upper 700 m of the ocean. “Think of the ocean as a big rain gauge,” says John Toole, physical oceanographer at Woods Hole Oceanographic Institution. Salty regions become saltier because more water is exported through evaporation, and fresh regions become fresher because increased rainfall dilutes those regions more. ...Changing the ocean's salinity and temperature also affects its water density, which in turn plays a key role in how water circulates. ...it takes a long time for surface effects to change deep ocean circulation patterns.... See full article at http://www.physicstoday.org/daily_edition/down_to_earth/with_a_grain_of_salt?type=PTFAVE.