What do changes in ocean salinity tell us about the global water cycle?

What does an amplified global water cycle look like?  While an intensification of the water cycle means increased evaporation and precipitation from both land and ocean surfaces, a recent article in the journal Science cites that "efforts to detect this long-term response in sparse surface observations of rainfall and evaporation remain ambiguous" and reports that "ocean salinity patterns express an identifiable fingerprint of an intensifying water cycle." The figure above depicts absolute surface salinity change over the period 1950-2000 (Durack & Wijffels, 2010) with blue representing ocean regions exhibiting a decreased salinity (freshening) and dominated by precipitation and red indicating ocean regions exhibiting increased salinity (salinification) and dominated by evaporation.

The authors of the Science article conclude that "ocean salinity is a particularly sensitive marker of water cycle change that provides us with a salty ocean–freshwater “gauge” from which to monitor 71% of Earth’s surface. Prompt your students to consider what changes to the water cycle will mean both locally and globally.

For more information visit CSIRO's Ocean Change Portal: Salinity.

Alignment to NC Essential Standards  (grades 9-12)
Bio2.1.1
EEn.2.3.1
EEn2.6.4