Some parts of oceans getting saltier: Study

Global warming is making some parts of the oceans saltier, a new study has claimed.

Updated: Apr 16, 2010, 18:50 PM IST

Washington: Global warming is making some
parts of the oceans saltier, a new study has claimed.

A research led by Australian scientists showed a clear
link between salinity changes at the surface and changes in
the deeper waters over the last six decades caused by the
warming seen over the same period.

"The saltiness or salinity of the oceans is controlled
by evaporation and rainfall at earth`s surface," said senior
researcher Paul Durack of CSIRO, the Australian government`s
research agency.

"The supercharging of weather patterns by global
warming is making some parts of earth`s oceans much saltier
while others parts are getting fresher," Durack wrote in the
Journal of Climate.

He said, the more evaporation there is at a given patch
of ocean, the more concentrated the salts get in the seawater
and the higher the salinity, however in places where lots of
rain is falling, the water gets more diluted, becoming

The team analysed more than 460,000 oceanic readings
collected by an army of 3,200 autonomous ARGO buoys and after
subtracting out such things as cyclical seasonal salinity
changes and other extreme events, they found a strong signal
of more evaporation and rainfall over the oceans -- an
enhancement to the average surface salinity.

What they found is that the subtropical,
evaporation-dominated waters of the Indian, Atlantic and
Pacific oceans are getting saltier while the tropical and
higher latitude waters are getting fresher -- these later
areas being where there is more rainfall than evaporation over
the year.

But the matter goes deeper than just the ocean surface
water, Durack said, adding "the ARGO buoys don`t just float
around on the surface, they can sink down to two kilometres
below the surface and rise again, gathering data the whole way
to create three dimensional ocean profiles".

These show that the salinity changes are actually
moving, following the paths that ocean water circulates from
the surface into the depths, Discovery Channel reported.

"While such changes in salinity would be expected at
the ocean surface (where about 80 per cent of surface water
exchange occurs), sub-surface measurements indicate much
broader, warming-driven changes are extending into the deep
ocean," said Durack.

"This is probably one of the most significant papers
we`ve seen yet in this area," said Dean Roemmich, part of the
ARGO leadership team.