ALANNA MITCHELL, GLOBE AND MAIL - The delicate salt balance of the
Atlantic Ocean has altered so dramatically in the last four decades
through global warming that it is changing the very heat-conduction
mechanism of the ocean and stands to turn Northern Europe into a frigid
zone. The conclusions are from a study in the journal Nature that is to
be published today. . . The study catalogues profound changes in the
salinity of the tropical and sub-tropical parts of the Atlantic Ocean.
That part of the ocean is becoming saltier because higher average global
temperatures are evaporating more ocean water than normal. Over time,
that water vapour travels north and south to the poles, where it
eventually replenishes colder oceans. Because the overall salt content
of the world's oceans is constant, this means that as the equatorial
ocean becomes saltier, the oceans at the poles are becoming less salty
and more fresh. . .
Under normal conditions, the saltier waters of the far north and south
sink from the surface of the ocean to the deep abyss. Then they are
pulled along the bottom of the ocean back to the equator. As that
massive amount of water moves from north to south, warm water from the
southern Gulf Stream moves north closer to the ocean's surface to fill
the void. It's akin to a gigantic water conveyor belt. . .
But as the waters of the far north become less salty, they lose their
ability to sink from the surface of the ocean to the abyss. The conveyor
belt is slowing down and may eventually stop. "Northern Europe will
likely experience a very significant cooling," Ms. Curry said, adding
that it is expected to be in the order of 5 to 10 C cooler in winter in
the course of 10 to 50 years, which is considered to be extremely rapid
climate change.