[at-l] Atlantic Thermo Cycle And Global Warming

[RoksnRoots at aol.com (RoksnRoots@aol.com)]

      From the NY Times:


         "   ~ ~ Normally, water circulates in the North Atlantic like this: 
Cold, salty water at the top sinks; that sinking water acts as a pump, pulling 
warm Gulf Stream water north and thus moderating winter weather. But now, 
fresh water from the thawing ice and heavier rain is accumulating near the 
ocean's surface; it's not sinking as quickly. (The tropics are faced with the 
opposite phenomenon. According to Dr Ruth Curry and her colleagues at the Woods Hole 
Oceanographic Institution, the tropical Atlantic is becoming saltier; as 
warming increases, so does evaporation, which leaves behind salt.) The 
"freshening" in the North Atlantic may be contributing to a high-pressure system that is 
accelerating trans-Atlantic winds and deflecting the jet stream - changes that 
may be driving frigid fronts down the Eastern Seaboard. The ice-core records 
demonstrate that the North Atlantic can freshen to a point where the deep 
water pump fails, warm water stops coming north, and the northern ocean suddenly 
freezes, as it did in the last Ice-Age. No one can say if that is what will 
happen next. But since the 1950's, the best documented deep-water pump, between 
Iceland and Scotland, has slowed 20 percent.

      Why now? After all, the planet's previous periods of global warming 
resulted from changes in the earth's tilt towards the sun, and recent 
calculations of these cycles indicate that our hospitable climate was not due to have 
ended any time soon. But because of the warming brought by the buildup of carbon 
dioxide, mainly from the burning of fossil fuels, the equations have changed. 
We are entering uncharted waters. It's something for New Yorkers to ponder as 
they bundle up. "