The Coastal Post - January, 1996

The Climate Is Really Changing

BY JIM SCANLON

More storms and...?

The Great Atlantic Conveyor Belt seems to be speeding up, bringing more warm surface water from the tropical Atlantic Ocean up to the freezing cold Arctic—which would be a lot colder if this global conveyor belt ever shut down, as it seems to have done in the past.

According to EOS, the weekly newspaper of the American Geophysical Union, 1995 was a record year for hurricanes and this may be an indication that the conveyor belt has speeded up, and also a signal that the 25-year lull in destructive Atlantic storms is over.

What drives the conveyor belt is the sinking of North Atlantic salt water after it gives up its heat and warms the atmosphere, thereby making Europe inhabitable. As it cools, salt water becomes dense and sinks, and this on an enormous scale is what drives an incredible current thousands of miles along the bottom of the Atlantic to the southern hemisphere and even hooking around into the Indian and Pacific Oceans. Warm surface waters heated by the equatorial sun move north to replace the cold sunken northern surface water. This system is called the conveyor belt.

No one knows exactly why warmer water off the coast of Africa, increased rain in the Sahel (south of the Sahara Desert) and the weakening of trade winds and El Nino off South America results in an increase in the number and severity of Atlantic Hurricanes, but researchers at Colorado State University have worked out a formula for predicting hurricanes that is so accurate as to be astonishing.

Over the last eight years the number of hurricanes predicted has been totally accurate three times, and has missed by one four times. This year nine were predicted but actually 11 occurred. The prediction for next year is for a few less storms but more than normal.

This year an upper atmospheric weather system over the East Coast prevented most storms from slamming into land and causing enormous destruction. Next year that system might not be there.

During the hurricane lull over the past 25 years, the entire eastern coast of the U.S. has been heavily built up and populated. Sensible people warned of the dangers of building on sand spits and barrier islands off the mainland, yet still build. With sea level rising slightly year in, year out, the stage seems to be set for ever-great domestic environmental and human disasters to fill our television screens each evening.

And, on another level, an increase in temperature which resulted in a massive runoff of glacial melt water could cause a massive increase in fresh water over the surface of the North Atlantic. This would slow down, or even shut down the conveyor belt and send Europe into a very deep freeze—and this has happened before, according to historical records and records written in ice cores.

Retreating glaciers

In the same issue of EOS, it is reported that Alpine glaciers all over the world are shrinking fast. Warming of higher elevations in the tropics is unexpectedly increasing and temperatures at high elevations in Peru may be higher now than at any time in the past 1,500 years and perhaps for an even longer period in China.

The computer programs attempting to conceptualize what will happen as human societies continue to grow, industrialize and change the atmosphere, predict that warming will take place mostly over high latitudes, but not the tropics.

These changes in tropical and temperate ice masses will produce important consequences for the societies that depend on water that runs off them.

Good news and bad news about the ozone hole

According to Geophysical Research Letters (December 1, 1995) the good news is that the Antarctic ozone hole won't get much worse as stratospheric chlorine continues to build up over the next 10 years. The bad news is that there is so little ozone in the ozone hole that it just can't get much worse. It's sort of like, "Once you've run out of gas, you have run out of gas."