by REP Policy Director Jim DiPeso published February 1, 2003 in the Chicago Sun-Times
When frigid air clamped down on the eastern half of the United States last month, the likely response to a question about global warming would have been, ''Bring it on.''
As strange as it sounds, however, the United States could see more and longer such cold snaps if nothing is done about global warming. That's right. Scientists keeping tabs on the Earth's oceans are concerned that global warming could actually lead to dangerously cold weather in North America and Europe.
The notion defies common sense, but the underlying physics are worth the close attention of citizens and national policymakers who would have to deal with the harsh consequences.
It starts with the Gulf Stream, a current of warm water in the Atlantic Ocean that transports warm air northward. That's why much of Western Europe, which is at about the same latitude as Canada, has a relatively mild climate. The Gulf Stream is actually part of an oceanic conveyor belt. As the Gulf Stream gives up its heat in northern latitudes, the current becomes saltier and heavier than surrounding waters and sinks, a process that propels the conveyor belt.
Global warming could interrupt this vital process. As temperatures warm, melting of glaciers and ice fields would accelerate. This is no idle theory. Glaciers worldwide are retreating. Glacier National Park is losing its namesake features. Ernest Hemingway's fabled snows of Kilimanjaro are disappearing.
Melting ice sending a surge of fresh water into the North Atlantic would dilute its saltiness. Less salty water is lighter. At some point, the Gulf Stream could stop sinking into the North Atlantic's depths, bringing the conveyor belt to a halt, like an engine that has seized up.
The consequences could be both abrupt and severe. Within a generation, average winter temperatures in the eastern United States and Western Europe could drop 10 degrees--a huge drop as averages go--and brutal winters could be the norm for the following decades or even centuries in the most economically developed region in the world. Ironically, the regional deep freeze could occur even as the Earth as a whole continues to warm, according to a presentation the Woods Hole Oceanographic Institute made to the World Economic Forum in Davos, Switzerland, on Jan. 27.
Oceanographers reported in Science magazine last year that the North Atlantic is rapidly becoming less salty. Does that mean the shutdown of the Gulf Stream could happen soon? Scientists do not know. However, there is good evidence from Earth's past that climate can shift abruptly. For example, scientists are investigating whether an abrupt climate shift caused the ''Little Ice Age'' between 1300 and 1850, a period of colder temperatures that resulted in crop failures, disease and mass migration.
So what should government policymakers do? The first step is to underwrite research that will improve scientific understanding of abrupt climate change--both how it occurred in the past and how it could recur in the future. The second, simultaneous step is to reduce the risk that global warming could trigger an abrupt climate shift, through prudent measures to reduce carbon dioxide and other greenhouse gases.
Earlier this month, Senators John McCain (R-Ariz.) and Joseph Lieberman (D-Conn.) introduced legislation to cut U.S. greenhouse gas emissions to 1990 levels by 2016.
The reductions would be accomplished through a market-based ''cap-and-trade'' system applied to electricity generation, petroleum refining, commercial and industrial sectors.
Deep emissions reductions will be needed over the next several decades to stabilize atmospheric concentrations of greenhouse gases.
But the McCain-Lieberman bill would be an excellent start and a clear signal that the United States, at last, is moving off the climate change sidelines.
For too long, the federal government has been frozen in denial and dithering about global warming. It's time to break the ice jam in Washington and head off a real deep freeze that would endanger our future.
