Global Warming's Effect on the North Atlantic Ocean Currents

Global Warming's Effect on the North Atlantic Ocean Currents

(NASA)

Dan Powers

November 18, 2008

Critical Thinking, HNRS 201

Dr. Paul Cesarini

An Introduction to a Cold Dark Future

In the 2004 movie The Day After Tomorrow the world is thrown into chaos when the Thermohaline circulation, an ocean current in the Atlantic, came to an abrupt halt. In a matter of days massive tidal waves destroyed the statue of liberty, giant hurricanes and tornadoes tore down everything in their path, and worse of all brought another ice age that covered the world. While this is an extremely exaggerated scenario, many people do not realize that it is based on a true possibility that have scientist and governments around the world worried about The Day After Tomorrow future (O'Hanlon, 2007).

The Thermohaline is a North Atlantic Ocean current that feeds off of the Gulf Stream and delivers warm winds that raise European temperatures by five to ten degrees Celsius. With out these warm winds it could potentially send Europe back into another ice age causing mass amounts of deaths due to the fact Europe will no longer be able to grow their crops under snow (Pearce, 2005). The power that ocean currents carry should not be underestimated. The heat in these ocean currents is equivalent to around a million nuclear power plants (Barry, 2004). "The Atlantic circulation moves heat toward the Arctic, and this helps moderate wintertime temperatures in the high-latitude northern hemisphere," says Ruth Curry, a physical Oceanography Research specialist at Woods Hole Oceanographic Institute on Cape Cod, Massachusetts (Roach, 2005). With out that energy reaching Europe and America, we could be in for a cold dark future.

Many country's governments are becoming worried about the possible affects if the current was to completely stop. In fact, Andrew Marshall, a Defense Department planner for the United States of America, has recently released an unclassified report stating that a shift in ocean currents in the near future could compromise national security. Governments are now starting and invest in research organizations to monitor the ocean currents strength and also using other departments, such as NASA's satellites to record the Arctic and Greenland's ice which could have a large impact on the Thermohaline current (Barry, 2004).

When Will the Current Stop Flowing?

At 40 degrees north, the latitude that runs through Portugal and New York, the current divides. Some water heads southwards in a surface current known as the Subtropical Gyre which is still running strong, while most of the water continues north in the Thermohaline current. The current's warm winds then help raise European temperatures. It is the Thermohaline that has scientist worried because of recent studies that show the very important current weakening. The National Oceanography Centre in Southampton, U.K. found a thirty percent reduction in the currents that carry warm water north from the Gulf Stream. What their research found was that most of the slow down occurred between the years of 1992 and 1998 (Pearce, 2005).

While the slow down is a cause for concern, the real question is whether the current will only slow down or completely shut off. According to computer models by Thomas Stocker and Andreas Schmitter of the University of Bern, showed that if the Arctic warms quickly enough it is possible it could completely stop the current in its tracks. However, if the Arctic warms at a more moderate pace it may only slow the currents for a couple of months (Barry, 2004). The outcome is largely due to whether the change is a consequence of man's actions or just another natural cycle in Earth's climate. Stefan Rahmstorf, a professor of ocean physics at Potsdam University in Germany, comments on the topic by stating, "Nobody would accept expanding nuclear power if there was a five percent risk of a major accident. Why would we accept expanding oil and coal power if there is a five percent risk of a major climate accident?" (Roach, 2005).

Most scientists in the field give a much greater chance than five percent of the complete shutdown of the Thermohaline. Some Scientist estimate that there is over a fifty percent chance of a complete shutdown of the Thermohaline current if global warming climbs by four to five degrees Celsius (7.2 to 9 F). Rahmstorf gives the shutdown a thirty percent chance. While other scientist state there is no possibility of a complete shutdown (Roach, 2005). The one thing that all of these scientists have in common is the agreement is that there is a slowdown in the current and if it continues it will have devastating effects.

Yet none of these effects have been seen or recorded. Richard Wood, chief oceanographer at the U.K. Met Hadley Centre for Climate Research in Exeter, says the Southampton team's findings "leave a lot unexplained." With changes as drastic as a thirty percent decrease in strength of the Thermohaline that there should have been a cut from European ocean heating by at least one-fifth. That's enough to cool Britain by one degree Celsius and Scandinavia by at least two degrees Celsius which, "we haven't seen yet," he points out (Pearce, 2005). Europe's average temperature is currently on the rise and shows no signs of stopping. Other climate researchers such as Andrew Weaver of Canada's University of Victoria are stepping off the ban wagon. "Abrupt climate change in this century is unlikely," said the climate researcher after a new study of seventeen different models concludes that the Thermohaline circulation will not stop dead and abruptly change regional climates anytime this century (O'Hanlon, 2007).

Freshwater Can Kill a Climate

Clean fresh water is the foundation of life on the planet. A human can not go with out water for over a week with out dying and it is ironic that same fresh water maybe the reason for the slowing of the Thermohaline that could kill thousands if not millions of people. In fact, freshwater dumping into the northern Atlantic Ocean from ice will cause the water to become less dense and prevent it from sinking. If the water is unable to sink then the water will not be able to travel south again along the Thermohaline current. This will in turn slow the tropic water heading north in a vicious cycle (Roach, 2005). When the warm water moves north through the Thermohaline it is a surface