Global Warming

Global Warming describes an increase in average temperature in the Earth's atmosphere and oceans. Increasing temperatures are the result of a strengthing greenhouse effect caused primarily by man-made increases in carbon dioxide and other greenhouse gases. This paper will discuss Global Warming and its effect on ocean currents, glaciers, and the saltiness of the ocean.

Global Warming is affecting us more and more every day and it probably will continue to do so unless humans change their lifestyles. The main cause for global warming is greenhouse gases being released into the air. Greenhouse gases are heat trapping gases that are being released into the air by humans. People release them when they burn fossil fuels like coal, gas and oil.(Scholastic News, 2005) Emitting some greengouse gases into the atmosphere is good. In fact, we could not live without greenhouse gases going into the atmosphere. Without any greenhouse gases in the atmosphere temperatures would be thirty degrees Celsius

or lower and Earth would be uninhabitable.(Wikipedia, 2005) Some greenhouse emissions are good, but the fact is that we are just emitting to much.

Most people do not know it, but the ocean is in constant motion. One reason they are moving is winds. Winds whip the surface waters into big time ocean currents. (Brown, 2000) The currents act like a conveyor belt, moving warmer surface waters to the poles, and moving colder, deeper waters to the Equater. As the warm surface waters push northward they release heat into the atmosphere and become cooler and denser. As they become denser, the waters sink into the deep and flow back southward. (Roach, 2005) The currents are known as the "Great Ocean Conveyor"(NASA 2005).

Global warming is starting to affect the conveyor drastically. If it interferes with it to much, the results could be catastrophic. Excessive amounts of freshwater dumped into the conveyor belt does not have a positive effect on it. Saltwater is denser and heavier than freshwater; therefore, freshwater coming into the current would make the surface layers more buoyant

. That could be a problem because the surface water needs to sink down toward the ocean floor to keep the conveyor belt moving along. Increases in freshwater runoff could prevent the sinking of North Atlantic surface waters which, in effect, could stop or slow the circulation of the current. (NASA, 2005) At present rates, scientists hypothesize that it will take about two centuries for freshwater runoff to completely halt the conveyor (Roach, 2005). If the conveyor did halt, it could plummet North America and Western Europe into a deep freeze, maybe within a few decades (NASA, 2005). In the 2004 movie The Day After Tomorrow, North American and Europe are distraught over a deep freeze that was caused by global warming halting the circulation of the North Atlantic currents (Roach, 2005). The film is severely embellished. With that said, Earth's climate has shifted suddenly and dramatically before: at the end of the last ice age about 13,000 years ago, melting ice sheets triggered an abrupt halt in the conveyor, which plunged the world back into a 1,300 year span of ice age-like conditions. (NASA, 2005) That might not be likely to happen again anytime soon, but it is definitely