News-Letter

Most people are aware of what many scientists have called the biggest crisis facing the environment today: global warming. New research has shown this problem to be an even more unpredictable and daunting challenge than previously expected. The complex cycling of water and air throughout the northern hemisphere is now known to be an incredibly intricate system for the distribution of heat.

Our planet retains heat through a process known as the greenhouse effect, named for its similarity to a botanical greenhouse. Radiation from the sun is reflected by the Earth's surface and then absorbed by gasses that trap the radiation close to the Earth's surface.

These greenhouse gasses, which are able to hold on to the Sun's energy, include carbon dioxide, methane and nitrous oxide. Although they comprise less than 0.3 percent of the atmosphere, they can induce powerful effects on climate.

Carbon, the primary element in most greenhouse gasses, is stored in various carbon sinks around the globe including forests, soil and oceans. Unfortunately, each sink has its limit of carbon containment.

Global warming occurs when excess carbon exits other sinks and enters the atmosphere. The growth of industry and the expansion of technology, especially cars and trucks, add tremendous quantities of carbon to the atmosphere. Forests and soil hold some of this extra carbon, but deforestation limits room for storage.

A major warm-water current known as the Gulf Stream runs through the northern Atlantic Ocean. This current flows from the equator, travels up the coast of North America and crosses the ocean to warm the waters off northern Europe. The dense, salty waters east of Greenland cause the Gulf Stream to sink to the ocean floor, losing its heat. The stream returns as a cold-water current along the seabed.

Scientists concerned with the effects of global warming on the Gulf Stream visited Greenland to study its ice, which compacts into layers due to annual snowfall. This ice is then used to serve as a record of annual temperatures and climate conditions in the past.

The researchers expected to find long gradual temperature changes over time -- slowly falling during the last ice age then gradually rising. Instead, they perceived Earth's climate history to consist of a flurry of rapid fluctuations in temperature. The temperature changes that the investigators had expected to occur over millennia happened in decades.

The cause of this flexibility was unknown until marine biologists discovered that the Gulf Stream's flow could change as rapidly as could temperature. The scientists examined small, shelled organisms residing on the North Atlantic sea floor. The scientists evaluated the nutrient content of each specimen's shell. Their analyses indicated that the Gulf Stream in fact has little consistency; it has switched on and off many, many times in the past thousands of years.

Soon after researchers noticed major changes off the coast of Greenland. Since the 1970s the waters off Greenland have greatly lost salt concentration, resulting in a decrease in the rate of Gulf Stream sinking, thus slowing the course of the entire current. The cause of this "freshening" is global warming.

Global warming increases the rate at which ice melts off Greenland. The freshly melted water enters salty waters that sink the Gulf Stream, causing these waters to have a lower salt content. Scientists have proven that a variety of factors causes a wide range of temperate changes throughout the northern hemisphere. It is now our responsibility to stabilize our planet's climate.

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