Rising sea level
Most scientists agree that the greatest threat to the environment is global warming. There is little doubt that the earth is heating up; in the last century the average temperature has climbed about 0.6 degrees Celsius (about 1 degree Fahrenheit) around the world. As oceans become warmer, the effects of global warming are more apparent; loss of coral reefs, melting of the ice cap on Mount Kilimanjaro, to name a few. However, the biggest danger is that global warming will cause sea levels to rise dramatically; even now the ocean level has already been raised 4 to 8 inches (10 to 20 centimeters) by thermal expansion. As temperature rise, more water flows to the seas from melting glaciers and ice caps, causing ocean water to warm and expands in volume. The process when warmer takes up more room than colder water is known as thermal expansion.
Arctic sea ice has thinned significantly over the past half century, and its extent has declined by about 10 percent in the past 30 years. In parts of Alaska, thawing ice has resulted in more than 15 feet of subsiding ground. Monstrous glaciers, massive ice fields, and sea ice are fast disappearing from Switzerland to the equatorial glaciers of Indonesia’s Irian Jaya, from the Arctic to Peru.
The unprecedented rate of warming that the earth is experiencing now is apparently the fastest warming rate in millions of years, suggesting in all probability that it is not a natural occurrence. In fact, most scientists believe the rise in temperatures will accelerate. One of the major concerns is the likelihood that the climate change will impact ecosystems, agriculture, and spreading of disease. An international study predicted that by the year 2050, more than a million species could be driven into extinction by the climate change. As glaciers and sea ice in both the Northern and Southern Hemispheres are melting at a rapid pace, animals like polar bears are at risk.
Cascading effects from rising sea level are equally worrying. Every inch of sea-level rise could result in retreating sandy beach shorelines due to erosion; crop raising and sources of drinking water are also threatened when salt water intrudes into freshwater aquifers. Widespread erosion and saltwater intrusion would be disastrous in delta areas; the effect would be worse in countries with little other arable land like Egypt. Experts warn of the catastrophic consequences if the massive ice sheets in the cold region, such as Greenland, are to melt. A series of maps created using computer models show that coastal cities and island countries are susceptible to the sea rising at different levels; a 3 foot (1 meter) rise would swamp cities along the U.S. eastern seaboard and the Gulf Coast, while the same rise by Greenland’s ice sheet would submerged low-lying countries like Maldives. In a simple word: even with a small rise in sea level, nations and their civilizations could be destroyed. Megacities like New York, Shanghai, Tokyo, Bangkok, and Jakarta, where the majority of populations are concentrated near the coasts or river deltas are at risk. Similarly, the humanitarian and economic impacts are potentially catastrophic on low-lying, poor countries like Bangladesh with its dense population.
