During the 20th century, the sea level rose by 4-8 in. (10-20 cm.) primarily as a result of melting glacier ice and thermal expansion of warmer ocean water. It has been predicted that sea level rise will be even greater as the oceans warm along with the rest of the Earth. This is due to the fact that water expands as its temperature increases. Climate change models have predicted that a global mean sea level rise as much as 33 in. (85 cm.) is expected during the 21st century. Accelerated global sea-level rise is expected to have far-reaching and dramatic impacts in vulnerable regions of the Earth where subsidence and erosion challenges already exist. Rising seawaters are already submerging, for example, coastal wetlands and mangroves in southern Florida, and approximately one million acres of Louisiana wetlands have become open water since the mid 20th century.
Sea-level rise has the potential of causing increases in the intrusion of saltwater into coastal aquifers. Shallow islands, and coastal aquifers supporting human use (such as those in Long Island, New York, and central California) could be at greatest risk. Rising sea level has also contributed to increased mortality of trees in coastal areas of Louisiana and southern Florida, where saltwater has already intruded into the groundwater on which trees depend.
Other impacts associated with sea-level rise include changes in salinity distribution in estuaries, altered coastal circulation patterns, destruction of transportation infrastructure in low-lying areas, and increased pressure on coastal levee systems. Atlantic and Gulf Coast shorelines will be especially vulnerable to long-term sea-level rise, as well as any increase in the frequency of storm surges or hurricanes. Most erosion events on these coasts are the results of storms, and the slope of these areas is so vulnerable and gentle that a small rise in sea level may produce a large inland shift of the shoreline. This increases the threats to coastal development, transportation, freshwater aquifers, infrastructure, and fisheries. These impacts can adversely affect the quality of water resources. Moreover, the potential negative impli cations of climate change for water quality include reductions in stream flows, increased storm surges, and higher water temperatures. An increase in the number of intense precipitation days could lead to increases in the variety of agricultural and municipal polluting substances being washed into rivers, estuaries, streams, and lakes, and sea-level rise would contribute to saltwater intrusion into rivers, estuaries, and coastal aquifers.
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Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.