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2.2 sea rise

2.2 sea rise






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    2.2 sea rise 2.2 sea rise Presentation Transcript

    • CT.LAKSHMANANCT.Lakshmanan
    • Sea-level riseAn increase in the average level of the sea or ocean. The global sea level is rising as a result of increasing global temperature because:(1)melting of ice in mountains and glaciers leads to more water in the ocean(glacial melt), and(2)warmer water in the oceans expands, occupying more volume.(thermal expansion) Local sea levels are determined by a combination of the global sea-level rise and the local rise or subsidence of the land (for instance due to geological processes). CT.Lakshmanan
    • Millions live near the coast CT.Lakshmanan
    • CT.Lakshmanan
    • CT.Lakshmanan
    • Although scientists are not in total agreement on the rate of rise or acceleration, the fact that it is rising is unquestionable.The impacts of sea level rise include beach erosion, inundation of low lying areas, salt water intrusion into aquifers, and increased flooding. CT.Lakshmanan
    • These issues are important to the entire world, as its population is increasingly moving toward the coast—about 60 percent (~3.6 billion) of the world’s population lives within 60 kilometers (37 miles) of the coast (UNESCO, 1998).Low-lying populated areas, such as cities built on deltas are most vulnerable to rising sea levels. CT.Lakshmanan
    • Rising sea level causes sandy beaches to retreat. There is a large multiplicative effect: one vertical unit of higher water level results in an average of 100 units of horizontal retreat CT.Lakshmanan
    • It is important to consider the behavior of the land in measuring rates of sea level rise.Some coastal areas experience subsidence whereas other areas experience uplift, which can result in a decrease in relative sea level.Venice, for example, has pumped out so much groundwater over time that it has subsided substantially and the uplift at Juneau, Alaska has resulted in a decrease in relative sea level of 42 cm over the last century CT.Lakshmanan
    • Key variables in calculating the ocean’s effects on the coast include mean sea level rise, tides, and storm surges. Tides may be measured in hours, days, seasons, and in inter-annual terms.One effect of an El Niño is to increase sea level by about one foot CT.Lakshmanan
    • Indian coast vulnerable to global warming"...global warming has started to show its far-reaching effects here," said Pranabes Sanyal, the eastern India representative of the National Coastal Zone Management Authority (NCZMA). "Many towns and cities along the coast will be devastated by the changing climate in coming years." Millions live along Indias 3 700km eastern coast and remain vulnerable to storms, flooding and tsunamis. The 2004 Indian Ocean tsunami killed about 230 000 people, around 16 000 of them in India. CT.Lakshmanan
    •  Sanyal said the wind speed of cyclones hitting the eastern states of Andhra Pradesh and Orissa had almost doubled to 250km per hour from 150km per hour in 2000. In addition, sea levels in some parts of the Bay of Bengal were rising at 3.14mm annually against a global average of 2mm, threatening the low-lying areas of eastern India. Water levels off the coast of Khulna in Bangladesh were rising at an even higher rate of 10mm every year, Sanyal added. CT.Lakshmanan
    • NCZMA officials say rising sea levels are eroding one metre of land every year along the coast of West Bengal state, inundating more and more coastal areas every year and leaving them "highly vulnerable". CT.Lakshmanan
    • Coastal marshes and the diverse ecosystems they support have been degraded by the rising seas.Marsh areas do not retreat easily, and so are mostly destroyed. This is one striking example of the close interconnection between the global issues of climate change and sea level rise on the one hand and protecting biodiversity on the other. CT.Lakshmanan