Sea Level Rise

Global warming causes the oceans to warm and expand, causing sea levels to rise. If ocean levels rise high enough, shoreline areas will be inundated and lost, forcing the populations that inhabit these areas to relocate and causing billions of dollars of economic losses in property damage.

Coastal lowlands worldwide are some of the most rapidly growing population areas. The land area referred to as the low elevation coastal zone (LECZ) is the contiguous area along the coast that is less than 33 feet (10 m) above sea level. This zone covers only 2 percent of the Earth's total land area but provides a home for 10 percent of the world's population and 13 percent of the world's urban population—more than 600 million people live in this zone, and 360 million are urban. Included in this group are the world's small island countries and those large countries that have heavily populated areas within delta regions.

In a study conducted by the International Institute for Environment and Development in 2007, mitigation measures may be the best way to avoid the risks brought on by climate change (such as sea-level rise), but it is too late to rely solely on mitigation measures. They believe that migration of the population from these low-lying coastal areas is important, but it can be very expensive and cause major disruptions to peoples' lives. Adjustments that can be made to protect residents, however, should be accomplished as much as possible. It should be clearly understood, however, that low-income groups living on floodplains are especially vulnerable, and because any mitigation to solve the problem is a lengthy process and takes a long time to complete, any future urban development in more suitable areas should be considered instead.

Settlement along coasts is not always easy to control, however. Historically, coasts were desirable places to settle because of their immediate access to trade and business. Today, as in the past, the recent expansion of international trade has also encouraged people to move to coastal locations. As an illustration, today China has one of the largest trade-related coastward movements the business world has ever seen.

Greenhouse Gases And Sea Level Rise

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Coastal Populations Living Less Than 60 Miles (100 km) from Coast




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City population in millions by 2015

If global warming causes sea levels to rise, millions of people will be negatively affected.

With global warming, the world's coastal populations are at risk from flooding, especially when high tides combine with storm surges and/or high river flows. According to the International Institute for Environment and Development, "Between 1994 and 2004, about one-third of the 1,562 flood disasters, half of the 120,000 people killed, and 98 percent of the two million people affected by flood disasters were in Asia, where there are large population agglomerations in the flood-plains of major rivers (such as the Ganges-Brahmaputra, Mekong, and Yangtze), and in cyclone-prone coastal regions (such as the Bay of Bengal, South China Sea, Japan, and Philippines)."

Worldwide, developers have drained wetlands in order to convert those ecosystems into urban areas. The problem with doing this, however, is that it removes a "natural buffer" against tidal floods. In delta regions, land compaction and subsidence from groundwater withdrawal can lead to sea-level rise, which also increases flood risk. Unfortunately, it is the low-income areas that are the most vulnerable.

According to the IPCC, faster sea-level rise of more than 3.3 feet (1 m) per century could result from accelerated melting of the Greenland ice sheet or the collapse of the West Antarctic ice sheet (although not likely during the 21st century). The IPCC estimates that without any other changes a sea-level rise of 15 inches (38 cm) would effect five times more people flooded by storm surges.

From a management perspective, the International Institute for Environment and Development believes that for these areas to fare better with global warming, they need to have effective coastal zone

(opposite page) Coastal erosion, saltwater intrusion into freshwater supplies, and coastal storms are all events that can harm developed coastal areas because of global warming. Because coastal areas are attractive areas to live, millions of people may face physical and economic disasters as global warming continues.

management applied to them. Because structures are permanent and cannot be relocated, taking potential risks into account before heavy development begins in new areas is important. Sometimes relatively small shifts in settlement location, such as out of a coastal plain onto more elevated ground, can make a major difference later on.

One area that is especially vulnerable is Bangladesh. According to Dr. Robert Buddemieir of the Kansas Geological Survey, "Bangladesh is massively populated, achingly poor, and something like a sixth of the country is going to go away." Bangladesh cannot afford to build barriers to hold back the sea, so people would have to move inland, increasing the population's density and leading to an increase in hunger and disease.

The Maldives in the Indian Ocean have the same problem. Consisting of 1,190 separate islands with an average elevation of five feet (1.5 m) above sea level, if the sea rises, more than 200,000 people would be forced to abandon their homes.

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  • Arlo
    Why is it important to know about greenhouse gases and sea level rise?
    1 year ago
  • Askalu
    How the green house gases causing the sea level rising?
    10 months ago

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