Global phenomena – sea level

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Geography - Global phenomena: sea levels

Sea levels

View this video to watch one view point about the effects of rising sea
levels.

Rising sea levels are obviously a global phenomenon. All continents have
coastal regions which will be affected by rising sea levels. Although, as a
percentage of the earth's surface, the region most under threat from rising
sea levels is not great, it does cover at least one third of the world's
coastal regions. Those coastal regions of the world most at risk are the
Pacific Islands, South East Asia, the eastern seaboard of the USA, Egypt
and north western Europe. The types of coastal environment most under
threat from rising sea levels are coral reefs, estuaries, deltas, mangroves
and coastal lake systems like the Gippsland Lakes. Use your atlas to name a
few of the other coastal regions which will disappear under the rising
oceans.

Many of the world's major cities, among them New York, Hong Kong, Rio de
Janeiro, Melbourne, San Francisco, Shanghai, Tokyo, Singapore and Lagos,
are located within regions of rising sea levels. These same regions are
also major population centres. The river deltas of Bangladesh, the coastal
lowlands of China and the eastern seaboard of the USA are regions of
exceptionally high population density. In these regions the population
density is over 4,500 people per square kilometre. Of course not all places
which will be most affected by rising sea levels are found in regions with
high population densities. The polar regions of northern Canada and Russia
and southern Chile are all among the least populated regions of the world,
the map shows that they are also likely to be greatly affected by rising
sea levels.

This phenomenon is primarily a natural occurrence although there is some
evidence to suggest that sea levels are rising more quickly now than ever
before. The effects of global warming, compounded by increased levels of
carbon in the atmosphere, are believed to be melting the permanent ice
fields and as a result raising sea levels. However, the earth's temperature
has altered many times before, even before humans were found on this
planet. There has been a natural progression of ice ages followed by
periods of global warming. During one ice age Port Phillip Bay was a grassy
plain crossed by rivers flowing to the sea. As sea levels rose the plain
was inundated by salt water forming the Bay, as we know it.

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