One Earth, One Future Our Changing Global Environment (1990) / Chapter Skim
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8. Coastlines and Rising Seas
8. Coastlines and Rising Seas
Pages 90-102
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From page 90... ...
Their techniques range from straightforward measures such as pumping sand onto eroded beaches, building levees, and relocating ports, to complex, multibillion dollar systems of carefully maintained dikes and sand dunes, such as the one that protects more than half of The Netherlands from inundation by the North Sea. if the earth's surface temperature grows warmer, as many researchers predict, the task of keeping the sea at bay will become more difficult, and more urgent.
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From page 91... ...
The reason for the rise is poorly understood and exceeclingly difficult to determine. Mark Meter, a glaciologist at the University of Colorado in Boulder, cautions that any projections for future sea level rise must be "tempered by the uncertainty of our understanding of the present." Estimates made in the last decade projected that we could expect global average sea level to rise from about 0.5 to 1.5 meters, with some estimates as high as 3 meters, in response to a 3° to 5°C warming that some estimate would be expected by 2050 with an effective doubling of carbon dioxide.
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From page 92... ...
The problem is that we don't yet know how to estimate very well what is going to happen." About some processes and conditions related to sea level rise, scientists are confident. Worldwide average sea level depends simply on the volume of water resting in the ocean basins.
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From page 93... ...
On the basis of current predictions of sea level rise, a 1989 Resources for the Future report explains that all land currently up to 5 meters (about 16.5 feet) above mean sea level is potentially vulnerable in the next one to three centuries to upstream effects of flooding, particularly storm surges walls of water pushed by heavy winds and to intrusion of saltwater into groundwater and estuaries.
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From page 94... ...
Perhaps no other impact of climate change would displace more people from their homes than rising seas, swelling a growing class of "environmental refugees." Not surprisingly, most of these refugees would be in developing countries, where scarce
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From page 95... ...
Many coastal ecologists fear that these obstacles squeeze the wetlands against the advancing sea. In the absence of human activity, coastal ecosystems are preserved by a highly effective mechanism that helps compensate for fluctuating sea levels.
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From page 96... ...
Nor is the future bright for the string of barrier islands that adorns the eastern United States and Gulf coasts. Barrier islands such as Hatteras Island, North Carolina, and Long Beach Island, New Jersey, are long, narrow islands and peninsulas only a few feet above sea level in elevation, with one side facing the ocean and the other side facing a bay that separates the island from the mainland.
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From page 97... ...
The delta is thrown out of equilibrium, with the accumulation of sediment no longer offsetting the subsidence. The Mississippi River delta in Louisiana is the most vulnerable area to relative sea level rise in the continental United States and provides a ready example of the changes uncler way in many of the world's deltas.
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From page 98... ...
The "worst case" assumes the maximum rise in sea level and the complete damming or diversion of the sediment carried by the river ciraining into the delta (in this case the sediment would not be able to replenish the delta so that natural subsidence would increase the relative rate of sea level rise)
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From page 99... ...
If the storms increase in frequency and sea level rises, the storm surges will reach even further toward the main centers of population. Egypt too would experience massive change with global sea level rise.
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From page 100... ...
These factors are perhaps more responsible than global climate change for local changes in relative sea level. PREPARING FOR RISING SEAS In many cases, decisions about how to prepare for rising sea levels come down to stark economic facts that will vary with specific countries and localities.
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From page 101... ...
The projected sea level rise should cause neither alarm nor complacency, researchers stress. The severity of impacts from sea level rise depends on how society responds and adapts.
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From page 102... ...
As Tom Goemans, a consultant with KPMG in The Hague, notes, accelerated sea level rise is a "manmade phenomenon that presents a perfect example of external costs, that is costs not included in the present price of energy from fossil fuel burning."
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