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April 7, 2002
EXCERPTS: The encroaching sea
Lester R. Brown points to the dangerous implications of climate change and the rise in the sea level
SEA level is a sensitive indicator of global warming since it is affected by both thermal expansion and the melting of land-based glaciers. The respective contributions to sea level rise of thermal expansion and ice melting are estimated to be roughly the same.
During the twentieth century, sea level rose by 10-20 centimetres (4-8 inches), more than half as much as it had risen during the preceding 2,000 years. If the earth’s temperature continues to rise, further acceleration is in prospect. The model used in the Intergovernmental Panel on Climate Change 2001 Assessment projects that sea level could rise by as much as 1 metre during the twenty-first century.
Rising sea level has numerous consequences. The most obvious is inundation as the oceans expand at the expense of continents. Another is saltwater intrusion. As sea level rises, salt water may invade coastal freshwater aquifers. This intrusion is exacerbated by the falling water tables that now plague coastal regions in many countries, including Israel, Pakistan, India, and China. A third effect is beach erosion: as waves break further inland, they erode the beach, compounding the effect of rising sea level.
The most easily measured effect of rising sea level is the inundation of coastal areas. Donald F. Boesch, with the University of Maryland’s centre for environmental sciences, estimates that for each millimetre rise in sea level, the shoreline retreats an average of 1.5 meters. Thus if sea level rises by 1 metre, the coastline will retreat by 1,500 meters, or nearly a mile.
With a 1-metre rise in sea level, more than a third of Shanghai would be under water. For China as a whole, 70 million people would be vulnerable to a 100-year storm surge. The rice-growing river flood plains and deltas of Asia would be particularly vulnerable. A World Bank analysis shows that Bangladesh would be hardest hit, losing half of its rice production — the food staple of its 140 million people. At current rice prices, this would cost Bangladesh $3.2 billion. Residents of the densely populated river valleys of Asia would be forced into already crowded interiors. Rising sea level could create millions of climate refugees in Bangladesh, China, India, Indonesia, the Philippines, and Vietnam.
Two thirds of the Marshall Islands and Kiribati would be under water. The United States would lose 36,000 square kilometres (14,000 square miles) of land, with the middle Atlantic and Mississippi Gulf states losing the most. And large portions of lower Manhattan and the Capitol Mall in Washington, D.C., would be flooded during a 50-year storm surge. A 1-metre rise in Japan would mean that 2,340 square kilometres of the country would be below high tide. Four million Japanese would be affected, many of them driven from their homes.
Coastal real estate prices are likely to be one of the first economic indicators to reflect the rise in sea level. People with heavy investments in beachfront properties will suffer most. A half-metre rise in sea level in the United States could bring losses ranging from $20 billion to $150 billion. Beachfront properties, much like nuclear power plants, are becoming uninsurable — as many homeowners in Florida, for example, have discovered.
Many developing countries already coping with population growth and intense competition for living space and cropland are now facing the prospect of rising sea level and substantial land losses. Some of those most directly affected have contributed the least to the buildup in atmospheric CO2 that is causing this problem.
Rising sea level will pose difficult and costly choices. Consider, for example, the effort and cost involved in relocating a million Chinese from the area to be inundated by the Three Gorges Dam. This would be trivial compared with the tens of millions, and eventually hundreds of millions in Asia, who would have to be relocated as the ocean rises if we continue with business as usual. Climate refugees may come to dominate the international flow of migrants since they are losing not just land, but food supplies and livelihoods.
More than 90 per cent of the world’s ice is in the Antarctic ice sheet, which, partly because of its size, is comparatively stable. The other 10 per cent, however, is in the Greenland ice sheet and mountain glaciers, which are more vulnerable to climate change. Now that the Greenland ice sheet has started to melt, we must ask, what if this trend continues? Greenland’s ice sheet is up to 2 kilometres (1.2 miles) thick in some areas. In an article in Science, NASA scientists calculate that if the Greenland ice sheet were to disappear entirely, sea level would rise by a staggering 7 metres (23 feet), markedly shrinking the earth’s land area and engulfing many coastal cities.
For the first time since civilization began, sea level has begun to rise at a measurable rate. It has become an indicator to watch, a trend that could force a human migration of almost unimaginable dimensions, and one that will shape the human prospect. It also raises questions of intergenerational responsibility that humanity has never before faced.
Rising temperatures and the power of storms are directly related. As sea surface temperatures rise, particularly in the tropics and sub-tropics, the additional heat radiating into the atmosphere causes more destructive storms. Higher temperatures mean more evaporation. Water that goes up must come down. What is not clear is exactly where the additional water will fall.
More extreme weather events are of particular concern to countries in the hurricane or typhoon belt. Among those most directly affected by increased storm intensity are China, Japan, and the Philippines in the western Pacific, India and Bangladesh in the Bay of Bengal, and the United States and the Central American and Caribbean countries in the western Atlantic.
Munich Re, which insures insurance companies, has maintained detailed, worldwide data on natural catastrophes — principally storms, floods, and earthquakes — over the last half-century. The company defines a great natural catastrophe as one that overwhelms the capacity of a region to help itself, forcing it to depend on international assistance. During the 1960s, economic losses from these large-scale catastrophes totalled $69 billion; during the 1990s, they totalled $536 billion, nearly an eightfold increase.
Recent years have seen some extraordinarily destructive tropical storms. Among them was Hurricane Andrew, which cut a large swath across the state of Florida in 1992. Storm alerts held the loss of human life to 65, but Andrew destroyed 60,000 homes and other buildings, inflicting some $30 billion in damage. In addition to the buildings it destroyed, it also took down seven insurance companies, as mounting claims left them insolvent.
Six years later, Hurricane Georges — a powerful storm with winds of close to 200 miles per hour — was stalled off the coast of Central America by a high-pressure system that blocked its normal path to the north. It claimed 4,000 lives and inflicted a staggering $10 billion worth of damage on El Salvador and Nicaragua. Damage on this scale, which approached the combined gross domestic products of the two countries, set economic development back by a generation. A storm that hit Venezuela in mid-December 1999 caused enormous flooding and landslides, claimed 20,000 lives, and registered economic losses of $15 billion — second only to Hurricane Andrew.
Excerpts from
Eco-economy: building an economy for the earth
By Lester Brown
Earth Policy Institute, 1350 Connecticut Avenue, NW Suite 403, Washington DC 20036,
Email: epi@earth-policy.org
ISBN 0-393-32193-2 333pp. $15.95
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