During the twentieth century, sea level rose by 20-30 centimeters (8-12 inches). The Intergovernmental Panel on Climate Change projects a rise of up to 1 meter during this century. Sea level is rising because of the melting of glaciers and the thermal expansion of the ocean as a result of climate change. This in turn is due to rising atmospheric levels of CO2, largely from burning fossil fuels.

As sea level has risen, Tuvalu has experienced lowland flooding. Saltwater intrusion is adversely affecting its drinking water and food production. Coastal erosion is eating away at the nine islands that make up the country.

The higher temperatures that are raising sea level also lead to more destructive storms. Higher surface water temperatures in the tropics and subtropics mean more energy radiating into the atmosphere to drive storm systems. Paani Laupepa, a Tuvaluan government official, reports an unusually high level of tropical cyclones during the last decade. (Tropical cyclones are called hurricanes in the Atlantic Ocean.)

Laupepa is bitterly critical of the United States for abandoning the Kyoto Protocol, the international agreement to reduce carbon emissions. He told a BBC reporter that "by refusing to ratify the Protocol, the U.S. has effectively denied future generations of Tuvaluans their fundamental freedom to live where our ancestors have lived for thousands of years."

Feeling threatened by the climate change over which they have little control, the island countries have organized into an Alliance of Small Island States, a group formed in 1990 specifically to lobby on behalf of these countries vulnerable to climate change.

In addition to island nations, low-lying coastal countries are also threatened by rising sea level. In 2000 the World Bank published a map showing that a 1-meter rise in sea level would inundate half of Bangladesh's riceland. (See map p 36 in Ch 2 of Eco-Economy.) With a rise in sea level of up to 1 meter forecast for this century, Bangladeshis would be forced to migrate not by the thousands but by the millions. In a country with 134 million people--already one of the most densely populated on the earth--this would be a traumatic experience. Where will these climate refugees go?

Rice-growing river floodplains in other Asian countries would also be affected, including India, Thailand, Viet Nam, Indonesia, and China. With a 1-meter 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 most easily measured effect of rising sea level is the inundation of coastal areas. Donald F. Boesch, with the University of Maryland Center for Environmental Sciences, estimates that for each millimeter rise in sea level, the shoreline retreats an average of 1.5 meters. Thus if sea level rises by 1 meter, coastline will retreat by 1,500 meters, or nearly a mile.

With such a rise, the United States would lose 36,000 square kilometers (14,000 square miles) of land--with the middle Atlantic and Mississippi Gulf states losing the most. Large portions of Lower Manhattan and the Capitol Mall in Washington, D.C., would be flooded with seawater during a 50-year storm surge.

A team at the Woods Hole Oceanographic Institute has calculated Massachusetts's loss of land to the rising sea as warming progresses. Using the rather modest U.S. Environmental Protection Agency projections of sea level rise by 2025, they calculated that Massachusetts would lose from 7,500 to 10,000 acres (3,035 to 4,047 hectares) of land. Based on just the lower estimate and a nominal land value of $1 million per acre for ocean-front property, this would amount to a loss of at least $7.5 billion of particularly expensive property by then. Some of the 72 coastal communities included in the study would lose far more land than others. Nantucket could lose over 6 acres and Falmouth 3.8 acres a year.

Coastal real estate prices are likely to be one of the first economic indicators to reflect the rise in sea level. Those with heavy investments in beachfront properties will suffer most. A half-meter 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 have discovered.

Many developing countries already coping with population growth and intense competition for living space and cropland now face 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.

While Americans are facing loss of valuable beachfront properties, low-lying island peoples are facing something far more serious: the loss of their nationhood. They feel terrorized by U.S. energy policy, viewing the United States as a rogue nation, indifferent to their plight and unwilling to cooperate with the international community to implement the Kyoto Protocol.

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. It also raises questions about responsibility to other nations and to future generations that humanity has never before faced.