Free The Attacking Ocean by Brian Fagan Page B

next century or so? There are, of course, some low-lying settlements and island populations that are already being forced to move, but such relatively small-scale shifts pale beside the decade- and century-long disruptions that lie ahead in densely populated nations like China, Europe, and the United States.
    At a general level, the figures are daunting. Roughly two hundred million people globally live along coastlines less than five meters above today’s sea level. By the end of the twenty-first century, this figure isprojected to increase to four hundred million to five hundred million. At the same time, coastal megacities will continue their breakneck growth. In Europe, a sea level rise of about a meter will threaten thirteen million people. A billion people live within twenty meters of mean sea level on land measuring only some eight million square kilometers, an area roughly equivalent to that of Brazil. The land loss will affect the gross national product of flooded areas, impinge on expanding urban settlement, inundate agricultural land, reduce job opportunities, and eradicate coastal wetlands that offer a measure of protection against flooding.
    Which nations are most vulnerable? Bangladesh is close to the top of any list, as are the Pacific Islands described in chapter 12 , and also the Bahamas. Vietnam with its Mekong delta is under threat. More than a third of the river’s delta will vanish underwater with a one-meter sea level rise. In a perhaps prophetic event, the Vietnamese government evacuated 350,000 people in the face of Tropical Storm Ketsana in September 2009. The same storm left 80 percent of Manila in the Philippines underwater. Shanghai with its estuary and dense urban population is also high on the list. In Europe, the Low Countries and the southern Baltic coast, including the Oder and Vistula estuaries, are potential victims, as is eastern England. In the Mediterranean, densely populated flatlands such as the Nile delta, and, of course, the Po delta and Venice, are under attack. Without sea level defenses already in place, constructed at vast cost, some of these areas would already be underwater.
    What about the United States, where millions of people live at, or close to, today’s sea level? Using government elevation databases, researchers at the University of Arizona have analyzed the vulnerability of every coastal city in the lower forty-eight states with a population of over 50,000 people. 1 The results provide sobering food for thought. Coastal cities along the Gulf and southern Atlantic coasts will be especially hard hit. Miami, New Orleans, Tampa, and Virginia Beach, Virginia, could lose more than 10 percent of their land areas by 2100. An average of 9 percent of land within 180 US coastal cities could be threatened within the same time frame. Collectively 40.5 million people live inthese cities, twenty of which have populations of over 200,000. This is apart from erosion and resulting temporary flooding as well as storm damage in a future of more extreme events.
    Global warming has raised sea levels about 20 centimeters since 1880 and the rate of rise is accelerating. Many scientists expect a rise of 20 to 203 centimeters this century, depending on the release of greenhouse gases and other pollutants into the atmosphere. More specifically, the Arizona study projects a 2.5- to 20-centimeter climb by 2030 and a 10-to 49-centimeter rise by 2050, the amount varying considerably from one location to another. If current rates of greenhouse gas emissions continue, global temperatures will rise to an average of thirteen degrees Celsius warmer than today by 2100. According to Jeremy Weiss of the University of Arizona, this would lock us into at least 4 to 6 meters of sea level rise in subsequent centuries, as parts of the Greenland and Antarctic ice sheets dissolve. 2 With an almost 3-meter rise, nine large cities, including Boston and New York, will have lost 10 percent of their current land areas.