PROTECTING CITIES FROM FLOODING
Hundreds of millions of people worldwide live in cities built close to the sea. Many of these cities have constructed massive walls along the coast to prevent them from being flooded. However, in recent years storms at sea have become exceptionally violent, bringing high and powerful waves crashing over these barriers. Cities in coastal regions of Japan and along the east coast of the United States, in particular, have been badly hit, with hundreds of thousands of homes destroyed by widespread flooding.(lines 1–6)
Global warming is thought to be responsible for the increased intensity of ocean storms. The higher temperatures of the Earth’s atmosphere also warm the oceans, causing sea levels to rise and increasing the likelihood that coastal cities will be flooded. As these trends will probably continue, sea walls won't offer protection in the future unless they are made much higher and stronger. Unfortunately, most coastal cities will be unable to afford the cost of providing adequate protection against flooding.(lines 7–12)
The seriousness of the situation is highlighted in the book The Last Beach, written by ocean scientists Orrin Pilkey and Andrew Cooper. Ideally, the authors say, vulnerable cities ought to be moved further away from the coast. However, recognizing that this solution would be extremely complex and expensive, they also suggest a simpler, cheaper approach: When neighborhoods have been flooded, they should no longer be rebuilt in the same location. Instead, those parts of the city should be constructed far from the coast, on higher ground.(lines 13–18)
As for new cities, Pilkey and Cooper believe they should all be built inland. In cases where construction near the coast cannot be avoided, engineers must make sure that natural sandy beaches are preserved. It is those beaches, explain the authors, which provide the most effective defense against the forces of the ocean. Their studies of coasts around the world have shown that the power of ocean waves is reduced as they break on wide stretches of beach. But when concrete barriers are built, much of the sand is removed, leaving only the barriers themselves to withstand the full force of the ocean.(lines 19–25)
Although Pilkey and Cooper’s views are widely accepted by ocean scientists, things are unlikely to improve anytime soon. With rapidly increasing populations that need housing, many small countries feel forced to build on all available land, including areas close to the sea. Under such circumstances, they don't consider protecting sandy beaches a priority. Apparently, they are not deterred by scientists' warnings that rising sea levels will lead to flooding within the next fifty years. It seems, then, that governments will introduce essential measures only when they repeatedly experience widespread destruction in their cities.(lines 26–32)