[Editor's Note: Today is World Water Day. In this article, Robert Kropp of SocialFunds discusses how rising sea levels and storm surges threaten commercial buildings, agriculture, nuclear plants and much more, and are already causing billions of dollars in insurance losses. Please also see the post by GreenOrder's Simon Lim on how energy companies manage their water footprints.]

Since 1880, average sea levels have increased by more than 8 inches, most if not all of which can be attributed to the impacts of climate change. According to Climate Central, in a report entitled Surging Seas, unchecked climate change is likely to make things much worse, and soon.

The study projects that sea levels could rise as much as an additional eight inches by 2030. Furthermore, "The rate of rise is accelerating," Climate Central reports. "Scientists expect 20 to 80 more inches this century."

One effect of rising sea levels is likely to be massive migration by populations in low-lying areas. The Center for International Earth Science Information Network has estimated that there could be as many as 700 million climate refugees by 2050. And CIESIN states, "Sea-level rise appears to be the impact most certain to result in displacement and resettlement."

"Migration may be the only adaptive response," the center continued. Cynthia McHale of Ceres recently reported on an extreme example of migratory adaptation, writing, "The president of Kiribati, a low lying nation of small South Pacific islands, announced that his country was buying 6,000 acres of land in Fiji because climate-driven sea level rise is threatening to submerge his country. The plan of last resort is to move the entire population of 103,000 to Fiji."

In case the U.S.-based reader is tempted to breathe a sigh of relief that the initial impacts will be felt at such a distance, it must be noted that the Surging Seas report focuses on impacts at home. Fifty-five sites within the U.S. were analyzed, and the report finds that three-quarters of them -- nearly 5 million people in 2.6 million homes -- live in areas lower than four feet above the high tide line; but average sea levels have already exceeded four feet. An additional 3.7 million people live less than one meter above the high tide line.

"The population and homes exposed are just part of the story," the report states. "Flooding to four feet would reach higher than a huge amount of dry land, covering some 3 million acres of roads, bridges, commercial buildings, military bases, agricultural lands, toxic waste dumps, schools, hospitals, and more."

To make matters even worse, Climate Central observes, "Rising seas dramatically increase the odds of damaging floods from storm surges." The likelihood of so-called "century floods" -- floods that are unlikely to appear more than once in a century -- is expected to double by 2030. In fact, at two-thirds of the locations analyzed by Climate Central, the annual risk of such floods has already doubled.

In New Jersey, the projected sea level rise is 15 inches by 2050, and the likelihood of century floods will have more than tripled by 2030.

Half the exposed population, as well as eight of the 10 most vulnerable cities, are located in Florida. The state is already experiencing flooding at extreme high tides and contamination of freshwater aquifers by the ocean. Because southern Florida uses manmade canals to handle storm runoff, 6 inches in sea level rise will cripple the system.

As McHale of Ceres notes, the Florida Climate Institute has estimated that sea levels in the state could increase by as much as 32 inches by 2100.