For the nearly 5 million people who live along the U.S. coasts from Maine to the Gulf of Mexico and the West Coast, rising seas fueled by global warming have doubled the risk of so-called once-a-century floods, according to a trio of environmental reports released Wednesday. These new reports -- one from the non-profit group Climate Central and two others published in the peer-reviewed journal Environmental Research Letters -- offer a detailed picture of where the most severe risks are along coastlines of the contiguous 48 states. Based on 2010 U.S. Census population data and a fresh analysis of high tide lines by the National Oceanic and Atmospheric Administration, the Climate Central report\'s findings can be seen online at surgingseas.org.South Florida may be \'indefensible\' South Florida may be \"indefensible\" against floods caused by higher seas and the bigger storm surges that are expected to result, according to Ben Strauss, an expert on ecology and evolutionary biology who is chief operating officer of Climate Central. He co-authored the two journal reports and the online report. “Sea level rise is like an invisible tsunami, building force while we do almost nothing,” Strauss told The New York Times. “We have a closing window of time to prevent the worst by preparing for higher seas.” Flooded in 60 minutes: NYC tunnel warning An estimated $30 billion in taxable property is vulnerable in southeast Florida alone, according to a preliminary independent analysis cited in the report. In California, some places that have never seen severe floods could be vulnerable to them in the next decade or two, Strauss said. Climate scientists maintain that people, businesses and infrastructure in low-lying coastal areas of the contiguous 48 U.S. states are vulnerable to sea level rise, and world sea levels have risen by 8 inches since 1880.This rise in the world\'s seas is caused by the expansion of ocean waters as they warm and by the melting of glaciers and ice sheets, Strauss said. This is due to global warming fueled by the emission of heat-trapping greenhouse gases, he and other climate scientists have said. The Times said that the “handful” of climate researchers who question the scientific consensus about global warming often assert that sea level rise, which they do not dispute, stems from natural variations in the climate and doubt the rate of rise is increasing. A \'waste\' of money? Myron Ebell, a climate change skeptic at the Competitive Enterprise Institute, a Washington research group, told the Times that “as a society, we could waste a fair amount of money on preparing for sea level rise if we put our faith in models that have no forecasting ability.” Forecasts for sea level rise this century range from 2 to 7 feet with most estimates centering around 3 to 4 feet, given a projected rise in global temperature of at least 2 to 3 degrees Fahrenheit, Strauss said. As sea levels rise, Kiribati eyes 6,000 acres in Fiji as new home for 103,000 islanders As seas rise, they amplify storm surges, the reports said.Global warming will more than double the odds of once-a-century floods by 2030 for more than two-thirds of the 55 coastal locations considered in the analysis, the Climate Central report said. For a majority of the locations, warming triples the odds of century floods.