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How Often Climate Change Has Caused Floods, City by City

Find your own (coastal) hometown!
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Between 1955 and 1964, there were six total days of flooding in Seattle. Between 2005 and 2014, there were 29 total days. The major difference between then and now, of course, is that the world's average temperatures are warmer due to human activities like cattle farming and the burning of fossil fuels. In fact, between 2005 and 2014, 26 days of flooding in Seattle were attributable to anthropogenic climate change, according to a new analysis. Only three were natural and would have occurred without global warming.

The analysis calculated the number of climate change-caused minor flood days for 27 American cities. You can check out the results below. Maybe your hometown is represented too. (Mine's Seattle.)

The floods recorded above aren't home- or life-threatening, but they may cause road closures, or shut off the plumbing for a while. In their own small way, these floods are costly to city governments and residents. In addition, these towns aren't the only ones to have contended with more troublesome floods as a result of global warming. They just happen to be the cities for which researchers had data available to them.

The analysis comes from Climate Central, a global warming reporting and research group. A team of scientists, including one from Climate Central, analyzed data from cities' hourly tide gauges, seeking numbers that exceeded each city's threshold for "flood." To find which floods were caused by global warming, they subtracted four and a half inches from each flood day's tide height—the amount by which sea levels have risen worldwide due to climate change, according to a recent study.

It's a simple calculation, and a rough estimate of the floods that are caused by global warming, but it offers an idea of the impact climate change has had on America's coasts. Overall, two-thirds of the floods the United States has experienced since 1950 wouldn't have happened without global warming, according to the Climate Central analysis.


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