Flood risk will rise with climate change, experts say

As the Northeast struggles with the aftermath of the massive storm Sandy, many experts say the government for years has underestimated how much of the nation is prone to flooding, given the increasing likelihood of extreme weather because of climate change and the prospect of future sea level rise.

These experts, who include not only environmentalists but also community planners, insurers and fiscal conservatives, have pressed agencies such as the Federal Emergency Management Agency to rethink the way the government evaluates the risk of floods. Such a change could affect where and how infrastructure is built and make it harder to develop vulnerable areas.

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The 10 costliest hurricanes and tropical storms in U.S. history: Hurricane Sandy has flooded towns and cities along the East Coast and caused massive power outages, leaving observers wondering where the devastating storm will fit among the nation’s costliest hurricanes. Here’s a look at the 10 costliest hurricanes as reported by the National Oceanic and Atmospheric Administration. Numbers were not adjusted for inflation.

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FEMA, which is updating flood insurance maps from the 1980s, is setting up a “technical mapping advisory council” that will study how the agency might take future climate change into account. At this point, it still bases its analysis on historical data.

But Sandy’s devastating punch might bolster the case for change, given how it exposed many areas’ vulnerabilities to storm surge and sea level rise.

New York Gov. Andrew Cuomo (D) said policymakers need to acknowledge that the infrastructure in place along the East Coast cannot withstand the changing climate.

“Anyone who thinks that there is not a dramatic change in weather patterns is denying reality,” Cuomo said at a news conference Tuesday. “We have a new reality, and old infrastructures and old systems.”

Flood planning is based on historical data rather than future projections. And much of the infrastructure damaged in a storm is rebuilt exactly the same way, without taking into account the climatic changes underway.

FEMA draws the flood maps to provide guidelines to local authorities who determine where things can be built. Many developers and homeowners have resisted the idea of expanding the definition of flood risk because it raises costs and can restrict development. Policymakers “are afraid of the political backlash,” said Georgetown Climate Center executive director Vicki Arroyo.

And expanding the maps means increasing the area covered by the 44-year-old National Flood Insurance Program, which covers Americans in flood-prone areas with federally backed insurance provided they meet federal standards aimed at minimizing risks. The program was at least $17.75 billion in debt before Sandy made landfall, and the storm could deplete the program’s remaining $3 billion statutory borrowing authority. The insurance is voluntary.

Proponents argue that the flood insurance program provides coverage that would otherwise be unaffordable and saves taxpayers money by prodding communities to take precautions. Critics say the program encourages Americans to build in vulnerable areas, with 40 percent of the total payout going to 2 percent of properties that were repeatedly flooded.

“Climate change is only happening in one direction,” said Kevin Trenberth, a senior scientist at the National Center for Atmospheric Research. “The temperature is warmer, the sea level is higher and the air is warmer so it can hold more moisture.”