WASHINGTON -- President Barack Obama issued an executive order Friday directing federal agencies to adopt stricter building and siting standards to reflect scientific projections that flooding will be more frequent and intense because of climate change.
It also applies to state and local governments drawing on federal funds.
The order, described by senior administration officials, represents a major shift for the federal government.
While the Federal Emergency Management Agency published a memo three years ago saying it would take global warming into account when preparing for more severe storms, most agencies continue to rely on historical data rather than future projections for building projects.
The new standard gives agencies three options for establishing the flood elevation and hazard area they use in siting, design and construction of federal projects.
They can use data and methods "informed by best-available, actionable climate science"; build 2 feet above the 100-year flood elevation for standard projects, and 3 feet above for critical buildings such as hospitals and evacuation centers; or build to the 500-year flood elevation.
The White House move comes just days after the U.S. Army Corps of Engineers released a report examining flood risks for 31,200 miles of the north Atlantic coast.
The research explicitly took sea-level rise induced by climate change into account and found, "Flood risk is increasing for coastal populations and supporting infrastructure."
Last month, the National Oceanic and Atmospheric Administration predicted coastal areas will face 30 or more days of flooding by midcentury because of sea-level rise.
According to the National Climate Assessment, more than $1 trillion of property and structures in the U.S. are at risk of inundation from a sea-level rise of 2 feet above current sea level -- an elevation that could be reached by that same point.
Despite these threats, more than half the U.S. population lives in coastal counties, administration officials said.
While global warming is a contested political matter in Washington, many state and local governments -- more than 350 -- already have adopted flood standards along the lines of what the Obama administration is now requiring.
Building to the stricter federal standards will add between 0.25 percent and 1.25 percent to the cost of construction, senior administration officials said. In the long run the move could save taxpayers money, they said, because it could significantly cut the nation's recovery costs.
The new policy does not make changes to the National Flood Insurance Program, which covers Americans in flood-prone areas with federally backed insurance, provided they meet federal standards aimed at minimizing risks.
But it will apply to grants the program provides, thereby affecting construction in flood-prone areas.
A Section on 01/31/2015