FEMA is attempting to do the impossible, and that is to predict future flood losses in a way that will allow changes to be made in the federal flood insurance program. E&E Daily reports:

Federal officials are struggling to calculate the fiscal impact that climate change could have on the nation’s troubled public flood insurance program, amid predictions of intensifying downpours and more potent hurricanes. The mission is proving extremely difficult, according to one researcher, who said the effort so far has failed to reveal even “squishy assumptions.”

The project’s lead researcher suggested that the entire effort was misguided (emphasis added):

Researchers are using data from the IPCC and the U.S. Climate Change Science Program to determine the climate risks to the insurance program. But there are glaring omissions in the overall knowledge needed to accurately depict the effects, says David Divoky, an expert with the consulting firm AECOM and the study’s lead researcher.

Detailed information about population growth is unknown, for example. So are the frequency, severity and location of future hurricanes, all of which can create large variations on the impacts on the flood insurance program. “There may be no solid projections. We’re not even coming up with squishy assumptions,” Divoky told an audience at the floodplain managers conference. “This whole thing is not what a sensible person should do.”

Once again I am reminded about a vignette from Nobel Prize-winning economist Kenneth Arrow (PDF):

As a weather forecaster in the Second World War, Arrow and his colleagues were told that their commanding officer needed a long-term forecast. The forecasters knew from experience that such forecasts had little scientific basis, and related this up the chain of command. The reply that came back was this: no matter, the general needs the forecast for planning purposes.

One prediction for the FEMA study seems spot on:

“The results could produce controversy regardless of the outcome”