Among the climate click-bait articles getting Google attention today is a piece in the Washington Post, ‘Millions of homeowners face flood risks without realizing it, and climate change is making it worse.” The article describes a new study by the First Street Foundation which claims millions more properties are at risk of flooding than are counted in the Federal Emergency Management Agency’s (FEMA) Special Flood Hazard Areas (SFHAs). Being in a FEMA SFHA allows home owners to enroll in the National Flood Insurance Program (NFIP). While federal flood maps may be flawed, meaning some properties at risk of flooding currently don’t quality for subsidized flood insurance, there is no evidence flooding is actually increasing across the United States due to climate change
The Post hypes the study, relying on speculative climate model projections. However by claiming in its title that “climate change is making it worse,” the Post lies about objective scientific evidence and even the findings of the United Nations Intergovernmental Panel on Climate Change (IPCC).
The First Street Foundation is undoubtedly correct the federal government’s flood maps are inadequate, failing to count possibly millions of properties at risk of flooding. Indeed, reports by SaferSmarter.org, the Cato Institute, and the Heritage Foundation, using government and private insurance data, have long pointed out federal flood zone maps are fundamentally flawed and merit significant revisions and updates. But while federal flood maps are flawed, meaning some properties at risk of flooding currently don’t quality for NFIP, there is no evidence flooding is actually increasing across the United States due to climate change.
As discussed Climate at a Glance: Floods, IPCC admits having “low confidence” in any climate change impact regarding the frequency or severity of floods, going so far as to say it has “low confidence” in even the “sign” of any changes—in other words, it is just as likely that climate change is making floods less frequent and less severe. And a 2017 study in the Journal of Hydrology discoing climate impact on flooding for the USA and Europe, concluded “… the number of significant trends [concerning floods] was about the number expected due to chance alone,” and “[c]hanges in the frequency of major floods are dominated by multidecadal variability.”
Costs from flood events, as with hurricanes, have increased dramatically in recent years. However, research demonstrates that is due to changes in landscapes and demographics.
More people are moving to coastal areas and along rivers. Also, as human societies have urbanized, they have changed the landscape, no more so than in waterfront areas along coasts, lake shores, and rivers. The conversion of floodplains and wetlands to urban development increases the amount of impervious surface, leading to ever greater run off during storms. The rapid draining of shallow aquifers, stream channelization, and land subsidence, also exacerbate flooding. Finally, flood insurance policies encourage construction in flood prone areas.
Neither the Washington Post nor the First Street Foundation provide any evidence showing that any increase in flooding in recent decades is due to climate change, as opposed to documented other factors.
Even the United Nations IPCC agrees with that.