Sinking tax base: Land and property at risk from rising seas

This new analysis by Climate Central delivers an assessment of sea level rise impact on the tax base of hundreds of coastal U.S. counties—specifically, the potential loss of taxable properties caused by shifting tidal boundaries. Coastal flooding caused by sea level rise is shifting the tide lines that many coastal states use to delineate boundaries between public and private property. Changes in property boundaries can have significant implications for both property owners and local property tax revenues—a primary source of funding for schools and services provided by local governments.

This analysis finds that by mid-century, more than 648,000 individual tax parcels, totaling as many as 4.4 million acres, are projected to be at least partly below the relevant tidal boundary level. Of those, more than 48,000 properties may be entirely below the relevant boundary level. Florida, Louisiana, and Texas have the largest number of affected parcels. Buildings may be concentrated at historically-safe elevations along the coast; when rising seas breach a certain threshold, these densely-developed elevation bands reach a tipping point and the number of affected buildings sharply increases. At least $108 billion of assessed value is at risk from rising seas by 2100, and because complete values were not available for all counties, the actual total is likely to be far higher.