American homes in flood zones are overvalued by hundreds of billions of dollars, according to a study published on Thursday in the journal Nature Climate Change. Low-income homeowners in states controlled by Republicans are especially at risk of seeing their home values deflate as global warming accelerates.

Flooding is a costly and deadly natural hazard across the United States. For decades, the Federal Emergency Management Agency offered flood insurance at discounted rates, incentivizing developers to build houses in flood-prone areas. The agency’s flood maps are also notoriously outdated. That has led to a dangerous situation for homeowners as they grapple with year after year of debilitating floods.

The study, published by a group of academic, nonprofit, and government organizations that include the Environmental Defense Fund and the Federal Reserve, revealed that homes in flood zones are overvalued by as much as $237 billion.

The researchers found that coastal property owners and homeowners in states that have inadequate or nonexistent flood disclosure laws, such as Florida, where there are no disclosure laws and homes are overvalued by $50 billion, were particularly vulnerable to overvaluation. They also found that a large share of overvalued homes are in areas that FEMA says aren’t currently at significant risk of flooding, a signal that flood maps need updating. The study’s authors told Grist that states need to gauge and clearly communicate flood risk to homeowners regardless of whether their home is located in one of the agency’s “special flood hazard areas,” where flood insurance is mandatory for most mortgages.

Read the full article about homes in flood zones by Zoya Teirstein at Grist.