Putting climate change into numbers: Why 300,000 homes are at risk

A new study puts the threats of climate change and rising sea levels into real, life-threatening numbers.

A national research analysis from the Union of Concerned Scientists (UCS) predicts that 311,000 coastal homes are at risk of flooding 26 times or more per year within the next 30 years, a phenomenon called a “chronic inundation.” By 2100, that number will exceed 2.4 million of today’s U.S. homes.

The UCS study breaks down the at-risk homes and areas by state, community and ZIP code. It also shows the current property value, estimated population, and portion of the property tax base at risk.

Related: New York, Boston face coastal flooding due to above-normal tides

UCS researchers emphasize that the flooding highlighted in this study is not caused by storms. It strictly analyzes the result of high tides rising higher and reaching farther inland as sea levels rise over the next several decades. This analysis provides important insight to homeowners, communities, and major industries — especially insurance — that will be adversely affected by this forecast of rapidly rising sea levels over the next 30 to 100 years.

The effects of climate change

The analysis warns that if swift action is not taken to reduce greenhouse gas emissions, rising tides will effectively and repeatedly flood $120 billion worth of coastal properties by 2045. These risks pose enormous financial and emotional turmoil to the nearly 500 million Americans living in these properties.

The analysis does provide some hope, however.

If the world were to take immediate and appropriate action to combat the effects of climate change, specifically by reducing the carbon emissions that cause global warming, study analysts say more than two million of today’s U.S. homes — collectively worth $782 billion today — could potentially be spared from frequent high-tide flooding or chronic inundation.

One of the UCS study maps breaks down the difference between a high rate of sea level rise associated with a continued increase in carbon emissions and ice melt, and a low rate of sea level rise, which is possible if nations successfully limit future warming to less than 2 degrees Celsius (the goal set by the Paris Climate Agreement) and ice loss is limited.

By 2100, the higher rate would lead to about 6.5 feet of global average sea level rise, while the lower rate would result in only about 1.6 feet.

Experts at UCS used federal data from a high sea level rise scenario projected by the National Oceanic and Atmospheric Administration (NOAA), and combined it with property data from Zillow to quantify the level of risk across the lower 48 states for their coastal property analysis.

The full report with detailed animated maps is available on their website.

Related: Taxpayers in the Hamptons among the most exposed to rising seas