Zillow: If Sea-Level Predictions Correct, 1.9M Homes Could be at Risk by 2100

Joe Setyon | August 5, 2016 | 1:58pm EDT
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Water level monitoring station in Alabama. (NOAA)


(CNSNews.com) – If climate change scientists’ predictions are correct, rising sea levels could put 1.9 million homes at risk of being underwater by the year 2100 and destroy $882 billion in real estate value, according to a report by real estate database Zillow.

“If sea levels rise as much as climate scientists predict by the year 2100, almost 300 U.S. cities would lose at least half their homes, and 36 U.S. cities would be completely lost,” an August 2nd Zillow report says.

“To quantify the impact of rising sea levels, we used maps released by the National Oceanic and Atmospheric Administration showing which parts of costal states will be underwater if sea levels rise by six feet," said the Zillow report. "Why six feet? Some estimates suggest sea levels will rise that much by the year 2100 if climate change continues unchecked. Using that data in conjunction with our database of information on more than 100 million homes nationwide, we determined which properties were at risk of being submerged (at least their ground floors) in the next century or so and what they’re currently worth.

“Nationwide, almost 1.9 million homes (or roughly 2 percent of all U.S. homes)--worth a combined $882 billion--are at risk of being underwater by 2100,” said the report.

But NASA data shows that since 1993, global sea levels have risen 87.4 mm overall, and are currently rising at an average rate of 3.5 mm a year.  

If sea levels continue to rise by 3.5 mm each year from now until 2100, there would be a total increase of 294 mm - 11.6  inches - over the next 84 years.

A disclaimer by NOAA says that “the data and maps in this tool are provided ‘as is,’ without warranty to their performance, merchantable state, or fitness for any particular purpose.”

According to the Zillow report, Florida would be the hardest hit state, with 12.56 percent of its houses (934,311 homes) underwater by the end of the century, causing $413 billion in damage. Miami in particular would suffer, Zillow says, as 30.5 percent of its housing stock (32,986 homes) would be affected.  

New Jersey ($93.1 billion in housing damage), New York ($71 billion), Massachusetts ($51.2 billion), California ($49.2 billion), South Carolina ($45 billion) and Hawaii ($25.3 billion) would be the next hardest hit states, according to the report.

The sea level predictions are based on an article published March 31 in Nature by Robert DeConto from the University of Massachusetts and David Pollard from Penn State, which claimed that melting ice in Antarctica could raise average sea levels by more than a meter (over three feet) in the next 84 years in addition to what was already expected for a nearly six foot total rise in sea levels worldwide "if [current carbon dioxide] emissions are not abated".

Beach houses at Cape May, N.J. after six-foot rise in sea level. (NOAA simulation)

Beach houses at Cape May, N.J. (NOAA)

However, according to Patrick Michaels, director of the Cato Institute’s Center for the Study of Science, the Nature study’s assumptions “are not supported in reality.”

“You can get a lot of ice to fall off of Antarctica if you tell a computer model to turn the snow to rain and have the rain dig 300-foot-deep crevasses in the onshore ice,” Michaels told CNSNews.com.

“But nobody’s ever seen that happen, and the computer model is just doing what it’s been programmed to do.”

Michaels believes that Antarctica is actually gaining ice because “if you warm up the ocean around Antarctica a small amount, that will put more moisture in the air, and when a storm system converts that moisture over Antarctica, it’s going to fall as snow.”

In an article he wrote with assistant director Chip Knappenberger, Michaels criticised the Nature study’s “ice dynamics model,” calling it “extremely sensitive to the settings of its large variety of handles and knobs—the settings of which can only be guessed at as the physics that the model is built upon is not well developed.”

Moreover, an October 2015 NASA study found that Antarctica has actually been gaining more ice than is being melted.

NASA said that the Antarctic ice sheet gained 112 billion tons of ice a year between 1992-2001, and 82 billion tons annually from 2003-2008.

“Antarctica is not currently contributing to sea level rise, but is taking 0.23 millimeters per year away,” said Jay Zwally, a NASA research scientist and the study’s lead author.

H. Sterling Burnett, a research fellow at the Heartland Institute, told CNSNews.com that Zillow’s damage estimates would be accurate “if sea levels were to rise six feet” by 2100, but added that “no one realistically expects” that to happen.

Burnett believes a more realistic estimate for sea level rise is between seven and 12 inches, similar to what occurred in the 20th century, because “there’s no evidence that rates of sea level rise are increasing despite greenhouse gas emissions.”

“Antarctica is adding tens of thousands of tons of ice and snow a year despite rising CO2 levels. It would have to completely reverse, and there’s no evidence that will happen,” he told CNSNews.

Burnett added that even though a reasonable amount of property damage can be expected over the next 84 years, much of it will be due to land “subsidence, not sea level rise” in places such as Florida and Houston, Texas where “sinking land…is causing the flooding problems.”

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