A Staten Island neighborhood, pre and post Hurricane Sandy. First Street Foundation photo
I posted recently about newly identifed “Climate Abandonment” areas, neighborhoods identified in a new peer reviewed study, where residents have moved out due to increasing local climate risk. The most common risk factor is flooding, and typically, these residents don’t move very far – they want to hold on to family structures, jobs, community – but it means that within some areas, even relatively prosperous areas, there are pockets of at-risk housing that could be, or already has been, devalued – and those residents left behind will find their holdings reduced in value. A separate study from Environmental Defense Fund, published earlier this year in Nature Climate Change, showed that significant blocks of real estate may be overvalued due to as yet unpriced climate risks.
A new study published in the journal Nature Climate Changeexamines the potential cost of unrealized flood risk in the American real estate market, finding that flood zone property prices are overvalued by US$121–US$237 billion. Authored by researchers from Environmental Defense Fund, First Street Foundation, Resources for the Future, the Federal Reserve, and several academic institutions, the study also examined how unpriced flood risk throughout the country could impact communities and local governments, finding low-income households particularly vulnerable to home value deflation.
“Increasing flood risk under climate change is creating a bubble that threatens the stability of the US housing market. As we’ve seen in California in the last few weeks, these aren’t hypotheticals and the risk is more extensive than expected—and that risk carries an enormous cost,” said Dr. Jesse Gourevitch, a postdoctoral fellow at Environmental Defense Fund and lead author of the study. “These risks are largely unaccounted for in property transactions, encouraging development in flood-prone areas. Accurately pricing the costs of flooding in home values can support adaptation to flood risk, but may leave many worse off.”
Currently, more than 14.6 million properties in the United States face at least a 1% annual probability of flooding, with expected annual damages to residential properties exceeding US$32 billion. Increasing frequency and severity of flooding under climate change is predicted to increase the number of properties exposed to flooding by 11% and average annual losses by at least 26% by 2050. The increasing cost of flooding under climate change has led to growing concerns that housing markets are mispricing these risks, thus causing a real estate bubble to develop.
Over the last two decades, as San Antonio and surrounding Bexar County, Texas, grew by more than 600,000 people, some 17% of the city’s blocks experienced a decrease in population.
That delta is largely due to flood risk that climate change exacerbates, according to a new report by the First Street Foundation, a data nonprofit with the mission of communicating climate hazards.
Bexar — sitting in a swath of Texas known as Flash Flood Alley — is part of a national trend of hyper-local migration to avoid flooding, which is hollowing out blocks within cities, the report finds. The research is based on a model, published Monday in the journal Nature Communications, that looks at population changes using granular US Census Bureau data and controls for factors besides flooding, such as nearby job opportunities and school quality.
In all, First Street finds, 3.2 million Americans moved away from high-flood-risk areas between 2000 and 2020. The full extent of the migration has been hidden, however, since most people didn’t move far.
“There appear to be clear winners and losers in regard to the impact of flood risk on neighborhood-level population change,” Jeremy Porter, head of climate implications research at First Street, said in a statement. “The downstream implications of this are massive and impact property values, neighborhood composition and commercial viability, both positively and negatively.”
The analysis also extrapolates these trends 30 years into the future, predicting that vulnerable areas will continue to lose population.
In the US, the frequency of disasters causing at least $1 billion in damages has gone from roughly three a year during the 1980s to an annual average of 17.8 over the period 2018 to 2022, according to the National Oceanic and Atmospheric Administration. Global warming has knock-on effects that exacerbate flooding in particular, including sea level rise, more ferocious hurricanes and more frequent and extended downpours.
Below, a Detroit area local news report about recent flooding in Southeast Michigan. No mention of the word “climate”, but neighbors talk about floods becoming more frequent, area disaster manager mentions “significant rainfall that we’re not used to seeing.”
I bagged a long sought after interview late last March, with Jeff Severinghaus (we have a connection I’ll explain tomorrow) of Scripps Oceanographic Institute. Big Ice guy.
Jeff has some current research that I’ll be examining in coming videos, but as I spoke to Jeff he was just returning from a stay in Antarctica, so I asked him to summarize the best assessments.
Then of course, Covid hit, and my county in Michigan got devastated by a dam failure, and a whole load of the madness that is 2020 got in the way – but I finally came back around to this. I matched Jeff’s clips with some from Richard Alley and Eric Rignot, well known to readers here. They spoke to me in New Orleans in 2017.
I had also talked to Susheel Adusumilli, also of Scripps, and I featured prominently the new work from Stef Lhermitte, of Delft University of Technology. Then I wrapped it with a summary from Twila Moon of the National Snow and Ice Data Center. My Yale Climate Connections colleague Karen Kirk also had a pass at this research as well, her @CC_Yale piece:
Climate researchers have long monitored ice sheet dynamics in the Amundsen Sea, focusing specifically on the Thwaites and Pine Island glaciers. The two sit side by side on Antarctica’s western peninsula covering an area roughly the size of nine U.S. coastal states stretching from Maine to Maryland. The two glaciers alone store ice that could account for about 4 feet (1.2 meters) of global sea level rise. Their “seaboard” location may help bring increased public attention and interest to the West Antarctic Ice Sheet, which if it melted could raise seas by a catastrophic 11 feet (3.4 meters).
An international effort led by the British Antarctic Survey recently published two papers (Hogan et al. and Jordan et al.) showing the first detailed maps of the seafloor at the edge of the Thwaites Glacier. The team mapped deep submarine channels that have been funneling warm water to this vulnerable location. High-resolution imagery pinpoints the pathways that allow warm water to undermine the ice shelf. Lead author Kelly Hogan of the British Antarctic Survey says the findings will improve estimates of sea-level rise from Thwaites Glacier. “We can go ahead and make those calculations about how much warm water can get under the ice and melt it,” Hogan said.
The other researchers, led by Stef Lhermitte, found stark visual confirmation of glacier disintegration using decades of time-lapse satellite imagery. Their work sheds light on the accelerating feedback process, wherein the rapid loss of ice is opening the door to ever-increasing melting.
