How sea-level rise contributes to billions in additional damage during hurricanes » Yale Climate Communications

When Hurricane Ian hit the coasts of southwest Florida on September 28, the hurricane’s strong winds of up to 150 miles per hour created a massive and destructive storm inland. A preliminary estimate from the National Oceanic and Atmospheric Administration (NOAA) puts Ian’s losses at more than $50 billion, and damage estimates from some private insurers approach or exceed $100 billion. It is possible that tens of billions of this damage was caused by a catastrophic storm of 10 to 15 feet, which settled countless structures on the lower barrier islands south of where the Eye of Ian came ashore.

Had Ian struck a century ago, when sea levels were nearly a foot lower, the storm would likely have caused billions of dollars less storm damage, according to the results of two studies looking at storm damage from Hurricane Sandy in New York in 2012. Combined, The study’s findings suggest that rising seas have left a large portion of the United States’ coastal infrastructure — much of it built during the 1920s.The tenth Horn – vulnerable to storm surge.

Small increases in storm surge can cause massive effects

Sea level rise – even just a few inches – can cause significant damage during storms. why?

To use the mathematical analogy, it is because the interaction of storms with the city is a game of inches and thresholds. Coastal cities are generally designed to take one event in every 100 years (an event that has a 1% chance of occurring in a given year) to cause significant destructive flooding: a storm surge must rise to the basic elevation of a city before it can inundate large areas. But once a storm crosses that threshold, every inch of additional rise in water levels can inundate large areas. And since just one inch of water in a 2,500-square-foot home can cause $27,000 in damage, and 12 inches can cause $72,000 in damage (according to FEMA), a few extra inches of storm surge can add a lot of damage in a hurry.

Storm surge height makes deaths more likely

As the storm plays the game of inches, the sudden rise in indoor ride above ocean levels magnified by human-caused sea level rise now has much higher odds of imposing a higher death toll than it did a century ago. Ian is blamed for at least 120 deaths in the United States — 114 in Florida, five in North Carolina, and one in Virginia. At least 58 of those deaths were by drowning, with storms claiming the highest number of casualties. Human-caused sea level rise has increased the odds of this many deaths.

To see how a few extra inches of human-caused sea level rise could exceed the limit responsible for killing someone, consider the case of the Hideaway Village Motel in Fort Myers Beach, where USGS Surge Survey It showed 7 to 12 feet high watermarks from Storm Ian which occurred on both sides of the hotel. like increase ian The building was torn to the ground and bearing him more than a third of a mile, four hotel-guests beat themselves on a mattress that floated to the ceiling; One of them died when troops hung her from the ceiling. If Storm Ian’s wave had been a foot low – as it would have been a century ago, before sea level rise – the victim may have survived, if the elevation wasn’t high enough to anchor it to the ceiling.

Figure 1. Initial rising water signs from storm surge plus waves from a USGS survey in October 2022. (Image credit: Michael Lowry)
Figure 2. High-resolution tidal data from a pressure sensor installed on the Fort Myers Beach Pier indicates storm tides up to 13 feet above Pre-Ian Beach, with waves helping to bring water levels up to 15 feet. Strong waves washed away the beach itself, and about 5 feet of sand was lost from pre-Ian levels. (Image credit: Michael Lowry)

Storm surveys of Ian’s damage revealed a gust of 10 to 15 feet

The US Geological Survey, or USGS, conducted a preliminary survey of storm surge in the weeks following Hurricane Ian. The results indicate that the peak eruption occurred in Lee and northern parts of Collier County, about 25 to 30 miles south of where the storm came ashore, near the radius of maximum overland flow winds. High water marks on Fort Myers Beach reached nearly 16 feet in spots, the National Hurricane Center chirp Based on a USGS survey, Ian reached 10-15 feet above usually dry land there. Watermarks seven feet or higher above ground level are found on a 70-mile stretch of the Florida coast from Cape Coral to the city of Everglades. (Rising water signs include wave action at the crest of the flow, and therefore generally higher than altitude.)

Figure 3. Sea-level rise since 1965 In Fort Myers, Florida, the tidal gauge has been about 7.6 inches (0.63 feet), or about 13.3 inches (1.11 feet) per 100 years. Sea-level rise has been accelerating due to human-caused climate change, dramatically increasing the risk of storm surges. (Image credit: NOAA)

The sea level rise since 1965 in Fort Myers, Florida, the tidal gauge has been 7.6 inches, or about 13.3 inches if estimated for a 100-year period (Fig. 3). Much of this sea level rise was due to human-caused global warming; The Global sea level rise since 1900 It is estimated to be approximately 7.5 inches (19 cm). Most of this rise has been caused by melting glaciers and by expanding water when heated.

Hurricane Sandy 2012: Billions of additional damage from sea level rise

Up to $8.1 billion of the $62.5 billion in damage caused by Hurricane Sandy in 2012 in New York, New Jersey and Connecticut was caused by the increase in sea levels caused by human-caused climate change, according to the 2021 sheets By scholars from Climate Central.

Hurricane Sandy caused a storm tidal wave (a combination of storm surge and natural tide) of 9.2 feet (2.8 m) into New York City, and scientists have estimated that if the storm surge was only 3.8 inches (9.6 cm) lower, the increase in the Tri- state that would affect 9.2% fewer people (71,000) and 8.8% fewer housing units (36,000), causing a 13% reduction in storm damage. They chose 3.8 inches as the threshold for the study, as this is the amount of sea level rise that has occurred since 1900 in New York City that can be confidently attributed to human-caused global warming. (The total sea level rise that occurred from 1900 to 2012 in New York City Much higher, about 12.9 inches, due to important natural components resulting from land subsidence and natural changes in ocean currents.)

The Climate Central study used the FEMA estimate that 100% of Sandy’s damage was from storms. A separate study by Lloyd’s of London (see below) estimated that storm surge was responsible for 65% of Sandy’s damage. Depending on the estimate of the damage fraction used, between $5.2 billion and $8.1 billion in Sandy damage (13% of total damage from storms) was due to the increase in sea levels caused by human-caused climate change.

Lead author Ben Strauss said Climate Central’s analysis provided only minimal estimates of the impact of climate change on Sandy’s damage. An interview with Carbon Brief: “We haven’t looked at the whole of Sandy, so we really see our estimate as a conservative, low-end estimate. We haven’t assessed whether climate change has made Sandy stronger or affected its trajectory…but we have isolated the impact of the onset of sea level rise, and that’s just something we can stand On it — it’s a very solid bedrock of understanding the impact of climate change.”

separate Study by Lloyd’s of London The study also found a significant impact of storm surge damage for Hurricane Sandy from sea-level rise – nearly 30% of New York’s insured Storm Sandy’s storm surge can be attributed to a 0.8-foot sea-level rise since 1950. Since the damage in New York calculated for 40% of Sandy’s total insured losses of $20-25 billion, and 65% of those losses were from a storm surge, this 30% damage increase equivalent to a $1.6-2.0 billion loss (2012 dollars). The total damages would be much greater, although the estimate was only for New York, and the insured damages are usually only about 50% of the total damages. However, the study did not separate the natural and human parts of sea level rise.

Suspension

With our cities built for 20The tenthSea level in the 21st centuryStreetThe storms of the century are now capable of doing much more damage due to rising sea levels. According to an analysis of coastal hurricane-prone locations in the United States central climate, what was once a one-in-100-year storm event for more than half of these cities is now a one-in-33-year event due to sea level rise. Strong hurricanes due to rising ocean temperatures create an additional risk factor; 2013 paper authors It was suggested that this change could lead to an additional factor of 2-7 in storm surge events at the level of Hurricane Katrina on the coast of the United States.

This dangerous shift in climate makes up a large part of our 20The tenthThe infrastructure of the century is unacceptably exposed to risks. Strong action is needed to prepare our coastal cities for a future with more storms and to prevent the situation from getting worse: a faster transition to a clean energy economy that does not burn fossil fuels is needed.

Things you can do:

1) Protect your home from flooding. FEMA He has some great suggestions on how to do this.

2) Know the dangers of flooding. Hosts the National Hurricane Center Storm Rush Hazard Maps which allows one to view the above-ground flooding of hurricanes on the five Saffir-Simpson levels. Make sure to look not only at your property but also at the escape routes you might take in the evacuation process to see if they might be flooded before your property is flooded. Also, consult Foodfactor.com, a tool first made available by the First Street Foundation in 2020, that allows a person to type in an address and see the specific flood hazards of that property. It’s a great new resource of a kind that was not previously available to the public and is free for non-commercial purposes. The tool also assesses the risks of wildfires and excessive heat for your property.

3) Know your height. If you live near the coast, or are considering buying property near the coast, it is in your financial and survival best interest to know the exact height of your home. If you’re a homeowner, your flood insurance certificate should tell you your elevation based on the best USGS surveys available for the area. If not, go to USGS site called National Map ViewerOr enter an address or just zoom in on the area of ​​interest. this site It contains detailed instructions on how to use the USGS tool to find elevation.

4) The Rising Seas Hazard Research Program from Climate Central has some great resources for assessing storm surge risks. here it is Detailed page about Fort Myers.

5) Support policies and vote for politicians who will realistically deal with the threat posed by sea-level rise to our hurricane-prone coasts. Ultimately, sea-level rise, combined with potentially stronger hurricanes, will make the cost of defending and insuring property in high-risk coastal areas prone to hurricanes so great that the coastal property market crashes, triggering a mass exodus away. from the coast. The sooner we recognize and plan for this reality, the less costly and disruptive it will be. Climate future Alex Stephen It assumes that, although unlikely, it is possible that Hurricane Ian may have already started this process in motion. Ian could cause a flurry of revaluations in at-risk places across the country, leading to a slump in investment, a loss of insurance, and a disruption to the local housing market.

We should heed the words of Dr. Oren Bilkey, an expert on sea level rise at Duke University, and co-authors of their excellent 2016 book, Retreat from a Rising Sea; Tough Choices in the Age of Climate Change:

Like it or not, we will be retreating from most of the world’s non-urban beaches in the not too distant future. Our withdrawal options can be described as either difficult or disastrous. We can plan now and retreat in a strategic and calculated way, or we can worry about it later and retreat into tactical chaos in response. on devastating storms. In other words, we can methodically turn away, or we can flee in a panic.”

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