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Storm Surge Could Flood NYC 1 in Every 4 Years

When a storm, such as Hurricane Sandy, sets waters in New York Harbor rising, those sloshing seas are now 20 times more likely to overtop the Manhattan seawall than 170 years ago, a new study finds.

Hurricane Sandy's tremendous storm surge flooded the South Ferry subway station in Manhattan.
Credit: MTA New York City Transit / Leonard Wiggins

The increased risk comes from a combination of sea level rise — which has raised water levels near New York City by nearly 1.5 feet since the mid-1800s — and storm tide, or the amount that local seas rise during a storm. Storm tide is itself a combination of storm surge (the water that a hurricane pushes ahead of it) and the astronomical tide.

The rise in sea level and storm tide combined puts the odds of storm waters overtopping Manhattan’s defenses at one in every 4 to 5 years, compared to only once in every 100 to 400 years in the 19th century, the study found. (Put another way, the annual chance of a storm overtopping the seawall has gone from about 1 percent to 20-25 percent.)

The storm tide at Battery Park, at the tip of Manhattan, during Hurricane Sandy reached a record 14.06 feet according to the National Hurricane Center’s report on Sandy. That high storm tide — more than 4 feet higher than the previous record set in December 1992 and the largest since 1821 — was created by a 9.4-foot storm surge and the evening high tide during a full moon, when tides are higher than normal (though the evening high tide was not as large as the morning one).

The extreme rise in water level sent the Harbor flooding into the streets of the Financial District and other parts of Manhattan, as well as other city boroughs at depths between 2 to 9 feet above ground level. An estimated 305,000 houses in New York were destroyed, mostly by storm surge, according to the NHC. Total damage to the city was estimated at $19 billion, including $5 billion in damage to the city’s subway systems caused by flooding. At least 21 people were killed by the storm surge on Staten Island.

The Portland State University researchers behind the new study, accepted for publication in the journal Geophysical Research Letters, noticed that three of the nine highest recorded water levels in New York Harbor had occurred since 2010 and that eight of the largest 20 had occurred since 1990. While sea level rise plays a large part in this trend, the researchers wanted to see whether increased storm tides might also be contributing, so they looked at hourly and daily tide gauge data going back to 1844, and found that storm tides have increased by 1 foot since that time.

This graphic shows factors that contributed to the top 10 high-water events measured at New York’s Battery Park from 1900 to present. The water height for each event is shown here against the benchmark of mean lower low water averaged between 1983 and 2001. Sea level rise (about a foot since 1900) is depicted as a component of storm surge. Although Sandy’s surge peaked close to high tide, other events had even higher tide levels.
Click image to enlarge. Credit: Carlye Calvin and Bob Henson, UCAR; data courtesy Chris Zervas, NOAA National Ocean Service.

While the rise in sea level is attributable to the expansion of warming ocean waters and ice melt, the cause of the rise in storm tide is not yet clear, nor is the possibility that the rise will continue into the future.

“You can see that trend; it’s there. But the question is, is it related to greenhouse gases or something else?” climate scientist Radley Horton of the Northeast Climate Science Center and NASA’s Goddard Institute for Space Studies, told Climate Central.

The researchers suggest that the trend in rising storm tide could be partly due to decades-long changes in a climate pattern called the North Atlantic Oscillation, as well as longer-term trends driven by climate change. More local effects, like the dredging of ship channels, could also play a role.

While other studies have looked at increasing storm tides, this study goes back further in time, study co-author Stefan Talke, an assistant professor of civil and environmental engineering at Portland State University in Oregon, said in a statement.

The study makes an important contribution to the understanding of coastal flood hazards in terms of extending the historical record tide gauge data, Horton, who was not involved in the study, said.

He added that the study “highlights the fact that rising sea levels have already stoked an increase in the frequency and intensity of coastal flooding” and that it “also suggests that storms themselves may have grown stronger.”

But Horton cautioned: “The verdict isn’t in yet about how coastal storms are going to change with climate change.”

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By Rich Persof (Watsonville CA 95076)
on April 24th, 2014

Seems to me that the hardening of the land-water interface by filling, sea-walls, etc. would increase the"sloshing” of the now more-confined storm surge as it left the open sea and was funneled by the converging coasts towards New York.

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By Robert H. Pike (Homestead, Fl)
on April 24th, 2014

Another serious flood event will be the “wake-up call” environmentalists have been waiting for.  Serious expensive flood damage will do more to change minds and get legislative funding going in one one-day event than years of petitioning, letter-writing, protesting and advertising.

  Al Gore referred to the issue charmingly in “Inconvenient truth” as the “Frog in slowly warming water vs the frog in hot water” experiment - the point being that the frog - the worlds’ population - doesn’t react if the change is slow.  It needs a sudden event to make the frog jump. 

And the frog will jump when NYC is hit by a perfect storm.

Hate to say it; but it won’t be a matter of if; it will be a matter of when; and for those of us who want change to get a “kick-start”, the sooner the better.

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By Oliver Snow (Melbourne, Australia)
on May 5th, 2014

It does seem inevitable that these storms will occur. I would like everyone who cares to get involved in actively fixing the problem by supporting fusion power research. It’s not well known, but fusion has been advancing at the sort of pace that made Moore’s Law famous in IT circles. (doubling of yield every 18months). On 6th May (i.e. tomorrow) Lawrenceville Plasma Physics is launching an Indiegogo campaign to help speed up cracking the last of three hurdles (temp and time of confinement are in the bag, only density is left. Timeline 12-18 months. More details here:
Fusion power will have a couple of benefits relevant to this debate: Start reversing the effects of fossil fuel consumption by making the active removal of CO2 from the atmosphere possible at an affordable price. Remove the need for fossil and fission fuels and finally, providing all the cheap power we’ll need to run the pumps that NYC will need.

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By Bob Bingham (Kerikeri)
on April 25th, 2014

it is still very early days with sea level rise and the melting ice has only just started to equal thermal expansion.The big melts so far have been from ice already in the sea but we are just approaching a time when the glaciers will melt and then we will see a surge in sea level rise. The ones to watch are Greenland and Pine Island glacier.

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By Viva Barbarella (11385)
on April 30th, 2014

Used Propane burners should be shipped to Mars, along with Fischer Tropsch reactors (which make synthetic hydrocarbons).  That’s because water vapor and CO2 are the main byproducts of Combustion. On Earth, all cooking appliances should be electrical to stem the flooding.

Used cars should also be shipped to Mars, including Nautilus machines;  they should be stored inside Olympus Mons.

Propane Combustion:  C3H8 + 5 O2—-> 3 CO2 + 4 H2O

To create a global magnetic field on Mars, imbed a Cryogen-free Superconducting Magnet deep into the ground, with a strength under 10 Tesla.

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By jim eberwine (Absecon, NJ 08201)
on April 30th, 2014

What happened in the northeast in particular New Jersey and New York had “nothing” to do with climate change. What happened with Sandy was nothing more than the track which brought the Hurricane from the deep ocean into the shallows and then on a perpendicular path at landfall. There have been several tropical cyclones take this track north of 35 Degree N but none since 1903 in New Jersey. The surge that resulted from Hurricane Sandy was show in the Slosh models 25 to 30 years ago when you have a coastline of NJ/NY that make a 90 degree angle. The water has no where to go and is then mechanically lifted and driven northwest into the East River. This is not knew and has been known for 30 years. The problem is when first presented back then we didn’t do anything to prepare our infra-structure for such and event. Consequently, a $60 billion dollar storm. I do not believe at all that NYC will flood 1 in 4 years. I will say that if you had similar strikes, i.e to the northwest in NJ then yes NYC would flood 1 in 4 years to that magnitude. Our tropical systems in 85 to 95 % of the time parallel the coast or come ashore farther south then move north inland with heavy rains and tropical storm force winds…but not the surge we saw in Hurricane Sandy. If you really want to consider an event, consider a CAT III making landfall in Ocean or Monmouth Counties moving 30 mph and approaching at high tide. Hurricane force winds sustained of 111-130 mph and a surge that would bring 21 to 26 ft of water into NYC. That is the worse case scenario and something that is our “Worst Case Scenario”, and it would not make a difference if climate change did or didn’t contribute to it. 

Six of the storms you cite above are non-tropical. We have not had a ‘classic” nor’easter in over 20 years here in the northeast. A classic is one which develops off Hatteras and then takes 3 to 5 days to move north and into the North Atlantic. The nor’easters of late have formed off Del/NJ coast and then moved north with the worst gradient north into New England. December 92’ affected north Jersey and NY as was perhaps the closest we have seen to the March 62’ storm.
March 84’ was a one high tide event. If we were to get another Ash Wednesday storm the $$ amount would top $200 Billion since it affected the Carolinas into New England with Harvey Cedars NJ ground zero.

What we should be doing is taking some of the $1 Billion Dollars a day spent on climate change research and use it on fortifying the coast, not just NJ but the US. If we took the moneys being spent over two years we would have $730 Billion to prepare for what scientist are saying is coming in the years 2050 or 2100. Lets put it to work over the next couple of years and see what we can accomplish.

The article is interesting, but I think that 1 in 4 years is not likely at all.

Jim E

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By NewYawk
on May 1st, 2014

All quite interesting and mostly missing from the article.

But I would differ one a couple points.

CC research is less than $1B year, worldwide, not $1B/day, USA.  Nobody with money stands to gain from researching it, it’s more a bottom-up thing.
CC has just barely begun. Whatever it’s going to do, we have only seen a trace of it.

Obviously, the effect of a 20 foot storm surge striking perpendicular to the coast should everything line up dwarfs the increment attributable to CC. But, a little difference can mean a great deal: when you have a city built to withstand a historic range of tide and surge, a couple feet more due to slightly higher sea level and slightly greater storm surge is the difference between a a flooded street here and there and another Sandy or worse.

So, I’m not convinced about the 1 in 4 odds, but we may have gone from chin deep to eyeballs deep when the next one hits.

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By emjayay (Brooklyn NY 11223)
on May 27th, 2014

And yet, we are actually spending real billions rebuilding on the Jersey shore barrier islands and The Rockaways barrier island in New York City (Queens borough). If we came across those today we would declare them parks and not build anything permanent on them. Instead, wall to wall buildings, soon to be underwater again. We also spend more money per foot to maintain the beach which the ocean doesn’t want there at the Rockaways than any other beach in the country, and more millions a year on Jersey beaches. All totally incredibly shortsighted to say the least.

The intelligent response to Katrina and ocean rise would have been to buy out every property owner on those islands and declare them parks. A large number of people living in the Rockaways are also in completely outdated, crime ridden housing projects.

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By hberwund (new york/ny/10019)
on May 5th, 2014

In addition to the sea level rise from melt, the storm surge increase due in part, at least, to warming, the East Coast is at greater risk because it has been sinking, somewhat but significantly enough. The increased warming also doesn’t just potentially stir up greater temperature disparities and thus more and more violent storms, it causes thermal expansion of even pre existing ocean water. Even the same amount of ocean water takes up more room when hotter. This last factor is highly significant.

While this article claims much more sea level rise around NYC since the 1800s than I’m used to reading, it is clear that anyone who states “climate change had nothing to do with Sandy” is an anti rationalist of the first order. As more and more storms of various kinds show up more often in very unusual configurations or in historically unexpected places, or during unexpected seasons, that sort of anti rational denialism will be hurried out of the court of public opinion, with mocking laughter.

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By Frank Arouet (Adamstown, Pa 19501)
on May 7th, 2014

18,000 years ago the sea levels were 400 feet lower…..... Is it hard to believe that sea levels still might change on their own as they have done for 4 billion years?

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By Michael D. Phillips (West Hollywood)
on May 14th, 2014

It is really amazing the extent to which politically-driven hostility over climate change causes cognitive malfunction.  Of course climate can change drastically (as in the last Ice Age, when sea levels were that low).  No, it isn’t hard to believe sea level changes “on its own”—when the climate changes!  The variation in climate that makes for an Ice Age is a drop of around 5-6 degrees Celsius or 8-10 degrees Fahrenheit from the global average (or what the average was if you throw out the last 30 years of data).  It takes just a few minutes to call up a graph showing the pattern of long Ice Ages and shorter “Interglacials.”  Our “Holocene” Interglacial, the past 12,000 years that made modern human civilization possible, has been wobbling slowly downwards from its temperature peak for thousands of years in a pretty tight range of slight up & down variation. 
  It’s forgotten today, but there was great concern 50-100 years ago about humanity facing a rapidly COOLING climate since it was possible that the favorably warm period we enjoyed might be ending—& the ice returning relatively quickly.
  Probably this is one reason why global warming took a long time to build a scientific consensus.  The temperature increases in the Antarctic oceans, in the atmosphere there and in the air over Greenland, where the ice core information from the past pretty much indisputable tell the story.  The slow up & down cycle every few hundred years gives way to a sudden multi-decade warm spike not seen in any of the Ice Age-Warm Period-Ice Age cycles of the past million years.  No one has come up with an explanation of what natural force could be making the poles warm so much & so fast at this stage in the natural cycle.  So, yes, our fossil fuel burning has probably made it certain we won’t be hunting mammoth on land that today is 300 feet under the sea anytime in the next few thousand years. 
  That said, if going down 5 C in average temperature gives us glaciers covering half of North America, now that PLUS 4 C is looking possible due to our dumping of carbon dioxide & methane into the atmosphere, how on earth can some people be so indifferent to what that world will look like when that happens?  Yes, this will take a long time most likely, but the point is we have destabilized the favorable balance that allowed us to thrive, & to no longer fear starvation daily (at least for most people in rich countries).  The ride up the temperature trend line is not going to be any more pleasant than a ride down would have been.  Eventually, even if the warming hadn’t started, humanity was going to have to decide whether to start preparing to (manage if possible &) adapt to the loss of global climate equilibrium; or to just let disaster unfold and perhaps fade away like the Maya.  Like it or not, that moment has arrived.

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By Kevin Feeney (20132)
on May 12th, 2014

$24 billion actual and future potential loss due to rising sea levels. This amount of loss could occur every 4 years and potentially accelerate due to rising temperatures and sea levels. It could double and essentially cost $10 billion a year. That doesn’t consider the loss of real estate values in the affected areas (I assume that property values will plummet in the storm areas.) I guess the insurance companies can absorb this amount (LOL). Ooops, I forgot New Jersey and those costs too. How about Norfolk and other coastal cities like Miami? How much does denying Climate Change cost all of us?

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By Roger Johnson (Robertsdale)
on May 12th, 2014

I find it odd that in your talk of high water events since 1900, the great hurricane of 1938 (AKA The Long Island Express) did not warrant a click on the chart. With tides of 14 to 18 feet across most of Long Island, Ah, but perhaps you forgot that one. It was summarized quite well so I will quote

“The hurricane hit Long Island around 3:30 PM which was just a few hours before astronomical high tide. At this time the eye was about 50 miles across and the hurricane was about 500 miles wide (Francis, 1998). High tide was even higher than usual because of the Autumnal Equinox and new moon. Combined with winds gusting over 180 mph, few on eastern Long Island’s south shore had a chance when the storm surge hit. Waves between 30 and 50 feet pounded the coastline with millions of tons of sea water, sweeping entire homes and families into the sea. The impact of the storm surge was so powerful that it was actually recorded on the earthquake seismograph at Fordham University in New York City (Francis, 1998). Most people did not even realize that a hurricane was upon them even as the waters began flooding their coastal homes. The hurricane produced storm tides of 14 to 18 feet across most of the Long Island and Connecticut coast, with 18 to 25 foot tides from New London east to Cape Cod. The destructive power of the storm surge was felt throughout the coastal community. Downtown Providence, Rhode Island was submerged under a storm tide of nearly 20 feet while downtown Westhampton Beach, a mile inland, was under 8 feet of water! Sections of Falmouth and New Bedford, Massachusetts were also submerged under as much as 8 feet of water.”

So yes, such a minor event, understandable that the author missed it.

(excerpt from

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By Don Kehoe (Westhampton Beach,NY,11978)
on May 12th, 2014

Earth Day 1970

“Man must stop pollution and curb his resources, not merely to enhance his existence but to save the race from intolerable deterioration and possible extinction”  NY Times Editorial

“Population will inevitably and completely outstrip whatever small increases in food supplies we make. The death rate will increase until at least 100 - 200 million people per year will be starving to death during the next ten years.” 
Stanford University Biologist Paul Erlich

The world has been chilling sharply for twenty years. If present trends continue the world will be about four degrees colder for the global mean temperature in 1990, but eleven degrees colder in the year 2000. this is about twice what it would take to put us into an ice age”  Kenneth Watt

These are just a few quotes from the same group that are now bringing us global warming/climate change.

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By Indulis B (London/UK)
on May 24th, 2014

Don, Have you read the actual scientific papers from the 1970s, not the heavily simplified quotes in the popular press at the time? If you do, you would see that these papers about “global cooling” were about the cooling effect of dust, soot, smoke, and other pollution (“called “aerosols” in the papers).  The papers were to do with what would happen based on these pollution factors by themselves, and did not include the effects of any other factors (e.g. CO2). The other factors were outside of the scope of the studies. Science has advanced so that now we can combine the known effects of regular “oscillations” (El Nino, and La Nina etc), dust and pollution, CO2, as well as other factors like changes in the Sun’s output (spoiler alert, there has been no significant change in solar output).

The current science says that the pollution in the air is in fact masking some of the CO2-caused temperature rise.

And that CO2 is the only factor known that fits the physical observations (heat retained more at night, so can’t be solar).

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By Gene Poole (Adirondack, NY )
on May 19th, 2014

In 1287 the Holland terpen and dikes that held back the North Sea failed, and water flooded the country. A new bay, called Zuiderzee (South Sea) was created over former farmland. For the next few centuries, the Dutch worked to slowly push back the water of the Zuiderzee, building dikes and creating polders (the term used to described any piece of land reclaimed from water). Once dikes are built, canals and pumps are used to drain the land and to keep it dry. From the 1200s, windmills had been used to pump excess water off the fertile soil; today most of the windmills have been replaced with electricity- and diesel-driven pumps.

Then, storms and floods of 1916 provided the impetus for the Dutch to start a major project to reclaim the From 1927 to 1932, a 30.5 km (19 mile) long dike called Afsluitdijk (the Closing Dike) was built, turning the Zuiderzee into the IJsselmeer, a freshwater lake. (Much of the Netherlands is essentially a delta for the Rhine and other rivers.

NYC may have to take on a project similar to what the people of Holland began in the 12th Century.  If mankind were to be removed from the Earth tomorrow, the chances are that the seas will continue to rise a couple of feet in the next 200 years.

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By William (Dudley, North Carolina, 28333)
on June 4th, 2014

We’ve heard the doom and gloom before from Malthis to Paul Urlick. Our pollutants will cause a new ice age (Time Magazine 1978) , we’ve only got ten years before the earth slips into an irreversable runaway heat catastrophy (Al Gore 1996).  OK, so just to be sure we add a couple of feet to New York’s seawall and have the subway and tunnel pumps ready. 2012 Sandy was pretty much worse case and the City recovered quickly. If you really want to worry about somethng worry about the volcanic island in the Canary Islands that if it collapses will send a 100 plus ft. tsunami that will wipe out the eastern seaboard from Maine to Florida. Tens of millions will die in a flash, including the academic alarmists at Harvard, Yale, Penn., and Princeton. But you see you can’t tax tsunamis and there is no grant money in hyping volcanos. Settled Science is a punchline.

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By Tristam Sculthorpe (Sault Ste. Marie)
on June 5th, 2014

After spending billions in a media campaign denying climate change, the owners next move will be to get the public to pay for massive public works to protect their assets.  But it’s too late.  No matter how much money is thrown at dikes and levees, coastal cities worldwide are doomed.  Ironically, so are all the owners private islands and oceanfront mansions.  Too bad, so sad..

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By Jerry Johnson (chicago, il 60606)
on June 7th, 2014

who cares.  in 100 years most of the cities on both coasts will be underwater and the US may be down to 49 states.  Better start moving Wall Street right now.

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