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Storm surge: Hurricane Sandy

Filed under: — group @ 29 October 2014

On the second anniversary of Superstorm Sandy making landfall, we are running an extract from a new book by Adam Sobel “Storm Surge: Hurricane Sandy, Our Changing Climate, and Extreme Weather of the Past and Future”. It’s a great read covering the meteorology of the event, the preparation, the response and the implications for the future.

Excerpts

On October 28, 2012, a giant, misshapen hurricane made a left turn from its previous northward trajectory over the Atlantic Ocean and headed for the New Jersey coast. On the evening of October 29, following a track never before seen in one hundred sixty years of Atlantic hurricane observations, the center of the storm made landfall near Atlantic City.

The size of the storm, like the track, was unprecedented in scientific memory. Sandy was the largest hurricane ever observed in the several decades since good measurements of hurricane size have existed in the Atlantic. At its landfall, gale-force winds covered a large fraction of the Eastern Seaboard and an enormous patch of oceanic real estate as well. To the north of the center, Sandy’s easterlies traversed a thousand-mile-plus fetch before coming onshore, driving a massive storm surge: a giant, slow wave that dragged the ocean inland, on top of the high tide, and onto some of the most heavily populated, economically active, and valuable land on earth.

The scale of the disaster was historic. In New York City, the water had not come this high since at least 1821, if then. For people in the hardest-hit areas, it was a life-crushing event—in some cases, literally. While the death toll was low compared to Hurricane Katrina’s, and extremely low compared to those of the worst tropical cyclone disasters in recent history worldwide, it was high enough to be grievously shocking here in New York City, where losing one’s life to a hurricane is thought of as something that happens only in faraway places. Many, many people saw their homes destroyed, and in some cases entire neighborhoods. The storm crippled the infrastructure of one of the world’s most vibrant economic and cultural centers for a period of weeks. The economic damage has been counted at fifty billion dollars at least, and perhaps as high as sixty-five billion.

The most fundamental lessons we can draw from Sandy revolve around predictions: how we make predictions of the atmosphere’s behavior, and how we respond to them once they are made. Weather prediction is a unique enterprise. People make predictions of many kinds: about the outcomes of elections or baseball games, or the fluctuations of the stock market or of the broader economy. Some of those forecasts are based on mathematical models. Most of those mathematical models are statistical, meaning they use empirical rules based on what has happened in the past. The models used for weather prediction (and its close relative, climate prediction), in contrast, are dynamical. They use the laws of physics to predict how the weather will change from one moment to the next. The underlying laws governing elections or the stock market—the rules of mass human behavior that determine the outcomes—are not known well, if they exist at all. The models need to be built on assumptions that past experience will be a guide to future performance. If weather prediction were still done in this way, it would have been simply impossible to predict, days ahead of time, that Hurricane Sandy would turn left and strike the coast while moving westward. No forecaster had ever seen something like that occur, because no storm had ever done it. For the same reason, no statistical model trained on past behavior would have produced it as a likely outcome.

In Sandy’s case, forecasters not only could see this outcome as a possibility over a week ahead of time, but they were quite confident of it by four or five days before the storm hit. Forecasts such as the ones we had as Sandy formed and moved up the coast don’t come from the heavens. They’re the result of a century of remarkable scientific achievement, beginning in Norway in the early 1900s. The intellectual foundation of the whole enterprise of weather prediction was the idea that the laws of physics could be used to understand the weather, a radical idea in the early twentieth century. Carrying this out required multiple conceptual advances, over decades, and improvements in technology (especially digital computers).

[T]he most serious problems highlighted by Sandy were not in the preparations right before the disaster or in the response right after. They were in the construction of our coastlines over the span of many decades. Over that long term, too, there had been good forecasts of what could happen to our built environment along the water in the New York City area. These were not forecasts of a specific storm at a specific date and time, but rather scientific assessments of the risk of a storm as bad as Sandy, or worse. It had been known for decades at least that New York City was vulnerable to flooding by a hurricane-induced storm surge. The consequences that would follow were also clear, in broad outline. The flooding of the subways, for example, had been envisioned since the 1990s.

Sandy didn’t need climate change in order to happen, and the story of the disaster doesn’t need climate change to make it important. The main subject of this book is Sandy, and you can read large fractions of the book without seeing climate change mentioned at all. But climate change looms large when we try to think about what Sandy means for the future.

Sandy was not just an extreme fluke, something that we can assume won’t happen for another few hundred years. But neither is it “the new normal”—something that is sure to happen again soon, and often from now on.

Almost certainly it’s somewhere in between. We’re very unlikely to see another Sandy this year, or next, or even in the next decade or two. We’re not that much more vulnerable today than we were a few decades ago. But at the time of Sandy, we were always more vulnerable than we realized. And the pace of change is quickening.

Because of sea level rise, most of all, our risk of more Sandy-type disasters is increasing. The science of hurricanes and climate change is still young, and some of the features that made Sandy’s surge so big (its enormous size, its hybrid character, the left turn and westward-tracking landfall) are among those whose connections to climate are least well understood. But because of sea level rise, we know that big coastal flooding events will become more frequent, almost regardless of what those connections are.

As far as the potential for flooding is concerned, every foot of sea level rise is equivalent to a substantial increase in storm intensity. Under the old Saffir-Simpson Hurricane Intensity Scale, when it still accounted for storm surge (before it was simplified to measure only the maximum wind speed), the step from category one to two, or the step from two to three, carried a three-foot increase in surge. By 2100 however, we are likely to see a permanent three-foot increase in sea level, and even six feet is not at all out of the question. That’s roughly equivalent to an increase of either one or two categories in hurricane intensity.

On the other hand, sea level rises slowly. We have time to prepare. If we adapt to it as it happens, then one foot of sea level rise in the future will not be equivalent to one foot of storm surge now, because we’ll be better protected. We could put other defenses in place that would have the same effect as if we had raised our cities and towns along with the sea. Then, a four-foot surge in the future, like a four-foot surge today, will not be a disaster. That would be climate adaptation. In the language of climate policy, that word refers to any action taken to reduce the harm from warming.

Even better, we could simultaneously do climate mitigation… If we were to reduce it enough, we could significantly slow the rate of global warming, and the rate of sea level rise. Some warming and some sea level rise are already locked in, because of the carbon we have already put into the atmosphere. But if we were to reach a serious international agreement to transform our energy systems to be more efficient, and more reliant on renewables such as solar and wind energy—or even nuclear, though that brings another set of risks—we could make a significant dent in the problem.

Will we do any of that, though?

32 Responses to “Storm surge: Hurricane Sandy”

  1. 1

    Thanks. I’ll be looking for this book at my local library.

    There appears to be a missing line in the third-last paragraph, though; the text currently reads:

    …wind speed), the step from category one to two, or the step from two to three, carried a three-foot

    –(lacuna?)–

    likely to see a permanent three-foot increase in sea level, and even six feet is not at all out of the…

  2. 2
    Tim Joslin says:

    The book does sound like a good read. A key paragraph of this post, though – the 4th from the end, starting “As far as the potential for flooding is concerned…” – is unfortunately missing some text.

    [Response: Fixed. Thanks! – gavin]

  3. 3

    Thanks for this informative posting and for the emphasis on shoreline overdevelopment–national folly that continues despite growing awareness of rising seas.

    Yes, the “most serious problems highlighted by Sandy were not in the preparations right before the disaster or in the response right after. They were in the construction of our coastlines over the span of many decades.”

    In Virginia there’s a potential national symbol of the problem and the folly: the new national monument–a form of national park–at low-lying, ocean-facing Fort Monroe, the Chesapeake Bay’s flat Gibraltar. The Army left in 2011. Developer-kowtowing politicians then contrived a token national monument, a form of national park. They bizarrely bifurcated it on the bayfront for developers.

    Earlier this year, the Union of Concerned Scientists issued the report National Landmarks at Risk: How Rising Seas, Floods and Wildfires are Threatening the United States’ Most Cherished Historic Sites. The report devotes three pages to Fort Monroe, emphasizing that Hurricane Isabel caused more than $100 million in damage there in 2003. That was long before anybody contemplated blanketing the sand spit with condos that politicians, apparently unaware of George Orwell, insist must be called historically compatible residences.

    Wetlands Watch has charged that despite “significant new residential development investments” planned for this “increasingly fragile and potentially dangerous landscape,” Fort Monroe’s newly approved development plan “does not consider the long-term costs/benefits.” That mid-Atlantic environmental group, sometimes cited in New York Times coverage of sea rise, called the development plan simply “stupid.”

    Note please that this 570-acre sand spit ranks high among US national treasures. It saw slavery’s 1619 beginning and then–as told in the 2011 New York Times feature “How Slavery Really Ended in America”–it also saw the 1861 start of slavery’s demise, in events that Civil War historian Edward Ayers once called “the greatest moment in American history.”

    Yet despite both sea-level rise and historic importance, politicians plan condos for the huge gap in the fake national monument that they contrived. Last year, the Norfolk Virginian-Pilot warned “a national treasure will be squandered.” The National Parks Conservation Association exclaimed “We can’t let this happen.”

    But we are letting it happen. It’s well worth noting, though, that the situation stands ready to be made a national symbol of our continuing national fecklessness and foolishness concerning sea-level rise.

    For links and for more information, please see http://www.fortmonroenationalpark.org/ .

  4. 4
    Edward Greisch says:

    I just started reading “Don’t Even Think About It [Why Our Brains Are Wired to Ignore Climate Change]” by George Marshall, 2014. Marshall talks about Sandy and other disasters that are possibly linked to GW. Disasters that are possibly linked to GW make people who are hurt by the disaster deny GW more than they did before the disaster. Did somebody say: Homo “Sapiens?” I would be willing to believe Homo Crazy.

  5. 5
    Gwyn Williams says:

    Comment #3 above makes a very important point relating to further implications of ignoring how development proceeds. And indeed not only is there a chance to behave responsibly here, but the benefits of so doing far outweigh those of additional coastal over-development. Fort Monroe National Park would be a true national treasure, while at the same time honoring and respecting important members of our society. I sincerely hope that Governor McAuliffe will step up to the plate on this one. Then this beautiful piece of coast would be preserved for everyone to enjoy, and for nature to take its course on the beaches and on the marshland that some people insist on spoiling with vulnerable development. Perhaps it’s also worth noting that there is also potential for development on the western part of Fort Monroe, so in principle we can all find a satisfactory solution to the future of this unique area.

  6. 6

    URLs for the science-community web sites cited in comment 3, as affirmed in comment 5:
    * The Union of Concerned Scientists’ report’s three pages about Fort Monroe: http://www.ucsusa.org/assets/documents/global_warming/National-Landmarks-at-Risk-Full-Report.pdf#page=28
    * Wetlands Watch’s labeling of the coastal-overdevelopment condo plan as “stupid”: http://www.wetlandswatch.org/NewsPublications/DirectorsBlog/tabid/110/ArticleType/ArticleView/ArticleID/121/Default.aspx

    The other material that I quoted from Wetlands Watch appears in a formal letter that the environmental group sent to the authorities. I can forward a copy if you contact me: SaveFortMonroe before the @ sign and gmail.com after it.

    Thanks.

  7. 7
    t. marvell says:

    Perhaps the most frightening thing about Sandy is its left turn. I hope that it remains rare and that global warming does not make that more likely.

    Here in Virginia there has been little costal hurricane damage for perhaps a century because hurricanes turn north-east. If they do not land by the time they get to the outer banks, we do not get them. The costal area is low all over, by the ocean, bays, and rivers. It is called “Tidewater Virginia.” A left turn by an ordinary hurricane would deluge Fort Monroe, as earlier commentators noted, and historic Jamestown Island. Also, the same would happen to populous, built-up areas like Virginia Beach, Norfolk, Portsmouth, Hampton, and Newport News. The territory affected would be much greater than with Sandy.

    Rising insurance rates should make residents and communities pay attention to the dangers of GW. After Sandy showed that a left hook is possible, insurance companies seem to be pulling out of the area, causing rates to rise.

  8. 8
    Edward Greisch says:

    I like comments 5 & 6 by Gwyn Williams — 1 Nov 2014 @ 12:30 PM
    and Steven T. Corneliussen — 1 Nov 2014 @ 3:33 PM
    The floodable areas should indeed be parks so that houses will be built on higher ground.

  9. 9
    Edward Greisch says:

    I like comments 5&6 by wyn Williams — 1 Nov 2014 @ 12:30 PM and Steven T. Corneliussen — 1 Nov 2014 @ 3:33 PM

    The floodable ground should be parks so that the houses will be built on higher ground.

  10. 10
    Erich Zann says:

    This is a problem between waterfront landowners and their insurance companies. Sea level will rise gradually over the next hundred years. That’s about 4 generations of people growing up and making life decisions about where to live. We may well retreat from the flat eastern coastline. We can make is a huge national park. Is that so bad?

  11. 11
    Hank Roberts says:

    > Erich Zann
    (congratulations on the Lovecraftian pseud)
    > Sea level will rise gradually

    Why do you believe the rise in sea level will occur ‘gradually’?
    http://www.nature.com/nclimate/journal/v4/n6/full/nclimate2226.html

    You know _you_ are the insurance company for federal flood insurance?

  12. 12
    John Pollack says:

    Regarding comment 7: Left-turning storms may not be as rare as you think. In 1983, Dean did make a left hook into Virginia after being well out to sea east of the Carolinas. Sandy’s track was rather similar, except that it made landfall further north (and with greater intensity). 1972 there were two storms that made serious landward turns. Agnes caused great devastation as it blew itself out over PA, recurving after cutting inland across the Southeast, then going out to sea. Although less damaging, the track of Dawn was even more extreme, as it moved northeast from southern FL, reached peak intensity as it recurved westward off NC, then moved back southeast, and eventually westward again to make landfall in GA and SC! In 1955, Connie moved north across the Outer Banks, began to curve left as it headed up the Chesapeake Bay, and eventually died over Lake Huron.

  13. 13
    Chris Dudley says:

    “Sandy didn’t need climate change in order to happen”

    As pointed out by Hansen, Sandy did need climate change to in order to happen when and where it did, that late in the season and that far north. It may be that regardless of basin storm frequency, a broadening of hurricane season at higher latitude in the mid-Atlantic will increase risk to infrastructure built with a much longer recurrence interval in mind.

  14. 14

    #10, Eric Zann–“Is that so bad?”

    Well, it would be economically very costly and politically destabilizing, and it would be happening on a global scale.

    True, the challenges to agriculture–summed up in the new Summary for Policy Makers under the rather dry formulations that “Assessment of many studies covering a wide range of regions and crops shows that negative impacts of climate change on crop yields have been more common than positive impacts (high confidence),” and “Climate change is projected to undermine food security (Figure SPM.9”)–probably pose a more dire threat. But it wouldn’t be good. And of course, we wouldn’t get to choose SLR or drastically reduced food security.

  15. 15
    Alan Millar says:

    This is a bit overblown isn’t it.

    Hurricanes have not been increasing. Indeed we are currently experiencing a record time period since the last major hurricane made landfall in the USA. This time period is already more than twice as long as the previous record making it a pretty extraordinary record.

    Hurricane Sandy wasn’t even a hurricane when it made landfall and whilst it did indeed have a large extent, Hurricane Olga in 2001 was much larger in size.

    It is unusual for such storms to make landfall at that time of year in that position but this was due to aligning meteorologic effects that have caused this to happen before and will cause it again sometime in the future.

    Alan

  16. 16
    Jim Eager says:

    Alan Millar wrote @ 15: “Hurricane Sandy wasn’t even a hurricane when it made landfall”

    That a sub-category-1 post tropical storm like Sandy can wreak that much havoc and destruction is not at all the reassuring fact that people like Alan seem to think it is.

    The prediction is not that hurricanes will become more numerous, but that they will on average become more powerful. Also, there is more hurricane/typhoon activity than just that in the Atlantic-Caribbean.

    And lastly, one of those aligning meteorologic effects, namely the persistent high pressure loop in the jet stream that caused the landward track, may well have been caused by a warming climate.

  17. 17
  18. 18

    #15–“Overblown” is a nice pun–but a poor descriptor for one of the biggest economic disasters in US history. You can throw in pretty much irrelevant stuff about landfalling major hurricanes and the observation that Sandy wasn’t the largest storm ever, but the fact remains that the flooding was indeed unprecedented and that one reason for that is that sea level is six inches higher globally than it was in 1900 (and about double that at the Battery tidal gauge in New York.)

  19. 19
    Jim Larsen says:

    11 Hank R said, “Why do you believe the rise in sea level will occur ‘gradually’?”

    The last phrase in your reference is:
    “indicating that East Antarctica may become a large contributor to future sea-level rise on timescales beyond a century.”

    The rise will be gradual, at least during this century.

  20. 20
    Hank Roberts says:

    > the rise will be gradual, at least during this century

    Think how that will sound in hindsight, eh?
    “Peace in our time”

  21. 21
    SecularAnimist says:

    Alan Millar wrote: “Indeed we are currently experiencing a record time period since the last major hurricane made landfall in the USA. This time period is already more than twice as long as the previous record making it a pretty extraordinary record.”

    First of all, I am not aware of any suggestions from the climate science community that global warming would have any effect one way or another on whether hurricanes would make landfall in the USA, so your statement is a strawman.

    Second, your claim about a “record period” is only true if the classification “major hurricane” is based SOLELY on maximum wind speed.

    If it is based on any other measure, then that “record period” includes multiple storms that set unprecedented records for flooding, and for the extent and amount of damage caused.

  22. 22
    Susan Anderson says:

    My points of likely/possible global warming involvement in causes of Sandy because these are the kinds of things that are changing, are:
    1. late season
    2. huge and hybrid: married with northeaster
    3. blocking high caused it to turn sharply (more than 90 degrees) on a dime in a few minutes (I was there watching in disbelief on local TV weather, though I had been warned)

    I was in its path caring for aging parents, so I have more than a peripheral interest. Near Princeton NJ we were well away from the worst, but many people in the area were without power for two weeks or more.

    oh help: “historical iearsay” captcha

  23. 23
    Alan Millar says:

    SecularAnimist says:
    5 Nov 2014 at 1:59 PM

    “First of all, I am not aware of any suggestions from the climate science community that global warming would have any effect one way or another on whether hurricanes would make landfall in the USA, so your statement is a strawman.

    Second, your claim about a “record period” is only true if the classification “major hurricane” is based SOLELY on maximum wind speed.”

    ‘Strawman’… hardly. If it is hypothesised that man is causing more frequent major hurricanes to occur then you would expect the periods between landfall in the USA, of major hurricanes, should become shorter. A percentage of major hurricanes have always and will always make landfall in the USA.

    I think a science site should look at the facts not hype.

    Long Island has been hit by much stronger hurricanes in the past. See 1938 and 1944 for instance.

    It is largely a matter of luck in how much damage they will cause, based on where exactly they hit and at what time. Stronger winds than Sandy as in 1938 and 1944 have the potential to cause much more damage.

    However, it was the alignment of the full moon and one of the highest tides of the year and the exact position of landfall that made Sandy so destructive with its storm surge. The storm surge in 1938 was four feet higher actually but occurred in a slightly different position. The high winds caused a huge loss of life though unlike Sandy.

    Of course you might say the increasing sea level exacerbated the damage and I suppose it did to a very minor extent. Can’t see what man could do about that though. Sea levels have been rising in NY ever since we started to measure them in 1850 and the rate of sea level rise has not altered over that time.

    Alan

    http://tidesandcurrents.noaa.gov/sltrends/sltrends_station.shtml?stnid=8518750

  24. 24
    Teachable Mo' says:

    I believe one of the scenarios for storms due to AGW is for a decrease in cyclonic storms because of a reduction in the steepness of the North-South temperature gradient. Large scale cyclonic storms are complicated and it isn’t a given that an increase in water temps will lead to an increase in their number.

    If I’m remembering something else, please correct me.

  25. 25
    Ray Ladbury says:

    Sigh,
    Alan Millar’s myopia is showing. While it is true that recent Atlantic hurricane seasons have been mild, the same cannot be said of the Pacific and Indian Ocean seasons. What is more, the predictions as to the effect of climate change on Atlantic hurricanes are mixed. Some predictions suggest that wind shear will actually suppress cyclonic activity. However, as sea level rises, those storms that make landfall will wreak more damage.

  26. 26
    Hank Roberts says:

    > Alan Millar

    Ya think it’s just silly of these New Yorkers to worry, eh?
    Why is it you’re sure there’s no change in rate of change?

    http://www.dec.ny.gov/energy/45202.html

  27. 27
  28. 28

    If it is hypothesised that man is causing more frequent major hurricanes to occur then you would expect the periods between landfall in the USA, of major hurricanes, should become shorter.”

    – See more at: http://www.realclimate.org/index.php/archives/2014/10/storm-surge-hurricane-sandy/comment-page-1/#comment-617160

    But it isn’t so ‘hypothesised.’ The current expectation is that hurricane frequency will likely decrease, but intensity will increase. See, for example:

    http://www.gfdl.noaa.gov/global-warming-and-21st-century-hurricanes
    http://www.gfdl.noaa.gov/21st-century-projections-of-intense-hurricanes

    The second link has a nice summary sentence:

    …we should expect an increase in the frequency of the strongest hurricanes in the Atlantic, roughly by a factor of two by the end of the century, despite a decrease in overall number of hurricanes, but we should not expect this trend to be clearly detectable until we near the end of the century, given a scenario in which CO2 doubles by 2100.

    I’m not quite sure how the category of ‘major hurricanes’ would shake out in this scenario, but quite clearly the current ‘record’ is not meaningful in the context of what’s projected.

    I would not be so sure that SLR hasn’t increased–especially based on one tidal gauge record! And that goes double for ‘eyeball-based’ analysis, but nevertheless I think I can see evidence of acceleration in the curve linked–note how both early and late portions of the curve are above the linear trend line, producing a slightly ‘cupped’ appearance. That’s what acceleration would look like. Moreover, more sophisticated analysis has shown that there is indeed acceleration in the global record:

    http://www.skepticalscience.com/print.php?r=365

    And this ‘man’ can indeed do something about–‘he’ can stop using the atmosphere as a dump for combustion by-products.

  29. 29
    Mal Adapted says:

    Alan Millar:

    I think a science site should look at the facts not hype.

    A science site, just like a scientist, should look at all the facts, and place them in well-founded theoretical contexts. Claims made on that basis are not hyperbole.

    DK-afflicted wannabes, OTOH, look at single facts in isolation, and overlook the body of literature integrating facts with established knowledge. Ensuing ‘hype’ can safely be ignored.

  30. 30
    Rik Myslewski says:

    Sobel’s excerpt, after reasonably suggesting efforts to accelerate climate-change mitigation efforts, soberly asks, “Will we do any of that, though?” I’m afraid that all current indications point to the most realistic answer being “Nope.”

    For example, Sen. James Inhofe, author of the relentlessly self-aggrandizing “The Greatest Hoax: How the Global Warming Conspiracy Threatens Your Future” is in line to take over the chairmanship of the US Senate Environment and Public Works Committee, and the soon-to-be Senate Majority Leader, Sen. Mitch McConnell, has vowed that his top priority will be “to try to do whatever I can to get the EPA reined in.”

    These setbacks are, of course, no reason to surrender in the battle to enact thoughtful, balanced, science-based climate policy, but it’s also good to remember the rueful wisdom of the late George Carlin, who once commented, “We’re all f*cked. It helps to remember that.”

  31. 31
    Bibasir says:

    In addition to what John Pollack said regarding comment 7: Left-turning storms may not be as rare – A 1938 hurricane turned left and hit the northern part of Long Island, Connecticut and Rhode Island. That area is not that much further north from where Sandy hit. Over 600 people were killed.

  32. 32
    lichanos says:

    I don’t get this author’s conceptual framework. He tells us that it is likely that sea level will rise 3-feet by 2100. That’s nearly 0.5 inches each year for the next 85 years. That seems mighty fast to me.

    Then he says, “On the other hand, sea level rises slowly…” Compared to the speed of urban development, I’d say 0.5″ a year is still fast.

    And then he says 6-feet of rise is not at all out of the question.

    I hope this guy isn’t running a city planning department.