James D. Agresti: Will global warming flood the coasts of the United States?

Two new studies are predicting accelerated sea-level rises on the East and West coasts of the United States, primarily due to global warming. Major media outlets—and in some ways the studies themselves—have painted a distorted picture of past, current, and future sea levels. In fact, the studies actually conflict with each other, a crucial fact that has gone unreported in news reports that have mentioned both of the studies.

One study, henceforth referred to as the “East Coast study,” was published in the journal Nature Climate Change and shows a “recent acceleration” of sea-level rise on the East Coast from North Carolina to Massachusetts. According to the Associated Press, “By 2100, scientists and computer models estimate that sea levels globally could rise as much as 3.3 feet,” and this study predicts that the East Coast could see “8 to 11 inches more” than this, hence “putting one of the world’s most costly coasts in danger of flooding….”

The other study, herein dubbed the “West Coast study,” was published by the National Research Council and publicized with a Los Angeles Times headline that reads “California sea levels to rise 5-plus feet this century, study says.”

Sensation versus information

First, a lesson in journalistic sensationalism: The AP’s claim about “scientists and computer models” predicting global sea-level rises by 2100 of “as much as 3.3 feet” could just as well have been worded “as little as 7 inches.” This 3.3 feet figure is not from the study that is the subject of the AP article, and by citing the authority of scientists and computer models, the AP gives the distinct impression that this result is universal. The reality, however, is that a 2011 paper in the Journal of Coastal Research explains that such projections run as low as 7 inches. An honest way to report this would have been to provide a range of estimates (such as 7 inches to 3.3 feet), not a single cherry-picked example.

The Los Angeles Times headline about the West Coast study—“California sea levels to rise 5-plus feet this century”—is even more misleading because the language is unequivocal. In truth, the study predicts a sea-level rise of 16.5 to 66 inches over this period. In the body of the article, theLA Times reporter walks back the headline and applies the qualifier “as much as” to the 5-plus-feet figure, but he fails to provide even a hint that this is the upper bound of a prediction that extends to as low as one fourth of this.

Reuters took the hyperbole a leap further by claiming that the East Coast study shows “sea levels from Cape Hatteras to Cape Cod are rising at a faster pace than anywhere on Earth.” This assertion appears to be completely fabricated. The study compares global average sea-level accelerations to those on the coastlines of the continental U.S. and southernmost portion of Canada. It says nothing about any other specific locations, and an email to one of the study’s authors confirms that the study “does not make comparisons ‘to anywhere on earth’.”


11 responses to “James D. Agresti: Will global warming flood the coasts of the United States?

  1. One study, henceforth referred to as the “East Coast study,” was published in the journal Nature Climate Change and shows a “recent acceleration” of sea-level rise on the East Coast from North Carolina to Massachusetts.

    I’ll believe the above when someone can prove they can make one end of a half filled bathtub higher than the other.

    • “Worldwide, sea level is not evenly distributed like it is in small bodies of water such as lakes. For instance, the sea level in the Indian Ocean is about 330 feet below the worldwide average, while the sea level in Ireland is about 200 feet above average. Such variations are caused by gravity, winds, and currents; and the practical effects of these phenomena are dynamic.”

    • Ben of Houston

      Ralph, that’s easy. Put a fan blowing water on one side and the water will be higher at one end than the other. Barely, but it will be higher. Or, you can slosh around the water and it will be higher in some places than others at any one time.

      The wind, currents, rivers, gravitational fluctuations, the sun, and the moon all exert significant forces that make the sea uneven.

      • You’re talking external forces not normal sea levels. Everyone talking rising seas levels aren’t saying it’s because of storm surge or high tides. The Atlantic can’t rise is selected areas unless those areas are sinking into the sea.

  2. As a resident of NC I became aware of the ridicule legislators faced when they decided not to use the results of the East Coast study for coastal planning purposes. Media outlets and comedians such as Stephen Colbert fanned the flames of public outrage with the usual antics of idiotic southern politicians. Specifically, they made the legislators that rejected the global warming model’s predicted seal level rise appear to be anti-science. In fact, if one considers the threats to coastal NC it is much more likely the NC coast will be confronted with a Category V hurricane than a 3.3 ft sea level rise attributable to global warming. What the critics of the NC legislature seem to evade is that public policy must be grounded in real threats in which the risk can be quantified so that taxpayers money is put to the most effective use. This was a good article. I appreciate your work.

  3. Having lived near Ocean Shores Washington for the past sixty eight years I can absolutely say the ocean rise is NON existent. If I measure the level in the early 1950’s compared to now there is NO diferrence. How can this be explained??

  4. “I’ll believe the above when someone can prove they can make one end of a half filled bathtub higher than the other.”

    Please pardon any redundancy…

    I can’t tell you how happy it makes me to encounter an open mind here.

    You can make the water in one end of the tub deeper the same way mother nature does it.


    Hold your applause…

    In general, the wind comes from the west at the lattitudes occupied by the U.S. so that sea level on the Pacific side can be and usually is, higher than on the Atlantic side.
    Science rocks!

    And for the metrically challenged, when a report says 3.3 ft, they’re translating. It’s really one meter.


    “public policy must be grounded in real threats in which the risk can be quantified ”

    Two things about that-

    In the real world, risk can seldom be quantified ahead of the fact. So to demand precision is wholly unrealistic, and a delaying tactic in some cases.

    The term ‘real threats’ has to include threats recognized by the preponderance of the experts in the field. For a legislator to decide on his or her own to reject what the scientific community holds as being highly probable is at best irresponsible, and at worst, lunacy.
    Ideology does not trump reality, at least, not for long.

    In the 50s, they prepared fallout shelters even though the probability of nuclear war was unknown.
    I have to buy liability insurance, my legislature makes me. But they have no idea what a superb driver I am…
    I don’t even get a discount.


    • The wind doesn’t blow constantly to keep sea water stay at a constant heigher level.

      • ralph, may I suggest you check out tides either end of the Panama Canal and note there is roughly a 7mtr range in the Eastern Pacific but only 1mtr less than 100Km away in the Western Atlantic. Note also how much different phases of ENSO deform the Pacific sea lens. Tuvalu tide gauge readings fall during El Niños but they rise further East. Water piles up due to gravitational attraction of the Antarctic ice shield and wells higher as currents cross submarine mountains. There’s plenty of examples of water piling up in the ocean “bathtubs”.

  5. Bruce of Newcastle

    Adam – I am not a climate scientist but I am a scientist and a modeller with a PhD in chemistry. I can from my personal experience see what the GCM people are doing wrong – leaving out significant variables. One is the solar magnetic effect on clouds, and another is the oceanic cycles. They can’t include these as the emergent climate sensitivity would then be well under 1 C/doubling and they’d be out of a job.

    Where I am getting to is that there is plenty evidence of a 60-ish year cycle in the oceans, with harmonics (eg the thermohaline cycles seem to be ~30 and ~90 years, ie 1/2 and 3/2 of the temperature/AMO signal [Knight et al 2005; figs 1 & 2]). And if you look at the UC sea level data you’ll see a suggestion of the same cycle. Which if true means even a linear trend is overstating the story. Furthermore if as expected the world temperature drops a degree or two with the current solar minimum average sea level will drop some more due to a reversal of the thermoexpansion of the last century.

    I really think the NC sea level hysteria is a parody of Chicken Little. Which I might add we have going on here in my town – there’s even a class action against our city council. NC would risk the same if they tried similar silly restrictions. On the empirical data its quite unlikely much of a change will occur by 2100.

    For more info see Dave Burton’s comments. He was a member of the scientific advisory committee.

  6. Remember Floyd and how far west the flooding went? There are places in Wilson that were I never new to flood that were under 4′ of water. The Outer Banks will not remain static, no matter how much wishful thinking and money we waste on them. Remember the billions spent on Jockey Ridge before some bright bulb figured out you can’t make sand dunes forever stable. According to some folks at East Carolina, the biggest danger to the Outer Banks is construction because it changes natural flows, not sea level rise. I think the legislature was right not to rely on being panicked by model.

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