Guest Post by Kip Hansen
Corrigendum: Due to the simple mis-reading of a multi-column spreadsheet from this paper, the magnitude of the AIG Subsidence for The Battery was misstated as “-2.3mm/yr”. The number given is for Sandy Hook, NJ. The correct figure for The Battery, NY is -1.35mm/yr. This changes the details of the posters at the end of the essay. The correct result for Absolute Sea Level Rise at The Battery is 3.34 inches over 50 years 1963-2013, over half of the measured 6 inches of Relative Sea Level Rise, not 1.7 inches. This change does not affect the conclusion of the essay. — Kip Hansen 20 Sept 2017
Note: The text of this essay is a bit long, even for me. It quotes a NY Times article, and I comment on it. The entire essence is contained in two simple posters at the end of the piece.
Justin Gillis, the last bastion of the NY Times’ now defunct Environmental News Desk, wrote a pretty good news piece on 13 January 2014, entitled The Flood Next Time.
His piece is not long, so I’ll try an essay form similar to that used by Dr. J. Curry over at Climate Etc. – putting blocks of the original piece in pull-quote sections and commenting on them in the main body of text like this:
Up close, though, the roof of the shed behind a Coast Guard building bristled with antennas and other gear. Though not much bigger than a closet, this facility is helping scientists confront one of the great environmental mysteries of the age. [referring to the tide gauge at the Battery, NYC]
The equipment inside is linked to probes in the water that keep track of the ebb and flow of the tides in New York Harbor, its readings beamed up to a satellite every six minutes.
While the gear today is of the latest type, some kind of tide gauge has been operating at the Battery since the 1850s, by a government office originally founded by Thomas Jefferson. That long data record has become invaluable to scientists grappling with this question: How much has the ocean already risen, and how much more will it go up?
Well, the tide gauge equipment just helps us to know what the tides have been doing. The equipment there that is really helping us know how much the sea is coming up is the CORS GPS-based equipment which measures how much the land itself is moving up away from , or down towards, the center of the Earth. More about that later.
Scientists have spent decades examining all the factors that can influence the rise of the seas, and their research is finally leading to answers. And the more the scientists learn, the more they perceive an enormous risk for the United States.
Much of the population and economy of the country is concentrated on the East Coast, which the accumulating scientific evidence suggests will be a global hot spot for a rising sea level over the coming century.
The detective work has required scientists to grapple with the influence of ancient ice sheets, the meaning of islands that are sinking in the Chesapeake Bay, and even the effect of a giant meteor that slammed into the earth.
The work starts with the tides. Because of their importance to navigation, they have been measured for the better part of two centuries. While the record is not perfect, scientists say it leaves no doubt that the world’s oceans are rising. The best calculation suggests that from 1880 to 2009, the global average sea level rose a little over eight inches.
Tide gauges along the East Coast show a long-term increase in relative sea levels, in part because the ocean is rising and in part because areas of the coast are sinking.
Mr. Gillis lays it, quite correctly, on the line: The land is sinking and the sea is rising. The oddest thing is that, although the scientists have spent a great deal of time and effort to quantify the amount of sinking and the amount of sea rising, Mr. Gillis doesn’t tell us, except in the vaguest of manner, either number. When he says “the best calculation” he is referring to the long-term overall global sea level rise believed to result from the Earth’s recovery from the Little Ice Age, or Global Absolute Sea Level , Global ASL, and widely accepted to amount to roughly 1.8 mm/yr pre-1960, and a bit more, up to 3.2 mm/yr, since then.
I have no wish at all to take up the one paper claim that the Northeast Coastal US “will be a global hot spot for a rising sea level over the coming century”—the link to the paper should work – I have looked at it and they are not simply saying the NE US coast is sinking. Here is a tiny panel of eight long-term sea-level graphs for eight northeastern US ports. (I am not fond of predictions made by line-drawing on graphs). Clicking on the imaging should bring up full page version.
All are from http://tidesandcurrents.noaa.gov/sltrends/ .
That may not sound like much, but scientists say even the smallest increase causes the seawater to eat away more aggressively at the shoreline in calm weather, and leads to higher tidal surges during storms. The sea-level rise of decades past thus explains why coastal towns nearly everywhere are having to spend billions of dollars fighting erosion.
The evidence suggests that the sea-level rise has probably accelerated, to about a foot a century, and scientists think it will accelerate still more with the continued emission of large amounts of greenhouse gases into the air. The gases heat the planet and cause land ice to melt into the sea. The official stance of the world’s climate scientists is that the global sea level could rise as much as three feet by the end of this century, if emissions continue at a rapid pace. But some scientific evidence supports even higher numbers, five feet and beyond in the worst case.
I would not have been surprised to find a statement like “scientists say even the smallest increase causes the seawater to eat away more aggressively at the shoreline in calm weather” on a poster at the high school science fair I judged. I was surprised to find it printed in the NY Times. This would mean that the physical properties of water would have to change between high tide and low tides, for example. I publicly challenge Mr. Gillis to provide a direct quote or a source supporting the statement.
That sea level rise also raises storm surges goes without saying, but adding 1/8th of an inch to an 8 foot or a 14 foot storm surge is a trivial matter, even on a calm sea, the smallest of ripples are higher than 1/8th inch. IPCC enthusiasts will know that the IPCC’s latest statement on sea level rise is “It is very likely that the mean rate of global averaged sea level rise was 1.7 [1.5 to 1.9] mm/yr – between 1901 and 2010, 2.0 [1.7 to 2.3] mm/yr between 1971 and 2010 and 3.2 [2.8 to 3.6] mm/yr – between 1993 and2010. It is likely that similarly high rates occurred between 1920 and 1950.” (AR5 SPM) and also “It is very likely that there is a substantial contribution from anthropogenic forcings to the global mean sea level rise since the 1970s.” We need to note here that the IPCC considers AGW contributions to sea level rise to start circa 1970 – not as often portrayed, at the beginning of the Industrial Revolution, in 1880 or 1890. This will arise later. As Mr. Gillis didn’t seem to remember, let me remind us all that Global Sea Level rise does not happen the way it does in your bathtub – when you add water to the tub, at the tap end, it rises instantaneously equally at the other end. Not so the seas. NOAA’a visual depiction of the sea level rise for the last 20 or so years:
As for Mr. Gillis’ last bit, “But some scientific evidence supports even higher numbers, five feet and beyond in the worst case.” he might have better said that there was some speculation about higher numbers. It is questionable to say that there is evidence about the far future – I for one would have thought a journalist would have known this important difference, imagine using this language in a courtroom.
Scientists say the East Coast will be hit harder for many reasons, but among the most important is that even as the seawater rises, the land in this part of the world is sinking. And that goes back to the last ice age, which peaked some 20,000 years ago.
As a massive ice sheet, more than a mile thick, grew over what are now Canada and the northern reaches of the United States, the weight of it depressed the crust of the earth. Areas away from the ice sheet bulged upward in response, as though somebody had stepped on one edge of a balloon, causing the other side to pop up. Now that the ice sheet has melted, the ground that was directly beneath it is rising, and the peripheral bulge is falling.
Some degree of sinking is going on all the way from southern Maine to northern Florida, and it manifests itself as an apparent rising of the sea.
I am very surprised that Mr. Gillis doesn’t simply give us the GIA (glacial isostatic adjustment ) subsidence numbers, they are not secrets, after all. They come from the same people that give him and us the tide and sea level rise numbers – NOAA at their National Geodetic Survey, using long-term continuous GPS readings. Here’s the link è http://www.ngs.noaa.gov/CORS_Map/ Richard Snay kindly directed me to this page ftp://cors.ngs.noaa.gov/cors/coord/coord_08/nad83_2011_geo.comp.txt for the latest computed results which include vertical movement for a selection of CORS sites. (unfortunately, not this particular page for the Battery).
The sinking is fastest in the Chesapeake Bay region. Whole island communities that contained hundreds of residents in the 19th century have already disappeared. Holland Island, where the population peaked at nearly 400 people around 1910, had stores, a school, a baseball team and scores of homes. But as the water rose and the island eroded, the community had to be abandoned.
Eventually just a single, sturdy Victorian house, built in 1888, stood on a remaining spit of land, seeming at high tide to rise from the waters of the bay itself. A few years ago, a Washington Post reporter, David A. Fahrenthold, chronicled its collapse.
A simple matter of rising sea levels affects us all and is therefore political.
Somehow, Mr. Gillis seems unable to keep clear in his own mind the relationship between the sinking of the land , erosion of sand bars, and the rising of the water itself. Chesapeake sand bar islands are famous for coming and going historically, it is no surprise to local Chesapeake watermen.
Aside from this general sinking of land up and down the East Coast, some places sit on soft sediments that tend to compress over time, so the localized land subsidence can be even worse than the regional trend. Much of the New Jersey coast is like that. The sea-level record from the Battery has been particularly valuable in sorting out this factor, because the tide gauge there is attached to bedrock and the record is thus immune to sediment compression.
It is simply not possible that a New York-based environmental journalist of the stature of Justin Gillis, who has been writing on environmental issues in and around NY City for so long, who has stood at the Battery and talked to the scientists who operate the tide gauge there, could be unaware of the continuously operating GPS system of the National Geodetic Survey which is being used to carefully the measure the ups and downs, norths and souths, easts and wests of the Earth’s crust. We know precisely (as precisely as we will ever know) how much the Battery has sunk in the last 50 years. All he had to do was ask. The latest subsidence numbers for the Battery, NYC come from this paper Using global positioning system-derived crustal velocities to estimate rates of absolute sea level change from North American tide gauge records by Richard Snay et al. at NOAA NGS who calculate a long-term geological rate of 2.2 mm/yr. By the way, Richard Snay was very responsive to my email requests for data and pointers to sources of information – which was welcome as the CORS website was a bit confusing for those not initiated to its complexities.
The last house on Holland Island in Chesapeake Bay, which once had a population of almost 400, finally toppled in October 2010. As the water rose and the island eroded, it had to be abandoned.
Perhaps the weirdest factor of all pertains to Norfolk, Va., and points nearby. What is now the Tidewater region of Virginia was slammed by a meteor about 35 million years ago — a collision so violent it may have killed nearly everything on the East Coast and sent tsunami waves crashing against the Blue Ridge Mountains. The meteor impact disturbed and weakened the sediments across a 50-mile zone. Norfolk is at the edge of that zone, and some scientists think the ancient cataclysm may be one reason it is sinking especially fast, though others doubt it is much of a factor.
The Chesapeake Bay area is a hotbed of subsidence. No amount of increasing the fight against Global Warming is going to change that, Mr. Gillis.
Coastal flooding has already become such a severe problem that Norfolk is spending millions to raise streets and improve drainage. Truly protecting the city could cost as much as $1 billion, money that Norfolk officials say they do not have. Norfolk’s mayor, Paul Fraim, made headlines a couple of years ago by acknowledging that some areas might eventually have to be abandoned.
Did I mention already that the neighborhood being bemoaned in Portsmouth, really, across the river from Norfolk proper, is a drained and filled swamp? that it has been sinking and flooding for years and years? that everyone there knows why this is so? The tides wash in through the fill and wash out the soil underlying the neighborhood, especially the road shown in the photo in the NY Times article. I’ve stood on that very spot twice, six years apart, anchored in the bay to the right of the photographer. Both times they were repairing the same street, the same seawall, for the same reason.
Up and down the Eastern Seaboard, municipal planners want to know: How bad are things going to get, and how fast?
One of the most ambitious attempts to take account of all known factors came just a few weeks ago from Kenneth G. Miller and Robert E. Kopp of Rutgers University, and a handful of their colleagues. Their calculations, centered on New Jersey, suggest this is not just some problem of the distant future.
This study (follow the link if you like) is quoted as follows: “A largely anthropogenically driven global sea-level (GSL) rise of 20cm during the 20th century [Church and White , 2011] caused Sandy to flood an area ~ 70km 2 x greater than it would have in 1880, increasing the number of people living on land lower than the storm tide by ~ 38,000 in New Jersey and by ~ 45,000 in New York City (Climate Central, Surging Seas Data Table, 2012, retrieved from SurgingSeas.org/downloadables, based on methodology from SurgingSeas.org/NationalReport, last updated February 2012).” I have already given the data from the IPCC that AGW sea level rise didn’t even begin until 1970 (not the entire 20th century as claimed), in a separate essay, I showed that Hurricane Sandy’s storm surge was not made more destructive by AGW. The data which Miller and Kopp have “retrieved” came from that bastion of scientific truth, ClimateCentral — SurgingSeas.org returns http://sealevel.climatecentral.org/ .
People considering whether to buy or rebuild at the storm-damaged Jersey Shore, for instance, could be looking at nearly a foot of sea-level rise by the time they would pay off a 30-year mortgage, according to the Rutgers projections. That would make coastal flooding and further property damage considerably more likely than in the past.
Even if the global sea level rises only eight more inches by 2050, a moderate forecast, the Rutgers group foresees relative increases of 14 inches at bedrock locations like the Battery, and 15 inches along the New Jersey coastal plain, where the sediments are compressing. By 2100, they calculate, a global ocean rise of 28 inches would produce increases of 36 inches at the Battery and 39 inches on the coastal plain.
These numbers are profoundly threatening, and among the American public, the impulse toward denial is still strong. But in towns like Norfolk — where neighborhoods are already flooding repeatedly even in the absence of storms, and where some homes have become unsaleable — people are starting to pay attention.
“In the last couple or three years, there’s really been a change,” said William A. Stiles Jr., head of Wetlands Watch, a Norfolk environmental group. “What you get now is people saying, ‘I’m tired of driving through salt water on my way to work, and I need some solutions.’ ”
The entire point of this essay is to point out that, with the exception of a few obligatory “Another Scary Movie”-type inclusions of very iffy speculative numbers concerning the far future or the well-known general whole world historical sea level rise number, Mr. Gillis simply left out numbers, actual quantitative figures, all together.
Had Mr. Gillis taken the time and effort to gather even the simplest of basic numbers and present them to us, we would have known where to concentrate our efforts in regards to the sea level rise problem here on the East Coast of the United States. I present this information in two simple posters, cartoons, if you will, showing 50 years of data. The data is for the Battery, NY City. It would be even more dramatic for Portsmouth/Norfolk, VA.
As they say on NPR: “Let’s do the numbers.”
Pre-AGW Global ASL – The IPCC gives these figures in the 5th Assessment as “It is very likely that the mean rate of global averaged sea level rise was 1.7 [1.5 to 1.9] mm/ yr – between 1901 and 2010” –we can expect at least 1.8 mm/yr from long-term ASL (global absolute sea level rise – that which is believed to be happening on average all over the globe). 1.8 mm/y x 50 yrs = 3.3 in. sea level rise
Sea Level Rise from AGW – The Battery, NYC – last 50 years. Unknown, but Mr .Gillis warns us over and over to expect the worst. Once we do the numbers, we’ll know the truth.
Relative Sea Level – The Battery, NYC – last fifty years. Source: New York State Sea Level Rise Task Force Report to the Legislature — Dec 31, 2010 “New York Harbor has experienced an increase in sea level of more than 15 inches in the past 150 years, with harbor tide gauges showing a rise of between 4 and 6 inches since 1960.” I use a figure of the full 6 inches sea level rise over the last fifty years, to prevent senseless quibbling.
AIG Subsidence – The Battery, NYC – last fifty years. Source: Using global positioning system-derived crustal velocities to estimate rates of absolute sea level change from North American tide gauge records by Richard Snay et al. at NOAA NGS. This paper gives a long-term -2.2 mm/yr vertical movement as the mean of five different groups’ calculation methods of the data, for a net 4.3 inches of land sinking since 1963 in two simple posters.
(NOTE: See important Corrigendum at top of essay)
Now you know too. Wasn’t that easy?
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Moderation and Commenting Note: This essay is not about CAGW, AGW, GW, CCC, CC, or any combination thereof. It is about journalism, poor and dodgy. I would like to hear from Justin Gillis and would like to apologize to him if I have misrepresented his NY Times piece. It is about sea levels on the East Coast of the US and the components of their rise. I’ll be glad to answer your questions in that regard. I have sailed and anchored at most of the locations mentioned, including the very harbor pictured in the NY Times article in Portsmouth, VA (though it is labeled Norfolk).