Are sea levels really rising?

Dennis Savageau's vision for 521 Round Hill Road

Dennis Savageau’s vision for 521 Round Hill Road

Not around here; not much. Mike Finkbeiner recently was hired by NYC to compare the 1811 sea level to now. His conclusion? High tide then was 4′ over mean low, 4.73 feet higher now.

In 1811 the Commissioner’s of the City of New York laid out the street grid system, and established an extensive series of elevation monuments at corner intersections, based on high tide of the era at zero.   EarthImage was asked to calibrate that system in relation to the modern determination of tidal level and land elevations.   Our conclusion was that the City Elevation Zero of 1811, now known as Manhattan Borough Datum, is 4.03 ft over modern mean lower low tide (the average daily low from 1978 to 2001.)  As the daily high today is 4.73 ft higher than that, one can speculate that tides have risen 0.70 feet (8.4 inches) since 1811.

What’s going on (I say, not Finkbeiner) is that the gummint is changing the methodology to achieve its political goals. Here in Greenwich, Diane Fox, Katie Blankley Deluca (whose father is now on our BET) and Denise Savageu, the triad responsible for forcing residents from their homes, are only too willing to go along with that process.

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6 responses to “Are sea levels really rising?

  1. Mickster

    The word “higher” in your first paragraph should read “high”. Confusing.

  2. pulled up in OG

    So what was high tide in 1978 and 2001?

    IOW, rate of change 1811-1978 vs 1978-2001 vs 2001-today.

  3. CF mis-quoted the conclusion about the Battery Park study. Each Federal tide station sits in its own independent datum, to be connected by future surveys to determine how the Earth crust moves relative to the observed tides. The measurements are from “mean lower low water” set to a height of zero in the local system. The is the average of the daily lowest tide over 19 years.

    In 1811 the mean high water elevation was 4.03 ft over this absolute point at Battery Park in the photo I took depicting the hardware there at their pier. Today’s mean high water is 4.73 ft over the same mark.

    Therefore, I concluded that actual sea level rise from 1811 to the 19 year epoch ending in 2001 was 0.70 ft.

    Several factors complicate the picture. Water levels around Manhattan are affected by river hydraulics, which depend on river flows and deposited silt and debris, minus dredge materials, including the whole subway system. Lower Manhattan is a very different place and shape from 1811 until now.

    Further, in setting up the national vertical system in 1929, it was wrongly assumed that there was a national value for “sea level.” Big mistake.

    The Sandy Hook Coast Guard Station in NY Harbor was used as a major reference value for this presumed number. Therefore the entire national survey vertical network in our area was warped down to meet that tide gauge station.

    Today sea level heights are determined from the elliptical orbits of satellites, as is crustal movement of the land surface. That accounts for the elevation shift in the FEMA mapping modernization program that came to Fairfield County in 2010.

    • pulled up in OG

      Nitpick. Just curious.

      “modern mean lower low tide (the average daily low from 1978 to 2001.)”

      19 years?

  4. Add in we are on Long Island Sound and the “raise” is ameliorated by our position in the Western portion of same.
    Speaking of politics the highly paid cadre of “experts” still on Town dollars orchestrated the stealing of Calf Island from our children by getting the bird nerd dependent politicians to act screaming “23 houses could be built there” in fact 2 at the most because of duhhhhFEMA regs. in place at the time.
    13 Deed Restrictions had to be eliminated by the then Attorney General now our Senator and his puppets.
    Each time you drive, walk, run, bike, wheelchair past the YMCA (that received 6.5 million in pork slices for the Island that legally could only have been transferred to an organization dedicated to giving children experience of outdoor/maritime life) and you see the green veil that is more than symbolic of the power play fraud.
    Real Planning does not exist.
    Political Planning invented by Robert Moses is imposed on us daily.
    Payback time ?

  5. Thanks, OG, for paying attention.

    The official epochs are:
    1960 – 1978
    1978 – 1983
    1983 – 2001.

    The explanation from:
    http://tidesandcurrents.noaa.gov/datum_options.html

    Definition:
    National Tidal Datum Epoch
    The specific 19-year period adopted by the National Ocean Service as the official time segment over which tide observations are taken and reduced to obtain mean values (e.g., mean lower low water, etc.) for tidal datums. It is necessary for standardization because of periodic and apparent secular trends in sea level. The present NTDE is 1983 through 2001 and is actively considered for revision every 20-25 years. Tidal datums in certain regions with anomolous sea level changes (Alaska, Gulf of Mexico) are calculated on a Modified 5-Year periods.