Timothy Birdnow

How NOAA reports sea level rise

From the article in Wattsupwiththat:

"These charts (and the original graphs of Sea Level change over time at individual tide gauges) do not show how much the surface of the sea is rising (or falling) — they do not show Absolute Sea Level rise or fall. They show Relative Sea Level Trends for individual tide gauge locations and taken together simply demonstrate visually the differing rates of vertical land motion between the stations. It is a pleasant surprise to find that NOAA, sometimes leaning towards Sea Level Rise catastrophe advocacy, not only explains this clearly, but goes on to reiterate that "global sea level rise is believed to be 1.7 +/- 0.3 millimeters/year during the 20th century” — a figure at great variance from that promulgated by NASA, which is currently claiming to show almost twice that at 3.0 +/- 0.4 mm/yr.

NOAA makes this perfectly clear: Tide Gauges measure Local Relative Sea Level and its changes and reflect mostly the magnitude/rate of vertical land movement.. Thus, Tide Gauges, by themselves, are not fit for the purpose of determining Global Average or Regional Average Sea Level changes, rise or fall."

End excerpt.

And yet NOAA often reports sea level rise as if it is accelerating and shows that global warming is going to drown us.

Sea levels have been rising for ten thousand years, since the end of the last ice age. They have been accelerating since the middle of the nineteenth century when the Little Ice Age ended.

But how this sea level rise is measured is important, and often things like erosion - a man-caused phenomenon that silts up the mouths of harbors - are not adequately taken into account. I remember Michael Mann wrote a paper about North Carolina tidal pools to show global warming was raising the sea level - and he didn't bother to take into account the construction of levees to the river that emptied into those pools, thus increasing water flow and pushing silt out to sea. It's a mistake that I don't think top scientists make by accident.

The author of this piece sums up:

" 1. Tide Gauges and tide gauge-based data can only be used to measure Local Relative Sea Level and its changes. This data is the only sea level data of importance to localities.

2. Comparing Tide Gauge sea level trends from one tide gauge to another, as the NOAA "northern Atlantic station trends” show, only gives us "an indication of the differing rates of vertical land motion”.

3. In order for Tide Gauges and Tide Gauge data to be useful for determining actual changes in sea surface height (or rates of change in sea surface height), regionally or globally, the Tide Gauge station must have an associated GPS@TG (GPS at tide gauge) Continuously Operating [GPS] Reference Station mounted on the same structure as the tide gauge that will precisely determine vertical movement (VLM) of the tide gauge itself.

End excerpt.

Noaa is less than truthful about all this, knowing full well most people won't understand how their data is compiled. It's a dirty trick, to put it mildly, but NOAA has been at the epicenter of climate change alarmism for decades and it promotes it's ideology religiously.

If AGW theory were on solid ground these scientists wouldn't need to resort to accounting tricks and gimmicks, and they would be more candid in what it is they are doing.

Posted by: Timothy Birdnow at 09:55 AM | Comments (3) | Add Comment
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