since peak glaciation,
20,000 years ago,
by over +400 feet so far.
They are expected,
to keep rising,
4 to 8 inches per century.
That is not dangerous,
The surface of the ocean,
is always in motion,
and even,
unusually smooth seas,
have ripples and waves,
of a few inches.
TIDE GAUGES
The most sensitive,
acoustic tide gauges,
have an accuracy,
of +/- 2 cm for each reading,
which is ten to twenty times,
the claimed annual rise,
of global sea levels.
Piers are built on pilings,
sunk into the mud,
rarely to bedrock,
with tide gauges,
attached to the piers.
Tide gauges move,
usually subsiding (sinking),
over the years,
because most gauges,
are located in harbors,
that typically have soft soils,
from sands and loose mud.
The geological structure,
to which a tide gauges
is attached, is important.
But a tide gauge,
attached to bedrock,
such as one at The Battery,
in New York City,
can have other problems.
Earth’s continental masses
move as they readjust,
to the loss of the ice,
(aka isostatic uplift)
from the last peak glaciation,
20,000 years ago.
For The Battery tide gauge,
there is some unknown amount,
of isostatic uplift.
SATELLITE MEASUREMENTS
The sea has ripples, waves, tides,
wind chop, reflected waves, boat wakes,
that add to, and cancel out,
one another, in chaotic patterns.
Jason series satellites,
have an orbit height,
of 830 miles.
(1,336 kilometers)
The satellite records,
the time it takes,
for an altimetry beam,
to bounce back,
from the ocean,
and the amount of “scatter”,
or noise, in the returned beam.
Satellite sea level rise calculations,
start with an assumption,
that sea level is rising,
1.8mm / year as a “base rate”,
based on uncorrected tide gauges,
that measure local sea level changes,
combined with an unknown amount,
of vertical land movement.
These data are corrected for,
“estimated” tides,
and the tidal waves,
that cause low and high tides.
NOAA states the correction,
or “calibration”,
for tides is done with data,
known to be accurate,
to around half a foot,
meaning the “calibrations”,
are far larger,
than claimed annual changes
in sea level !
The satellite receiving antenna's,
distance from Earth,
will vary by many centimeters,
with ‘satellite position’,
and there is no indication,
of any antenna orientation correction,
before reporting sea level changes,
in millimeters per year!
The sea level rise reporting,
by the Colorado University,
Sea Level Research Group,
is very suspicious,
for one example:
Colorado University
(see above chart),
has made huge,
data "adjustments",
such as the rate of sea level rise,
for the year 2000,
originally reported in 2004,
as over +2.1mm per year,
... but by 2006, that number,
had been "adjusted" upward,
by about 50%,
and was being reported as,
almost +3.1mm per year !
Sea level data are obviously
reported with false precision,
just like NASA and NOAA,
are claiming their,
global average temperature,
has a margin of error,
of only +/- 0.1 degrees C.,
when +/- 1.0 degree C.,
may be too small !
And those smarmy bureaucrats,
have the nerve to announce,
to the gullible public,
that one year was warmer,
than the prior year,
by a few hundredths,
of a degree C. !