Originally Posted by owedtojoy

You may underestimate the statistical work involved
in merging tidal gauge and satellite data.

They aren't the same. Trying to make one match the
other is a fool's mission.

Originally Posted by owedtojoy

On the other hand, I know scientists are not infallible

Yes, they can be corrupted.

Originally Posted by owedtojoy

I saw a statement in a Nenem paper we can both agree with.
The satellite sea level data as yet shows no sign of an accelerating
sea level rise.

That's right hasn't accelerated these last 20 years.
Their current data shows a higher rate for the first
ten years by the way. Check it out.

Originally Posted by owedtojoy

Nenem reckons more date is required. OTOH, sea level rise is
NOT decelerating.

For practical purposes it's a linear around 2 mm/yr.

Originally Posted by owedtojoy

We need to let it plod along for a few more years & see what
happens. In my view, as the ice caps melt, sea level cannot
do anything else but rise.

And they are rising, they just aren't rising faster & faster.

Originally Posted by Steve Case

They aren't the same. Trying to make one match the
other is a fool's mission.


Yes, they can be corrupted.


That's right hasn't accelerated these last 20 years.
Their current data shows a higher rate for the first
ten years by the way. Check it out.


For practical purposes it's a linear around 2 mm/yr.


And they are rising, they just aren't rising faster & faster.

Nah. I'll go with the science - just over 3mm/ yr. You can stick with your fond wishes.

Of course tide gauges and satellite are "not the same". But from my own brief reading, I can understand in outline from the papers I looked at how they can be aligned. It depends on collecting data simultaneously for a while. Then from the cross matching of the data in suitable cells in space (they use 1 degree latitude x 1 degree longitude) and in time (1 month), they use Bayesian methods for the distributions of the oceanic measurements, given the tide gauge readings. They then apply the statistical "learning" to the older tidal data. Easier to describe than to do. It could not be done in one go, and could keep a statistician busy for a good part of his career.

Don't know about you, but to me the rates of sea level rise in the second half of the 20th century look distinctly higher than those in the first half (on average, of course). That 35-year smooth tells the story.

There used to be a "argument" going around about earth warming "Mars is warming too, so it must be the sun".

We don;t hear that one any more, but NASA released a fascinating video about carbon dioxide on Mars. Any "warming" there seems to be due to the planet's orbital variations.



Martian melting – A Few Things Ill Considered

I don't think this has been posted yet. Jason Box's look at the future of ice.

Humans have already set in motion 69 feet of sea-level rise | Grist

Originally Posted by Agnotologist

I don't think this has been posted yet. Jason Box's look at the future of ice.

Humans have already set in motion 69 feet of sea-level rise | Grist

Here is what 69 feet of sea level rise looks like on the coast of the US:

The “good” news is that this might take 1000 to 2000 years (or longer), and the choices we make now can affect the rate of rise and whether we blow past 69 feet to beyond 200 feet.

Manmade Carbon Pollution Has Already Put Us On Track For 69 Feet Of Sea Level Rise | ThinkProgress

Originally Posted by owedtojoy

Here is the way I obtained the chart below.

I aggregared all the tide guage sea level
anomalies into years rather than months.

Using Excel's SLOPE() function, I got the
linear slope of every 10-years of data.
That gave me 123 data points from 1879 to
2001 - the "X"'s in the chart below.

Then I fitted a LOESS 35-year smooth to the
data and got the red line.

The red point and errors bars were fitted
from the satellite data.]



LOESS (Locally Estimated Sum of Squares)
is a standard smoother, and is not an Excel
function. However, Jon Peltier has designed
a useful (and free) add-in. This is the 3rd
time I have told you about it. Go here
LOESS Smoothing in Excel | Peltier Tech Blog | Excel Charts

You seem to estimating 35-year slopes and
over-smoothing the data.

PS Note that for most of the 20th century,
while sea level rates have fluctuated, they
have almost always been positive.

Thanks once again for the link to your
LOESS page.

I've been looking at what you did on that chart,
and the one thing that sticks out is the data
you used. It's Church & White (2006) which
is the opus I have the most issues with. As you
know Church & White list the tide gauge stations
they used
Zip C&W Tide Gauges
I've put critiques of that up before, but I looked
at it with your ten year slope averaging technique
you describe giving you those 123 data points.
So I processed the C&W stations and ALL the stations
in the exact same manor and looked at just the last
ten years which coincides with the satellite era
quite nicely and here's what I find:

Code:

 Ten Year Slope & Difference

YYYY ... ALL .... C&W ... Delta	

1992 ... 1.76 ... 1.55 .. -0.20
1993 ... 1.14 ... 0.79 .. -0.35
1994 ... 1.00 ... 0.56 .. -0.44
1995 ... 0.84 ... 1.37 ... 0.53
1996 ... 0.71 ... 1.77 ... 1.06
1997 ... 0.72 ... 1.38 ... 0.66
1998 ... 0.54 ... 1.87 ... 1.33
1999 ... 1.65 ... 2.57 ... 0.91
2000 ... 2.22 ... 3.29 ... 1.07
2001 ... 3.25 ... 4.02 ... 0.77
			
Average .................. 0.53

The Church & White selection of stations yields a
significantly higher average rate of sea level rise
(0.53 mm/yr) for those ten years. By the way, the
tide gauge data is listed with (C&W 2011) So while
I may have said earlier that their 2011 opus seems
a bit more realistic I am speaking of their final
treatment, not the selection of initial data.

Originally Posted by Steve Case

Thanks once again for the link to your
LOESS page.

I've been looking at what you did on that chart,
and the one thing that sticks out is the data
you used. It's Church & White (2006) which
is the opus I have the most issues with. As you
know Church & White list the tide gauge stations
they used
Zip C&W Tide Gauges
I've put critiques of that up before, but I looked
at it with your ten year slope averaging technique
you describe giving you those 123 data points.
So I processed the C&W stations and ALL the stations
in the exact same manor and looked at just the last
ten years which coincides with the satellite era
quite nicely and here's what I find:

Code:

 Ten Year Slope & Difference

YYYY ... ALL .... C&W ... Delta	

1992 ... 1.76 ... 1.55 .. -0.20
1993 ... 1.14 ... 0.79 .. -0.35
1994 ... 1.00 ... 0.56 .. -0.44
1995 ... 0.84 ... 1.37 ... 0.53
1996 ... 0.71 ... 1.77 ... 1.06
1997 ... 0.72 ... 1.38 ... 0.66
1998 ... 0.54 ... 1.87 ... 1.33
1999 ... 1.65 ... 2.57 ... 0.91
2000 ... 2.22 ... 3.29 ... 1.07
2001 ... 3.25 ... 4.02 ... 0.77
			
Average .................. 0.53

The Church & White selection of stations yields a
significantly higher average rate of sea level rise
(0.53 mm/yr) for those ten years. By the way, the
tide gauge data is listed with (C&W 2011) So while
I may have said earlier that their 2011 opus seems
a bit more realistic I am speaking of their final
treatment, not the selection of initial data.

As I understand it, C&G did not make a random sample, or even claim to make a random sample. Nor did they cherry-pick.

From the notes with the file:

These locations are on a 1 degree x 1 degree grid, to correspond with the grid that the satellite altimeter data is on. A location can have one or more tide gauge records mapped onto it.

The selection critieria for tide gauges are given in their 2004 paper - they are trying to link the tide gauges with the spatial variability of the satellite data, so as not to bias the results with using too many gauges in some areas, and few in others.

http://journals.ametsoc.org/doi/pdf/...O%3E2.0.CO%3B2

I have not had time to read this yet, so it will have to wait.

Originally Posted by Steve Case

In the video Jason Box says that each year Greenland contributed 1.6 mm
to sea level rise, and land ice almost as much and Antarctica about half as
much or about 3 - 4 mm of sea level rise per year.

Why do these guys have exaggerate everything? The Climate Desk interviewer
just sat there nodding his head. The logical question to have been asked would
be to point out that neither the satellite nor tide gauge records support the
3-4 mm/yr figure and how does that square with what Box just said?

Catastrophists can make any figure fit anything, they hope no one will notice and in so doing, they achieve the intended goal of frightening even more people.

Originally Posted by owedtojoy

As I understand it, C&G did not make a random sample,
or even claim to make a random sample. Nor did they
cherry-pick.

From the notes with the file:

The selection critieria for tide gauges are given in
their 2004 paper - they are trying to link the tide
gauges with the spatial variability of the satellite
data, so as not to bias the results with using too
many gauges in some areas, and few in others.

I have not had time to read this yet, so it will have
to wait.

I've been through the 2004 paper

Estimates of the Regional Distribution of Sea Level Rise over the 1950–2000 Period

I gleaned some numbers and put them into
tabular order as follows:

Code:

Record..Status..........Reason

1159....RLR	
1950....Met	

-256....eliminated......Records >2 years
-1063...eliminated......Redundant
-95.....eliminated......beyond TOPEX/Poseidon range
-37.....eliminated......<250 km to Alt grid point.

1658....records for further assessment.	

??......eliminated......Disagreement nearby records
??......eliminated......Locations
??......eliminated......Fragmented
??......eliminated......Noise
??......eliminated......Residual trends <10 mm/year

-713....Eliminated......For above 5 reasons? (1658-945=713)

945.....combined	

-491....eliminated......by combination

454.....records for further assessment.

-28.....eliminated......No useful data

426.....records for further assessment.

Comments:

Really, because Topex/Poseidon didn't cover the range they
tossed the data? I don't think that makes sense, but I
suppose there's a reason for that.

In the text they go from 1658 records down to 945 records
but don't give us any numbers as to how many were eliminated
for the five reasons tabulated above. Residual Trends
<10 mm/yr is reasonably objective. The other four listed are
somewhat subjective without any guidelines as to what
constitutes unsuitable locations, too much noise, too much
fragmentation, or how much disagreement with other records
is allowed or how near by they must be. After combining the
945 records there was another group of records eliminated for
having no useful data. What was not useful? As far as I’m
concerned, there is room for some subjectivity in perhaps
several hundred deletions of data.

Originally Posted by owedtojoy

I aggregared all the tide guage[sic] ..

What the heck is a "guage" when it's at home?