From Watts Up With That?

Note by Kip Hansen

I was checking to see if the Water Levels at the tide gauge at The Battery, New York had come back into its normal range – it had been running exceptionally high and out of line with the long-term trend:

And, as we can see, the latest datum is right back in line with the trend, as expected.  There are reasons for the spike that lasted a couple of months.  Savvy readers can inform us in comments.

Since I was in the NOAA Tides and Currents site, I took a look at the database view called “Variation of 50-Year Relative Sea Level Trends”, seldom visited.  Here it is for The Battery:

Do you see that interesting wave shape?   I do.

What exactly is this?  NOAA says:

“Linear relative sea level trends were calculated in overlapping 50-year increments for stations with sufficient historical data. The variation of each 50-year trend, with 95% confidence interval, is plotted against the mid-year of each 50-year period. The solid horizontal line represents the linear relative sea level trend using the entire period of record.”

Curiosity took hold and scrolling down the page, I see that NOAA had supplied the same view for 40 tide gauges around the United States.

Here are 12 selected from the Northeast coast of the United States, first in a PowerPoint slide show, one after another:

They all have the same/similar wave form, or the segment of the wave over shorter time periods.  How similar?  Let’s see.

Putting all 12 images on top of one another, aligning the vertical scales in millimeters:

Visually, we can see the wave form repeated at each gauge.  As we get closer to present time, more tide gauges are added to the mix and we see more variability. 

One more look:

In the image above, I have aligned the “linear sea level trend using the entire period of record” for each gauge (the arrow points to that line).

With this view, collectively, we reveal remarkable similarity across the entire range of tide gauges. 

It is possible to see what looks like higher Rates of Relative SLR in the 1950s and the 1960s  than those we see in the latest 50 year period. 

It is also possible to chop off the earliest portions of the chart, leaving only the time period that the tide gauge record shares with the satellite sea level measurement record.  Doing that results in graphs like this one from NASA:

This graph starts in 1993…and shows that rising trend in the last three 50-year periods of the tide gauge graph.  I have blown up the lower right corner, just because it seemed odd to me that NASA drops the first few data points below zero and they are obscured by the white tick mark for 1993. 

Remember, Relative Sea Level Rise is the additive product of Vertical Land Movement (VLM, land moving up or down) and any change in the actual height of the sea surface (up or down).    For a tide gauge, the measurements must be taken at the same place on the same structure (pier, dock, wharf):  Sea Surface Height by a modern tide gauge and VLM by a Continuously Operating GPS station attached to the same structure.   NOAA attributes the differences in RSLR rate to differences in the rate of VLM (in most cases, “negative VLM” or  downward).

NASA explains East Coast VLM in an article titled: America’s Sinking East Coast. 

The press however, urged on by the major Climate Crisis propaganda outfits, gives us stories like these:

Northeast is likely to experience more than a century’s worth of sea level rise from 2000 to 2050, report finds

Federal report predicts a foot of sea level rise by 2050, with higher levels in the Northeast

It is an interesting way to look at the NOAA tide gauge records for the Northeast United States and the rate of relative sea level rise revealed in it.

# # # # #

Author’s Comment:

What do you make of that?  I’ll try to get time to do the same for the West Coast, and the Gulf Coast.  If I can find similar data, for Europe and Asia as well.

NASA has added the absolutely required “acceleration curve” as a thin red line.  That line is entirely subjective, a matter of opinion and some fancy statistical skullduggery – which involves all the primary sins of time series analysis – most importantly, using a very short time period, 30 years,  for a phenomenon that operates over centuries. 

The graphs of Rates of RSLR from the tide gauges show that there is a cyclical patter to the rate of rise – at least in the NE U.S.

Thanks for reading.

# # # # #