The Sea is RISING! . . . or IS It?

Posted in At Sea, Mixed Nuts on November 20th, 2008 by MadDog
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Ten years or so is nowhere near enough time to make any kind of statistically reliable statement about sea level changes. That’s unless the West Antarctic glob slithers into the sea or the Greenland ice cap gets all frayed and falls apart like an old baklava. If something like that happens, we’ll know Pretty Darn Quick!

However, I have for you today some interesting research from my boss’s boss (My wife is my boss – yes, kiddies – it’s quite literally true. This is from her boss.)

By the way, the following comes from someone whose interest in and knowledge of the sea is not to be sneezed at. Kyle and his wife, Kathy and their ship’s cat, Dory sailed a thirty foot boat from Moline, Illinois, down the Mississippi, across the Gulf of Mexico and all the way to Madang. You can read about it here.

Let me mention that Kyle and I are on rather opposite sides of the fence vis a vis the whole global warming kafuffle. I think that we’re doing very bad things to ourselves and we really ought to stop – or else! Kyle takes the view that the models have not shown to be anywhere near accurate, let alone predictive (look at the ranges!) and it wouldn’t do us much good to wreck the world economy and then find out it was mostly part of a natural cycle.

THIS FROM: Kyle Harris

I have been interested in the alleged affects of global warming on the sea level here in PNG so I was pleasantly surprised to find on line a collection of sea level data taken on Manus Island dating back to 1994.

SEAFRAME at Maunus Island

The tables give hourly sea level values for the entire year. The early years are a bit spotty with large holes in the data but later years are pretty much complete. (A full year of hourly readings comes to 8760 readings.)

Data
Year    Average  Points
1996      0.752    7120
1997      0.615    8719
1998      0.617    8735
1999      0.772    8740
2000      0.786    8784
2001      0.771    8760
2002      0.675    8760
2003      0.723    8349
2004      0.732    8784
2005      0.740    8760
2006      0.745    8760
2007      0.765    8760
Average   0.715

Having downloaded all the files, I ran a simple average on the yearly data from 1996 through 2007. I excluded the earlier years because of the large holes in the data. I then plotted the data to see if there were any discernible trends. The data shows a dip in the average sea level in 1997 and 1998, followed by a sharp increase of almost .2 meter for the following three years. Then there is another dip followed by a gradual increase through 2007.

Chart of the SEAFRAME data

Chart of the SEAFRAME data

In trying to make sense of the data for 1996 though 2002, I checked the NOAA web site for el Niño and la Niña data. During La Niña years, the Southeast trade winds in the South Pacific are stronger than normal. This pushes the water in the Pacific westward and results in a “piling up” of the water in the Western Pacific. The opposite is true in el Niño years. So one would expect years of strong la Niña would correspond to higher than normal sea levels while years of strong el Niño would correspond to lower than normal levels.

The NOAA Data

The NOAA Data

According to NOAA there was a strong el Niño in 1997 and 1998 followed by a strong la Niñael Niño again in 2002. Since then there have been short-lived el Niño and la Niña which started the end of 2007 and which ended in 2008. starting the second half of 1998 and finishing the first part of 2001. There was a medium strength events but nothing too significant. There was a fairly strong

The el Niño in 1997 and 1998 seem to correspond to the dip in sea levels of the corresponding period. And, the quick rise in sea levels immediately thereafter correspond to the lengthy la Niña event. This is followed by another el Niño and another dip in average sea levels. Since 2002 we have seen a gradual increase in the average sea levels of approximately 1.5 inches total.

I realize that this is a quick and dirty analysis but I believe it does illustrate the difficulty in quantifying sea levels over the short term.

While it is fashionable to jump on the climate change bandwagon to explain sea level variation, there may be other factors at work such as el Niño and la Niña and subsidence associated with plate movement that may explain at least some of the changes in the observed data.

Whew!

We all have anecdotes concerning the imminent danger of loosing our front yards to the sea (at the very least). I would be willing to swear by Britney Spears‘ Jeans that the water in front of my house has risen by at least ten centimetres in the twenty years or so that I’ve lived there.

However, there may be another explanation for this.

I worked for a couple of weeks on Miss Rankin while some scientists were traipsing around studying the effects of ancient tsunami. One of them told me that Madang (essentially the armpit of Astrolabe Bay – and I mean that in a geographical sense) is on one end of a big raft of geology that is sinking while the other end (up around the cape, I think) is rising. How much and how fast, I don’t remember.

So much for science.

It still seems to me that my front yard is disappearing at an alarming rate. I may have to learn to do the Jesus Walk even before I’m taken up into the clouds.

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