Tag Archives: sea level

Sea Level Questions Continue

Yesterday, I read a piece in our local newspaper discussing the problems rising sea level will cause.   Built into the article were two assumptions, both of which are probably  incorrect.

  • Assumption 1 – Sea level could rise by as much as a meter by the year 2100
  • Assumption 2 – Man can take actions to alter this in some significant way.

When I look at sea level data I see confusion.   Today was no exception.   My inquiry began with a look at Satellite data courtesy of  Colorado University.

Sea level, according to CU, is rising at a rate of about 3.2 millimeters a year (plus or minus 12.5%).  That’s about an 1/8 of an inch per year or about a foot per century.  Plus or minus an inch or two.  Not exactly a meter, but coastal regions will have difficulties.  Sea level has been rising since the Little Ice Age ended some 250 years ago.   If I had land in Key West, I’d be worried.

But sea level in Key West isn’t rising at 3.2mm/yr, it’s rising at 2.24 mm/yr.  And the trend has been steady for the 100 years of the data.

chart: Mean Sea Level Trend, 8724580 - Key West, Florida

Key West may be under water at some date in the future, but the rate of change appears to be much less than predicted by IPCC scientists.  I suppose Key West could be an oddity, but it’s unlikely.   I visited the NOAA web site and checked many places I thought might be interesting.   Places like Bermuda, Honolulu, San Francisco, Venice.   Yep, Venice, well Trieste, it’s just across the bay.


Trieste’s rate is less than 40% of the Satellite predicted rate.

1.24/3.4 = .397 or 39.7%

The margin for error is half the satellite data rate (.2 mm vs .4mm)

Every place I checked  had a trend rate that was less than the satellite data.   In most cases the predicted margin for error was less than the satellite data too.    A few select data points have a longer history too. I tabulated the results

City                                            rate of change       data history

San Francisco                             2.01 mm/yr       160 years                                              Honolulu                                       1.50 mm/yr       110 years                                                     New York                                     2.77 mm/yr       120 years                                                 Bermuda                                       2.04 mm/yr         70 years                                          Narvik, Norway                       -2.06 mm/yr          60 years                                          Cochin, India                              1.71 mm/yr          70 years                                                Hong Kong                                  2.92 mm/yr          60 years                                        Nagasaki, Japan                        2.20 mm/yr         45 years                                          Sydney, Australia                     0.65 mm/yr         130 years                                     Auckland, New Zealand         1.29 mm/yr         120 years

This data doesn’t tell the full story of the confusion.  Individual sites provide lots of conflicting data.   Honolulu has been trending down since about 2002:

chart: Mean Sea Level Trend, 1612340 - Honolulu, Hawaii

The NOAA presentation of the Bermuda data a bit odd:

chart: Mean Sea Level Trend, 2695540 - Bermuda,

Most of the increase shown in Bermuda happened before 1960.  Had the data set begun in 1955 instead of 1934 the trend line would have shown nearly no net change.  Sea level rose fairly rapidly from 193o until 1955 and has been relatively stable since then.  Go figure.

Virtually every city I checked showed a less ominous looking trend line than the satellite data.  This land based data has it’s limitations.   Many international cities have tiny data sets, particularly in South America and Africa.   Only one data point exists for all of Antarctica

chart: Mean Sea Level Trend, 999-003 - Argentine Islands, Antarctica

I would argue that the Antarctica data doesn’t really suggest a trend but NOAA calculates the trend at  1.43mm/yr.  When I look at the data I see no net changes since 1960.  Sounds kind of like Bermuda’s data to me?

Something is wrong.   Every land site I checked showed less overall change than the satellite data.   How can that be?   The satellite data is an average for the whole world.   Some specific locations should be higher and some places should be lower.

Northern locations like Alaska and Norway are showing reduced sea level due to reduced gravitational pull from the Arctic Ice Sheet (presumably).  Where are the equatorial places that are compensating for that reduction?   I can’t make sense of the data.   Satellite data and measurements at land interfaces don’t tell the same story.

Sea level is extraordinarily difficult to calculate.   Sea level changes in one part of the world can take years and years  to impact the ecosystem.  I understand that storms and changing ice sheets impact the data.  Change that can take decades to correct.

WHY is the satellite data very nearly ALWAYS significantly higher than the land data?

The Satellite data has been higher every year since the data began in 1993.   Every year! Most places I have checked disagree by about 1 mm per year.  After 20 years of data the sources disagree with each other by about 20 mm.  or about .78 inches.  The longer this condition exists, the less I trust the data sets.

It really is difficult to make accurate predictions about sea level if you don’t have the ability to accurately graph the underlying trend line.  Sea level, almost certainly,  has been rising since the end of the Little Ice Age some 250 years ago.  But by how much?   Almost no statistical data exists before the Civil War. I suspect SWAG.

Sea level has been steadily rising for probably 250 years.   How much has been man’s impact? I don’t know and I’ll go a step further…nobody knows!

I am not convinced that we have the tools necessary to accurately predict the future course of events as it relates to sea level.    Sea level appears to be an indicator that follows rather than leads climate change.   How much of today’s changes in sea level were impacted by global temperatures of 20 or 50 or 100 years ago?  I don’t know.  I see guessing here, there and everywhere.

IPCC scientists might have the trends right….but even that is…I fear …. a guess.







Sea Level Confusion — Part 2

I’ve been reading, trying to understand better why sea level varies so much from location to location. I conducted a google search and found a site affiliated with Yale University.

The site is called Environment 360.   An article titled The Secret of Sea Level Rise: It Will Vary Greatly By Region  provided a bit of insight and some climate propaganda.  The climate propaganda makes me a bit nervous. If the author is inclined to misrepresent in one area, perhaps the rest of the article is less than impartial.  The first paragraph included the following tidbit:

Recent projections suggest a global average warming of perhaps 3 to 4 degrees C, or 5.4 to 7 degrees F, by the end of this century.

A little later in the article:

Sea level, according to the best current projections, could rise by about a meter by 2100, in large part due to melting of the Greenland and West Antarctic ice sheets.

The article was written in 2010.   Best current projections, give me a break.  In 2010 his best projections would have been IPCC AR4 report published in September of 2007.   That report made no predictions about Greenland and said that data on the Antarctic ice sheet was inconclusive.  AR4 predicted the following in a section titled Projections for Future Changes in Climate:

For the next two decades, a warming of about 0.2°C per decade is projected for a range of SRES emission scenarios

Almost immediately thereafter  sea level rise by 2100 makes an appearance in the form of a chart.  The sea level rise that matched 4 degrees C was …are you ready…between .26 and .59 meter.   The data in the chart (labeled SPM 1 in AR4) showed a range of best guess temperatures from 1.1 to 4.0 degrees C.   4.0 was the highest best guess on the chart.   The author took the highest number possible, and made it sound like the most likely event!

And so far temperature predictions made in the AR4 report have been wild high.

Since Y2K there has been no net change in the temperature of the Earth’s surface.  Temperatures peaked in 1998 and have been wandering in  a narrow range for some 15 years.   Carbon dioxide has been rising steadily, temperature has not.  I have no idea what kind of projections he was referring to.   IPCC projections will, in AR5, almost certainly be less specific.  Nobody likes to have their mistakes so easily documented.

That said the article offers some interesting tidbits about why sea level changes.  Most are short term lasting anywhere from a few days to up to 30 years.   Wind, atmospheric pressure, and changes in the ocean bottom are discussed.    None seemed to help explain the errant data I was seeing (see my last post).   And then I read about gravity!

Supposedly, changes in gravity at the poles can impact sea level.   When the Arctic ice cap shrinks (as it has been doing since the 1970’s) this changes the gravitational force in the area.  Sea level goes down.   And this article predicted significant changes.   The whole thing sounded a bit S.W.A.G.-ish to me.  And given the exaggeration in the beginning of the article I had suspicions.   Still it is an interesting notion.

Another article said that when ice in Greenland melts it can take up to 30 years for that change in sea level to work it’s way around the world.   Another article talked about how difficult is to measure sea level.   The subject seethes with SWAG potential.

NOAA keeps all sorts of data on sea level.   They monitor hundreds of sites (perhaps thousands).   But the sites are not uniformly distributed.   Most are in the USA and in Europe.  Africa has only one official site.  Antarctica has none.

Maybe Antarctica could help explain some of the strangeness of the data.  The ice sheet in Antarctica has been growing in recent years.  2013 has set one record after another.  The ice sheet is the largest it has been (surface area) since satellite data began in 1979,or so says the National Snow and Ice Data Center.  And they have pictures:

It looks like gravitational forces in Antarctica have been increasing in recent years.  Sea level should be higher near the coast of Antarctica and lower in the middle of the Pacific.  It would help explain why Hawaii’s sea level is increasing less than ….say San Francisco.   Perhaps the amount of ice over land in Antarctica might offset the melting in Greenland .

Antarctica and the Arctic might be offsetting each other.

It doesn’t explain why folks in Australia show a rise in sea level that does not persist in California.  Maybe it will even out some time in the next 30 years or so, one way or the other?

Antarctica’s mass is growing.  That’s my best guess for why some sea level data makes no sense.  That and time.   Much of the data in the NOAA data base is less than 30 years old.   There you have it,  my current best wild ass guess.   Absent field measurements of actual sea level activity near Antarctica…who’s to say I’m wrong.

At least I admit I’m guessing!

Sea Level Confusion

Mean sea level confuses me.   Intuitively I want sea level to be the same all over the world.  But it isn’t.   One reason the Panama Canal has locks, sea level on the Pacific side averages 8 inches higher than on the Atlantic side….and the tides are higher on the Pacific side too.   Without the locks, water would constantly be flowing from the Pacific side to the Atlantic side.

And sea level is not changing at the same rate all around the world.  Some places have a rising sea level, others falling.   Supposedly worldwide sea level is rising steadily as demonstrated by this chart courtesy of the Australian government:

Plot of global sea level from 1993 to 2012

NOAA keeps data for all the 50 states of the USA and that data generally shows a much slower rise….and in some cases no rise since 1990.  Something doesn’t make sense…and that confuses me.  Let’s begin looking at NOAA data for San Francisco.   The data for San Francisco is some of the oldest available.  It goes back over 150 years.  Here is the sea level data chart for San Francisco:

chart: Mean Sea Level Trend, 9414290 - San Francisco, California

San Francisco peaked in 1998 (a strong El Nino year).  NOAA also provides charts that show the change year to year.   They call these charts interannual charts.  Here is the interannual chart for San Francisco.residual1980.png

Since 1998 sea level is San Francisco has been going down.   How about Miami Beach Florida:


Miami appears to have peaked in the 1940’s?   But the data shows no real net change in the 50 years the data has been kept.  NOAA must have changed where they keep data for this area as the data stops in the 1980’s.  But the data is interesting as it shows variations that should have predated man caused climate change.  The data does not match the San Francisco data.   It has less overall movement and it peaks at a different time. Now lets see how the Pacific Ocean has been doing by taking a peak at Honolulu, Hawaii:

chart: Mean Sea Level Trend, 1612340 - Honolulu, Hawaii

Honolulu has been rising, but slowly.  It looks a lot like San Francisco.  Let’s zoom in on the data since 1990 by looking at interannual variation chart .


The change since 1990 has been minimal.  The area above the zero line on the chart roughly equals the area below the line.

Are you confused yet?  Now let’s look at data for Seward, Alaska:

chart: Mean Sea Level Trend, 9455090 - Seward, Alaska

An earthquake in 1964 is probably the reason for the shift in data.  The Seward waterfront was devastated by a tidal wave following the Good Friday Earthquake on March 28th 1964.  The trend of the data is …down.  Sea level has been going down in Seward since at least 1964.    How can that be?  If the worldwide sea level has been rising steadily since 1990, how can it be going down in Seward?  The NOAA data appears to contradict the Australia data?

Now let’s look at Juneau, Alaska.  Are you ready…this one’s really weird:

chart: Mean Sea Level Trend, 9452210 - Juneau, Alaska

Juneau makes no sense to me at all.   The world has been warming, glaciers have been melting.  Sea level should be going up world wide.   I have no reason not to believe the data provided by NOAA.  After all they are pretty good at this stuff.

Climate activists have been talking global disaster for years and years.  One really big disaster has been a rapidly rising sea level.   Al Gore featured it in his 2006 film, An Inconvenient Truth.   The UN’s Intergovernmental Panel on Climate Change (IPCC) has been making claims in advance of the 2014 release of their AR5 climate assessment.   Sea level rise has made the news as this link to an article in the Yale forum on Climate Change and the Media demonstrates.  Here is a chart prepared by the IPCC from that article:

I suspect guessing.  Wild Ass Guessing!  AND I am confused.