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Lies, Damn Lies and Sea Level Data

A Drudge headline this morning points to this story that claims sea levels have been falling for the past 6 years.  And the story is correct.   Here's the graphic proof based on data from the National Oceanic and Atmospheric Administration:

Sea Level (bad science)

Nothing to look at here.  Everyone's safe.  No worries. 

But, perhaps unsurprisingly, given the source, the picture fails to tell the whole story. 

Here is the same graph extended back to 1910. 

Sea Levels

According to the data–yes, the same data used in the top graph–sea levels fell from about 1920-1930, and again from 1945-1950, and again from 1970 to 1980, and again from 2000-2005 and from 2008 to 2009 and from 2010-2016. 

Yet somehow sea levels rose from 1910-2016. 

By almost .4 meters.

Upshot:  Part of the story doesn't tell the whole story.  As I tell my students in my econometrics classes:  If you tell me the conclusion you want people to draw, I can find data to support your conclusion.  But the trick to good statistics is to draw conclusions from the data and not draw data for the conclusions.    

 

 
 

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  1. Ironman Avatar
    Ironman

    There’s also doesn’t seem to be much of a direct correlation between changes in CO2 levels and sea level – at least in the period from 1960 to the present where we have that overlapping data for CO2. I had thought that there was supposed to be a stronger link that would almost certainly show up in the contemporary sea level data, especially since the rate at which CO2 has increased in the atmosphere since 1998 has been consistently higher than it was in the decades beforehand.
    Perhaps there’s something more there that a more detailed analysis might turn up, but on a simple first pass, I’m somewhat surprised.

    Reply
  2. Wintercow20 Avatar
    Wintercow20

    This, too, however, is only part of the story. Sea level rises are different in different cities. How does Helsinki compare to Atlantic City? How does London compare to Sydney?
    And even THAT is only part of the story.
    How has sea level changed not over 100 years, but 1000, or 10,000 or any other significant geological time scale?
    And even THAT is only part of the story.
    What are the various things that impact sea levels and how much do we know about those?
    And even THAT is only part of the story?
    What about the resolution within which we measure sea-level rise both in terms of precision of measurements of today versus in the past, but more important the rate of sampling. Ancient sea level rise estimates are based on samples drawn from every 100 or 1000 or longer time chunk of data. And we are comparing that to daily measurements taken today. Those historical, low-resolution measurements are very likely masking very dramatic inter-measurement changes in sea-level that we simply cannot “see” using our current technology.
    Good post.

    Reply

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