Sea Level Rising?

Climate alarmists put forth scary scenarios saying that global warming is causing unprecedented sea level rise and the rise is accelerating. Well, don’t sell your beach-front property yet.


Measuring sea level is more complicated than pounding a stake into a beach. There are daily and seasonal variations, storm surges, and effects from periodic oscillations such as El Niño. And there are tectonic events: is the ocean rising or is the land sinking?

Ideally, global sea level would be a rotating oblate ellipsoid of polar radius of 6365.752 km and equatorial radius of 6378.137 km in absence of any other forces. Gravity, distorts this ideal shape to make it lumpy. Or, as the National Geodetic Survey of NOAA puts it, global mean sea level is “The equipotential surface of the Earth’s gravity field which best fits, in a least squares sense” the ideal geoid.

Since the end of the last glacial epoch, sea level has risen 120 meters (393 feet), about one meter per century.   The graph above is a reconstruction of sea level rise since the end of the last glacial epoch. (Source: ).

Larsen and Clark (2006) studied the rate of sea level rise for the past 6,000 years, based on geologic evidence and the historic record. The researchers found that there has been no acceleration of sea level rise in response to increased temperature or CO2 levels.

In another study, Holgate (2007), using data from worldwide coastal tidal gauge records, shows that the rate of sea level rise is decreasing. Specifically, the mean rate of global sea level rise was “larger in the early part of the last century (2.03 ± 0.35 mm/yr 1904-1953), in comparison with the latter part (1.45 ± 0.34 mm/yr 1954-2003).” [NOAA puts normal rise at 1 to 3mm per year, about the thickness of one or two pennies.]


The second graph shows satellite measurements of sea level. Notice there has been no acceleration of rise and that the rate levels off beginning in 2006. But the rate of rise is 3.2±0.4 mm/yr. This rate is higher than Holgate’s 1.45 mm/yr and thus gives the impression that the rate is increasing.

However, it depends where you start looking. Holgate’s study shows that the rate of sea level rise is cyclical. See the third graph below.

It just so happens that the satellite measurements were taken during an upswing of the cycle, thereby giving the false impression that the rate was accelerating. (Unfortunately, Holgate’s graph stops at the year 2000.)

Notice that although the cycles have greater amplitude, the general trend of the rate of sea level rise has been decreasing since the 1950s.


Holgate does not address possible causes of the rate cycle. However, Kolker and Hameed2007), report “a major fraction of the variability and the trend in mean sea level at key sites along the Atlantic Ocean are driven by shifts in the position and intensity of the major atmospheric pressure centers that reside over the Atlantic Ocean, the Azores High and the Icelandic Low,” which they refer to as atmospheric centers of action. Apparent sea level is also affected by variability of storms, winds, floods, waves, shifts in major ocean currents, volcanically-induced ocean heat content variations, the El Niño Southern Oscillation, subsidence, uplift, tectonics, and freshwater fluxes.

These data show that the current rate of sea level rise is neither unprecedented, nor is it accelerating.

Note also, that even if all Arctic and Antarctic sea ice melts, it will have no effect on sea level because floating ice displaces an equal weight of water.


Holgate, S.J. 2007. On the decadal rates of sea level change during the twentieth century. Geophysical Research Letters 34: 10.1029/2006GL028492

Kolker, A.S. and Hameed, S. 2007. Meteorologically driven trends in sea level rise. Geophysical Research Letters 34: 10.1029/2007GL031814

Larsen, C.E. and Clark, I. 2006. A search for scale in sea-level studies. Journal of Coastal Research 22: 788-800.

Graph #1, Post-Glacial Sea Level Rise, created by Robert A. Rohde / Global Warming Art


  1. I like it.  This is a well-presented argument.  The material is a little dense for the average person, but your explanation makes it understandable.

    Is it expected that the graph showing the rise in sea level over time continues in the future as it has in the past?  Are there any anticipated consequences of continued rise?  You mentioned the theoretical melting of all the Arctic and Anarctic ice.  Since the ice is fresh water, what would the loss of all these stores of fresh water mean, if it were to happen? 

    Unfortunately, the labels on the second graph didn’t reproduce well and are hard to read.  

    Very interesting.    

    1. It is my understanding that sea ice is salt water, but even if it were fresh water, it will be recycled throught the normal process of evaporation and precipitation.

      What are anticipated consequences?  Sea level will continue to rise slowly until the next glacial epoch. 
      By the way, during the Cretaceous Period, all the ice melted, including the land-based ice, and sea level was 100- to 200 feet higher than now.   Maybe I’ll do a blog sometime on how Arizona looked during that time.

  2. Sorry, this is the TucsonCitizen chat blogs.
    Were you looking for the National Science Foundation?
    Dont you think you are making the point to the wrong audience? I would love to read a response to this article after it is submitted to a credible journal – not the TucsonCitizen blogs.

  3. First, let’s consider Wry Heat’s source. His post is essentially a rewrite, graphs included, of a July 22 post at World Climate Report. Patrick J. Michaels is the Chief Editor of World Climate Report. Here’s what Source Watch says about Michaels: Patrick J. Michaels (±1942- ), also known as Pat Michaels, is a global warming skeptic who argues that global warming models are fatally flawed and, in any event, we should take no action because new technologies will soon replace those that emit greenhouse gases.Michaels is Editor of the World Climate Report, a blog published by New Hope Environmental Services, “an advocacy science consulting firm”[1] he founded and runs. In an affidavit in a Vermont court case, Michaels described the “mission” of the firm as being to “publicize findings on climate change and scientific and social perspectives that may not otherwise appear in the popular literature or media. This entails both response research and public commentary.”[2] In effect, New Hope Environmental Services is a PR firm.Michaels’ firm does not disclose who its clients are, but leaked documents have revealed that several were power utilities which operate coal power stations. On a 2007 academic CV, Michaels disclosed that prior to creating his firm he had received funding from the Edison Electric Institute and the Western Fuels Association. He has also been a frequent speaker with leading coal and energy companies as well as coal and other industry lobby groups.[3]Michaels is also associated with a number of think tanks and advocacy groups which dispute global warming. He is a Visiting Scientist with the George C. Marshall Institute, a Senior Fellow in Environmental Studies with the Cato Institute[4] and a member of the Advisory Board of the Committee for a Constructive Tomorrow.[5]Here’s the Wikipedia take on Michaels:A number of prominent scientists have criticized Michaels’ research conclusions. John Holdren, now Science Advisor[22] to President Barack Obama, told the U.S. Senate Republican Policy Committee, “Michaels is another of the handful of U.S. climate-change contrarians… He has published little if anything of distinction in the professional literature, being noted rather for his shrill op-ed pieces and indiscriminate denunciations of virtually every finding of mainstream climate science.” [23]Climate scientist Tom Wigley, [24] a lead author of parts of the report of the Intergovernmental Panel on Climate Change, is quoted in Ross Gelbspan‘s book The Heat is On[25]: “Michaels’ statements on [the subject of computer models] are a catalog of misrepresentation and misinterpretation… Many of the supposedly factual statements made in Michaels’ testimony are either inaccurate or are seriously misleading.”[26]Peter Gleick, a conservation analyst and president of the Oakland-based Pacific Institute, said: “Pat Michaels is not one of the nation’s leading researchers on climate change. On the contrary, he is one of a very small minority of nay-sayers who continue to dispute the facts and science about climate change in the face of compelling, overwhelming, and growing evidence.”[27]In short, Michaels, and World Climate Report Contributing Editor Robert C. Balling Jr., are among a small group of undistinguished writers with close associations to the fossil fuel industry who have made a profession of global warming denial.For a coherent discussion of  global warming induced sea level rise, I recommend Gavin A. Schmidt’s post at Real Climate – that string, here’s an abstract by Church and White published in Geophysical Research Letters 6 Janaury 2006:Multi-century sea-level records and climate models indicate an acceleration of sea-level rise, but no 20th century acceleration has previously been detected. A reconstruction of global sea level using tide-gauge data from 1950 to 2000 indicates a larger rate of rise after 1993 and other periods of rapid sea-level rise but no significant acceleration over this period. Here, we extend the reconstruction of global mean sea level back to 1870 and find a sea-level rise from January 1870 to December 2004 of 195 mm, a 20th century rate of sea-level rise of 1.7 ± 0.3 mm yr−1 and a significant acceleration of sea-level rise of 0.013 ± 0.006 mm yr−2. This acceleration is an important confirmation of climate change simulations which show an acceleration not previously observed. If this acceleration remained constant then the 1990 to 2100 rise would range from 280 to 340 mm, consistent with projections in the IPCC TAR.While I’ve spent a fair amount of timing working on (for National Wildlife Federation) and reading about global warming, I am not a climate scientis
    t any more than Wry Heat is..What I do know is that Wry Heat is posting a lot of extreme right wing global warming denial posts dressed up with charts and graphs to look impressive.Of course he’s got a right to post this stuff and people have a right to believe it if they want. But understand, he’s shoving aside the research, findings and projections of the solid majority of climate change scientists, represented principally in the UN’s Intergovernmental Panel on Climate Change and the U.S. National Academy of Sciences.The analogy is the “scientists” hired by the tobacco industry who for decades helped confuse the public about the lethal reality of smoking. If you liked them, you’re going to love Michaels, World Climate Report and Wry Heat.

    1. Jonathan isn’t doing anything the climate alarmists aren’t doing also. Both sides have a nasty tendency to cherry-pick the facts that suit their cause. The problem for climate alarmists is that the paucity of  data they have is being extrapolated and filled by the very models the little data they have was used to create. Small wonder then that their models appear to be valid, at least to them.

      It’s a lot like atronomers and “dark matter” and “dark energy”. The astronomers cannot explain their observations with the tools they have, so they assume that there must be something else to make everything go the way they believe it should. Then they set out to prove their equation-balancers actually exist. This is all well and good, but they might be better served by making sure all of their assumptions about how the universe works are correct first, just as the climate alarmists might want to fully understand all of the components that go into creating a climate before running about claiming the world is doomed. 

    2. Hi Ben,
      I looks like you spend much time attacking the messenger rather than addressing the facts.

      The RealClimate article you refer to takes the IPCC to task because their latest projections for sea level rise are lower than Gavin Schmidt likes. But notice that Schmidt is not arguing about real data; he is arguing about modeled projections made by the IPCC.
      In my post, I use real data.
      So Ben, what is a real climate scientist? I content that geologists qualify because we study the history of the planet and the climate history is preserved in the rocks.

  4. Well yeah, I don’t agree with Mr. DuHamel’s conclusions and I am aware of his background and POV on the issue.  Nonetheless, I support his right to voice his arguments and I am actually delighted that there are people like Mr. McNitt and Mr. DuHamel both presenting information about this important topic.  

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