Sea Level Rise: Denial by Bullshit

Sea level rise is such a huge problem, and is so undeniable, that climate deniers have gone loony trying to blame it on anything and everyting but global warming. It’s not working; the recent idiocy from congressman Mo Brooks trying to blame sea level rise on rocks and dirt filling the oceans didn’t increase doubt about human cause like he hoped, rather it raised extreme doubt about his competence. He, and his idea, quickly became a laughingstock. Others have been ridiculed for similarly ridiculout ideas. Now Roy Spencer has joined the crowd with something almost as dumb as rocks.

His “thesis” is that sea level rise before 1950 had to be all natural. His thesis is wrong. He further supposes that since 1950 it has continued to rise at the pre-1950 rate for entirely natural reasons. His further supposition is wrong. Only by using such blatantly false suppositions can he conclude that the human contribution to sea level rise is only 0.3 inches per decade (that’s 0.76 mm/yr). His conclusion is wrong.

Let’s consider his (and others’) first premise, that everything before 1950 had nothing to do with human activity but was all natural. Typically he says “sea level has been rising naturally, for at least 100 years before humans could be blamed.

Here’s the CO2 concentration since 1958 according to data from the Mauna Loa atmospheric observatory, and before that from the Law Dome ice core:

The value in 1950 was just about 312 ppm, the pre-industrial level about 278 ppm. That means that in 1950 it was already 34 ppm higher than pre-industrial. Since it’s presently about 409 ppm, 26% of the rise due to human activity was already there. Earth to Roy Spencer: 26% is not nothing. It’s not even negligible.

What about mankind’s influence on global temperature up to 1950? Climate models can estimate how Earth’s temperature has changed over time due to many factors, some natural, some not. They are often run with only the natural forcings, leaving out the human contribution, enabling us to compare how it would have changed without mankind’s interference to how it changed with human influence. I averaged global temperature (yearly averages) for all model runs using only natural influences, and for all model runs including all forcings (natural + anthropogenic), then computed temperature anomaly using a baseline from 1880 to 1900, and got this:

Clearly the natural-only behavior is not the same “before 1950.” But Roy Spencer wants us to believe that pre-1950 the human influence is nothing. Here’s the estimated difference which is due to human influence:

Human activity — not natural forces — caused about 0.15°C warming from 1900 to 1950 alone. That’s not nothing, it’s not even negligible. But in addition, there’s good reason to believe Earth had already warmed by about 0.2°C from 1750 to 1900 due to human activity — not natural forces. That makes around 0.35°C warming by 1950 from human influence alone. Earth to Roy Spencer: that’s not nothing. It’s not even negligible.

Roy Spencer’s premise — that the human influence can be neglected before 1950 — is one of the most common techniques of climate deniers in general. In my opinion, it’s not just mistaken, not just ludicrous, it’s sometimes dishonest, because some people, like Roy Spencer — really ought to know better.

Perhaps Spencer’s most hilariously ridiculous comment is when he cautions that “…it is dangerous to extrapolate any short term trends far into the future.” Yet that is exactly what he did. He took the sea level trend up to 1950, called it “entirely natural” (when it isn’t), then extrapolated it to the present (nearly 70 years). Question for Roy Spencer: when you said your caution against extrapolation, were you paying attention?

The main reason that sea level rise is getting so much attention from climate deniers is that it’s such a major and undeniable problem. They can no longer deny that it’s happening (except for a few fringe nut-cases). Hence they’re scraping below the bottom of the barrel to find any excuse to blame it on anything but the real reason: man-made global warming. Roy Spencer: when you retire, I suggest you buy yourself a lovely beachfront home. May I suggest Miami Beach?

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29 responses to “Sea Level Rise: Denial by Bullshit

  1. The fundamental Spencer problem is what constitutes “natural” pre-1950. Why would sea level be rising naturally prior to 1950 and at what rate? I am waiting for a model.

  2. Hi, may I ask what negative forcing is causing the cooling before 1880?

    • Don’t you mean right after 1880? If so: the Krakatau eruption

      • No, I mean the fact that the blue and red line differ before 1880, which seems to imply that there was a human forcing towards cooling and I was wondering what is it. Sulfate aerosols, maybe? Between 1880 and 1910 there is no difference, then the warming forcing appears.

        [Response Not necessarily. These are anomalies and the baseline is 1880-1900 so they are offset to have the same average during that period.]

    • crispy2058

      I see cooling in the early 1880s. That would be particulate matter from Krakatoa, wouldn’t it? There’s a similar dip in the early 1990s from Mount Pinatubo.

  3. The ‘no significant pre1950 AGW’ nonsense I feel is easiest debunked by pointing to the forcings driving today’s AGW of +0.18ºC/decade and then pointing to the forcings pre-1950 which were pretty close to a third the size. Thus, back of a fag packet, pre-1950 AGW would have been raising temperatures at +0.06ºC/decade. After five decades or so, that would result in roughly +0.15ºC.
    You would have to be as dumb as rocks not to understand that. But perhaps the denial these denialists suffer from with AGW makes then as dumb as rocks, so my debunking may be overly complex for the poor darlings.

    • Lars Träger

      It get’s better: as the deniers keep pointing out, the relationship between GW gases and resulting warming isn’t linear but logarithmic, so the first third of the forcings increase must cause more than a third of the resulting warming. Sorry Roy, you can’t have it both ways.

      • Do note I was talking “forcings” not CO2. If you tot up the positive anthropogenic climate forcings as set out in IPCC AR5 AII Table 1.2 for the two periods, prior to 1940 and prior to 2010, the forcing ratio is slightly above 3:1. And including the IPCC’s best estimate of negative forcing, thr ratio climbs to 4:1. Even at 4:1, the pre-1950 AGW remains significant and poor old Woy shows his denialist credentials rather than his climatologist credentials (not that he has a great deal of those) by ignoring it.

  4. I played around with the Church & White data for a bit after reading Spencer’s piece. One particularly curious result is that a quadratic fit from the beginning of the data 1880 to 1960 or any later endpoint produces virtually the same curve as the complete data set through 2013. This further suggests that sea level rise “acceleration” has been underway for quite a long time.

    I also found a paper that suggests anthropogenic causes (carbon soot) in the Alps starting in the mid-1800s. It’s not clear the quantitative contribution to SLR from this, but is another strike against Spencer’s premise. ( )

  5. rabiddoomsayer Some put the effect of humans on climate starting thousands of years ago.

    • Robert Damon

      William Ruddiman (University of Virginia) has also written about this. For example, in his book “Plows, Plagues & Petroleum” (2005, Princeton University Press) he argues that humans have been changing the climate for some 8,000 years as a result of agricultural practices. Ruddiman has authored a number of guest articles at over the years, presenting his hypothesis to that audience. A search in Google Scholar will turn up a list of his scientific publications.

  6. s/ridiculout/ridiculous/
    (and point well made). It’s good to see that one can’t lie about obvious physical matters indefinitely without people noticing. It’s bad that it does take some people 20 years to notice that they are being had.

  7. Spencer should get into a different line of work. He wrote a book a few years ago that was supposed to debunk the concerns about human caused global warming. However, he stated emphatically that his chapter on economics was the most important one in the book. So, it was obvious to me that his whole premise on denying the dangers and even the reality of human caused global warming was based on his dogmatic belief in the “magic” of the market place and an unfettered global capitalism system. Anything that interferes with that belief has to be debunked, even if there is overwhelming evidence from climate research that demands we change business as usual as rapidly as possible. His latest hypothesis seems to fit that pattern and deserves to be thoroughly debunked as Tamino has done.

  8. Perhaps they misread the IPCC statements in this document ?

    Working Group I Contribution to the IPCC Fifth Assessment Report Climate Change 2013: The Physical Science Basis Summary for Policymakers

    The document states in several places that humans were the dominant cause of warming since 1950 or “the mid-twentieth century”. Doesn’t say none earlier, but clearly identifies when they are CERTAIN of the starting point. There is a reason they picked that point in time to work with and I am betting that it is with the intention of being able to misuse the IPCC statements.

    Never regard them as being innocently stupid (some of them are, but the sources of this are not). They are being stupid with malice aforethought, and their intention is far from innocent.

  9. At a certain point, denial by bullshit becomes denial by batshit.

  10. entropicman


    The 95% confisence limits for the temperature datasets are all about +/- 0.1C.

    Simplifying slightly, the gap between two year’s global averages becomes statistically significant when their 95% confidence limits no longer overlap. That is a difference of 0.2C. This is also the difference between 1880 and 1950 average global temperatures, 13.8C and 14.0C

    From the IPCC viewpoint “There is no significant warming before1950” means that warming took place between 1880 and 1950, but it took until 1950 for the warming to become statistically significant.

    From the climate denier viewpoint it is easy to jump from “no significant warming before1950” to “no warming before1950”.

    • Yes, for denialati in general “no significant warming” is precisely equal to “no warming.” It’s a “convenient untruth.”

      • To re-phrase that, the result that leads a scientist to say “I’m not quite sure enough to confidently say that that this shows warming” will lead the denialati to say “I’m absolutely certain that there isn’t any warming at all”.

      • I have to ask: Does one have cancer if their tumor is there but too small to be detected?

      • Seems like a fair question, doesn’t it, jg?

      • Martin Smith

        re jgnfld’s cancer question: I had prostate surgery about 8 months ago. Prior to diagnosis, an increasing PSA trend is only meaningful as a sign that further tests are needed. After removal, PSA should drop to 0, so the PSA test becomes a good sign of whether the tumor is still there or not. But the PSA test is only accurate to 0.1 ug/L, so the best test result is: < 0.1 ug/L, which I have had twice now. Knock on wood. 4 of those results over a year is taken to mean the tumor is gone, but…

      • Fingers crossed…

  11. “…it is dangerous to extrapolate any short term trends far into the future.”

    This is the same Roy Spencer that has been projecting the results of his own short satellite derived temperature series into the future for decades .
    The contradictory garbage Spencer has to use to make himself believe there is no risk from climate change are only becoming more obvious over time.
    I type this with yet another extreme rainfall event happening right now outside my windows .
    Those in denial are beginning to look insane to every one not just the informed.

  12. Tamino, This comment is off-topic so you will want to delete it. I just want to point you to an interesting sea ice chart by
    Lars Kaleschke of Arctic Basin sea ice extent, 1978 through June 7, 2018.

    Best regards.

    • We shall see what the season brings. The Arctic has a seemingly endless ability to surprise; last year we had record-low extent basically all winter, and suddenly in June melt slowed drastically with a persistent pattern of cool, cloudy weather. The result in September was a year that was bad for ice, but much less bad than most of us expected in May. There’s still a lot of influence exerted by natural variability in any given year–including this one.

      Of course, the CO2 keeps rising and the planet keeps on warming, and the result of that is as predictable as anyone could wish (or wish against). *Some* year the variability will line up *against* ice extent, and we’ll see another year that shocks people, as we were shocked in 2007 and 2012. Could be this year–or not. But it’s coming.

    • Rad,
      That graphic you present here seems at odds with the gaphic here which uses austensibly the same data source. The traces look quite similar but the values plotted are greatly different – early May 2018 6.3M on one and 7.2M on the other, latest 2018 values 6.3M, and 5.9M.
      My first thought wa that the graphic had been produced with an Arctic Basin region missing, but I cannot see one that would provide the right adjustment.
      As for this year’s Arctic melt, pan-Arctic-wise it is very melty in terms of Extent (second to 2016 which was eye-bulgingly melty through the Spring) (this graphic – usually 2 clicks to ‘download your attachment’- uses JAXA data and shows the situation with the SIE Anomaly). 2018 is less melty in terms of Area (suggesting a more compact ice pack) and with Volume assessments (eg PIOMAS) suggesting more of ice needs melting relative to recent years. Also it was amazingly snowy this spring and while much of the NH snow-cover has now gone (graphic of Rutger’s Snow Lab NH Snow cover anomalies), they are still much larger tha recent years (excepting 2017 which was also very snowy & which had problems melting it).

      • The thing is if you look at the volume results, e.g.

        You’ll see 1m thick ice where their own measurements show open water?

      • Phil.,
        The DMI are aware of the disparity you highlight as they say “Der kan forekomme forskelle i iskantens placering i de to kort, ”Havisens udbredelse” og ”Havisens tykkelse og volumen”, da modelberegningerne ikke altid stemmer helt overens med satellitsensorernes registrering af isens udbredelse,” although obviously that is in Danish which may need translation.