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No Underlying Global Temperature Increase For 20 Years

April 18, 2015

By Paul Homewood


I was reminded about a paper from last year, authored by Ben Santer amongst others, Volcanic contribution to decadal changes in tropospheric temperature.

The paper looked at recent temperature trends in the lower troposphere, and attempted to isolate the effect of volcanoes and ENSO changes.



Despite continued growth in atmospheric levels of greenhouse gases, global mean surface and tropospheric temperatures have shown slower warming since 1998 than previously1, 2, 3, 4, 5. Possible explanations for the slow-down include internal climate variability3, 4, 6, 7, external cooling influences1, 2, 4, 8, 9, 10, 11 and observational errors12, 13. Several recent modelling studies have examined the contribution of early twenty-first-century volcanic eruptions1, 2, 4, 8 to the muted surface warming. Here we present a detailed analysis of the impact of recent volcanic forcing on tropospheric temperature, based on observations as well as climate model simulations. We identify statistically significant correlations between observations of stratospheric aerosol optical depth and satellite-based estimates of both tropospheric temperature and short-wave fluxes at the top of the atmosphere. We show that climate model simulations without the effects of early twenty-first-century volcanic eruptions overestimate the tropospheric warming observed since 1998. In two simulations with more realistic volcanic influences following the 1991 Pinatubo eruption, differences between simulated and observed tropospheric temperature trends over the period 1998 to 2012 are up to 15% smaller, with large uncertainties in the magnitude of the effect. To reduce these uncertainties, better observations of eruption-specific properties of volcanic aerosols are needed, as well as improved representation of these eruption-specific properties in climate model simulations.


Ignore the misdirection about early twenty-first-century volcanic eruptions. What the paper addresses are the El Chichon and Pinatubo eruptions of 1982 and 1991 respectively, generally reckoned to be the two biggest eruptions, in terms of stratospheric input, of the last century.

Santer’s charts below show the raw data, after adjusting for ENSO, and finally adjusting for the volcanic eruptions as well. Note that the black line represents the average of the models.





After taking out the effect of ENSO and eruptions, it is apparent that temperatures have been flat since the early 1990’s; indeed they have arguably been falling since.

This is significant. We are often told that the 17-year pause, with which we are all familiar, is solely dependent on cherry picking the big El Nino year of 1998 as a starting point.

What Santer’s study shows is that there has been no underlying upward trend in global temperatures for more than 20 years.

  1. April 18, 2015 1:59 pm

    Well, the multi-model average goes up, so it must mean the data are wrong.

    • David A permalink
      April 19, 2015 11:02 am

      The bottom chart looks wrong to me. (The black squiggly) With ENSO and volcanoes removed I think the decadal warming rate of the multi model mean is supposed to be at least .3 per decade. To the eye it appears to be at about .1 per decade, and, at .2 degrees for the period from 1994 to 2014, it is still well above the observations.

  2. April 18, 2015 1:59 pm

    Reblogged this on

  3. April 18, 2015 2:28 pm

    “…Oh computer models! I believed everything that you said,
    I really believed that Mother Nature was dead.
    I cast reason aside, threw away all common sense;
    Now are you telling me it was all a pretence?…”
    Read more:

  4. April 18, 2015 2:57 pm

    Thanks, Paul.
    This period of no global temperature increase when atmospheric CO2 has kept on increasing indicates a very low climate sensitivity.

  5. April 18, 2015 9:29 pm

    Reblogged this on Centinel2012 and commented:
    Not to worry they will make it hotter any way, what does Mother Nature know about this subject anyway!

  6. April 18, 2015 9:53 pm

    It is 25 years. Remember you heard it from me first. I have tried to inform the climate debaters on the blogosphere a number of times over the last 4 years, that the temperatures between 2010 and 2012 were tracking those between 1990 and 1992, for example:

    “CO2-Correlated Global Warming Only Occurred 1976 – 1989/90”

    As for the CO2 “climate sensitivity”, my 2010 Venus/Earth Temperature vs. Pressure (T-P) curves comparison revealed the FACT that there is NO global warming greenhouse effect whatsoever, that climate science went wrong when it threw away the knowledge of the Standard Atmosphere (which my Venus/Earth comparison PRECISELY confirmed) to chase “runaway global warming”, and that the last two generations of climate scientists have been fundamentally miseducated (so that all of those who now are touted as the authoritative voices, the “experts”, in climate science, are thoroughly incompetent, not to mention religiously deluded in their defense of the “consensus” theories–this includes both the alarmists and the “lukewarmers”). The CO2 climate sensitivity is precisely zero.

    The intellectual atmosphere in the climate change debates–and the positions of all of our suborned institutions, being presented to the public as scientific fact–is full of nonsense and lies. It is in fact insane. The whole system is broken, both scientifically and politically.

  7. April 19, 2015 5:11 am

    Apr 18 4:25am on Radio 5 Live “hottest March ever” story is being done
    Dargan M.W. Frierson of University of Washington used all the hype terms 97% of scientists” “increasing extreme weather” both him and presenter Doton used the word denier, deniers etc.

    “hottest March ever” 2015 – gives results
    as does
    “hottest March ever” 2014, 2013, 2012 etc.etc.

  8. anthony cox permalink
    April 19, 2015 6:13 am

    Good post; if you can’t believe Santer, who can you believe?

  9. Scott Scarborough permalink
    April 19, 2015 2:35 pm

    After these “Corrections” it looks like there has been no warming, outside of the error bars on the data, for the entire satellite period!

  10. Mick J permalink
    April 20, 2015 11:11 am

    Detrend for the PDO/AMO and we are back with the coming ice age scare of the 1970s. 🙂

  11. April 21, 2015 8:15 am

    Reblogged this on Climatism.

  12. Ricky permalink
    April 21, 2015 3:36 pm

    I’m confident in my 100% for sure prediction regarding the state of the climate in 100 years, none of us reading this post will be alive to experience it !

  13. April 21, 2015 6:21 pm

    …Does the SUN enter into these calculations AT ALL????.*


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