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The Pause Started In 1993

November 23, 2015

By Paul Homewood 

  

h/t Vrig 

 

One of the many papers published to explain the temperature hiatus was one last year from Benjamin Santer and many others, Volcanic contribution to decadal changes in tropospheric temperature, which attempted to blame it on increased volcanic activity.

 

Abstract:

Despite continued growth in atmospheric levels of greenhouse gases, global mean surface and tropospheric temperatures have shown slower warming since 1998 than previously. Possible explanations for the slow-down include internal climate variability, external cooling influences and observational errors. Several recent modelling studies have examined the contribution of early twenty-first-century volcanic eruptions 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.

 

What was intriguing was this comment:

 

Our analysis uses satellite measurements of changes in the temperature of the lower troposphere (TLT) made by Microwave Sounding Units (MSU) on NOAA polar-orbiting satellites. Satellite TLT data have near-global, time-invariant spatial coverage; in contrast, global-mean trends estimated from surface thermometer records can be biased by spatially- and temporally non-random coverage changes.

 

In other words, they admitted that satellite measurements of tropospheric temperatures was more reliable than surface data. (They referenced the Cowton & Way study).

 

But of even more interest was this graph:

 

image

 

The top graph shows the familiar trend of RSS and UAH data, with little change since 2001. (Please bear in mind that the study was published in Feb 2014, so temperatures since then have ticked up as the El Nino has developed).

Graph B removes ENSO effects, so, noticeably, the 1998 peak has gone. (In other words, this is theoretically what they believe the temperature record would have said without ENSO changes)

Finally, Graph C removes the effects of El Chichon and Pinatubo as well as ENSO. We find that, once the dip after Pinatubo is removed, there has effectively been no increase in temperatures since around 1993.

It seems that the temperature standstill has lasted longer than we all thought.

24 Comments leave one →
  1. November 23, 2015 8:00 pm

    The graphs were a little hard for me to read, so I extracted the image from Dr. Santor’s paper, and put a bigger version (150%) here:

    You’re right, Paul! Two things stand out:

    1. The models (the black line) show a lot more warming than the satellites. The models show about 0.65°C warming over the 35-year period, and the satellites show about half that. And,

    2. As you noticed, the measured warming is all in the first 14 years. His 3rd graph (with both ENSO and volcanic corrections) shows no noticeable warming in the last 21 years.

  2. November 23, 2015 8:52 pm

    This seems too complicated an argument against the data: similar to the humagenisation by NOAA. It risks hiding the simple fact that global temperatures have risen slowly over a century or so with occasional jumps up or down and carbon dioxide has shown no measurable influence on this.

    I find that the believers revert to the sophisticated mathematical models that are fundamentally flawed, but will defend them to the death as true believers do.

    It is a sad fact that the Paris terrorist attacks may have been the nail in the coffin of COP 21 rather than the non-allowed rational debate.

  3. justanotherpersonii permalink
    November 23, 2015 9:35 pm

    Very interesting. Thanks, Paul.

  4. macha permalink
    November 23, 2015 10:29 pm

    GIGO. Analysing garbage data is pointless. Ie. Use satellite and balloon data, not poorly sited landbased, “adjusted” thermometers, missing non populated areas, and even relatively parse argo bouys. Models are merely supporting tools not factual evidence.

  5. Vrig permalink
    November 23, 2015 10:36 pm

    Another point to note is the list of co-authors include representatives from RSS, MIT, NASA-GISS (G. Schmidt), and Canadian Center for climate modeling and analysis. I don’t think anyone could argue these are a group of AGW deniers.

    • January 22, 2016 8:09 am

      Ironically, Schmidt has just tweeted a graph which removes ENSO, yet leaves a perfect rising trend, quite unlike the one found in this paper. Which to believe?

      • January 22, 2016 10:40 am

        I certainly would not believe the much altered GISS figures

      • January 22, 2016 6:12 pm

        Gavin Schmidt’s tweeted graph shows temperatures increasing steadily from the mid-1960s all the way through the 1970s. The reality is that temperatures had finally plateaued during that period, at a quite frigid level, after falling steadily since about 1940. Temperatures fell so much over 30-40 years that in the 1970s the news was full of stories about scientists fretting about the disastrous end of the interglacial and the return to ice age conditions.

        Here’s an example, from an article in the April 28, 1975 issue of Newsweek:

        “…after three quarters of a century of extraordinarily mild conditions, the earth’s climate seems to be cooling down. Meteorologists disagree about the cause and extent of the cooling trend… But they are almost unanimous in the view that the trend will reduce agricultural productivity for the rest of the century.”

        Note the temperature graph in that 1975 article:

        You can see roughly the same 1940-1979 cooling trend in this graph from a 1999 Hansen paper:

        PopTech has a large collection of other news stories from the 1970s about the global cooling scare:
        http://www.populartechnology.net/2013/02/the-1970s-global-cooling-alarmism.html

  6. Don Keiller permalink
    November 23, 2015 10:55 pm

    What it shows is that you can “adjust” the data to show what you want.
    Stupid Santer is so used to “adjusting” the data he has forgotten just what it is he is trying to show.

  7. Ghost permalink
    November 23, 2015 11:52 pm

    Essentially the same point was made by IPCC insiders Fyfe, Gillett and Zwiers in AR5.

    http://www.stat.washington.edu/peter/statclim/fyfeetal.pdf

    “we considered trends in global mean surface temperature computed from 117 simulations of the climate by 37 CMIP5 models… The observed rate of warming given above is less than half of this simulated rate, and only a few simulations provide warming trends within the range of observational uncertainty”

    “The divergence between observed and CMIP5- simulated global warming begins in the
    early 1990s…”

  8. November 24, 2015 5:34 am

    Smoothed UAH and RSS adjusted for volcanic events and ENSO would be interesting to see on this graph.

    However, even without smoothing Paul is right.

    In my examination of this graphic I am assuming that because the claimed precision is 0.1 degree Celsius.

  9. Ant permalink
    November 24, 2015 10:02 am

    Was that “muted” spposed to be “mooted”?

  10. November 24, 2015 10:39 am

    O/T News in Australia of a regional drought area getting rain
    2 weeks ago we talked about a BBC World presenter misleading, by Australia was in drought, but it seems to me if she was talking about one area West Queensland she would be right. They’ve been in drought since August 2013. They even have a drought charity..So far not every farm has been lucky to get rain.
    “More than 80 per cent of Queensland and parts of northern New South Wales are in severe drought, with some areas not seeing decent rainfall in three years.” Hyperbolic ABC (but probably not 100% liars)

  11. Vrig permalink
    November 24, 2015 1:53 pm

    Some significant points that come out of this paper.
    1) The pro-AGW authors recognize the “pause” and recognize the superiority of satellite based data. The list includes NASA-GISS who continue to promote land based temps.
    2) In an effort to explain the pause, and divergence between CMIP-5 predictions and actual data, they remove first ENSO warming effects (graph 1B). Its an interesting plot where you can see after ENSO is removed the difference between CMIP-5 average and satellite is greatly reduced(see right side of graph). Does this mean that the original CMIP-5 models greatly overestimate the heating effects of ENSO? That would be the obvious answer if removing ENSO narrows the gap between graphs 1A and 1B to such a degree.
    3) Removing volcanic cooling doesn’t really change the match between CMIP-5 on the final graph C, but does push the pause back to 1993 on the satellite data. The CMIP 5 average model still exaggerates heating.
    4) In the author’s conclusion they state errors in CMIP-5 simulations are not confined to volcanics, but also likely to exist in treatment of solar irradiance, water vapor, ozone and aersols. At least there is admission that modeling a complex multi-variant system like climate is difficult at best.

    This work also reduces the criticism of using the 1998 En Nino as a starting point for the current pause, after removing Pinatubo the pause is pushed back further than 98. Has anyone ran across 20th century temperature plots that attempt to merge pre-satellite trends with the satellite record post 1979? WOuld like to see the entire post Little Ice Age warming with satellite rolled into the record…

  12. November 24, 2015 3:21 pm

    Paul,

    They haven’t removed the ENSO signal. They’ve subtracted the NINO3.4 data. NINO3.4, however, does not capture the full extent of the ENSO process. Global warming since the late 70s is caused by the “ENSO residual”, after the NINO3.4 is removed. This residual manifests itself in the West Pacific, the Indian Ocean (mainly in the eastern part) and in the North Atlantic (AMO).

  13. Cato Younger permalink
    November 24, 2015 3:32 pm

    is there some reason that we think temperature records over a period of 150 years are “definitive” for a planet that is billions of years old?

    • Vrig permalink
      November 24, 2015 5:12 pm

      Cato, i agree with that comment 100%, the 20th century warm is a mere blink of the eye in geologic perspective, and is no more extreme in increase (degrees/century) than any of the prior warmings during the Holcene. Go back to the last ice age and temperature swings called D-O events were unlike anything we have seen in the Holocene warm and unrelated to CO2 or GHG. The press and alarmists continue to evaluate global weather/climate on a human time scale, or even worse internet speed time scale so every storm or event is expressed with alarm.

  14. November 25, 2015 9:19 am

    Sorry Paul, you’re wrong, there never was a pause at all. Top climate scientist Stephan Lewandowsky says so.

    https://theconversation.com/global-warming-pause-was-a-myth-all-along-says-new-study-51208

  15. John Wilbye permalink
    November 25, 2015 9:46 am

    No pause at all.

    Researchers led by Professor Stephan Lewandowsky of Bristol’s School of Experimental Psychology and the Cabot Institute, examined 40 peer-reviewed scientific articles published between 2009 and 2014 that specifically addressed the presumed pause in global warming, and found no consistent or agreed definition of such a ‘hiatus’, when it began and how long it lasted.
    The earth’s warming trends over the ‘hiatus’ were compared to the equivalent length in the entire record of modern global warming, and researchers found there to be no exceptional differences in the context of other trend patterns.
    The researchers also found that, if sample size is small, the ‘hiatus’ will always appear to be present. For example, anyone making a claim for a ‘hiatus’ of 12 years or below – a claim made by a third of the articles studied – will find one, not because something new and different is happening, but because small sample sizes provide insufficient statistical power for the detection of trends.
    Professor Lewandowsky said: “Our study raises the question: why has so much research been framed around the concept of a ‘hiatus’ when it does not exist?
    “The notion of a ‘pause’ or ‘hiatus’ demonstrably originated outside the scientific community, and it likely found entry into the scientific discourse because of the constant challenge by contrarian voices that are known to affect scientific communication and conduct.”
    Discussing climate change using the terms ‘pause’ or ‘hiatus’ creates hazards for the public and the scientific community, the study concludes.
    Professor Lewandowsky added: “Scientists may argue that when they use the terms ‘pause’ or ‘hiatus’ they know – and their colleagues understand – that they do not mean to imply global warming has stopped.
    “But while scientists might tacitly understand that global warming continues notwithstanding the alleged ‘hiatus’, or they may intend the ‘pause’ to refer to differences between observed temperatures and expectations from theory or models, the public is not privy to that tacit understanding.
    “Therefore, scientists should avoid the use of ‘pause’ or hiatus’ when referring to fluctuations of global mean surface temperature around the longer-term warming trend. There is no evidence for a pause in global warming.”

  16. rah permalink
    November 25, 2015 8:28 pm

    Now let them present how much CO2 each of those volcanic events emitted into the atmosphere next to their claim for contribution from human caused sources. Then put those two measures beside the estimated reduction in emission of from human sources IF such emissions were instantly cut by 50%. Don’t expect them to do that because if they did it was done and presented accurately it would destroy the whole AGW scam.

  17. January 22, 2016 12:36 pm

    Reblogged this on WeatherAction News.

  18. Broadlands permalink
    April 1, 2016 8:10 pm

    I’m late in joining this discussion, but the “pause” is not a “cherry-picked” starting point. The strong ENSO (back-to-back El-Nino and La-Nina) of 1997-1998 “picked” that date. It started the “pause”. The “monster” ENSO created the record high 1998 temperatures. It stopped the rise in temperatures at what was described in 2000 as a “change point”, a place that was forecast to lead to even stronger rises. These “tipping point” predictions have not materialized so it should not come as a surprise that there are many who want to make their forecasts (or lack thereof?) go away with various “adjustments” and ignore the temperatures they published with such confidence in 1995.

    But, If this “pause” really doesn’t exist, it must now be embarrassing for so many authors to have published papers explaining in various ways something that isn’t there, was never there.

    Additionally, while the ENSOs are universally recognized as unpredictable natural events, they have been PRESUMED to have had a global warming “boost” or amplification of their impact. This is a presumption that is directly contradicted by the evidence… there is no correlation between the ONI 3.4 (Oceanic Nino Index) and the Mauna Loa CO2 values, monthly or annual. Our steady emissions and additions of which are deemed the cause of that global warming.

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