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What The IPCC Said About Glaciers In 1990

April 25, 2017
tags:

By Paul Homewood

 

 

When we talk about glaciers retreating, it is worth recalling what the first IPCC Report in 1990 had to say about the matter:

 

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http://www.ipcc.ch/ipccreports/far/wg_I/ipcc_far_wg_I_full_report.pdf

 

In other words, glaciers began receding in the second half of the 19thC, and the fastest rate of retreat was 1920-60, before CO2 emissions could have had any significant impact.

 

The IPCC also added the following chart showing how, on a range of glaciers, rapid retreat began in the 19thC.

image

 

They also added:

image

 

And:

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16 Comments
  1. Steve Borodin permalink
    April 25, 2017 10:10 am

    An interesting piece Paul. I am aware that the likes of Tyndall and Agassiz remarked on the considerable retreat of the Rhone Glacier. That would have been around 1870 so presumably there was a period of fast retreat before the trace shown in your figure 7.2. It would be interesting to compare these IPCC quotations with their tune in later reports. I would guess that political interference before publication may have given a quite different interpretation.

  2. April 25, 2017 11:14 am

    A great article – of course like any large mass, glaciers take time to respond to changes in heat. (Goes away to work it out)

    • April 25, 2017 12:04 pm

      OK because it’s complex – time for waffle. The simple answer is that thermal diffusivity is not that different to rock. The other way to answer the question is “what happens to temperature change following a sinusoidal at the surface)

      If the temperature were to vary as a sinusoidal with period 100years, The temperature at approx 25m deep would be 1/2 that of the surface. The temperature at 60m would be delayed by 25years.

      Due to some oddities in the way heat penetrate objects… (don’t blame me it’s the physics)

      If that sinusoidal were 1000years long, it would be 1/2 amplitude at ~80m and delayed by 250years at 190m deep.

      But if 10,000 years long, heat at around 250m would be responding to half the surface change and it would be delayed by 2500years at 600m deep.

      So in rough terms (ignoring water flow through the ice) the ice of a glacier about 100m deep is responding to temperature changes that were occurring around 50-100years ago.

  3. April 25, 2017 12:44 pm

    ‘before CO2 emissions could have had any significant impact’

    If indeed they have ever had any ‘significant impact’, given that CO2 is only a trace gas in the atmosphere (0.04%), only a third of which has appeared in the period in question.

  4. dearieme permalink
    April 25, 2017 1:53 pm

    I don’t see why you’d assume that glaciers retreat simply by melting. Wouldn’t they be governed by a “mass balance” whereby new snow increases their mass and melting decreases it? If so, a glacier could retreat if its melting rate was unchanged as long as the relevant precipitation rate declined. No?

  5. John F. Hultquist permalink
    April 25, 2017 2:19 pm

    We visited Canada and the Athabasca Glacier area in the early 1970s. Crossed a small bridge to the ice front in the morning. A few hours later water covered the bridge to 8 cm. The ice front was dark with small rocks and grit. Great experience.

    Around 1800, the Athabasca Glacier peaked, then went through a period of recession, and then advanced again until 1840, when it began receding until the present day.
    https://www.triposo.com/loc/Columbia_Icefield/history/background

    Lat/Long near the “toe” of Athabasca Glacier — at the parking area:
    52.21254, -117.23275

  6. Old Englander permalink
    April 26, 2017 9:10 am

    This is IPCC 1990 when they openly talked about the Little Ice Age and the Mediaeval Warm Period – the famous Fig 7.1(c) is on the facing page to Paul’s Fig 7.2 on glacier termini, unattributed, as many have remarked. I believe Steve McIntyre did a forensic analysis of where it may have come from and who produced it (links etc gratefully received). I don’t believe it is in Lamb, who was equivocal about the MWP being a global phenomenon because he didn’t have sufficient historical info except from NW Europe.

    As most here know, the LIA and MWP were airbrushed from history by the hockey stick. One great weakness of scientific professionals is that they tend not to read too much history. Were they to do so, the hockey stick would have been laughed off the platform before it ever got endorsed by the IPCC.

  7. dearieme permalink
    April 26, 2017 11:27 am

    One great weakness of scientific professionals is that they tend not to read too much history.

    Very true, in my experience.

  8. April 27, 2017 4:07 pm

    Reblogged this on Climate Collections.

  9. Terbrugghen permalink
    April 29, 2017 3:27 pm

    Antarctic Sea Ice bottom falls out. Need help with this one.

    • AndyG55 permalink
      April 29, 2017 11:12 pm

      1980 was lower than current

      Sea ice area is rapidly gaining on the decadal minimum.

    • bea permalink
      April 30, 2017 8:33 am

      “…bottom falls out…Need help…”

      It is ‘anal proplapse.’ Using vaseline…

    • bea permalink
      April 30, 2017 9:30 am

      When the sea-ice round Antarctica was above average, just a year or two ago, we were told that this was “proof positive” of global warming because it validated . Therefore, below-average sea ice must mean that global warming has been cancelled. Rejoice.

      Actually, it is mere natural variation which means f-all. If people want to see signs and portents in anything and everything, they will.

  10. bea permalink
    April 30, 2017 9:34 am

    “…it validated…”

    the models.

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