The Palaeoclimate Problem – Net Zero Watch

Posted: November 19, 2021 by oldbrew in climate, data, methodology, modelling, paleo, Temperature
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The author notes, with examples, that ‘it is difficult to reconcile this latest research with many other lines of inquiry to determine past temperatures.’ Using a single computer model to ‘fill in gaps’ in data has its own drawbacks, as mentioned below.
– – –
Modern warming differs from the gradual rise in temperature seen in the past 10,000 years. That’s the conclusion of a paper just published in the journal Nature, says David Whitehouse.

Reconstructing the temperature timeline back to 24,000 years ago – the so-called Last Glacial Maximum – a team of researchers show that recent warming is unusual.

Knowledge of past climate is important to put our present climate into context, allowing us to see what climatic variations can take place in the absence of contemporary amounts of greenhouse gasses.

Because there were no thermometers back then scientists have become adept at looking for proxies – things that are affected by temperature – such as tree rings, stalactites and isotope ratios in sea shells to give a few examples.

The temperature of the current geological epoch – the Holocene – has in this new work been reconstructed in remarkable detail by melding proxy data (plankton and microbes found in sediments) with a computer model of the climate.

It is said that the benefits of this hybrid approach is that it brings the model closer to reality allowing confidence when the model fills in the gaps in the timeline when no data is available.

The work by Matthew Osman of the University of Arizona and colleagues has been hailed as a triumph by two of the pioneers of paleoclimatic reconstruction, Shaun Marcott of the University of Wisconsin-Maddison and Jeremy Shakun of Boston College.

Looked at in more detail you could say this work has straightened and lengthened the infamous hockey stick and removed the Medieval and Roman Warm Period, or at least showed they were too local to have a global effect.

They found a gradual warming from 11,650 BP that is somewhat different from that seen in other reconstructions although another recent study by Samantha Bova of the University of San Diego draws similar conclusions to Osman whilst using a different technique.

As the authors admit this will require verification as the technique is expanded. This time it incorporates no terrestrial data and had big data gaps in the major oceans. What’s more, it uses only one climate model which is clearly a direction to enlarge.

Osman et al find that the Ice Age was about 7 degrees C cooler than pre-industrial temperatures, which is about a degree colder than previous estimates.

In addition, the new findings contradict the Milankovich theory that links changes in the Earth’s axial inclination to climate by finding that increases in summer solar radiation as a result of axial changes coincide with cooler global temperatures.

However last year a temperature reconstruction using several hundred terrestrial proxies showed the opposite to Osman et al.

Taking a wider view of the field it is difficult to reconcile this latest research with many other lines of inquiry to determine past temperatures.

Continued here.

Comments
  1. Graeme No.3 says:

    It is amazing what you can come up with, so long as you discard every bit of evidence that doesn’t fit your theory while incorporating the bits that were discarded as unreliable by others.

  2. hdhuffman says:

    The consensus-following “scientists” are wallowing in the mud of their own fundamental incompetence. I am reminded of that running joke of a few years ago, “when you’re ….that’s what you do.”

    Everything they say about the Earth more than roughly 10,000 (+/- 2,000) years ago is false. The deliberate, comprehensive re-formation of the Earth was completed then. That astounding new scientific truth — from my unprecedented research into the “Ancient Mysteries”, as a competent physicist (the most rigorous and universal of sciences) — is being upstaged and avoided by the fact that what they are saying about it today, and especially since the rise of the “greenhouse effect” physical lie, is also false.

  3. […] The Palaeoclimate Problem – Net Zero Watch — Tallbloke’s Talkshop […]

  4. vuurklip says:

    “… new work been reconstructed in remarkable detail …”. Haha. In remarkable detail. The detail may be remarkable but is it correct?

  5. Gamecock says:

    ‘Reconstructing the temperature timeline back to 24,000 years ago – the so-called Last Glacial Maximum – a team of researchers show that recent warming is unusual.’

    Because that is what they set out to do.

    ‘Knowledge of past climate is important to put our present climate into context’

    No, not really.

    ‘allowing us to see what climatic variations can take place in the absence of contemporary amounts of greenhouse gasses.’

    Huh?

    ‘Because there were no thermometers back then scientists have become adept at looking for proxies – things that are affected by temperature – such as tree rings, stalactites and isotope ratios in sea shells to give a few examples.’

    Adept? Rilly? Tree rings are affected by moisture, as well. Amazing they can tease out just the temperature effects. Stalactites form in caves. I.e., isolated from weather.

    ‘The temperature of the current geological epoch – the Holocene – has in this new work been reconstructed in remarkable detail by melding proxy data (plankton and microbes found in sediments) with a computer model of the climate.’

    ‘Detail’ doesn’t make it right. A false precision fallacy.

    ‘It is said that the benefits of this hybrid approach is that it brings the model closer to reality allowing confidence when the model fills in the gaps in the timeline when no data is available.’

    ‘It is said?’ What, Jeremy Clarkson doing their narrative?

    ‘model closer to reality’

    K. Not reality, yet. But closer to it is somehow better. They can now have confidence in not reality.

  6. Phoenix44 says:

    Climate science is begging to make Gender Studies look like a real science. This stuff is childish nonsense.

    I mean, increased summer solar radiation leads to cooler temperatures? Presumably that has to happen to make the model work to get the results they wanted. BUt really, more radiation is cooling sometimes but warming at other times?

  7. Angusmac says:

    They have ignored that rapid
    climate change in the occurred in the past. For example, approximately
    11,500 years ago temperatures increased by 5-10°C in a few decades.
    The source is Alley (2002) who states:
    ”…the end of the Younger Dryas interval involved: 5-10°C warming…Most of these changes
    occurred in less than a few decades, and possibly in less than a few years…
    Large, rapid, widespread changes were common in the pre-agricultural past, especially in
    regions near the North Atlantic, but apparently also in monsoonal regions affected by the
    North Atlantic, and likely elsewhere or even globally.”
    It is worth noting that Alley is certainly not a climate change sceptic.

  8. Chaswarnertoo says:

    Another adjustocene paper. Truly incredible.

  9. Adam Gallon says:

    More modelled junk, in other words.

  10. oldbrew says:

    removed the Medieval and Roman Warm Period, or at least showed they were too local to have a global effect

    How would climate periods lasting centuries remain ‘local’? Oceans circulate, the Earth rotates. In any case there’s evidence that they weren’t local at all, e.g.:

    Study finds Medieval Warm Period evidence in Argentina

  11. Phil Salmon says:

    The worse a temperature proxy is, the better Marcott and Shakun like it. Just blend it in with another few hundred bad proxies and all climate history of the Holocene is eradicated to a straight line. Then bolt on the modern instrumental record and there’s your hockey stick.

  12. Paul Vaughan says:

    discussing “global average temperature” (equals “climate”) without considering water cycling and geography = (sarc) sensible (/sarc)

    powers are having a lot of fun letting divide-and-conquer run imaginations wild
    they must find it hilarious watching the “discourse” (and realizing what it has done for them)

    pour a little money over here (left or whatever else)
    a little over there (right or whatever else)
    watch them fight
    rule the divided masses with ease (laughing obviously)

    still climate is interesting despite this (just don’t play to win against elite jokers)

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