Australian Politics Forum - Paleoclimate reconstructions pushed back 24K years

Jovial Monk Gold Member Offline Dogs not cats! Posts: 43612 Gender:	Paleoclimate reconstructions pushed back 24K years Apr 3^rd, 2021 at 7:56pm EarthArXiv @EarthArXiv "Globally resolved surface temperatures since the Last Glacial Maximum" By Osman et al., https://doi.org/10.31223/X5S31Z
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Jovial Monk Gold Member Offline Dogs not cats! Posts: 43612 Gender:	Re: Paleoclimate reconstructions pushed back 24K years Reply #1 - Apr 3^rd, 2021 at 7:58pm This was easier and neater with XenForo!
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lee

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Re: Paleoclimate reconstructions pushed back 24K years
Reply #2 - Apr 3^rd, 2021 at 8:31pm

From the paper - "This is a Preprint and has not been peer reviewed. This is version 1 of this Preprint. " Wink

Abstract :
Quote:

Climate changes across the last 24,000 years provide key insights into Earth system responses to external forcing. Climate model simulations and proxy data have independently allowed for study of this crucial interval; however, they have at times yielded disparate conclusions. Here, we leverage both types of information using paleoclimate data assimilation to produce the first observationally constrained, full-field reanalysis of surface temperature change spanning the Last Glacial Maximum to present.

Models all the way down. They observed 24K year climate? Grin

It sure is amazing what they can do with computers and models. Wink

Edit : "Of particular note, Shakun et al.and Marcott et al. established a global mean surface temperature (GMST) estimate spanning the deglacial and Holocene periods using a limited (n≤80), globally dispersed marine and terrestrial temperature proxy database (hereafter, the Shakun-Marcott Curve; SMC)."

Oh Shakun and Marcott. Grin

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« Last Edit: Apr 3^rd, 2021 at 8:37pm by lee »

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Jovial Monk Gold Member Offline Dogs not cats! Posts: 43612 Gender:	Re: Paleoclimate reconstructions pushed back 24K years Reply #3 - Apr 3^rd, 2021 at 8:37pm You forgetting the proxy data? Just WHY are you so shitscared of AGW? You will be safely and cosily dead and it will be your kids and grandkids, likely, that have to cope with the worst parts of it.
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lee

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Re: Paleoclimate reconstructions pushed back 24K years
Reply #4 - Apr 3^rd, 2021 at 9:11pm

Jovial Monk wrote on Apr 3^rd, 2021 at 8:37pm:

You forgetting the proxy data?

No petal. We know it has uncertainties. We also know the climate models are crap. Even tuned to the past. Grin

Jovial Monk wrote on Apr 3^rd, 2021 at 8:37pm:

You will be safely and cosily dead and it will be your kids and grandkids, likely, that have to cope with the worst parts of it.

You mean 3C at RCP 8.5 like a recent paper? Is that maximum or minimum? Because CO2 theory says the temperature rise is supposed to be at night. Grin

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Jovial Monk Gold Member Offline Dogs not cats! Posts: 43612 Gender:	Re: Paleoclimate reconstructions pushed back 24K years Reply #5 - Apr 3^rd, 2021 at 9:17pm So why are you shitscared of AGW?
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lee Gold Member Offline Australian Politics Posts: 16400 Gender:	Re: Paleoclimate reconstructions pushed back 24K years Reply #6 - Apr 3^rd, 2021 at 9:56pm Whenever you can't debate you fall back on your own little fallacies.
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Jovial Monk Gold Member Offline Dogs not cats! Posts: 43612 Gender:	Re: Paleoclimate reconstructions pushed back 24K years Reply #7 - Apr 3^rd, 2021 at 10:15pm No, you really are scared of AGW. And you cope by trying to pretend it isn’t real.
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Jovial Monk

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Re: Paleoclimate reconstructions pushed back 24K years
Reply #8 - Apr 4^th, 2021 at 10:30am

The paper really is interesting:

Quote:

Abstract

Climate changes across the last 24,000 years provide key insights into Earth system responses to external forcing. Climate model simulations and proxy data have independently allowed for study of this crucial interval; however, they have at times yielded disparate conclusions. Here, we leverage both types of information using paleoclimate data assimilation to produce the first observationally constrained, full-field reanalysis of surface temperature change spanning the Last Glacial Maximum to present. We demonstrate that temperature variability across the last 24 kyr was linked to two modes: radiative forcing from ice sheets and greenhouse gases; and a superposition of changes in thermohaline circulation and seasonal insolation. In contrast with previous proxy-based reconstructions our reanalysis results show that global mean temperatures warmed between the early and middle Holocene and were stable thereafter. When compared with recent temperature changes, our reanalysis indicates that both the rate and magnitude of modern observed warming are unprecedented relative to the changes of the last 24 kyr.

Thermohaline refers to stuff like the Gulf Stream.

The modern AGW–driven warming is unprecedented in amount and rapidity of change (“. . .rate and magnitude. . .”

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Jovial Monk

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Re: Paleoclimate reconstructions pushed back 24K years
Reply #9 - Apr 4^th, 2021 at 10:46am

We see the max glacial conditions:

Quote:

The LGMR highlights the exceptional and spatially heterogeneous nature of deglacial climate change (Fig. 2). Reconstructed global mean surface temperature (GMST) reveals a significant (p <0.05; Methods) three-part sequence across the last 24 ka. From 24–17 kyr BP, the Earth is in a ubiquitously cold glacial state. The thermal imprints of the North American and Eurasian ice sheets are near their maximum extent, with terrestrial cooling relative to the pre-industrial in excess of−20◦C across the glaciated high northern (>45◦N) and southern (>45◦S) latitudes (Fig.722). At 17.2 ka (95% CI = 18.7–16.4 ka, Methods), global-scale deglaciation (the second stage) abruptly begins.

https://eartharxiv.org/repository/view/2219/

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Ajax Gold Member Offline CO2 has never controlled temperature on Earth Posts: 10958 Australia Gender:	Re: Paleoclimate reconstructions pushed back 24K years Reply #10 - Apr 4^th, 2021 at 11:23am JV you just love hockey sticks, dont you........
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Jovial Monk Gold Member Offline Dogs not cats! Posts: 43612 Gender:	Re: Paleoclimate reconstructions pushed back 24K years Reply #11 - Apr 4^th, 2021 at 12:07pm I am sorry Ajax but that is the shape of all paleoclimate reconstructions. I wish the blade at the end was not so bloody big and growing so bloody fast, 0.2°C/decade! I can add that I have never played ANY form of hockey in my life! I would be happy if it was in the shape of a gold club.
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lee

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Re: Paleoclimate reconstructions pushed back 24K years
Reply #12 - Apr 4^th, 2021 at 1:50pm

Jovial Monk wrote on Apr 4^th, 2021 at 10:30am:

The modern AGW–driven warming is unprecedented in amount and rapidity of change (“. . .rate and magnitude. . .”

And what are the error bars and what smoothing was used? 120 years like Marcott? Wink

Nope it is worse -

"In each iteration, we produce a surrogate 24 ka GMST time series by6411) normal random sampling of temperature for each 200-yr interval"

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« Last Edit: Apr 4^th, 2021 at 1:58pm by lee »

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Ajax

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Re: Paleoclimate reconstructions pushed back 24K years
Reply #13 - Apr 4^th, 2021 at 2:02pm

Jovial Monk wrote on Apr 4^th, 2021 at 12:07pm:

I am sorry Ajax but that is the shape of all paleoclimate reconstructions.

I wish the blade at the end was not so bloody big and growing so bloody fast, 0.2°C/decade!

I can add that I have never played ANY form of hockey in my life! I would be happy if it was in the shape of a gold club.

Oh look the medieval warm period and the little ice age.

5680 year tree ring data study and temperature chart here

https://www.sciencedirect.com/science/article/pii/S0277379119306924

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2. "One hour of freedom is worth more than 40 years of slavery & prison" Regas Feraeos

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Ajax

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Re: Paleoclimate reconstructions pushed back 24K years
Reply #14 - Apr 4^th, 2021 at 2:08pm

OOPS some more information on the MWP & LIA

Scientific papers that say Medieval warm period warmer than today and was GLOBAL.

Dahl_Jensen et al 1998
Wagner & Melles 2001
Kaplan et al 2002
Jiang et al 2002
Moore et al 2001
Grudd et al 2002
Seppa & Birks 2002
Dansgaard et al 1975
Korhola et al 2000
Naurzbaev et al 2002
Vaganov et el 1996
Briffa et al 1998
Scweingruber & Briffa 1996
Knudsen et al 2004
Grinsted et al 2006
Besonen et al 2008
Wagner et al 2008
Vare et al 2009
Norgaard-Pedersen & Mikkelsen 2009
Andresen et al 2004
Vinther et al 2010
Kobashi et al 2010
Kobashi et al 2008
Stuiver et al 1995
Dansgaard et al 1975
Jenings & Weiner 1996
Johnsen et al 2001
Vinther et al 2010
Larsen et al 2011
Hill et al 2001
Joynt & Wolfe 2001
Hantemirov & Shiyatov 2002
Andersson et al 2003
Helama et al 2005
Mazepa 2005
Weckstrom et al 2006
Jiang et al 2007
Zabenski & Gajewski 2007
Grudd 2008
Justwan et al 2008
Scire et al 2008
Axford et al 2009
Bjune et al 2009
Cook et al 2009
Fortin & Gajewski 2010
Buntgen et al 2011
Divine et al 2011
Ran et al 2011
Velle et al 2011
D’Andrea et al 2012
Esper et al 2012

752 individual scientists from
442 separate research institutes from
41 countries around the globe

http://joannenova.com.au/2019/07/erasing-2000-years-of-the-medieval-warm-period-...

http://co2science.org/cSearch.php?action=SEARCH&lan=&keyword=medieval+warm+perio...

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1. There has never been a more serious assault on our standard of living than Anthropogenic Global Warming..Ajax
2. "One hour of freedom is worth more than 40 years of slavery & prison" Regas Feraeos

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