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PETM – Finally an example of CO2 causing heat? Finally an example where CO2 and the greenhouse gasses can be the direct initiator of heat in real data?
- Now and then the Global Warming hypothesis is defended by mentioning the ”PETM”.
The “Paleocene–Eocene Thermal Maximum” lasted around 100.000 years, occurred 55 million years ago and separates the Paleocene and Eocene periods.
The PETM reached a maximum global temperature around 5-6 Kelvin above temperatures before and after the PETM, and the PETM was accompanied by raise in CO2 content in the atmosphere.
In other words, the PETM is one more large temperature/CO2 rise in addition to the large temperature peaks during the ice ages that enables analysis of the supposed strong warming effect of CO2.
In the case of the ice age temperature peaks, I reach the conclusion that data cannot show the supposed strong warming effect of CO2:
- Can the PETM finally show the supposed strong warming effect of CO2? Can we finally have some data that actually shows the strong CO2-effect?
For the PETM, what came first, the heat or the CO2?
In many sources, this quite central issue is not mentioned, and the Dutch scientist Appy Sluijs from the University of Utrecht has compiled a fantastic useful and competent overview of all writings about the PETM where all specific issues of the PETM is considered wisely.
Sluijs has found and summarized the writings that comments on the timing: What came first, heat or CO2?
The general conclusion is, that the Carbon input to the atmosphere for the PETM appeared around 3000 thousand years AFTER the temperature rise….
In this context read chapter 7:
Sluijs: "Global warming leads the carbon isotope excursion at the Paleocene-Eocene thermal maximum"
Examples from different studies referred to in Sluijs conclusion:
1) "Assuming above sedimentation rates, the onset of the Apectodinium acme leads the onset of the CIE by in the order of 4-5 kyr."
- the onset of the Apectodinium acme is an indicator of heat
- the onset of the CIE is the indicator of Carbon input to the atmosphere, due to changes isotopic content of Carbon.
2) "Critically, the record implies that the onset of anomalous warming is located ~25-30 cm below the CIE, with approximately half of the PETM warming occurring before the onset of the CIE (Fig. 2). Assuming above sedimentation rates, the onset of warming preceded the onset of the CIE by approximately 2.5-3 kyrs"
3) At Wilson Lake, the onset of the CIE, representing the main negative step in δ13C, is assigned to 109.8 mbs based on both δ13CDINO and δ13CBC (Fig. 3). This implies that also here the onset of the Apectodinium acme (~110.4) leads the CIE 112 Warming precedes the CIE by ~0.6 m. Assuming the above sedimentation rates this would represent about
4) Atthe North Sea site, the lowermost position to which the onset of the CIE can be attributed is at ~2927 meters below sea floor (mbsf) (Fig. 3), while the onset of the δ13CTOC CIE by ~0.5 m, which represents about 4 kyr at this site.
The PETM episode like the glacial temperature peaks shows CO2 increasing after temperatures. Like the Glaical temperature peaks, the PETM episode does not rule out some effect of CO2, but we still need the evidence that CO2 it self can drive temperatures strongly.
This is interesting because we have many huge volcanoes inducing CO2 over the time, so it should be possible to show many peaks of temperature rise based on CO2 (and greenhouse gasses) only? It should be possible to point out the real evidence of CO2 warming if it is there.
Why is it, that we dont really have an independent volcano induced large CO2-input to the atmosphere that actually STARTS a large temperature jump?
Last changed: 7th May, 2010 at 13:36:13
Kevin Trenberth to Michael Mann, Oct 12, 2009:
The fact is that we can’t account for the lack of warming at the moment and it is a travesty that we can’t. The CERES data published in the August BAMS 09 supplement on 2008 shows there should be even more warming: but the data are surely wrong. Our observing system is inadequate.
Kevin Trenberth to Tom Wigley, Oct 14, 2009
How come you do not agree with a statement that says we are no where close to knowing where
energy is going or whether clouds are changing to make the planet brighter. We are not
close to balancing the energy budget. The fact that we can not account for what is
happening in the climate system makes any consideration of geoengineering quite hopeless as
we will never be able to tell if it is successful or not! It is a travesty!
“I know that most men, including those at ease with problems of the greatest complexity, can seldom accept even the simplest and most obvious truth if it be such as would oblige them to admit the falsity of conclusions which they have delighted in explaining to colleagues, which they have proudly taught to others, and which they have woven, thread by thread, into the fabric of their lives.”
“We have 25 or so years invested in the work. Why should I make the data available to you, when your aim is to try and find something wrong with it.” -
Phil Jones to Michael Mann Feb 21, 2005:
The IPCC comes in for a lot of stick.
Leave it to you to delete as appropriate !
PS I'm getting hassled by a couple of people to release the CRU station temperature data.
Don't any of you three tell anybody that the UK has a Freedom of Information Act !
Tom Wigley to Phil Jones Sep 27, 2009:
If you look at the attached plot you will see that the
land also shows the 1940s blip (as I'm sure you know).
So, if we could reduce the ocean blip by, say, 0.15 degC,
then this would be significant for the global mean — but
we'd still have to explain the land blip.
I've chosen 0.15 here deliberately. This still leaves an
ocean blip, and i think one needs to have some form of
ocean blip to explain the land blip (via either some common
forcing, or ocean forcing land, or vice versa, or all of
these). When you look at other blips, the land blips are
1.5 to 2 times (roughly) the ocean blips — higher sensitivity
plus thermal inertia effects. My 0.15 adjustment leaves things
consistent with this, so you can see where I am coming from.
Removing ENSO does not affect this.
It would be good to remove at least part of the 1940s blip,
but we are still left with "why the blip".
Let me go further. If you look at NH vs SH and the aerosol
effect (qualitatively or with MAGICC) then with a reduced
ocean blip we get continuous warming in the SH, and a cooling
in the NH — just as one would expect with mainly NH aerosols.
The other interesting thing is (as Foukal et al. note — from
MAGICC) that the 1910-40 warming cannot be solar. The Sun can
get at most 10% of this with Wang et al solar, less with Foukal
solar. So this may well be NADW, as Sarah and I noted in 1987
(and also Schlesinger later). A reduced SST blip in the 1940s
makes the 1910-40 warming larger than the SH (which it
currently is not) — but not really enough.
So ... why was the SH so cold around 1910? Another SST problem?
(SH/NH data also attached.)
This stuff is in a report I am writing for EPRI, so I'd
appreciate any comments you (and Ben) might have.
Tim Osborn to Michael Mann and Ian Macadam , Oct 5, 1999:
Dear Mike and Ian
Keith has asked me to send you a timeseries for the IPCC multi-proxy
reconstruction figure, to replace the one you currently have. The data are
attached to this e-mail. They go from 1402 to 1995, although we usually
stop the series in 1960 because of the recent non-temperature signal that
is superimposed on the tree-ring data that we use. I haven't put a 40-yr
smoothing through them - I thought it best if you were to do this to ensure
the same filter was used for all curves.
> For the record, I do believe that the proxy data do show unusually
>warm conditions in recent decades. I am not sure that this unusual warming
>is so clear in the summer responsive data. I believe that the recent warmth
>was probably matched about 1000 years ago. I do not believe that global
>mean annual temperatures have simply cooled progressively over thousands of
>years as Mike appears to and I contend that that there is strong evidence
>for major changes in climate over the Holocene (not Milankovich) that
>require explanation and that could represent part of the current or future
>background variability of our climate. I think the Venice meeting will be
>a good place to air these isssues.