This new paper (in review at the discussions section) at Climate of the Past has some interesting approaches using
Oxygen 18 isotope records from benthic foraminiferas acquired in Deep Sea Drilling project (DSDP) on the Kerguelen Plateau off the coast of Antarctica and in the Cape Basin off the coast of Namibia. These drill holes provide
18O records with a resolution of order 10 000 yr across the Eocene-Oligocene boundary thus providing an excellent proxy for deep-ocean temperature.
C, for a doubling of pCO2. Where published values are in units
C/(Wm−2), the published value is multiplied by 3.7 for the purpose of this comparison. Note that Asten’s median value of 1.1 agrees with Douglas and Christy.
Estimate of climate sensitivity from carbonate microfossils dated near the Eocene-Oligocene global cooling
M. W. Asten
School of Geosciences, Monash University, Melbourne, VIC 3800, Australia
Abstract.
Climate sensitivity is a crucial parameter in global temperature modelling. An estimate is made at the time 33.4 Ma using published high-resolution deep-sea temperature proxy obtained from foraminiferal δ18O records from DSDP site 744, combined with published data for atmospheric partial pressure of CO2 (pCO2) from carbonate microfossils, where δ11B provides a proxy for pCO2. The pCO2 data shows a pCO2 decrease accompanying the major cooling event of about 4 °C from greenhouse conditions to icecap conditions following the Eocene-Oligocene boundary (33.7 My).
During the cooling pCO2 fell from 1150 to 770 ppmv. The cooling event was followed by a rapid and huge increase in pCO2 back to 1130 ppmv in the space of 50 000 yr. The large pCO2 increase was accompanied by a small deep-ocean temperature increase estimated as 0.59 ± 0.063 °C.
Climate sensitivity estimated from the latter is 1.1 ± 0.4 °C (66% confidence) compared with the IPCC central value of 3 °C. The post Eocene-Oligocene transition (33.4 Ma) value of 1.1 °C obtained here is lower than those published from Holocene and Pleistocene glaciation-related temperature data (800 Kya to present) but is of similar order to sensitivity estimates published from satellite observations of tropospheric and sea-surface temperature variations.
The value of 1.1 °C is grossly different from estimates up to 9 °C published from paleo-temperature studies of Pliocene (3 to 4 Mya) age sediments. The range of apparent climate sensitivity values available from paleo-temperature data suggests that either feedback mechanisms vary widely for the different measurement conditions, or additional factors beyond currently used feedbacks are affecting global temperature-CO2 relationships.
Discussion Paper (PDF, 1101 KB) Interactive Discussion (Open)
Readers that have access to Climate of the Past can leave a short comment until 30 Nov 2012. You can also watch the open review process as editors and reviewers leave comments. Constructive comments are welcome.
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I may have read this abstract too quickly, but to me the term “climate sensitivity” assumes atmospheric CO2 drives global temperature, whereas the data I am familiar with clearly shows that CO2 lags temperature and is driven at least in part by temperature.
ooh, 1.1C (+/) will put quite a damper on Alarmist frenzies…..not much of a pretext for panic there…. they will need to find ways to discredit or ignore this paper!
p.s. typo alert for “Table 2” which reads “Tbale 2 from the paper”
When the climate cooled, more CO2 dissolved in the world’s oceans. When warmth returned so did the CO2.
Based on the well established metric that the small the number of authors, the more important the paper, this result is significant.
I have a problem with this “doubling” thing. CO2 levels haven’t doubled for tens (maybe hundreds) of thousands of years so why do we discuss the impossible?
I found this relevant to the post, so here ya go!
If you have the time, you will find it quite interesting, let alone the series…….
I think the earth will warm by a qua-jillion degrees Centigrade.
Haven’t they heard that it has been shown that CO2 changes follow temperature over these periods ?
Dr Burns,
Correct. Which completely deconstructs the CO2=CAGW nonsense. ΔT causes ΔCO2, not vice versa — at least not that we can measure.
Dr Burns says:
October 5, 2012 at 8:20 pm
Haven’t they heard that it has been shown that CO2 changes follow temperature over these periods ?
Of course they have,but why let proven facts get in the way of a good crisis?
One thing is very interesting. This is very, very close to the best estimate of the date of inception of the Antarctic Circumpolar Current (opening/deepening of Drake Channel) at 33.6 My.
http://www.es.ucsc.edu/~jzachos/pubs/Bijl_etal_09.pdf
One could assume this produced a massive increase in Southern Ocean cyanobacterial productivity as, for the first time, it allowed for the mixing of volcanic dust (Southern Andes), glacial particulate material (Antarctica, Patagonia) and desert dust (Australia, Southern Africa) to blow and fallout onto and circulate through, the entire Southern Ocean.
This in turn would have pumped a whole lot more DMS (dimethyl sulfide) and other cloud nuclei into the air over the entire Southern Ocean thereby producing a marked dampening of global climate sensitivity (which persists to this day).
Personally, I’m getting real old just waiting for Barack Obama to put his jive mouth where our money is, bring one or two of those 100s of B-57 left over from the Cold War out of mothballs and top dress a big swathe of ocean with cheap (now the Chinese don’t want it) Aussie iron ore to show he really is the miracle man with the answer to Life, the Universe and damn well everything, (and the good ol’ US of A really does know how to lick that pesky CAGW).
Since it’s both negative and imaginary, would that mean all CO2 sensitivity numbers should be multiplied by -1, or by its square root? Or both?
Why is there a semi-quaver preceding Oxygen 18?
[Reply: The HTML for Δ is “&+Delta+;”. But if you forget to capitalize Delta, you get: δ. — mod.]
Gee, that’s awfully close to the calculable and measurable Planck response of the climate to CO2.
1.23 degrees per doubling.
Sorry – typo in my post. I really meant B-52s not B-57. And the more I think about it , that would be a truly spectacular way for Barack Obama to demonstrate he isn’t just a One Trick Pony.
I believe this symbol is used to indicate a particular isotope of oxygen [or any other element]
The way the world’s economies are stagnating, we’ll be lucky to keep the plant-benefiting, biosphere-enriching increase in CO2 we’ve already got. Getting anywhere near a “doubling” will be next to impossible.
My recollection is that 1.1 ° C/ doubling sensitivity is actually close to John Christie’s estimate based on modern data & actually fits the current observed warming fairly well. Can anyone confirm that? Potentially another body blow to the scientific arguments of the alarmists, not that it will stop them from their alarming claims.
From the paper linked to above:
Some thoughts:
Better structured and organized than some of the other papers we’ve tried to look over.
Wording is still typical loose climatespeak with personal affections expressed that, in this case, muddy otherwise reasonably clear statements.
An apparent huge dependence on previous work casually aligning CO2 and Temperature lines and using their derived ratios to drive results in this paper. I didn’t see any attempts to verify pre-existing derived ratios prior to use.
As shown above, they admit coincidence. Then after admitting coincidence, they proceed to use the derived ratios to build their own graphs of coincidences.
Three separate data segments are defined on the charts (a,b, c). Each data segment appears to cover somewhat less than 90,000 years. Data segment ‘a’ provides; hole 744 – 12 points, hole 522 – Cibicidoides 4 points, Gyroidinoides 2 points. I assume this means 18 sections/slices of the core were tested. Furthermore, these specific slices were only tested for oxygen isotopes with only 18O isotope identified for us.
18 data points may make for a rough idea where the values are at points over 90,000 years. But I have difficulty accepting these data points in a discussion about temperature and CO2. It’s a shotgun pattern and they’re stating ‘error (1-sigma)’ results less than .023 average. ‘error (1-sigma)’ resullts for derived ‘change in temperature (deltaT)’ is .063. Which leaves me with the questions; OK, this is an accurate math result for change in temperature for a point in time, how is 90,000 years a point in time? And how does this make a reasonable coincidence with CO2?
CO2, according to the paper is an accepted pCO2 baseline from a Kilwa Formation coring… But I did not see any cross validation of holes 744, 522 to the Kilwa Formation core, especially for all points tested for this paper. How do I know they’re not comparing data points thousands of years apart?
While I think their conclusion sounds sensible; that does not make me feel comfortable that they’ve really done more than test two cores for oxygen isotopes. Calling it an “Estimate of climate sensitivity…” makes this paper another climate research coincidence, long on maybe, short on definitely.
CO2 following temperature is a positive feedback. Not a very strong one, but there, none the less. Because of it the temperature will be higher no matter the driving force that causes CO2 to increase. But what really matters is what happens next, and there is no evidence in history that what happens next is runaway heating or cooling. The temperature cycles up and down for varying periods but has never run off the dial at either end.
So what does happen next, or at least has always happened next so far? Temperature increases or decreases stop growing in the direction they were and begin to retreat. This has been going on for billions of years. Nobody can claim to know why.
Prof Murry Salby’s talk to the Sydney institute covers this topic very well.
Why is a seismologist writing a paper on CO2 and climate sensitivity?
dp says:
October 5, 2012 at 9:57 pm
“CO2 following temperature is a positive feedback. Not a very strong one, but there, none the less. Because of it the temperature will be higher no matter the driving force that causes CO2 to increase.”
Perhaps I am unclear, but could you explain what these three sentences mean. Thank you in advance.
Garry says:
October 5, 2012 at 10:06 pm
Why is a seismologist writing a paper on CO2 and climate sensitivity?
It’s ground breaking research. get it?
What I find interesting is the “confidence” part in this one table. What the heck? That’s not science. That’s rolling dice. Seems like a way out for them. If it doesn’t happen they can always say “look, we weren’t 100% confident about it anyway.” More proof that science has been corrupted.