The data is not cherry picked – it is the data from EPICA ice core from the reference given

Scaling is changed to get a suitable period on the plot nothing more.

I have requested the original author look at this ice core data as it is longer and more detailed than the Vostok core. I would have expected him to download and plot the data himself rather than relying on my plots. If you disbelieve mine then it is a simple matter to replicate the plots yourself.
Anyway, in all but one the plots (which include all the ends of cold periods in 800000 years as far as I am aware) CO2 is in sync with the rise in temp.
The exception is at 722000 years bp in plot
http://img27.imageshack.us/img27/634/iceageco2ch4650740et7.jpg

Allowing for the granularity of the data (as much as 2000 years between points) I would suggest the temp and CO2 are increasing in synchronism. (remember that the graphs have their time scales reversed – earlier is to the right of the plot – scale is years before present [1950])

I am not suggesting that CO2 or CH4 are the only forcings in operation but CO2 is certainly one of them.
Mike

I would think a method that claimed uniform levels up to 90 km is a method I’d like to see in detail before bought that. Darn unlikely is the first thought that leaps to mind.

Perhaps there is some major change in dating methodology that may still turn this relation right side up for you, I certainly hope so, I am freezing my backside off. This data however doesn’t seem to do it.

The Antarctic Vostok ice core provided compelling evidence of the nature of climate, and of climate feedbacks, over the past 420,000 years. Marine records suggest that the amplitude of climate variability was smaller before that time, but such records are often poorly resolved. Moreover, it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records. Here we report the recovery of a deep ice core from Dome C, Antarctica, that provides a climate record for the past 740,000 years. For the four most recent glacial cycles, the data agree well with the record from Vostok. The earlier period, between 740,000 and 430,000 years ago, was characterized by less pronounced warmth in interglacial periods in Antarctica, but a higher proportion of each cycle was spent in the warm mode. The transition from glacial to interglacial conditions about 430,000 years ago (Termination V) resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases, but there are significant differences in the patterns of change. The interglacial stage following Termination V was exceptionally long—28,000 years compared to, for example, the 12,000 years recorded so far in the present interglacial period. Given the similarities between this earlier warm period and today, our results may imply that without human intervention, a climate similar to the present one would extend well into the future.

http://www.nature.com/nature/journal/v429/n6992/abs/nature02599.html

Dust/CO2/CH4/clathrates/O3/H2O/NO2/Insolation/ etc/etc need to be looked at to fully explain ice age cycles. But from looking at EPICA data CO2 could be one reason for the exit from an ice age.

One need also to understand that the ice core data is a very coarse set of data with most records being separated by 1-10,000 years. Not good for deciding which came first – heat or CO2
Mike

Surely this depends on your stating and finishing times?

… the ice core data provides no evidence to support their claims – and Al Gore was grossly incorrect in his usage of the giant ice core plot in his movie.

Cannot comment on this as I have not watched the film, sorry.

The point is that the ice core data is irrelevant to the argument. All that it shows is that CO2 follows temperature.

but this is just not true. If you look at the EPICA core data then CO2 levels rise just at the point where the temperature begins to rise from the lows. The point at which temperatures start falling is more messy but CH4 and/or CO2 frequently begin to fall at that time. Dust during low temperature periods is often elevated.

If you would have a look at the EPICA data I think you should agree that CO2 rise and temp rise ar synchronised.
Mike

If the climate is cyclical, then there will be an equal number of rising and falling transitions. The claim from Hansen, Gore etc. is that the climate has reached a “tipping point” where it is moving exponentially upwards. Whether or not they are correct about the tipping point, the ice core data provides no evidence to support their claims – and Al Gore was grossly incorrect in his usage of the giant ice core plot in his movie.

The point is that the ice core data is irrelevant to the argument. All that it shows is that CO2 follows temperature.

Hansen doesn’t say that the “climate has reached a “tipping point” where it is moving exponentially upwards” (what is “it” btw, that is “moving exponentially upwards”?). Hansen iseems to be pretty explicit about what he says. He considers that the Earth can’t support a significant Greenland ice sheet at CO2 levels above 450/500 ppm at equilibrium (likely to be achieved on the millenial timescale). He considers that the climate sensitivity is likely to be a good bit higher than 3 oC, once the extremely long time scale ice dynamics are factored into the analysis. In another context he considers that burning all of the fossil fuels would result in truly catastrophic consequences and these might well involve non-linear effects that could be considered “tipping points” (e.g. massive die-off of tropical rainforests; massive release of methane from deep-sea clathrates as oceans warm…that sort of thing).

We may as well address his views in the context of what he actually says/writes!

And in fact the ice core data is highly relevant to the argument. One can’t inspect the ice core data visually and infer lack of effects of greenhouse gas levels from an absence of obvious visually-apparent signatures. One of the facts of life of modern science (since the mid 19th century at least) is that we can address phenomena that aren’t revealed by simplistic visual inspection. The ice age cycles have to be addressed in terms of a full consideration of the radiative forcings, feedbacks and amplifications. Everyone knows very well that changes in greenhouse gas levels don’t instigate transitions between glacial and interglacial periods. That’s the result of Milankovitch cycles. However the Milankovitch cycles produce puny changes in insolation and their effects can only produce the observed record once ice sheet dynamics and greenhouse gas forcings are included in the analysis. In terms of the record these contributors are pretty much “mixed together”. So while increases in atmospheric CO2 driven by Southern hemisphere sea ice retreat may lag the temperature rise recorded in Antarctic cores by 800 (+/- 600) years, that doesn’t mean that rising CO2 levels don’t contribute to the subsequent 4000-ish years of warming through a glacial-interglacial transition….and vice versa in a cooling transition.

If one wants to understand these phenomena, all of the evidence needs to be considered. It’s helpful to know, for example, that while temperature changes precede CO2 changes in Antarctic cores, the rise in atmospheric CO2 levels occurs in advance of warming in the tropics (probably) and in the high Northern latitudes (very likely).

http://icebubbles.ucsd.edu/Publications/CaillonTermIII.pdf

(and subsequent work has reinforced that conclusion)

http://www.sciencemag.org/cgi/content/abstract/1143791

I understand enough chemistry to understand that the bottom line is that the absorption spectrum of CO2 is already saturated. All radiation in these frequencies is absorbed within 10 m of the Earth’s surface. No amount of CO2 can absorb frequencies that have already been extinguished. In other words, all the energy that CO2 can possibly absorb is already being absorbed.

No, that’s incorrect:

If one considers longwave IR emitted from the Earth’s surface, the wavelength/energy of the emitted wavelength has to be considered, since the absorption coefficient (k) is inversely related to the wavelength of the absorption band. The transmisivity, t, (absorbtivity = 1-transmisivity) of a column of air is given by:

t = e^(-k*p*l)

where k is the absorption coefficient, p is the partial pressure and l is the path length.

since the absorption coefficients for the absorption bands of the greenhouse gases are known[***], we can calculate the pathlength required to effectively absorb all of the radiation at that energy/wavelength.

For 99% absorption, the pathlength of the 4-5 micron absorption band of CO2 is 625 metres at current atmospheric CO2 concentrations

and for the ~14-20 micron absorption band, CO2 at 385 ppm is still unsaturated at 7,800 metres of altitude.

likewise for the 12-20 micron infrared absorption band of water at 0.4%, water vapour is still absorbing at 1,700 metres.

So the radiation is certainly not absorbed within 10 metres of the Earth’s surface!

(iii) Thus, at current atmospheric greenhouse gas concentrations, the absorption bands aren’t saturated; enhancement of the concentration of greenhouse gases, particularly at higher altitudes [see (iv)], is effective in trapping more of the longwave IR emitted from the Earth’s surface.

(iv) In any case, the altitude of absorption of IR emitted from the Earth’s surface isn’t that important. A key element of the greenhouse effect is the altitude of emission of longwave IR into space. This has to happen for radiative balance between incoming radiation and outward radiation.

As greenhouse gases are added to the Earth’s atmosphere, the radiation of IR into space is suppressed at any altitude (especially altitudes far from the Earth’s surface). So the radiation emitted to space from (say) 5 km is suppressed by enhanced CO2 concentrations, and so the altitude of mean radiation to space is increased. Since an increased altitude in the troposphere is at a lower temperature, the efficiency of radiation to space is decreased. The troposphere must warm in order to restore radiative balance. Since the surface and troposphere are strongly coupled, the warming of the troposphere is transmitted to the earth’s surface (and vice versa).

[***] This has been well known for more than half a century. See for example:

RM Goody and GD Robinson (1951) Quart. J. Roy. Meteor. Soc. 77, 151-185

NASA Climate Change Satellite Has Troubled Launch

Oh, really sir. Assembled where?? How many are feeding on the public teat?? How many are really Climate Scientists??
or just politically appointed advocates who are not being held accountable?? Why are so many other Climate Specialists now forging a publicly visible rebuttal?? Do you regard political activists hijacking public policy through bad science to be a moral issue or a “feedback” of some sort.

regards

1500 years.??????? good grief!! this looks like a “get out”
Look back 1500 years and see how far humanity has come technologically. Just look back 100 years !!

The EcoDruids are in panic mode as shown by the Steig Affair
and that noteworthy attempt to involve the last man standing in this sordid affair of AGW, Antartica.

regards

If the climate is cyclical, then there will be an equal number of rising and falling transitions. The claim from Hansen, Gore etc. is that the climate has reached a “tipping point” where it is moving exponentially upwards. Whether or not they are correct about the tipping point, the ice core data provides no evidence to support their claims – and Al Gore was grossly incorrect in his usage of the giant ice core plot in his movie.

The point is that the ice core data is irrelevant to the argument. All that it shows is that CO2 follows temperature.

and then there’s this
http://www.john-daly.com/artifact.htm

The conclusion of this research was
“the absorption is 0.054 W/m2 – and not 4.3 W/m2.
This is roughly 80 times less than IPCC’s radiative forcing.”

All because you can find something on the internet doesn’t make it right. The objection about the CO2 bands already being saturated is discussed here in the historical context: http://www.aip.org/history/climate/co2.htm (search on saturated). The fact that the forcing is around 4 W/m^2 is so universally agreed to be scientists, even skeptics like Richard Lindzen and Roy Spencer that it is way out in the weeds to try to argue otherwise.

Seriously, I don’t understand…does that mean it counts more than it would as a feedback?…less?….the same? Is it counted in the 4.3 w/m2?

Think about it. The calculation that gets the climate sensitivity of ~3/4 C per (W/m^2) from the ice age – interglacial transition includes in the W/m^2 the forcing due to changes in ice sheets and the resulting albedo change. However, when we are talking about calculating the climate sensitivity to changes in CO2, that is the only forcing that we are including. So, changes in the albedo due to such land ice sheet changes will then produce additional “forcing” that we haven’t really counted because it is part of the feedback process. This will cause some additional temperature change.

But now you have really confused me with your statement above.

1). Do you mean that if you chose a CO2 level that occurs when the temperature is changing there are as many positive temperature transitions as negativ? – But surely mathematically there must always be as many positive transitions as negative?

2). Or do you mean that if CO2 is increasing and is at a particular % it is as likely to be cooling as warming?

3). Or do you mean that when CO2 is –
above x% it is as often cold as hot
below x% it is as often hot as cold

If you mean the latter I will have a look at my EPICA results tonight and see if there is a transition CO2 level at which cold is prevalent
Mike

I said nothing of the sort. What I said is that there is no correlation between CO2 levels and the direction which the temperature is moving. It is trivial to prove this. Pick any CO2 level on the ice core graph and count how many times that level correlated to downwards and upwards movements in temperature. You will find that the two quantities are equal, meaning there is 0% correlation between CO2 level and the temperature trend.

If you are going to comment, please take the time to read what I said more carefully.