http://simpleclimate.wordpress.com/2013/...
I'm not surprised by this paper. The CO2 lag has always referenced the Vostok core as the source, but when you look at the data directly, then the lag isn't immediately apparent. At first glance you would say the major events (co2 concentration change and temperature change) are synchronous. Some lagging of co2 is apparent, at a mathematical level, but it is is not always the case. I never had much confidence that this time lag wasn't mostly inside the error margins for temporal accuracy of the data.
http://www.southwestclimatechange.org/fi...
I never understood the mechanism for a significant (hundreds of years) lag of co2 behind temperature... (other than perhaps co2 being locked in the thermohaline, but I would see a first pulse, followed by a later one for this case). I would expect a lag, but at a very short time increment. My expectation is that co2 concentration will always follow average global ocean temperature (in the pre-human record). It should never precede it.
The milankovitch cycles are normally cited as the trigger for the climate switching between glaciated and interglacial, but a close look at the data shows that this is an incomplete answer... something else is happening too, the timing of Milankovitch cycles alone doesn't fit to the timing of the interglacials.
Look at this chart, at the interglacial 400,000 years ago.
http://upload.wikimedia.org/wikipedia/co...
Discussed more here
http://arxiv.org/pdf/1002.0597v2.pdf
Thanks for the link DaveH! Frédéric Parrenin shows that there is a comparable correlation that links CO2 closer to temperature changes. Within 150 years maybe? It seems that they haven't proven that CO2 precedes temperature rises though, but they are trying. I would venture to say that this is a critical finding and actually shows a better explanation of why CO2 continues to rise. Humans net input at any given time to the greenhouse effect is less than 1%. The cumulative effect is what has people yelling through their blow horns. It would be great to know that human emitted CO2 isn't as detrimental as thought. This info should "heat up" the controversy anyway.
I can sense your frustration mike, wanting to keep up with the cutting edge research but unable due to lack of access to scientific research papers. I wonder why the denialist that told you about this paper didn't explain it for you? Maybe they'll publish something about it on monday since these kind of professionals do their best work during business hours.
Anyway, this paper addresses the uncertainty in previous records:
"The most highly resolved aCO2 record during the last deglacial warming, Termination I (TI), is from the European Project for Ice Coring in Antarctica (EPICA) Dome C (EDC) ice core. In this record, aCO 2 appears to lag local Antarctic temperature (AT) by 800-600 years at the onset of TI, in agreement with an earlier study on the Vostok and Taylor Dome ice cores, which identified a lag of 600-400 years at the end of the past three terminations. However, uncertainties in the relative timing of aCO2 and AT remain for two reasons. First, air is trapped in fallen snow only when it has recrystallized enough to create enclosed cavities, typically at a depth of 50 to 120m below the surface (depending on site conditions), at the bottom of the so-called firn. This results in a depth difference (Ddepth, see Fig. 1) between synchronous events recorded in the ice matrix and in the trapped gas bubbles or hydrates. We used air d15N data from the EDC ice core to determine the past Lock-In Depth (LID), which is the depth at which air in the ice is permanently trapped. The LID estimates are transformed to Ddepth estimates, using a constant firn average density and a modeled vertical thinning function. Our approach is further validated with two independent methods. Second, using only the isotopic record from one ice core produces a noisy reconstruction of past temperature variations in Antarctica. We used a stack of AT variations based on five synchronized ice cores."
SO by compiling multiple ice core temp records, they reduced the overall noise of the temp record. Then they improved the uncertainty of the age of this record by using three different methods (two of which were verifications of the initial method). They did this by using delta15N as a chronology record, which had the lowest uncertainty of all possible methods.
"Our chronology and the resulting aCO2 -AT phasing strengthens the hypothesis that there was a close coupling between aCO2 and AT on both orbital and millennial time scales. The aCO2 rise could contribute to much of the AT change during TI, even at its onset, accounting for positive feedbacks and polar amplification, which magnify the impact of the relatively weak rCO2 change (Fig. 4) that alone accounts for ~0.6°C of global warming during TI. Invoking changes in the strength of the Atlantic meridional overturning circulation is no longer required to explain the lead of AT over aCO2."
The reason to propose a revision is to contribute to the cutting edge of human knowlege. Do you not even understand the reason for published research?
The implications have to wait. They are proposing that CO2 did not lag temperatures in the Antarctic whereas previous studies specifically at Vostok concluced there was a 800 year gap. It remains to be seen how this research fits with other research, and how it will contribute to better understanding of the past.
Remember this is all Southern Hemisphere, which started warming about 2,000 years after the Northern Hemisphere. One major question for paleoclimatolgists has been how did the south warm so fast in reaction to the Milankovitch Cycles triggered changes in the north. In natural climate change, 2000 years is surprisingly fast.
If there was not the 800 year lag from southern temperatures to CO2 increases, it could be showing that the south warmed only after (or in lock step) with increasing CO2 from warming oceans in oppostion the the recent alternatively theory such the warming Atlantic caused the shut down of the thermohaline circulation which in turn increased winds from the tropics to the south.
The advancing research of paleo climates is helping us understand how the increase in CO2 is affect climate now and in the future.
I am sorry and sad to say, that I see science today is no longer a search for the truth, I see bias towards self interest in almost every science report published, not just AGW anti AGW, but in agriculture (corn oil against palm oil) (gm crops) in the food industry (meat industry soy industry) especially the Pharmaceutical industry, They make billions selling statins and suppress research showing a link between cholesterol and cardiac disease is not proven, or that statins improve cholesterol levels but not cardiac health.
I have reached a point that I disbelieve almost everything I am told by so called scientists, and media.
Science is not a religion that we should believe absolutely, scientists are human like you and me and have faults and failings like you and me.
Once again the warmmongers aren't curious that the previous lag which was inconvenient to their cult is magically waived away. What a shock. It was an inconvenience because they had to concoct mechanism involving water vapor etc that hasn't been shown to be true. They are never curious when the past data is modified to exaggerate the present. For them, anything that supports their AGW god is worthy of worship. The new explanation is probably the previous ice core data was collected and interpreted before the AGW religion and therefore is not valid. It must be interpreted in the context of AGW and it isn't so difficult to find ways to make it disappear. If it seems there is contempt in my sarcasm, it is because I am being nice today.
What makes you think that they are attempting to rectify it because it posed a problem for the CAGW theory? Maybe you should get your head out of the conspiracy theorist mindset. This, as with every other bit of information, is science. It follows that this data and this study will be added onto the other studies until a general agreement with what happened is formed.
The New York Times is talking about scientists who revise their conclusions when this seems warranted by new scientific evidence. Anti-science deniers like you change from one shell game distortion and trick to another trying to stay one step ahead of being exposed as frauds and liars. Now you have one less shell to hide your shriveled old fossil fuel industry propaganda source pea under. If posting your umpteenth fake question here makes you feel better, so be it.
It was always considered not a problem because of the margin of error of such data. It was only the deniers that grasped at pathetic straws.
"Here we propose a revised relative age scale for the concentration of atmospheric CO2 and Antarctic temperature for the last deglacial warming, using data from five Antarctic ice cores." http://www.sciencemag.org/content/339/6123/1060.abstract
Well that's interesting. So what were they trying to do? This perhaps:
"We find no significant asynchrony between them (temperature and CO2), indicating that Antarctic temperature did not begin to rise hundreds of years before the concentration of atmospheric CO2, as has been suggested by earlier studies."
I thought the hundreds of years gap was suggested by the data? I also thought the lag was not a problem for the CAGW theory so why adjust it?
(Note: The study is pay-walled and I can't find it eslewhere. It would be nice to know what "revised" mean.)
