Science has just published a new analysis of ice core data from Antarctica, covering the last 800,000 years.In brief, the authors worked on the ice core dating problem (previous attempts at dating each tiny slice of ice had error bars measured in centuries -- way to wide for comfort). With five synchronized independent ice cores now available, and with ice core events now matched to the Laschamp geomagnetic event (41,000 years ago) via the bipolar "seesaw" hypothesis, it is possible to be much more accurate with the dating.The result still has some residual error, and as before that error increases with the depth of each core. However, it is now possible to resolve the dates of four critical rapid warming events to within a century or so, for both temperatures and carbon dioxide.Their conclusion: up to the limit of their temporal resolution, the increase in temperature and carbon dioxide are essentially synchronous. There is no resolvable lag of either variable behind the other. The circa 800-year lag of temperature rise behind CO2 rise is not visible in the high-resolution data.On scales less than a century, the ice core data is silent. Perhaps someday, with many more cores and much better synchronization tools, it may be possible to draw conclusions about which variable causes what kind of change, and on precisely what time scale, but we aren't there yet.Authors' Abstract:Understanding the role of atmospheric CO2 during past climate changes requires clear knowledge of how it varies in time relative to temperature. Antarctic ice cores preserve highly resolved records of atmospheric CO2 and Antarctic temperature for the past 800,000 years. 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. We infer the phasing between CO2 concentration and Antarctic temperature at four times when their trends change abruptly. We find no significant asynchrony between them, 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.Editor's Summary:Changes in the concentration of atmospheric CO2 and surface air temperature are closely related. However, temperature can influence atmospheric CO2 as well as be influenced by it. Studies of polar ice cores have concluded that temperature increases during periods of rapid warming have preceded increases in CO2 by hundreds of years. Parrenin et al. present a revised age scale for the atmospheric component of Antarctic ice cores, based on the isotopic composition of the N2 that they contain, and suggest that temperature and CO2 changed synchronously over four intervals of rapid warming during the last deglaciation.www.sciencemag.org/content/339/6123/1060.abstractThe link given above is only for the abstract. The actual paper is hidden behind a pay wall -- contact me for assistance.Loren
Ah, scooped. Here is the summary I wrote.As long as snow is simply packed tight and not yet impermeable ice, atmospheric gasses will continue to diffuse to lower and older layers of packed snow. How to measure how long this diffusion went on? Measure the percentage of nitrogen-15 which diffuses to lower layers faster than nitrogen-14.Of the nitrogen gas that makes up about 78 percent of the atmosphere, some molecules contain atoms of nitrogen-14’s heavier brother, nitrogen-15. Simply because of gravity, the heavier nitrogen-15 will be over-represented near the bottom of the diffusion zone and therefore also in this ice. The thicker the diffusion zone, the more prevalent nitrogen-15 will be. (You can think of a footrace between a fast and slow person—the longer the sprint, the greater the fast person’s lead at the finish.)So by measuring the ratio of nitrogen isotopes in the air bubbles, glaciologists can infer how big the offset between contemporaneous ice and air must have been.Using this technique, a group of European researchers analyzed the timing of events at the end of the last ice age in the EPICA Dome C ice core from Antarctica. The original study that examined the record of carbon dioxide in this core put the start of the warming 800±600 years before the rise in carbon dioxide 18,000 years ago. Using the new age scale, however, the new study sees the change in CO2 leading by a statistically insignificant 10±160 years. In other words, as near we can determine, they happened at the same time.The study also looked at three prominent wiggles in the 8,000 years that followed. They largely showed the same behavior—with CO2 and temperature changing at about the same time—though temperature appeared to lead by at least several decades in one instance.http://arstechnica.com/science/2013/02/ice-age-chicken-and-e...AGW skeptics love to cite the belief that temperature rise in the Antartic preceded CO2 rise by about a thousand years. This new study points to a simultaneous rise.Peter
A little scientific speculation by a lay person.Nitrogen-14 is one of two stable (non-radioactive) isotopes of the chemical element nitrogen, which makes up about 99.636% of natural nitrogen.http://en.wikipedia.org/wiki/Nitrogen-15N-14 fraction = .99636N-15 fraction = .00364So about 4 out of every 1000 Nitrogen atoms are N-15. Combine one million N atoms where 3640 are N-15 with another million N atoms:3640 * .00364 = 13.24 molecules of N-15:N-15.These double N-15 molecules will be even heavier than the standard N-15 molecules. Measuring this percentage (if possible) might give even a finer tool for N-15 diffusion.Peter
AGW skeptics love to cite the belief that temperature rise in the Antartic preceded CO2 rise by about a thousand years. This new study points to a simultaneous rise.So now we have one paper that says simultaneous and several others that show a carbon dioxide lag of several hundred years. Don't ya love dueling papers?DB2
This new study points to a simultaneous rise. What simultaneous rise? Currently the CO2 is rising and the temperature is declining for the last 20 years or so contradicting your study. In other words, this finding does not reflect reality!Imagine that. AGW skeptics love to cite the belief that temperature rise in the Antartic preceded CO2 rise by about a thousand years. Citing the belief? What belief? How about citing numerous studies showing that CO2 follows temperature in the Vostok Ice Cores? - After temperature rises, it takes 800 years before CO2 starts to rise and follow temperature. And if you want studies how about: Caillon, N., Severinghaus, J.P., Jouzel, J., Barnola, J.-M., Kang, J. and Lipenkov, V.Y. 2003. Timing of atmospheric CO2 and Antarctic temperature changes across Termination III. Science 299: 1728-1731.Clark, P.U. and Mix, A.C. 2000. Ice sheets by volume. Nature 406: 689-690.Fischer, H., Wahlen, M., Smith, J., Mastroianni, D. and Deck B. 1999. Ice core records of atmospheric CO2 around the last three glacial terminations. Science 283: 1712-1714.Genthon, C., Barnola, J.M., Raynaud, D., Lorius, C., Jouzel, J., Barkov, N.I., Korotkevich, Y.S. and Kotlyakov, V.M. 1987. Vostok ice core: Climatic response to CO2 and orbital forcing changes over the last climatic cycle. Nature 329: 414-418.Idso, S.B. 1982. Carbon Dioxide: Friend or Foe? IBR Press, Tempe, AZ.Idso, S.B. 1988. Carbon dioxide and climate in the Vostok ice core. Atmospheric Environment 22: 2341-2342.Idso, S.B. 1989. Carbon Dioxide and Global Change: Earth in Transition. IBR Press, Tempe, AZ.Indermuhle, A., Monnin, E., Stauffer, B. and Stocker, T.F. 2000. Atmospheric CO2 concentration from 60 to 20 kyr BP from the Taylor Dome ice core, Antarctica. Geophysical Research Letters 27: 735-738.Monnin, E., Indermühle, A., Dällenbach, A., Flückiger, J, Stauffer, B., Stocker, T.F., Raynaud, D. and Barnola, J.-M. 2001. Atmospheric CO2 concentrations over the last glacial termination. Science 291: 112-114.Mudelsee, M. 2001. The phase relations among atmospheric CO2 content, temperature and global ice volume over the past 420 ka. Quaternary Science Reviews 20: 583-589.Petit, J.R., Jouzel, J., Raynaud, D., Barkov, N.I., Barnola, J.-M., Basile, I., Bender, M., Chappellaz, J., Davis, M., Delaygue, G., Delmotte, M., Kotlyakov, V.M., Legrand, M., Lipenkov, V.Y., Lorius, C., Pepin, L., Ritz, C., Saltzman, E., and Stievenard, M. 1999. Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature 399: 429-436.Smagorinsky, J., Bryan, K., Manabe, S., Armi, L., Bretherton, F.P., Cess, R.D., Gates, W.L, Hansen, J. and Kutzbach, J.E. (Eds.). 1982. Carbon Dioxide and Climate: A Second Assessment. National Academy Press, Washington, DC.Yokoyama, Y., Lambeck, K., Deckker, P.D., Johnston, P. and Fifield, L.K. 2000. Timing of the Last Glacial Maximum from observed sea-level minima. Nature 406: 713-716. and Petit et all 1999 — analysed 420,000 years of Vostok, and found that as the world cools into an ice age, the delay before carbon falls is several thousand years.Fischer et al 1999 — described a lag of 600 plus or minus 400 years as the world warms up from an ice age.Monnin et al 2001 – looked at Dome Concordia (also in Antarctica) – and found a delay on the recent rise out of the last major ice age to be 800 ± 600Mudelsee (2001) - Over the full 420,000 year Vostok history Co2 variations lag temperature by 1,300 years ± 1000.Caillon et al 2003 analysed the Vostok data and found a lag (where CO2 rises after temperature) of 800 ± 200 years.See Palisad for the most informative detailed graphics on what the Vostok and Dome Ice cores mean and why they strongly mathematically suggest CO2 follows temperatures and has little effect on them.This is what you need to see to understand “feedback” or the postulated “amplification”. -=Ajax=- http://www.co2science.org/articles/V6/N26/EDIT.php http://joannenova.com.au/global-warming-2/ice-core-graph/
DB2 So now we have one paper that says simultaneous and several others that show a carbon dioxide lag of several hundred years. Don't ya love dueling papers?That is the way science works. A slow approach to the best estimate of the truth.You notice that there are NO papers suggesting that the earth is not warming or that humans are not to blame.Peter
You notice that there are NO papers suggesting that the earth is not warming or that humans are not to blame.Who said there was?
True.... Even Ajax doesn't actually cite any science. Most legitimate "denial" has (for the most part) morphed into "how much"... for which there isn't a word unless we use "lukewarmism".
Tightened constraints on the time-lag between Antarctic temperature and CO2 during the last deglaciationPedro et al.www.clim-past.net/8/1213/2012/Abstract:Antarctic ice cores provide clear evidence of a close coupling between variations in Antarctic temperature and the atmospheric concentration of CO2 during the glacial/interglacial cycles of at least the past 800-thousand years. Precise information on the relative timing of the temperature and CO2 changes can assist in refining our understanding of the physical processes involved in this coupling. Here, we focus on the last deglaciation, 19000 to 11000 yr before present, during which CO2 concentrations increased by ~80 parts per million by volume and Antarctic temperature increased by ~10 °C. Utilizing a recently developed proxy for regional Antarctic temperature, derived from five near-coastal ice cores and two ice core CO2 records with high dating precision, we show that the increase in CO2 likely lagged the increase in regional Antarctic temperature by less than 400 yr and that even a short lead of CO2 over temperature cannot be excluded. This result, consistent for both CO2 records, implies a faster coupling between temperature and CO2 than previous estimates, which had permitted up to millennial-scale lags.DB2
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