Watanabe, O., Jouzel, J., Johnsen, S., Parrenin, F., Shoji, H. and Yoshida, N. 2003. Homogeneous climate variability across East Antarctica over the past three glacial cycles. Nature 422: 509-512.
What was done
The authors describe the large-scale features of the ğ18O record obtained from an ice core extracted from Dome Fuji, which is situated about 1,500 km from Vostok in a different sector of East Antarctica. They also compare this record with the Vostok ğD (deuterium) record -- both of which parameters (ğ18O and ğD) are measures of temperature -- over the full extent of the new Dome Fuji record, which (being the second longest such record after the first-place Vostok record) goes back in time about 330,000 years and includes the last three glacial-interglacial cycles.
What was learned
Among the many things learned, three major findings stand out. First, the authors say "the similarities between the inferred Dome Fuji and Vostok climate records, which hold for the whole period and even for very detailed features, are remarkable given the distance between the two sites and a plausible different precipitation origin." Second, they note that the Dome Fuji record adds considerably to the geographical significance of millennial-scale events which, "for the last glacial period (Bender et al., 1999; Blunier and Brook, 2001), are counterparts of the Dansgaard-Oeschger events recorded in the Greenland records (Dansgaard et al., 1993)." Third, the temperature peaks of the last three interglacials (marine stages 5.5, 7.5 and 9.3) "were much warmer than the most recent 1,000 years (~4.5°C for stage 5.5 and up to 6°C for stage 9.3)."
What it means
The first observation, in the words of the authors, "clearly supports the conclusion that the broad features of the Vostok record are of geographical significance for a large area (Antarctica and part of the Southern Hemisphere)," i.e., they are of more than just local significance. The second observation demonstrates that the same type of millennial-scale cycling of climate that occurs in the Northern Hemisphere also occurs in the Southern Hemisphere, essentially confirming the global nature of this pervasive phenomenon (see Climate Oscillations in our Subject Index). The third observation, as we have noted in other of our writings, confirms that earth's current warmth is indeed unprecedented -- and over at least the last third of a million years -- but that its uniqueness lies not in the fact that it is warmer than normal, but that it is very much colder than normal, i.e., than what has been typical of the peak warmth of the several prior interglacials (see our Journal Reviews of Petit et al. (1999) and Herbert et al. (2001) plus our Editorials of 9 August 2000, 8 May 2002, 26 June 2002 and 2 April 2003).
Taken together, these findings strengthen the emerging realization of most thinking people, i.e., that the Modern Warm Period is simply the most recent incarnation of the warm node of the millennial-scale oscillation of global climate that was manifest in the Medieval Warm Period and the still earlier Roman Warm Period, and that if there is anything unusual about these climatic intervals it is that they have all been far cooler than the peak warmth of the most recent prior interglacials, when the air's CO2 content was much lower than it is today, all of which observations suggest that the increase in atmospheric CO2 concentration that began with the Industrial Revolution has had nothing whatsoever to do with the current warmth that was naturally programmed to follow the cold of the Little Ice Age.
Bender, M., Malaize, B., Orchado, J., Sowers, T. and Jouzel, J. 1999. High precision correlations of Greenland and Antarctic ice core records over the last 100 kyr. In: Mechanisms of Global Climate Change at Millennial Time Scales (Clark, P.U., Webb, R.S. and Keigwin, L.D., Eds.), Geophysical Monograph Series 112, American Geophysical Union, Washington, DC, pp. 149-164.
Blunier, T. and Brook, E.J. 2001. Timing of millennial-scale climate change in Antarctica and Greenland during the Last Glacial Period. Science 291: 109-112.
Dansgaard, W., Johnsen, S.J., Clausen, H.B., Dahl-Jensen, D., Gundestrup, N.S., Hammer, C.U., Hvidberg, C.S., Steffensen, J.P., Sveinbjörnsdottir, A.E., Jouzel, J. and Bond, G. 1993. Evidence for general instability of past climate from a 250-kyr ice-core record. Nature 364: 218-220.
Herbert, T.D., Schuffert, J.D., Andreasen, D., Heusser, L., Lyle, M., Mix, A., Ravelo, A.C., Stott, L.D. and Herguera, J.C. 2001. Collapse of the California Current during glacial maxima linked to climate change on land. Science 293: 71-76.
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.
Reviewed 23 April 2003