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A New Ice Core from North Greenland
Reference
Andersen, K.K., Azuma, N., Barnola, J.-M., Bigler, M., Biscaye, P., Caillon, N., Chappellaz, J., Clausen, H.B., Dahl-Jensen, D., Fischer, H., Fluckiger, J., Fritzsche, D., Fujii, Y., Goto-Azuma, K., Gronvold, K., Gundestrup, N.S., Hansson, M., Huber, C., Hvidberg, C.S., Johnsen, S.J., Jonsell, U., Jouzel, J., Kipfstuhl, S., Landais, A., Leuenberger, M., Lorrain, R., Masson-Delmotte, V., Miller, H., Montoyama, H., Narita, H., Popp, T., Rasmussen, S.O., Raynaud, D., Rothlisberger, R., Ruth, U., Samyn, D., Schwander, J., Shoji, H., Siggard-Andersen, M.-L., Steffensen, J.P., Stocker, T., Sveinbjornsdottir, A.E., Svensson, A., Takata, M., Tison, J.-L., Thorsteinsson, T., Watanabe, O., Wilhelms, F. and White, J.W.C. 2004. High-resolution record of Northern Hemisphere climate extending into the last interglacial period. Nature 431: 147-151.

Background
Two deep ice cores from Central Greenland that were drilled in the early 1990s produced reliable proxy climate data extending back to 105,000 years before present (105 kyr BP). Their older sections, however, were disturbed in chronology due to ice-folding near the underlying bedrock; and, hence, prior to the present there were no trustworthy climate-related data from Greenland covering the portion of the last interglacial (the Eemian) that could reveal the nature of the world's descent into the great ice age that preceded the interglacial in which we currently live (the Holocene).

What was done
The international team of 49 scientists that produced this report, which is based on a new ice core obtained from the North Greenland Ice Core Project (NGRIP) site at 75.10N and 42.32W, derived an undisturbed proxy climate record that extends all the way back to 123,000 years BP.

What was learned
The NGRIP team reports that climate was stable during the last interglacial period, with temperatures at least 5C warmer than those of today. Then came "a slow decline in temperatures" from 122 to 115 kyr BP, leading them to state that the end of the last interglacial "does not appear to have started with an abrupt climate change, but with a long and gradual deterioration of climate." Once into that deterioration, however, they report that an abrupt cooling occurred at about 119 kyr BP followed by an abrupt warming at about 115 kyr BP. Noting that these events are also apparent in proxy climate records as far away as the Iberian coast, they report they are "believed to be large-scale features typical of the North Atlantic region."

What it means
These observations clearly indicate that it is possible to have much higher temperatures than those of the present with much lower atmospheric CO2 concentrations (as much as 100 ppm lower, in fact), which makes one wonder why the current interglacial is so inordinately cool. They also demonstrate that warmth promotes climatic stability, which is just the opposite of what the world's climate alarmists would have one believe. In discussing this topic, for example, Cuffey (2004) notes that "the persistence of stable climate under such warm conditions is a key observation." And why is that? It is because climate alarmists would have one believe that CO2-induced global warming will trigger a collapse of the global ocean's thermohaline circulation that will bring on another ice age, as in The Day After Tomorrow," the Hollywood movie that Cuffey describes as being most notable for "its public abuse of thermodynamics," where a new ice age starts in only one week. In the real world, by contrast, Cuffey notes that the start of the last glacial period "was characterized by a mostly gradual cooling, lasting about five millennia."

With this much good stuff in just the overview of the Project, we can hardly wait for the detailed analyses that will surely follow.

Reference
Currey K.M. 2004. Into an ice age. Nature 431: 133-134.


Reviewed 6 October 2004