By the late 1990s and early 2000s, however, the bottom began to fall out of the poorly constructed bandwagon, as the evidentiary glue that held it together began to weaken.  Advances in ice-coring instrumentation and techniques had improved considerably, and newer studies with finer temporal resolution began to reveal that, if anything, increases (decreases) in air temperature drive increases (decreases) in atmospheric CO2 content, and not vice versa [see Indermuhle et al. (2000), Monnin et al. (2001) and many of the other references contained in the CO2-Temperature Correlations section in our Subject Index].  Thus, a severe blow was dealt to the climate-alarmist community, as a major tenant of the CO2-induced global warming hypothesis was shown to be contradicted by real-world observations.

The most recent of these studies (Caillon et al. (2003) demonstrates that during Glacial Termination III, "the CO2 increase lagged Antarctic deglacial warming by 800 ± 200 years."  This finding, in their words, "confirms that CO2 is not the forcing that initially drives the climatic system during a deglaciation."

In spite of this admission, Caillon et al., and many others, hold to the view that the subsequent increase in atmospheric CO2 -- which is believed to be due to warming-induced CO2 outgassing from the world's oceans -- serves to amplify the warming that is caused by whatever prompts the temperature to rise in the first place.  This belief, however, is founded on unproven assumptions about the strength of CO2-induced warming; and it is applied without any regard for biologically-induced negative climate feedbacks that may occur in response to atmospheric CO2 enrichment [see Feedback Factors (Biophysical) in our Subject Index].

A second major blow to the CO2-induced global warming hypothesis comes from the instrumental temperature record of the more recent past.  This second setback is manifested in the contradiction between observed and model-predicted Antarctic temperature trends of the past several decades.  According to nearly all climate models, CO2-induced global warming should be most evident in earth's polar regions; but analyses of Antarctic near-surface and tropospheric air temperatures tell a radically different story.

Doran et al. (2002), for example, examined temperature trends in the McMurdo Dry Valleys of Antarctica over the period 1986 to 2000, reporting a phenomenal cooling rate of approximately 0.7°C per decade.  This dramatic rate of cooling, they state, "reflects longer term continental Antarctic cooling between 1966 and 2000."  In addition, the 14-year temperature decline in the dry valleys occurred in the summer and autumn, just as most of the 35-year cooling over the continent as a whole (which did not include any data from the dry valleys) also occurred in the summer and autumn.

In another study, Comiso (2000) assembled and analyzed Antarctic temperature data obtained from 21 surface stations and from infrared satellites operating since 1979.  They found that for all of Antarctica, temperatures had declined by 0.08°C and 0.42°C per decade, respectively, when assessed via these two data sets.  And in yet another study, Thompson and Solomon (2002) also report a cooling trend for the interior of Antarctica.

In spite of the decades-long cooling that has been observed for the continent as a whole, one region of Antarctica has actually bucked the mean trend and warmed over the same time period: the Antarctic Peninsula/Bellingshausen Sea region.  But is the temperature increase that has occurred there evidence of CO2-induced global warming?

No.  According to Vaughan et al. (2001), "rapid regional warming [our italics]" has led to the loss of seven ice shelves in this region during the past 50 years.  However, they note that sediment cores from 6000 to 1900 years ago suggest the Prince Gustav Channel Ice Shelf - which collapsed in this region in 1995 - "was absent and climate was as warm as it has been recently," when, of course there was much less CO2 in the air.

Although it is tempting for climate alarmists to cite the 20th century increase in atmospheric CO2 concentration as the cause of the recent regional warming, "to do so without offering a mechanism," say Vaughan et al., "is superficial."  And so it is, as the recent work of Thompson and Solomon (2002) suggests that much of the warming can be explained by "a systematic bias toward the high-index polarity of the SAM," or Southern Hemispheric Annular Mode, such that the ring of westerly winds encircling Antarctica has recently been spending more time in its strong-wind phase.

This is also the conclusion of Kwok and Comiso (2002), who report that over the 17-year period 1982-1998, the SAM index shifted towards more positive values (0.22/decade), noting that a positive polarity of the SAM index "is associated with cold anomalies over most of Antarctica with the center of action over the East Antarctic plateau."  At the same time, the SO index shifted in a negative direction, indicating "a drift toward a spatial pattern with warmer temperatures around the Antarctic Peninsula, and cooler temperatures over much of the continent."  Together, the authors say the positive trend in the coupled mode of variability of these two indices (0.3/decade) represents a "significant bias toward positive polarity" that they describe as "remarkable."

Kwok and Comiso additionally report that "the tropospheric SH annular mode has been shown to be related to changes in the lower stratosphere (Thompson and Wallace, 2000)," noting that "the high index polarity of the SH annular mode is associated with the trend toward a cooling and strengthening of the SH stratospheric polar vortex during the stratosphere's relatively short active season in November," which is pretty much the same theory that has been put forth by Thompson and Solomon (2002).

In another slant on the issue, Yoon et al. (2002) report that "the maritime record on the Antarctic Peninsula shelf suggests close chronological correlation with Holocene glacial events in the Northern Hemisphere, indicating the possibility of coherent climate variability in the Holocene."  In the same vein, Khim et al. (2002) say that "two of the most significant climatic events during the late Holocene are the Little Ice Age (LIA) and Medieval Warm Period (MWP), both of which occurred globally (Lamb, 1965; Grove, 1988)," noting further that "evidence of the LIA has been found in several studies of Antarctic marine sediments (Leventer and Dunbar, 1988; Leventer et al., 1996; Domack et al., 2000)."

To this list of scientific journal articles documenting the existence of the LIA in Antarctica can now be added Khim et al.'s own paper, which also demonstrates the presence of the MWP in Antarctica, as well as earlier cold and warm periods of similar intensity and duration.  Hence, it is getting ever more difficult for climate alarmists to continue claiming that these several-hundred-year cold and warm periods were confined to lands bordering the North Atlantic Ocean.  They clearly were global; and they clearly demonstrate the reality of the likely solar-induced millennial-scale climatic oscillation that is manifest in the post-1850 warming of the world that climate alarmists misconstrue as having been caused by the concomitant rise in the air's CO2 content.

Further evidence that the Antarctic as a whole is in the midst of a cooling trend comes from the study of Watkins and Simmonds (2000), who analyzed region-wide changes in sea ice.  Reporting on trends in a number of Southern Ocean sea ice parameters over the period 1987 to 1996, they found statistically significant increases in sea ice area and total sea ice extent, as well as an increase in sea ice season length since the 1990s.  Combining these results with those from a previous study revealed these trends to be consistent back to at least 1978.  And in another study of Antarctic sea ice extent, Yuan and Martinson (2000) report that the net trend in the mean Antarctic ice edge over the last 18 years has been an equatorward expansion of 0.011 degree of latitude per year.

When all is said and done, therefore, the temperature history of Antarctica provides no evidence for the CO2-induced global warming hypothesis.  In fact, it argues strongly against it.

But what if the Antarctic were to warm as a result of some natural or anthropogenic-induced change in earth's climate?  What would the consequences be?  For one thing, it would likely help to increase both the number and diversity of penguin species (Sun et al., 2000; Smith et al., 1999), and it would also tend to increase the size and number of populations of the continent's only two vascular plant species (Xiong et al., 2000).  With respect to the continent's great ice sheets, there would not be much of a problem either, as not even a warming event as dramatic as 10°C is predicted to result in a net change in the East Antarctic Ice Sheet (Näslund et al., 2000), which suggests that climate-alarmist predictions of catastrophic coastal flooding due to the melting of the world's polar ice sheets are way off the mark when it comes to representing reality.

References
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Comiso, J.C.  2000.  Variability and trends in Antarctic surface temperatures from in situ and satellite infrared measurements.  Journal of Climate 13: 1674-1696.

Domack, E.W., Leventer, A., Dunbar, R., Taylor, F., Brachfeld, S. and Sjunneskog, C.  2000.  Chronology of the Palmer Deep site, Antarctic Peninsula: A Holocene palaeoenvironmental reference for the circum-Antarctic.  The Holocene 11: 1-9.

Doran, P.T., Priscu, J.C., Lyons, W.B., Walsh, J.E., Fountain, A.G., McKnight, D.M., Moorhead, D.L., Virginia, R.A., Wall, D.H., Clow, G.D., Fritsen, C.H., McKay, C.P. and Parsons, A.N.  2002.  Antarctic climate cooling and terrestrial ecosystem response.  Nature advance online publication, 13 January 2002 (DOI 10.1038/nature710).

Grove, J.M.  1988.  The Little Ice Age.  Cambridge University Press, Cambridge, UK.

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.

Khim, B-K., Yoon, H.I., Kang, C.Y. and Bahk, J.J.  2002.  Unstable climate oscillations during the Late Holocene in the Eastern Bransfield Basin, Antarctic Peninsula.  Quaternary Research 58: 234-245.

Kwok, R. and Comiso, J.C.  2002.  Spatial patterns of variability in Antarctic surface temperature: Connections to the South Hemisphere Annular Mode and the Southern Oscillation.  Geophysical Research Letters 29: 10.1029/2002GL015415.

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Leventer, A. and Dunbar, R.B.  1988.  Recent diatom record of McMurdo Sound, Antarctica: Implications for the history of sea-ice extent.  Paleoceanography 3: 373-386.

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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.  Nature 291: 112-114.

Näslund, J.O., Fastook, J.L and Holmlund, P.  2000.  Numerical modeling of the ice sheet in western Dronning Maud Land, East Antarctica: impacts of present, past and future climates.  Journal of Glaciology 46: 54-66.

Smith, R.C., Ainley, D., Baker, K., Domack, E., Emslie, S., Fraser, B., Kennett, J., Leventer, A., Mosley-Thompson, E., Stammerjohn, S. and Vernet M.  1999.  Marine ecosystem sensitivity to climate change.  BioScience 49: 393-404.

Sun, L., Xie, Z. and Zhao, J.  2000.  A 3,000-year record of penguin populations.  Nature 407: 858.

Thompson, D.W.J. and Solomon, S.  2002.  Interpretation of recent Southern Hemisphere climate change.  Science 296: 895-899.

Thompson, D.W.J. and Wallace, J.M.  2000.  Annular modes in extratropical circulation, Part II: Trends.  Journal of Climate 13: 1018-1036.

Vaughan, D.G., Marshall, G.J., Connolley, W.M., King, J.C. and Mulvaney, R.  2001.  Devil in the detail.  Science 293: 177-179.

Watkins, A.B. and Simmonds, I.  2000.  Current trends in Antarctic sea ice: The 1990s impact on a short climatology.  Journal of Climate 13: 4441-4451.

Xiong, F.S., Meuller, E.C. and Day, T.A.  2000.  Photosynthetic and respiratory acclimation and growth response of Antarctic vascular plants to contrasting temperature regimes.  American Journal of Botany 87: 700-710.

Yoon, H.I., Park, B.-K., Kim, Y. and Kang, C.Y.  2002.  Glaciomarine sedimentation and its paleoclimatic implications on the Antarctic Peninsula shelf over the last 15,000 years.  Palaeogeography, Palaeoclimatology, Palaeoecology 185: 235-254.

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