What was done
Noting that temperature changes in high latitudes are (1) sensitive indicators of global temperature changes and that they can (2) serve as a basis for verifying climate model calculations, the authors developed a 2,427-year proxy temperature history for the part of the Taimyr Peninsula, northern Russia, lying between 70°30' and 72°28' North latitude, based on a study of ring-widths of living and preserved larch (Larix gmelinii (Rupr.) Rupr.) trees, noting further that "it has been established that the main driver of tree-ring variability at the polar timber-line [where they worked] is temperature (Vaganov et al., 1996; Briffa et al., 1998; Schweingruber and Briffa, 1996)."

What was learned
Naurzbaev et al. report that "the warmest periods over the last two millennia in this region were clearly in the third [Roman Warm Period], tenth to twelfth [Medieval Warm Period] and during the twentieth [Modern Warm Period] centuries."  With respect to the second of these three periods, they emphasize that "the warmth of the two centuries AD 1058-1157 and 950-1049 attests to the reality of relative mediaeval warmth in this region."  Their data also reveal three other important pieces of information: (1) the Roman and Medieval Warm Periods were both warmer than the Modern Warm Period has been to date, (2) the "beginning of the end" of the Little Ice Age was somewhere in the vicinity of 1830, and (3) the Modern Warm Period peaked somewhere in the vicinity of 1940.

What it means
All of these observations are at odds with what is portrayed in the thousand-year Northern Hemispheric hockeystick temperature history of Mann et al. (1998, 1999) and its thousand-year global extension developed by Mann and Jones (2003), wherein (1) the Modern Warm Period is depicted as the warmest such era of the past two millennia, (2) recovery from the Little Ice Age does not begin until after 1910, and (3) the Modern Warm Period experiences it highest temperatures in the latter part of the 20th century's final decade.

Once again, we note that these results apply to but the specific portion of the planet studied by Naurzbaev et al., but that there are many such "specific portions of the planet" that tell the same story.  Hence, we continue to describe the unique but similar temperature records of these numerous locations, as new studies become available and we discover older studies we have not previously reviewed.  All of them will someday have to be recognized as carrying considerably more weight, in their totality, than the controversial and highly-debated hockeystick record, which is beginning to look more and more questionable with each passing week.

References
Briffa, K.R., Schweingruber, F.H., Jones, P.D., Osborn, T.J., Shiyatov, S.G. and Vaganov, E.A.  1998.  Reduced sensitivity of recent tree-growth to temperature at high northern latitudes.  Nature 391: 678-682.

Mann, M.E., Bradley, R.S. and Hughes, M.K.  1998.  Global-scale temperature patterns and climate forcing over the past six centuries.  Nature 392: 779-787.

Mann, M.E., Bradley, R.S. and Hughes, M.K.  1999.  Northern Hemisphere temperatures during the past millennium: Inferences, uncertainties, and limitations.  Geophysical Research Letters 26: 759-762.

Mann, M.E. and Jones, P.D.  2003.  Global surface temperatures over the past two millennia.  Geophysical Research Letters 30: 10.1029/2003GL017814.

Schweingruber, F.H. and Briffa, K.R.  1996.  Tree-ring density network and climate reconstruction.  In: Jones, P.D., Bradley, R.S. and Jouzel, J. (Eds.), Climatic Variations and Forcing Mechanisms of the Last 2000 Years, NATO ASI Series 141. Springer-Verlag, Berlin, Germany, pp. 43-66.

Vaganov, E.A., Shiyatov, S.G. and Mazepa,V.S.  1996.  Dendroclimatic Study in Ural-Siberian Subarctic.  Nauka, Novosibirsk, Russia.