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Temperature (Trends - Regional: Asia, Russia) -- Summary
Controversy abounds over the temperature history of the earth, particularly that of the past one to two millennia.  The debate was initially sparked by the papers of Mann et al. (1998, 1999), which suggested that both the rate of warming of the Northern Hemisphere and the level of warmth it attained in the latter part of the 20th century were without precedent over the past millennium.  The debate was further flamed by the paper of Mann and Jones (2003), which suggested that this thermal "unprecedentedness" actually applies to a two-millennia period and pertains to the entire earth.

Why are these claims controversial?  They are controversial because climate alarmists use them to bolster their most cherished contention of all, i.e., their claim that late 20th-century warming must have been caused by the large increase in the air's CO2 content that occurred concurrently, which we shall call their Prime Contention.  Hence, it is extremely important to determine the true nature of late 20th-century warming.  Although verification of climate-alarmist claims about it is not a sufficient condition to establish the correctness of their Prime Contention, it is surely a necessary one.  In this summary, therefore, we review pertinent real-world temperature data from Russia with a view to hastening the resolution of this important issue.

We begin our investigation with a brief synopsis of the findings of Naurzbaev and Vaganov (2000), who developed a 2200-year proxy temperature record using cores obtained from 118 trees near the upper timberline in Siberia for the period 212 BC to AD 1996.  This record revealed a cool period in the first two centuries AD, a warm period from AD 200 to 600, cooling again from AD 600 to 800, followed by the Medieval Warm Period from about AD 850 to 1150, the cooling of the Little Ice Age from AD 1200 though 1800, followed by the temperature rise that led to the development of the Modern Warm Period.

With respect to the late 20th-century portion of this latter warming (which must be truly unprecedented to provide any support at all for the climate-alarmist contention that it was CO2-induced), Naurzbaev and Vaganov state that it was "not extraordinary" and that "the warming at the border of the first and second millennia [AD 1000] was longer in time and similar in amplitude."  What is more, they note that fluctuations in average annual temperature from the Siberian record agree well with air temperature variations reconstructed from Greenland ice cores, suggesting, in their words, that "the tree ring chronology of [the Siberian] region can be used to analyze both regional peculiarities and global temperature variations in the Northern Hemisphere," which presents a real problem for the climate alarmists' Prime Contention in view of the expanded area of applicability of Naurzbaev and Vaganov's findings.

Concentrating on the past six centuries, Vaganov et al. (2000) used tree-ring width data to develop a proxy temperature history for the entire Asian subarctic.  These data revealed that the region experienced a small warming trend from the start of the record until about 1750.  Thereafter, a severe cooling trend ensued, followed by a 130-year warming trend from about 1820 through 1950, after which temperatures again declined.  In considering the entire record, the group of six scientists concluded that the amplitude of 20th-century warming in the Asian subarctic "does not go beyond the limits of reconstructed natural temperature fluctuations."

In attempting to determine the cause(s) of the observed temperature fluctuations, Vaganov et al. reported finding a significant correlation with solar radiation and volcanic activity over the entire 600-year period (R = 0.32 for solar radiation, R = -0.41 for volcanic activity), which correlation improved over the shorter interval of the industrial period from 1800 to 1990 (R = 0.68 for solar radiation, R = -0.59 for volcanic activity).  It is also interesting to note that in this particular region of the world, where climate models predict large increases in temperature as a result of the historical rise in the air's CO2 concentration, real-world data show an actual cooling trend since around 1940, when the greenhouse effect of CO2 should have been most prevalent.  And, where warming does exist in the record (between about 1820 and 1940), much of it correlates with changes in solar irradiance and volcanic activity - two factors definitely free of anthropogenic influence.

Changing pace just a bit, Zeeberg and Forman (2001) analyzed 20th-century changes in glacier terminus positions on north Novaya Zemlya, a Russian island located between the Barents and Kara Seas in the Arctic Ocean.  They report that an accelerated post-Little Ice Age glacial retreat was observed in the first and second decades of the 20th century, but that by 1952 the region's glaciers had experienced between 75 to 100% of their net 20th-century retreat.  In fact, during the next 50 years, the recession of over half of the glaciers stopped, and many tidewater glaciers actually began to advance.  These glacial stabilizations and advances were attributed by the two researchers to observed increases in precipitation and/or decreases in temperature.  In the four decades since 1961, for example, weather stations at Novaya Zemlya show summer temperatures to have been 0.3 to 0.5C colder than those of the prior 40 years, while winter temperatures have been between 2.3 to 2.8C colder than what they were over the prior 40-year period.  These observations, in the words of Zeeberg and Forman, are "counter to warming of the Eurasian Arctic predicted for the twenty-first century by climate models, particularly for the winter season."

More different yet was the study of Ye (2001), who analyzed first and last snowfall dates for 139 stations throughout north central and northwest Asia for the period 1937-1994.  This work revealed statistically significant positive trends in snow season length over much of the area, with most of the stations having a trend greater than four days per decade.  The increase in snow season length, according to Ye, "can be attributed more to earlier snowfall than to later last snowfall," although both phenomena played a role in the overall lengthening of the snowfall season.  In the mean, the data indicate a lengthening of the snowy season of somewhat more than 23.2 days over the 58-year period; and since the mean snow season length of the stations studied ranged from 60 to 260 days, this increase in snow season length amounts to an extension of anywhere from 10 to 40%, which is huge.  Perhaps that is why Ye was confident in stating that his findings are "contrary to a general assumption that the length of the snow season would have decreased due to increasing surface air temperatures," which perhaps says something about the temperatures themselves.

Fast-forwarding three years, we come to the study of Jacoby et al. (2004), who extracted cores from century-old oak trees growing within one km of the Pacific Ocean on Kunashir Island (the southernmost large island in the Kurile Island chain belonging to Russia that is located between the Sea of Okhotsk and the northwest Pacific Ocean) and developed them into a four-century tree-ring width index series that was shown to correlate strongly with Kunashir Island summer air temperature.  The scientists report finding that "the recorded temperature data and the tree-ring data show similar correlation patterns with sea-surface temperatures of the North Pacific."  More specifically, they found that "the tree-ring series explains more than 33% of the variance of the July-September Pacific Decadal Oscillation and has similar spectral properties, further supporting the concept of multidecadal variation or shifts in North Pacific climate, for four centuries."

Of perhaps even more interest is the fact that the Kunashir summer mean maximum temperature reconstruction shows no long-term trend (neither cooling nor warming) over the entire period from 1600 to 2000, nor does it show any net temperature change over the 20th century.  Also of note, the peak warmth of the last hundred years occurs right at the mid-century mark, after which temperatures decrease considerably to end up just about where they started the century.  And with Kunashir temperatures being "strongly influenced by the surrounding sea-surface temperatures," in the words of Jacoby et al., we wonder how much more of the Pacific Ocean behaves similarly.

We conclude our summary of Russian temperature data with a brief review of the study of Raspopov et al. (2004), who analyzed two temperature-related data sets: a "direct and systematic air temperature record for the Kola Peninsula, in the vicinity of Murmansk," which covers the period 1880-2000, and an "annual tree-ring series generalized for 10 regions (Lovelius, 1997) along the northern timberline, from the Kola Peninsula to Chukotka, for the period 1458-1975 in the longitude range from 30E to 170E."  This work resulted in the discovery of "climatic cycles with periods of around 90, 22-23 and 11-12 years," which were found to "correlate well with the corresponding solar activity cycles."  Of even more interest to us, however, was what Raspopov et al. learned about the temporal development of the Modern Warm Period.  Their presentation of the mean annual tree-ring series for the northern Eurasia timberline clearly shows that the region's thermal recovery from the coldest temperatures of the Little Ice Age may be considered to have commenced as early as 1820 and was in full swing by at least 1840, whereas the Mann et al. temperature reconstruction does not show warming commencing until after 1910.  In addition, the northern Eurasian timberline data show that the rising temperature peaked just prior to 1950 and then declined to the end of the tree-ring record in 1975.  Thereafter, however, the Kola-Murmansk instrumental record indicates a significant temperature rise; but it peaked in the early 1990s at about the same level as the pre-1950 peak, and after that time it declined to the end of the record in the year 2000.

Considered in their entirety, these several sets of Russian data provide a vastly different picture of the thermal history of a large portion of the Northern Hemisphere than that painted by Mann et al.  Most importantly, they depict a millennial-scale oscillation of climate that is clearly non-CO2-induced, the last full cycle of which testifies to the reality of the Medieval Warm Period, the Little Ice Age and the beginning of the Modern Warm Period, none of which epochs are evident in the Mann et al. temperature record except for the last one.  Even here, however, there are important differences.  Whereas the most striking feature of the temperature history of Mann et al. is a warming over the last two decades of the 20th century that is portrayed as being unprecedented over the past two millennia, the bulk of the Russian data depict cooling over this period, as do many other parts of the earth, especially those in high latitudes of both hemispheres, where CO2-induced warming is predicted to be most strongly and earliest expressed.  Consequently, we have no alternative but to conclude that something is seriously wrong with Mann et al.'s portrayal of earth's climate history.

References
Jacoby, G., Solomina, O., Frank, D., Eremenko, N. and D'Arrigo, R.  2004.  Kunashir (Kuriles) oak 400-year reconstruction of temperature and relation to the Pacific Decadal Oscillation.  Palaeogeography, Palaeoclimatology, Palaeoecology 209: 303-311.

Lovelius, N.V.  1997.  Dendroindication of Natural Processes.  World and Family-95.  St. Petersburg, Russia.

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.

Naurzbaev, M.M. and Vaganov, E.A.  2000.  Variation of early summer and annual temperature in east Taymir and Putoran (Siberia) over the last two millennia inferred from tree rings.  Journal of Geophysical Research 105: 7317-7326.

Raspopov, O.M., Dergachev, V.A. and Kolstrom, T.  2004.  Periodicity of climate conditions and solar variability derived from dendrochronological and other palaeoclimatic data in high latitudes.  Palaeogeography, Palaeoclimatology, Palaeoecology 209: 127-139.

Vaganov, E.A., Briffa, K.R., Naurzbaev, M.M., Schweingruber, F.H., Shiyatov, S.G. and Shishov, V.V.  2000.  Long-term climatic changes in the arctic region of the Northern Hemisphere.  Doklady Earth Sciences 375: 1314-1317.

Ye, H.  2001.  Increases in snow season length due to earlier first snow and later last snow dates over North Central and Northwest Asia during 1937-94.  Geophysical Research Letters 28: 551-554.

Zeeberg, J. and Forman, S.L.  2001.  Changes in glacier extent on north Novaya Zemlya in the twentieth century.  Holocene 11: 161-175.

Last updated 2 March 2005