Climate of the Past
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2007
10.5194/cp-3-237-2007
http://www.clim-past.net/3/237/2007/
http://www.clim-past.net/3/237/2007/cp-3-237-2007.html
http://www.clim-past.net/3/237/2007/cp-3-237-2007.pdf
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242
2007-05-22
Climatic changes in the Urals over the past millennium – an analysis of geothermal and meteorological data
D. Yu. Demezhko
ddem54@inbox.ru
I. V. Golovanova
Institute of Geophysics UB RAS, Ekaterinburg, Russia
Institute of Geology, URS RAS, Ufa, Russia
This investigation is based on a study of two paleoclimatic curves obtained
in the Urals (51–59° N, 58–61° E): i) a ground surface temperature
history (GSTH) reconstruction since 800 A.D. and ii) meteorological data for
the last 170 years. Temperature anomalies measured in 49 boreholes were used
for the GSTH reconstruction. It is shown that a traditional averaging of the
histories leads to the lowest estimates of amplitude of past temperature
fluctuations. The interval estimates method, accounting separately for the
rock's thermal diffusivity variations and the influence of a number of
non-climatic causes, was used to obtain the average GSTH.
<br><br>
Joint analysis of GSTH and meteorological data bring us to the following
conclusions. First, ground surface temperatures in the Medieval maximum
during 1100–1200 were 0.4 K higher than the 20th century mean temperature
(1900–1960). The Little Ice Age cooling was culminated in 1720 when surface
mean temperature was 1.6 K below the 20th century mean temperature.
Secondly, contemporary warming began approximately one century prior to the
first instrumental measurements in the Urals. The rate of warming was
+0.25 K/100 years in the 18th century, +1.15 K/100 years in the 19th and
+0.75 K/100 years in the first 80 years of the 20th century. Finally, the mean rate
of warming increased in the final decades of 20th century. An analysis of
linear regression coefficients in running intervals of 21 and 31 years,
shows that there were periods of warming with almost the same rates in the
past, including the 19th century.
Bartlett, M. G. and Chapman, D. S.: The timing, depth, and duration of snow events: implication for ground surface temperature histories recovered from boreholes, 1998 AGU Fall Meeteng abstracts, San Francisco, F842, 1998.
Beltrami, H. and Mareshal, J.-C.: Recent warming in eastern Canada inferred from geothermal measurements, Geophys. Res. Lett., 18, 4, 605–608, 1991.
Demezhko, D. Yu. and Shchapov, V. A.: 80,000 years ground surface temperature history inferred from the temperature-depth log measured in the superdeep hole SG-4 (the Urals, Russia), Global and Planetary Change, 29(1–2), 219–230, 2001.
Demezhko, D. Yu.: Geothermal method for palaeoclimate reconstructions (examples from the Urals, Russia), Ekaterinburg, UB RAS, 144 p., 2001 (in Russian).
Demezhko, D. Yu., Utkin, V. I., Shchapov, V. A., and Golovanova, I. V.: Variations in the Earth's Surface Temperature in the Urals during the Last Millennium Based on Borehole Temperature Data, Doklady Earth Sciences, 403, 5, 764–766, 2005.
Golovanova, I. V., Harris, R. N., Selezniova, G. V., and \vStulc, P.: Evidence of climatic warming in the southern Urals region derived from borehole temperatures and meteorological data, Glob. Planet. Change, 29, 167–188, 2001.
Golovanova, I. V.: Thermal field of the South Urals, Moscow, Nauka, 189 pp, 2005 (in Russian).
Hansen, J. and Lebedeff, S.: Global trends of measured Air surface temperature, J. Geophys. Res., 92, 13 345–13 372, 1987.
Klimenko, V. V. and Klimanov, V. A.: Climate of the North Hemisphere in the Medieval Optimum, Doklady Akademii Nauk, 371, 4, 539–543, 2000 (in Russian).
Moberg, A., Sonechkin, D. M., Holmgren, K., Datsenko, N. M., and Karl'en, W.: Highly variable northern hemisphere temperatures reconstructed from low- and high resolution proxy data, Nature, 433, 613–617, 2005.
Pollack, H. N., Demezhko, D. Yu., Duchkov, A. D., Golovanova, I. V., Huang, S., Shchapov, V. A., and Smerdon, J. E.: Surface temperature trends in Russia over the past five centuries reconstructed from borehole temperatures, J. Geophys. Res., 108(A4), 2180, doi:10.1029/2002JB002154, 2003.
Pollack, H. N. and Smerdon, J. E.: Borehole climate reconstruction: Spatial structure and hemispheric averages, J. Geophys .Res., 109, D11106, doi:10.1029/2003JD004163, 2004.
Smerdon, J. E., Pollack, H. N., Cermak V., Enz, J. W., Kresl, M., Safanda, J., and Wehmiller J. F.: Daily, seasonal, and annual relationships between air and subsurface temperatures, J. Geophys. Res., 111, D07101, doi:10.1029/2004JD005578, 2006.
\vStulc, P., Golovanova, I. V., and Selezniova, G. V.: Climate Change in the Urals, Russia, inferred from Borehole Temperature Data, Studia Geoph. et Geod., 41, 225–246, 1997.
Shiyatov, S. G.: Rates of changes in the upper treeline ecotone in the Polar Ural Mountains, Pages Newsletter, 11(1), 8–10, 2003.
Tyson, P. D., Mason, S. J., Jones, M. Q. W., and Cooper, G. R. J.: Global warming and geothermal profiles: The surface rock-temperature response in South Africa, Geophys. Res. Lett., 25, 14, 2711–2713, 1998.