Climate of the Past Discussions
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2007
10.5194/cpd-3-1-2007
http://www.clim-past-discuss.net/3/1/2007/
http://www.clim-past-discuss.net/3/1/2007/cpd-3-1-2007.html
http://www.clim-past-discuss.net/3/1/2007/cpd-3-1-2007.pdf
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17
2007-01-10
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 AD 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 for obtaining 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 was 0.38 K higher than the 20th century mean temperature
(1900–1960). The Little Ice Age cooling was culminated in 1720 when surface
mean temperature was 1.58 K below than 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
+0.25K/100years in the 18th century, +1.15 K/100years in the 19th and +0.75
K/100years in the first 80 years of the 20th. Finally, the mean rate of
temperature warming increased in final decades of 20th century. An analysis
of linear regression coefficients in running intervals of 11, 21 and 31
years, shows that there were periods of warming with almost the same rates
in the past, including the 19th century.
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