ISSN 1028334X, Doklady Earth Sciences, 2013, Vol. 449, Part 1, pp. 319–323. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © M.M. Arzhanov, I.I. Mokhov, 2013, published in Doklady Akademii Nauk, 2013, Vol. 449, No. 1, pp. 87–92.
GEOPHYSICS
Temperature Trends in the Permafrost of the Northern Hemisphere:
Comparison of Model Calculations with Observations
M. M. Arzhanov and Corresponding Member of the RAS I. I. Mokhov
Received October 2, 2012
Abstract—We present the results of analysis of numerical calculations of the thermal state of permafrost
grounds at different depths using a model of heat and moisture transport in the ground developed at the
Oboukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS). For highlatitude
regions of Russia, the modelestimated temperature trends in grounds (around 0.3°C/10 years at a depth
of 3 m) are quite consistent with empirical estimates for the past few decades.
DOI: 10.1134/S1028334X1303001X
We compare the estimates of contemporary tem
perature trends in permafrost grounds of the Northern
Hemisphere (NH) obtained by model calculations
with observational data for the past few decades. We
present the results of analysis of numerical calcula
tions of the thermal state of permafrost grounds at dif
ferent depths using a model of heat and moisture
transport in the ground (DMPG) developed at the
Oboukhov Institute of Atmospheric Physics, Russian
Academy of Sciences [1]. In estimating the contem
porary temperature trends at different depths in the
permafrost on the basis of DMPG, the innerannual
and interannual variations in atmospheric effects
(forcing) and the corresponding boundary conditions
on the surface were specified using monthly mean
reanalysis data for the past few decades. The quality of
model calculations was assessed in comparison with
local data of longterm temperature measurements at
different depths in the permafrost at geocryological
stations. The model estimates of temperature trends in
the ground were compared as a function of latitude
and longitude with empirical estimates based on data
from meteorological and geocryological stations for
the second half of the 20th century and the early 21st
century. In general, for highlatitude regions of Rus
sia, the model estimates for temperature trends in
grounds (around 0.3°C/10 years at a depth of 3 m) are
quite consistent with empirical estimates for the past
few decades [2, 3]. In addition, we obtained estimates
for possible temperature trends in the permafrost of
the NH using DMPG with various values of atmo
spheric forcing according to calculations with differ
ent global climate models under the SRESA1B sce
nario of anthropogenic impacts for the 21st century.
The problem of changes in the permafrost regime is
not only of regional (particularly, for Russian regions)
Obukhov Institute of Atmospheric Physics, Russian Academy
of Sciences, Pyzhevskii per. 3, Moscow, 119017 Russia
email: [email protected]
but also global importance [4–12]. Permafrost degra
dation causes considerable damage, and the risk of
adverse effects should increase with warming [4, 5].
This problem is particularly significant for Russia,
where permafrost covers around twothirds of the coun
try. This problem is especially significant for the Asian
territory of Russia with towns and relevant communica
tion systems, power lines, and oil and gas pipelines in
permafrost areas. The degradation of permafrost due to
global warming destabilizes and dissociates methane
hydrates with potentially large atmospheric emissions
of methane, which is a much more radiatively active
greenhouse gas than carbon dioxide [12].
In assessing the contemporary temperature trends
at different depths in the permafrost on the basis of
DMPG, the innerannual and interannual variations of
atmospheric forcing and the corresponding boundary
conditions at the surface were specified using monthly
mean reanalysis data ERA40 [13] for the past few
decades. For comparison, we used spatially interpo
lated data of longterm measurements of ground tem
perature at 65 meteorological stations (at depths of 1.6
and 3.2 m) and 8 permafrost stations (to a depth of
10 m) in northern Russia [2, 3].
The basic version of the onedimensional DMPG
has 500 levels with a full depth of the calculation layer
of 310 m and a step of 5 cm for the upper 10 m and 1 m
for the subsequent layers. The upper 40 levels relate to
the snow cover. Two levels are covered by the organic
layer, the thermophysical characteristics of which
largely affect the permafrost parameters [1].
For a more detailed testing (how adequate is the
model in reproducing the thermodynamic regime of
frozen grounds?), this study used longterm measure
ment series of ground temperature profiles at a num
ber of geocryological stations (see http://nsidc.org/
data/docs/fgdc/, http://gcmd.nasa.gov). In particu
lar, two of the selected stations (67.4° N, 63.38° E (I);
67.45° N, 63.35° E (II)) are located in the Russian
Arctic (in the Ob River basin), another station
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ARZHANOV, MOKHOV
T, °C
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1969 1971 1973 1975 1977 1979 1981
Fig. 1. Modeled (solid lines) and observed (dots) data for ground temperature at geocryological stations I, II, and III: (I) at depths
of 2 m (a) and 3 m (b); (II) at depths of 5 m (c) and 7.5 m (d); (III) at depths of 1 m (e) and 3 m (f). The dashed line indicates the
variations in ground temperature at the upper level.
(69.0° N, 51.0° E (III)) is located on the southwestern
coast of Greenland (Ilulissat). To validate the model
calculations for each station, the longest continuous
series of ground temperature measurements were
selected [14, 15]. The total length of the selected series
of monthly mean data is 8 years (1989–1996) for sta
tion I, 7 years (1978–1984) for station II, and 13 years
(1969–1981) for station III.
These numerical experiments used as input data
linearly interpolated (with a step of 24 h) monthly
mean ground temperature data at the upper level. The
results of comparisons of calculated temperature at
different depths with observed data for the three
selected stations are shown in Fig. 1. For station I, the
model almost exactly reproduces the annual varia
tion of ground temperature from observation data of
1989–1996, in particular, at depths of 2 and 3 m
(Figs. 1a, 1b). The model likewise adequately repro
duces the specific features of interannual variability
characteristic of this station, including the significant
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TEMPERATURE TRENDS IN THE PERMAFROST OF THE NORTHERN HEMISPHERE
temperature drop in early 1989 and the relatively weak
interannual variability of ground temperature in
1994–1996. For station II, the model reproduction of
the annual variation and interannual variability of
ground temperature is likewise adequate, particularly
at depths of 5 and 7.5 m (Figs. 1c, 1d). There is some
difference between model estimates and observation
data at the depth of 5 m in early (January to March)
1979 (Fig. 1c). For station III also, the numerical
experiments show a good quantitative agreement
between modeled and observed data (Figs. 1e, 1f). For
a depth of 1 m, the comparison was conducted with the
available observational data for 1969–1971 (Fig. 1e).
For a depth of 3 m, the model estimates have smaller
amplitudes of the annual harmonic for 1969–1973.
For 1974–1981, the calculated values of ground temper
ature are quite consistent with observed data (Fig. 1f).
For all the stations considered, the model reproduces
well the observed decrease in the amplitude of the annual
variation of ground temperature with increasing depth.
Figure 2 presents the estimates of linear trends of
annualmean surface temperature according to ERA40
data for 1965–2001 and the annualmean ground
temperature at a depth of 3 m according to model cal
culations for mid and high latitudes of the NH. The
maximum trends in surface warming were obtained for
Western Siberia, some areas of Yakutia, and northern
Alaska. A comparison of Fig. 2a and Fig. 2b for the
spatial distributions of trends of air temperature near
the surface and the ground temperature indicates only
a partial coincidence between the corresponding
domains of maximum and minimum temperature
trends. The maximum (over 0.05°C/year) trends of air
temperature near the surface and grounds coincided in
the central and northern parts of Western Siberia.
There are regions where against the background of high
trends of surface warming no significant trends of ground
temperature were found. In particular, minimum trends
(less than 0.01°C/year) of ground temperature were
obtained in northern East Siberia and in mid and high
latitude areas of North America, and the surfacetemper
ature trends here can reach 0.04°C/year. One should also
note the areas of ground temperature trends found by
model calculations, which exceed the trends of air tem
perature near the surface (Transbaikalia, some regions of
East Siberia, and Alaska).
The resulting model estimates for ground tempera
ture were compared with the latitude–longitude dis
tribution of the groundtemperature trend in northern
Russia according to observations at meteorological
and geocryological stations in 1966–2005 [3]. The
results of comparison between model and empirical
estimates for the trends of ground temperature indi
cate that the areas of maximum values in the central
part of Western Siberia and Yakutia largely coincide.
The absolute values of the model trends of ground
temperature in these regions are consistent with esti
mates obtained from observations. In particular,
according to observations, the groundtemperature
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0.01
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Fig. 2. Trends (°C/year) of annualmean air temperature
near the surface by ERA40 reanalysis data (a) and annual
mean ground temperature by model calculations (b) for
1965–2001.
trend in Yakutia was estimated to be 0.033°C/year [3].
The corresponding model estimate for the regional
groundtemperature trend of 0.032°C/year is quite
consistent with the empirical estimate. A good agree
ment between regional modeled and observed trends
of ground temperature was obtained for northern East
Siberia: 0.021 and 0.024°C/year, respectively. In this
case, the model estimate for the trend of ground tem
perature (0.044°C/year) was significantly higher than the
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ARZHANOV, MOKHOV
(а)
(b)
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Fig. 3. Trends (°C/year) of annualmean ground temperature in the 21st century by calculations with DMPG and changes in atmo
spheric forcing according to the numerical results from the global climate models INMCM3_0 (a), CCCMA_CGCM3_1_T63 (b),
UKMO_HADGEM1 (c), and GISS_AOM (d) under the scenario of moderate anthropogenic impact SRESA1B.
empirical estimate (0.031°C/year) for Western Siberia.
For northern Russia in general, the trend of ground tem
perature by model calculations (0.032°C/year) is quite
consistent with the trend (0.030°C/year) estimated in [3]
from observation data.
Good model reproduction of not only the annual
mean regimes and annual variation of the thermal
state of permafrost grounds in key regions of their dis
tribution, but also contemporary regional trends is a
necessary, although not sufficient, condition for the
adequacy of respective model estimates for different
scenarios of possible climate changes. To estimate the
possible changes in the thermal states of permafrost
grounds in the 21st century, we used the new DMPG to
perform numerical experiments with changed values of
the atmospheric forcing according to calculations by
the global climate models CCCMA_CGCM3_1_T63,
GISS_AOM, INMCM3_0, UKMO_HEADGEM1
(within the CMIP3 international project: http://
wwwpcmdi.llnl.gov/projects/cmip/) for the scenario
of moderate anthropogenic impact SRESA1B.
Figure 3 shows the calculated linear trends of
annual mean ground temperature in the 21st century
at a depth of 3 m for mid and highlatitude areas of
the NH. The differences in Fig. 3 indicate that there
are significant differences in changes in the atmo
spheric effects of global climate models. This is due to
differences not only in regional changes of air temper
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TEMPERATURE TRENDS IN THE PERMAFROST OF THE NORTHERN HEMISPHERE
ature at the surface, but also precipitation, and thus
the regime of snow cover, including the water equiva
lent and duration of snow cover. The changes in the
permafrost regime are largely related to changes in the
regime of snow cover, which are significantly (up to the
sign) different in various (particularly, Russian)
regions.
The largest areas with extreme values of the trend of
ground temperature (more than 0.05°C/year) in the 21st
century at high latitudes of the NH were obtained using
the estimates of climate changes according to calcula
tions with the models CCCMA_CGCM3_1_T63
UKMO_HADGEM1 (Figs. 3b, 3c). The length of the
corresponding regions is significantly smaller for esti
mates of climate changes according to calculations
with the GISS_AOM and especially INMCM3_0
models (Figs. 3a, 3d). One should particularly note the
significant differences in the estimates of possible
trends of ground temperature in West Siberia, Alaska,
and Greenland. For more reliable estimates of the cor
responding trends in Greenland, simulation of the ice
sheet should be adequate.
The rather good agreement of contemporary trends
of ground temperature between the modeled and
observed data suggests that the dynamic model of heat
and moisture transfer in the ground developed at the
IAP RAS is useful for both qualitative and quantitative
estimates of local and regional changes in the perma
frost under climate changes. This model makes it pos
sible to analyze the relative contribution of different
factors to the formation of groundtemperature
trends, except for the surface temperature of the pre
cipitation regime in particular. Such an analysis is nec
essary because the mentioned regional trends of sur
face temperature and ground temperature are signifi
cantly different, which is, among other factors, due to
regional trends of the water equivalent and duration of
snow cover. The revealed uncertainty in the estimates
for regional changes in ground temperature on the
basis of calculations with different global climate
models confirms the need for a detailed regional anal
ysis of the effect of different factors on the formation
of the trends in permafrost changes.
ACKNOWLEDGMENTS
This work was supported by the Russian Foundation
for Basic Research (project nos. 110500576a, 1205
01092a, 120533050molaved, 110500579a,
110500531a, 120591323SIG_a, and 1105
12024ofi2011), the President of the Russian Federa
tion (grant no. NSh_5467.2012.5), the Ministry of
Education and Science of the Russian Federation
(state contract nos. 11.519.11.5004, 16.525.11.5013,
21.519.11.5004, and 11.519.11.5006, 74OK/114),
and programs of the Russian Academy of Sciences.
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