ATMOSPHERIC AND OCEANIC SCIENCE LETTERS, 2012, VOL. 5, NO. 6, 495−498
Projected Changes in Köppen Climate Types in the 21st Century over
China
SHI Ying, GAO Xue-Jie, and WU Jia
The Laboratory of Climate Study, National Climate Center, China Meteorological Administration, Beijing 100081, China
Received 14 May 2012; revised 23 June 2012; accepted 25 June 2012; published 16 November 2012
Abstract Future changes in the climate regimes over
China as measured by the Köppen climate classification
are reported in this paper. The analysis is based on a
high-resolution climate change simulation conducted by a
regional climate model (the Abdus Salam International
Center for Theoretical Physics (ICTP) RegCM3) driven
by the global model of Center for Climate System Research (CCSR)/National Institute for Environment Studies
(NIES)/Frontier Research Center for Global Change
(FRCGC) MIROC3.2_hires (the Model for Interdisciplinary Research on Climate) under the Intergovernmental
Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A1B scenario. Validation of the
model performances is presented first. The results show
that RegCM3 reproduces the present-day distribution of
the Köppen climate types well. Significant changes of the
types are found in the future over China, following the
simulated warming and precipitation changes. In southern
China, the change is characterized by the replacement of
subtropical humid (Cr) by subtropical winter-dry (Cw). A
pronounced decrease of the cold climate types is found
over China, e.g., tundra (Ft) over the Tibetan Plateau and
sub-arctic continental (Ec) over northeast China. The
changes are usually greater in the end compared with the
middle of the 21st century.
Keywords: climate change, regional climate model,
Köppen climate, China
Citation: Shi, Y., X.-J. Gao, and J. Wu, 2012: Projected
changes in Köppen climate types in the 21st century over
China, Atmos. Oceanic Sci. Lett., 5, 495–498.
1
Introduction
The issues of climate change caused by increasing atmospheric greenhouse gases due to anthropogenic activities have drawn more and more attention from the climate
community and the general public. The projection of future climate at the regional and local scale is important for
the development of local, national, and international policies to mitigate and adapt to the threat of climate change.
However, as the primary tools in projecting future climate,
atmosphere-ocean coupled general circulation models
(AOGCMs) have deficiencies at this spatial scale because
of their coarse resolutions. These deficiencies are particularly apparent over the East Asia region because of this
region’s complex topography and unique weather and
climate systems. High-resolution regional climate models
Corresponding author: SHI Ying, [email protected]
(RCMs) can better meet these needs (Gao et al., 2001,
2006, 2008).
The Köppen climate classification (Köppen, 1936) is
one of the most widely used climate classification systems.
The Köppen classification can be used to validate the
model performance (e.g., Jacob et al., 2012). Future
changes of the Köppen climate types have been reported
by different authors on the basis of either global or regional climate model simulations (e.g., de Castro et al.,
2007; Gao and Giorgi, 2008; Ruble and Kottek, 2010).
Studies that have applied the Köppen climate classification over China in recent years include Xie et al. (2007)
and Baker et al. (2010), etc. However, few studies have
been performed with a focus on the future changes over
China, particularly studies based on high-resolution RCM
simulations.
In this paper, we present the projected changes of
Köppen climate types over China in the 21st century from
an RCM climate change simulation. A short description of
the model and simulation design, as well as the Köppen
climate classification, is provided in Section 2. A basic
validation of the model performance is given in Section 3.
The projected changes are then discussed in Section 4,
and conclusions are presented in Section 5.
2 Model simulations and the Köppen climate
classification
The simulation employed in the study was conducted
by the Abdus Salam International Centre for Theoretical
Physics (ICTP) RegCM version 3 (RegCM3) (Pal et al.,
2007). In the simulation, RegCM3 is driven at the lateral
boundaries from the global model of Center for Climate
System Research (CCSR)/National Institute for Environment Studies (NIES)/Frontier Research Center for Global
Change (FRCGC) MIROC3.2_ hires (the Model for Interdisciplinary Research on Climate) (Hasumi et al., 2004)
and is run at a 25 km grid spacing. The simulation period
is 1951–2100 plus three years of spin-up time, with observed CO2 concentrations before 2000 and SRES A1B
scenario concentrations (Nakicenovic et al., 2000) after
2000. Analysis has shown that RegCM3 improves the
simulation of the present day temperature and precipitation compared with that of the driving GCM (Gao et al.,
2012a, b), particularly in the monsoon precipitation.
Of the total 150 years’ simulation, the 1981–2000 period is considered as the present day, 2041–2060 is as the
middle period, and 2081–2100 is as the end of the 21st
century. The temperature and precipitation datasets de-
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ATMOSPHERIC AND OCEANIC SCIENCE LETTERS
veloped by Wu and Gao (2012) at a 0.25°×0.25° (latitude
by longitude) resolution are employed to validate the
model performance. The model outputs are also interpolated from 25 km×25 km to this 0.25°×0.25° grid.
We used a modified Köppen climate classification described by Trewartha and Horn (1980), which is developed from Köppen (1936). The classification is based on
a combination of average annual, monthly, and seasonal
surface air temperature and precipitation, and it divides
climate into six main groups from A to F, each having
several types and subtypes, as shown in Table 1. The
original classification of Köppen (1936) is also provided
for a comparison between the two.
3
Model validation
Figures 1a and 1b compare the distribution of Köppen
climate types over China as obtained from the observation
dataset and from the present-day simulation of the model,
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respectively. As shown in Fig. 1a, subtropical humid (Cr)
is dominant south of the Yangtze River over eastern China,
followed by a transition zone of temperate oceanic (Do)
to the north. Temperate continental (Dc) covers parts of
North China and most part of the Northeast China, except
for sub-arctic continental (Ec) in the northernmost region
and dry semiarid (Bs) in the middle. Dry arid (Bw) and
semiarid (Bs) climates dominate in Northwest China except over the mountains, where Dc, Ec, and tundra (Ft)
exist. General distributions of Ft are found over the Tibetan Plateau, and subtropical winter-dry (Cw) is found in
southwest China and the Sichuan Basin.
The model mostly reproduces this observed distribution of Köppen types, as shown in Fig. 1b. The largest
differences are mainly found in northern and northeastern
China, with a broader distribution of Dc instead of Bs,
and in the northwestern part of the Tibetan Plateau, with
Fi (ice cap) and Ft instead of Bs in the observation. The
Table 1 Modified Köppen-Trewartha (K-T) and Köppen climate types and definitions of K-T climate classification.
Climate
K-T
Köppen
Definitions
Tropical humid
Ar
Af
Tropical wet-dry
Aw
Aw, As
Dry arid
Bw
Bw
Annual precipitation P (in cm) ≤0.5×A(2)
Dry semiarid
Bs
Bs
Annual precipitation P (in cm) >0.5×A(2)
Subtropical summer-dry
Cs
Cs
8–12 months >10°C, annual rainfall ≤89 cm and dry summer(3)
Subtropical summer-wet
Cw
Cw
Same thermal criteria as Cs, but dry winter(4)
Subtropical humid
Cr
Cf
Same as Cw, with no dry season
Temperature oceanic
Do
Cf, Cw
Temperature continental
Dc
Df, Dw, Ds
Sub-arctic oceanic
Eo
Df, Dw, Ds
Up to 3 months >10°C, coolest month >–10°C
Sub-arctic continental
Ec
Df, Dw, Ds
Up to 3 months >10°C, coolest month ≤–10°C
Tundra
Ft
Et
All months <10°C
Ice cap
Fi
Ef
All months <0°C
All months>18°C, less than 3 dry months(1)
Same as Ar, but 3 or more dry months(1)
4–7 months >10°C, coolest month ≥0°C
4–7 months >10°C, coolest month <0°C
(1) Dry month: Less than 6 cm monthly precipitation.
(2) A=2.3T–0.64Pw+41, where T is the mean annual temperature (in °C) and Pw the percentage of annual precipitation occurring in the coolest six
months.
(3) Dry summer: The driest summer month with less than 3 cm precipitation and less than 1/3 of the amount in the wettest winter month.
(4) Dry winter: Precipitation in the wettest summer month greater than 10 times that of the driest winter month.
Figure 1 Calculated Köppen climate types in the present day (1981–2000): (a) observation; (b) simulation by RegCM3 (Aw: tropical wet-dry, Bs:
dry semiarid, Bw: dry arid, Cw: subtropical summer-wet, Cr: subtropical humid, Do: temperate oceanic, Dc: temperate continental, Eo: sub-arctic
oceanic, Ec: sub-arctic continental, Ft: tundra, and Fi: ice cap).
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SHI ET AL.: PROJECTED CHANGES IN KÖPPEN CLIMATE TYPES OVER CHINA
discrepancy of the difference in northern and northeastern
China can be mostly attributed to the overestimated precipitation over the areas, as shown in Gao et al. (2012a).
For the difference in the northwestern part of the Tiberan
Plateau, it may largely be due to the quality of the observation data over this inhabited area, with almost no station
observations available (Wu and Gao, 2012). The precipitation in this area is interpolated from the stations in the
north surrounding the Tarim Basin and the Taklimakan
Desert, which may lead to the great underestimation over
the Tibetan Plateau (see Wu et al., 2011, for further details). Similarly, the possible absence of greater precipitation over the eastern part of the Tianshan Mountains in the
observation dataset (the stations are usually located in
valleys and plains with less precipitation) may contribute
to the differences of Ec and Dc in the simulation but Bw
in the observation. Finally, the overestimation of precipitation in winter leads to the dominance of Cr instead of
Cw in the Sichuan Basin.
4
Future changes
As is common in climate change and impact studies, a
perturbation method is used in the analysis of future
changes of Köppen climate zones in the present study
(e.g., Arnell et al., 2003; Gao and Giorgi, 2008; Shi et al.,
2010). The method consists of adding the temperature and
precipitation change signals from the future simulations to
the observed climate. This step is performed to filter out
the bias in the simulation over the region, as discussed in
Section 3 and in Gao et al. (2012a). The resulting scenarios of the Köppen climate zones in the middle and end of
the 21st century are shown in Figs. 2a and 2b, respectively,
which should be compared with Fig. 1a.
Dramatic changes of the Köppen climate types in the
mid-21st century can be found over the Tibetan Plateau,
characterized by the replacement of Ft by a drier climate
of Bs in the western part and Dc in the eastern part. The
most obvious change in the northeast is the disappearance
of Ec, the sub-arctic continental climate, due to warming.
A greater increase of Aw (tropical wet-dry climate) over
Hainan Island can be found, reaching the nearby coast in
Guangdong. A northward shift of Cr and a retreat of Do
are observed in eastern China. Cw shows the extension
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from southwest China to the southern coastal areas in the
east, mostly due to the decrease of precipitation there in
the cold months (Gao et al., 2012a).
These changes in Köppen climate types are generally
larger in the end of the 21st century (Fig. 2b). One of the
most significant changes in eastern China is the widespread replacement of Cr by Cw. This change is caused by
the different directions of the precipitation changes in the
middle (increase) and end (decrease) of the 21st century
there (Gao et al., 2012a). A general retreat of Ft replaced
by Dc, Eo (sub-arctic oceanic climate), Ec (sub-arctic
continental climate), and Bs is found over the Tibetan
Plateau, while a further extension of Aw from Hainan
Island to the coastal areas of Guangdong and Guangxi in
the continent is found.
The percentage of coverage of the Köppen climate
types over China for the present day and the middle and
end of the 21st century are presented in Fig. 3. Bs is the
dominant type over China in the present day, accounting
for 23.1%, and it will further extend to 26.9% and 25.9%
in the middle and end of the 21st century, respectively. A
retreat of Bw, Cr, and Ft is found in general in the future.
Among these changes, the decrease of Ft is more significant in the mid-21st century, following the large reduction
in its major distribution area in the Tibetan Plateau. A
slight increase in the mid-21st century followed by a larger decrease reaching 6.6% at the end of the 21st century
are found for Cr. The coverage of Bw decreases from
19.0% in the present day to 17.7% and 16.7% in the middle and end of the 21st century, respectively. The decrease
of Ft can be attributed mostly to warming, while that of
Cr and Bw is mostly due to the change in precipitation.
An expansion of Aw, Cw, Dc, and Do is found. The Aw
coverage increases from 0.2% in the present day to 0.4%
and 1.0% in the middle and end of the 21st century, respectively. The changes of Cw and Dc show a slight increase in the mid-21st century, but a larger increase at the
end of the century.
5
Conclusions
In this paper, we analyze the changes of climate zones
over China using the Köppen climate classification in the
21st century under increased greenhouse gas concentra-
Figure 2 Calculated Köppen climate types in the future: (a) Mid-21st century (2041–2060); (b) End-21st century (2081–2100). The colors represent
the different types, as in Fig. 1.
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Figure 3 Distribution of Köppen climate types in the present day
(1981–2000) and in the middle (2041–2060) and end (2081–2100) of the
21st century over China (%).
tions (A1B scenario) as simulated with the high-resolution (25 km grid spacing) RegCM3. Validation of the
model’s performance shows that it reproduces the distribution of the observed Köppen climate patterns well, although with discrepancies associated with the biases of
the temperature and precipitation simulation.
Changes of climate types are found in the future. The
magnitude of these changes is usually in line with the
time evolution for most of the types, although exceptions
can be found for Bs, Cr, Eo, and Ec. Increases in type Dc
are found in the northern part of China and along the
edges of the Tibetan Plateau. An increase of Cw and a
decrease of Cr are found in southern China due to the
decrease in winter precipitation over the region. The
warming leads to a significant decrease of Ft over the
Tibetan Plateau and the complete disappearance of Ec in
the middle and end of the 21st century in Northeast
China.
Changes of the Köppen climate classification also indicate a shift in potential vegetation cover in the future
over China. However, more studies are needed to examine
the changes in vegetation cover, preferably conducted by
more complicated models (e.g., Zhang, 1993; Zhang and
Zhou, 2008; Yu et al., 2010; Jiang et al., 2011).
Acknowledgements. This research was jointly supported by the
Special Research Program for Public-Welfare Forestry (Grant No.
200804001) and the National Basic Research Program of China
(Grant No. 2009CB421407).
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