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Impacts of the Human Emisions on Climate Change in China

as Simulated by Multi-model Ensembles

Zong-Ci Zhao, Yong Luo, Xuejie Gao, Ying Xu, and Yihui Ding

Laboratory for Climate Research, Meteorological Administration, Bejing, China
corresponding e-mail: zhaozc12@ccsr.u-tokyo.ac.jp

1. Introduction

The IPCC WG1 2001 report reported on the global warming in the 20th and 21st centuries as simulated and projected by the many coupled GCMs with human emission scenarios (Houghton et al., 2001). Our research has focused on the impacts of the human emissions on the climate changes in China for the 20th and 21st centuries as simulated and projected by the totality of the available
multi-model and scenario ensemble. More than 25 runs from various climate models and scenarios have been employed and summarized in this research. Here CT represents control run; GG runs with increasing greenhouse gases only and GS runs with greenhouse gases plus sulphate aerosols. Note that the SRES scenarios A1, A2, B1 and B2 were used for the model CCSR/NIES. GCM7 represents the ensemble of CCCGG, CCSR/NIES1-GG, CSIRO-GG, DKRZ-GG, GFDLGG,HADL-GG, NCAR-GG, GCM7-GG, CCC-GS,
CCSR/NIES1-GS, CSIRO-GS, DKRZ-GS, GFDL-GS, HADL-GS, NCAR-GS, GCM7-GS, LASG/IAP1-GG, LASG/IAP2-GG, LASG/IAP2-GS, LASG/IAP2-GS, NCC/IAP T63-GG, NCC/IAP T63-GS, RegCM/CN-GG, RegCM/CN-GS, YONU-GG, CCSR/NIES2 SRES A1, A2, B1, B2. The method of ensembles used takes the simple mathematical mean of all models and scenarios (Luo and Zhao, 1997; Gao et al., 2001; Guo et al., 2001; Zhao and
Xu, 2002; Xu et al., 2002; Ma et al., 2002; Zhao et al., 2003).

2. Changes of the annual surface air temperature in China

Fig. 1 gives the evolutions of surface air temperature in China for the 20th and 21st centuries as simulated and projected by the climate models with the different scenarios. The anomalous correlation coefficients (ACC) of temperature for all models with GG and GS had much larger positive values than those of CT.

For example, the ACC of GCM7 were 0.37 (GG 1900~1999) and 0.74 (GS 1900~1999), 0.65 (GG 1950~1999) and 0.69 (GS 1950~1999), respectively (Table 1). They reached the 95% significant levels of the confidence. The ranges of ACC of the GCMs with the different emissions
are 0.07~0.74 for 1900~1999 and 0.26~0.69 for 1950~1999, respectively. The linear trends of the observed temperature in China were 0.39oC/100y for 1900~1999 and 0.78oC/50y for 1950~1999, respectively. The linear trends of the simulated temperature by GCM7 with CT were relatively small. The linear trends of temperature for GCMs with GG overestimated. The linear trends of
temperature for GCMs with GS in both 1900~1999 (0.38oC/100y) and 1950~1999 (0.71oC/50y) were near the observed values, especially for 1900~1999. The investigations also presented the similar situations for the maximum and minimum temperatures in China (Zhao et al., 2003). It means that the combined effects of both greenhouse effects and sulfate aerosols very likely cause the observed warming of the 20th century in China, especially for the last 50 years. It is also noticed in Fig.1, Tables 1 and 2 that results of the multi-model and scenarios ensembles were better than a single model to compare with the observations.

The linear trends of the annual mean temperature change in China for the 21st century are 4.9 oC/100y and 2.9 oC/100y as projected by the GCM7-GG and GS with the range 3.0~9.2 oC/100y and -0.3~6.9 oC/100y of all models and scenarios respectively. It is also noticed that the change of temperature in China for the 21st century as simulated by the GCM7-GG and GS is greater than the
global and East Asia changes , the linear trends of which were 3.7 oC/100y and 2.7 oC/100y with the ranges of 2.9~7.5 oC/100y and 0.4~5.5 oC/100y respectively.

3. Changes of the annual precipitation in China

Similar to the study of temperature, Fig. 2 shows the evolution of precipitation in China for the 20th and 21st centuries as simulated and projected by the climate models with the human emission scenarios. The anomalous correlation coefficients and linear trends of precipitation changes for the observations and the simulations by the models did not present any significant relationships (Tables are not shown). It means that there was no strong evidence and signal to indicate
precipitation change in China for the 20th century caused by the human emissions.

The calculations indicated that the linear trends of the annual precipitation in China for the 21st century are 48~60mm/100y as projected by the multi-model ensembles with a range of -78~185mm/100y by all models.

4. Conclusions and discussions

As summarized in the above sections, the simulations of the surface air temperature and maximum and minimum temperature in China by the multi-model and multiscenarios ensembles are better than a single model to compare with the observations in the 20th century.

Changes in the precipitation over China show no significant trend either in the observations or the models through the 20th century and are relatively small into the 21st century, implying some value in refining the use of the multi-model approach for prediction of future changes in this parameter.

The further research will concentrate on narrowing the uncertainties.

Acknowledgments

This research was supported by the IPCC-China project and the project on National Report of Climate Change (China). The authors sincerely thank the model groups and the DDC/IPCC for providing their simulations.

References

Gao, X., Z. Zhao, Y. Ding, R. Huang, and F. Giorgi, 2001: Climate change due to greenhouse effect in China as simulated by a regional climate model. Adv. Atmos. Sci., 18, 1224-1230.

Guo, Y., Y. Yu, X. Liu, and X. Zhang, 2001: Simulation of climate change induced by CO2 increasing for East Asia with IAP/LASG GOALS model. Adv. Atmos. Sci., 18, 53-66.

Houghton, J.T., Y. Ding, D.J. Griggs, M. Noguer, P.J. van der Linden, X. Dai, K. Maskell, C.A. Johnson (Eds.), 2001: Climate Change 2001: The Scientific Basis. Cambridge University Press, Cambridge, UK, 308-337.

Luo, Y., and Z. Zhao, 1997: Numerical simulation of East Asian regional climate with NCAR RegCM2. Quart. J. Appl. Meteor., 8, 124-133 (in Chinese).

Ma, X., 2002: The simulation of the climatic effects induced by external forcing factors. Chinese Academy of Sciences, PhD thesis, 137pp (in Chinese).

Xu, Y., 2002, A study of numerical simulation of impact of human activities on climate change. Chinese Academy of Meteorological Sciences, PhD thesis, 244pp (in Chinese).

Zhao, Z., and Y. Xu, 2002, Detection and scenarios of temperature change in East Asia. World Resource Review (USA), 321-333.

Zhao, Z., A. Sumi, C. Harada, and T. Nozawa, 2003: Projections of extreme temperature over East Asia for the 21st century as simulated by the CCSR/NIES2 coupled model. Proceedings of International Symposium on ClimateChange, WMO/TD No.1172, China Meteorological Press, Beijing, China, 158-164.

Source: Clivar Exchanges (No. 28 (Vol. 8, No. 4) December 2003)
2004.01.30