Geosciences Journal Vol. 14, No. 2, p. 173 - 190, June 2010 DOI 10.1007/s12303-010-0017-1 ⓒ The Association of Korean Geoscience Societies and Springer 2010 Climate response over Asia/Arctic to change in orbital parameters for the last interglacial maximum ABSTRACT: The climate response over Asia/Arctic to the change in orbital parameters for the last interglacial maximum (LIGM) is investigated using the NCAR CCM3. After implementing LIGM orbital parameters, the insolation decreases in January and increases in July in the northern hemisphere in comparison to present values. The reduced net short-wave radiative heat fluxes in January lead to the surface cooling in low to mid latitudes of Asia, whereas a warming is obtained in northern Asia where the net short-wave radiative heat fluxes change little. The January warm- ing in northern Asia/Arctic in the LIGM, consistent with proxy records, is mainly due to the marked increase in downward long wave heat fluxes associated with the increase in cloud and in part by the increase in the Arctic Oscillation polarity. In July, the increased insolation leads to the surface warming over most Asia, even though a slight cooling is obtained in low latitudes in spite of the increase in insolation, due to the decrease in the short-wave heat fluxes at the surface by the increase in the cloud amount. Pre- cipitation overall increases at South and East Asia in July, due to the stronger southwest and southerly winds. The change in inso- lation due to the orbital parameters determines the climate change pattern in low- to mid-latitudes over Asia in the LIGM, even though the degree of climate change is much lower than suggested by proxy estimates. The results obtained in this study implies that, under the different climate background such as future global warming, the change in greenhouse effect associated with cloud feedback could play an important role in determining the climate change over Asia/Arctic. Key words: last interglacial maximum, climate change, numerical sim- ulation, Asia/Arctic, orbital parameters 1. INTRODUCTION The last interglacial maximum (LIGM) occurred at 126,000 years before present (BP) provides opportunity to investi- gate the effect of orbitally induced insolation changes on regional climates (Kukla et al., 2002; CAPE-Last Intergla- cial Project Members, 2006). Many of paleoclimate proxy data have indicated that the LIGM climate was as warm as or warmer (from about 0.5 °C to 2.0 °C) than present (van der Hammen et al., 1971; Ruddiman and McKintyre, 1976; Woilard, 1978; Keen et al., 1981; Mangerud et al., 1981; Miller et al., 1983; De Vernal et al., 1986; LIGA members, 1991; Cortijo et al., 1994; Zagwijn, 1996; Aalbersberg and Litt, 1998; Kukla et al., 2002; EPICA Community mem- bers, 2006; CAPELast Interglacial Project Members, 2006, and references there in) and sea level was about 6 m higher than present level (Bloom et al., 1974; Ku et al., 1974; Dodge et al., 1983), due to the melting of the west Antarctic ice sheet (Stuiver et al., 1981) and melting of the Greenland ice sheet (Otto-Bliesner et al., 2006). The LIGM warming was observed to be much more pro- nounced in Asia than global level. For example, pollen records obtained in northern Asia suggested that air tem- peratures were higher during the LIGM by more than 10 °C in winter and 4-8 °C in summer in northern Siberia and 2-6 °C in winter and 1-2 °C in summer in the Lake Baikal, and precipitation was about 100-150 mm above the modern values with a spread of Taiga (Grichuk, 1969; Rindzyun- skaya and Pakhomov, 1977; Frenzel et al., 1992; Lozhkin and Anderson, 1995; Velichko et al., 1998; Tarasov et al., 2005). The warmer Asian climate during the LIGM is also supported by the enhanced Asian monsoon reconstructed by the analysis of stalagmites from Dongge Cave (Yuan et al., 2004) and increased precipitation in the lake Baikal (Granoszewski et al., 2005). In order to investigate the causes of the climate change in the LIGM, several lines of numerical experiments were per- formed. Using CCM1 atmospheric general circulation model (AGCM) coupled with mixed layer ocean model, Harrison et al. (1995) obtained warming by more than 8 °C in north- ern Scandinavia and Beringia over the Arctic in northern winter during the last interglaciation associated with the Seong-Joong Kim* Jun Mei Lü Sangheon Yi Taejin Choi Baek-Min Kim Bang Yong Lee Sung-Ho Woo Yoojin Kim } Korea Polar Research Institute (KOPRI), KORDI, PO Box 32, Incheon 406-840, Republic of Korea Chinese Academy of Meteorological Sciences, Beijing 100081, China Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon 305-350, Republic of Korea Korea Polar Research Institute (KOPRI), KORDI, PO Box 32, Incheon 406-840, Republic of Korea *Corresponding author: seongjkim@kopri.re.kr