中文摘要：

气候冷暖变化问题是全球科学家研究的一个聚焦点,但高海拔地区的气候变化过程尚不十分清楚,作为全球气候变化的敏感区的青藏高原更是如此.以青藏高原北部的古里雅冰芯、唐古拉冰芯和南部的达索普冰芯、宁金岗桑冰芯δ18O记录作为温度代用指标,同时结合青藏高原西北缘的吉尔吉斯斯坦Naryn站长期气象记录和北半球同时期的气温变化进行比较,研究了过去100 a来青藏高原北部和南部的温度变化.结果显示：青藏高原过去100 a来共出现1910年左右、1920年左右、1950年左右、1970年代4个冷期,各冷期之间对应出现4次暖期,并且变冷的程度越来越弱而变暖的程度越来越强.其次,青藏高原气候的变冷变暖在不同地区和不同时段差异很大：从空间尺度上看,青藏高原北部变暖过程比南部更强烈;从时间尺度上看,1910年左右和1920年左右的两次变冷十分明显,但1950年左右和1970年代的两次变冷不明显.另外,虽然有发生在1990年代早期的短暂降温过程,但与其说是一个冷事件,还不如说是一次变暖过程中的短暂停顿,随后表现为持续升温.

英文摘要：

Climatic change is focused intensely by worldwide scientists. However,it is not clear how climate changes at high elevation,particularly,on the Tibetan Plateau with an average altitude of more than 4 000 m. In this study,a comparison of δ18O values as temperature proxies from ice cores extracted from Guliya,Tanggula,Dasuopu and Ningjingangsang during the past 100 years is conducted. Meteorological records from Naryn and Northern Hemisphere for the same period are compared with the four ice cores records. The result shows that the Tibetan Plateau has experienced four cold periods during the 100 years： around 1910, around 1920,around 1950 and the 1970s. In addition,four warm periods had appeared after each cold event. Furthermore,the warming trend was getting stronger and stronger while the cooling trend was getting weaker and weaker. Spatially, the warming process in northern Tibetan Plateau was stronger than that in the southern Tibetan Plateau. Temporally,two cold periods around 1910 and around 1920 were recorded obviously,and the other two cold periods of around 1950 and the 1970s were inconspicuous. Although there was a short cooling event in the early 1990s,it was defined not as a cold period,but as a pause during a warming trend,followed by a continuous climate warming after that event.