过去两千年青藏高原百年尺度温度变化的时空格局

Spatio-temporal Patterns of Centennialscale Temperature Change Over the Tibetan Plateau During the Past Two Millennia

基于青藏高原过去2000 a高分辨率的温度代用序列,通过区域对比以及集成分析方法,深入分析青藏高原过去2000 a温度变化的时空特征。结果表明:过去2000 a青藏高原温度变化可以划分为4个世纪尺度的冷暖时期,即0—600 AD和1400—1900 AD的冷期、600—1400 AD和20世纪的暖期,其中1400—1900 AD和600—1400 AD可能分别对应于欧洲的小冰期和中世纪暖期;青藏高原过去2000 a温度变化存在很强的季节性特征,年平均气温变化存在争议,但夏季温度变化较为一致;夏季温度记录表明20世纪升温并不是很显著,中世纪暖期是过去2000 a中升温最显著且最温暖的时段。目前,青藏高原过去2000 a古温度记录仍存在空白区域,转换函数的选取、气候指标的季节性差异以及定年误差等因素都可能增加温度序列的不确定性。未来,在青藏高原还需要重建更多高质量(高分辨率、有准确的年龄控制、明确的季节性以及精确的气候指示意义)的古温度记录,以更深入地揭示青藏高原温度变化的时空格局及机制。

Based on the high resolution temperature proxy series over the Qinghai-Tibet Plateau during the past two millennia,the spatial and temporal characteristics of temperature changes over the Qinghai-Tibet Plateau are analyzed by regional correlation and integrated analysis.The results reveal that temperature changes during the past two millennia can be categorized into four centennial-scale cold and warm periods:cold intervals in 0-600 AD and 1400-1900 AD,as well as warm intervals in 600-1400 AD and the twentieth century.The time periods of 1400-1900 AD and 600-1400 AD correspond to the Little Ice Age and the Medieval Warm Period in Europe,respectively.Temperature variations on the Tibetan Plateau over the past two millennia are not uniform and exhibit strong seasonality.While the patterns of mean annual temperature change on the plateau during this period remain inconclusive,summer temperature fluctuations generally display consistency.The summer temperature reconstructions suggest that the warmest period of the past two millennia occurred during the Middle Ages,rather than in the recent 20th century.Currently,the climate records on the Tibet Plateau during the late Holocene are still scarce.Seasonal bias,applicability of the transfer function,and chronological error might cause uncertainty in temperature reconstruction records.It is crucial to develop high-quality quantitative paleotemperature series with clear seasonality,site-specific proxy-temperature calibration,and better chronologic constraints in order to further reveal the spatio-temporal pattern and mechanism of temperature change on the Tibetan Plateau.