运用子波分析方法探讨了δ¹⁸O和积累量记录多尺度振荡特征,发现在年代际尺度上近百年来的升温仅是近2000年来的一次正常波动;在百年尺度上的升温是过去1700年来最强烈的一次,小冰期的三次冷期在该时间尺度上表现最明显,而中世纪暖期没有明显的反映。在温度和降水的组合中,无论在年代际尺度,还是在百年尺度和千年尺度上,暖湿、暖干、冷湿和冷干等四种类型的温湿组合气候都出现了。但是,在百年尺度上,以公元800's为界,气候出现了转型,在此之前为暖干、冷湿,此后呈现暖湿、冷干的气候特征。伴随着气候状态转折的是200年左右的周期发生了根本变化,之前该周期不明显,此后该周期的功率很强,达到了95%的信度标准。

Multi-timescale oscillating features of δ¹⁸O and glacial accumulation are approached by using wavelet analysis technique. We found that the warming of recent 100 years is only one of normal fluctuations under the background of the last 1700 years on inter-decadal time-scale. On century time-scale, however, the recent 100 years warming is the strongest, the three cold stages of the Little Ice Age occurred remarkably, but the Medieval Warm Period didn't take place. On the combination of temperature and precipitation, all four climatic types such as warm-wet, warm-dry, cold-wet and cold-dry appeared whether on inter-decadal or on century and millennium time scales. In addition, on the century time-scale, around the 800's A. D. was one key transition period of climatic change, the climate before the period was characterized by warm-dry and cold-wet type and warm-wet and cold-dry after the period. With the transition of climatic condition, the 200a period or so changed too. Its power was not obvious before the 800's but very strong afterwards with 95% confidence level.