试论未来极端气候事件发展趋势的不确定性

极端气候事件是在一定时间尺度上发生的不同于气候系统平均状态的气候突变.早第三纪的最热事件（PETM）,第四纪中国黄土高原古土壤S4、S5记录的暖湿事件,砂黄土L9、L15记录的干冷事件等都是在轨道时间尺度上发生的极端气候事件.末次冰消期的YD冷事件、全新世9次冷事件是在千—百年尺度上发生的极端气候事件.这些极端气候事件出现于地球气候系统不同的冷暖背景下,它们的成因机制和表现形式有很多不确定性.20世纪以来发生的干旱、洪水、飓风、雪灾、沙尘暴等极端气候事件,无法用持续增加的温室气体的变化来解释.关于极端气候事件发生频率和强度随＂全球变暖＂而增加的结论也存在一定程度的不确定性.因此,简单地将现代极端气候事件统统归因于＂气候变暖＂既不科学也不合理.深入研究各个时间尺度上发生的极端气候事件的波动性、周期性和不确定性特征,有助于科学预测未来气候变化背景下极端气候事件的发展趋势.

Discussion on the Uncertain Development Tendency of Extreme Climate Events in Future

Variations and trends in extreme climate events have recently received much attention since it is becoming more frequently and costly.Extreme climate events are happening on a certain time scale,being different from the abrupt climate change of climate system on the average state.The extreme climate events had happened at orbit scales and Millennial-Centennial scales,such as Paleocene-Eocene Thermal Maximum,the great warmth in Quaternary reflected by S4,S5 soils,and the severe dry-cold periods evidenced by the L9 and L15 at Chinese Loess Plateau,and the Younger Drays Event,the nine severe cold events respectively occurred in the last deglaciation and Holocene.These extreme climate events appeared in the earth′s climate system under the background of different changes in temperature,however,there are a lot of uncertainties in their formation mechanism and representation.Since the 20th century,many extreme climate events such as droughts,floods,hurricanes and dust storms have taken place,which could not be explained only by the increasing of greenhouse gas,and the conclusion that the frequency and intensity of extreme climate events would increase along with the global warming still remains uncertain.Therefore,it is neither scientific nor reasonable if we simply ascribe modern extreme climate events to climate warming.So,an intensive study for the volatility,periodicity and uncertainty of the extreme climate events happened at different time scales will help us to predict the development tendency of extreme climate events under the background of climate change in the future.