The Past Century Of Abrupt Climate Change And Extreme Events, The Detection And Attribution Of A Preliminary Study

Based on the normalized high-resolution climatic proxy data, high-order moment method is used to detect the climate extreme anomalies in recent 2000 years in this paper first. Meanwhile, combining with filtering method to abstract the dominant components with physical backgrounds from the normalized data, then, analyze the information and its contribution of each component of the climate extreme events. The results show that: (1) On the timescale of more than 100 years, climatic oscillation with the period of about 1000 years may exits; besides, the 20th century is the most active period of climate extreme anomaly phenomenon in recent 2000 years, it may correspond to an active period of climate extreme anomaly phenomenon. (2) On 20-60-year timescale, climate extreme anomaly phenomenon in the period of A.D. 300-1100a is relatively distinctive and that in time span of A.D.1100-1980a is comparatively mitigative. Possibly, this level makes no considerable contribution to the climatic anomaly of 20th century. This level and the century scale both reflect that for climatic change in recent 2000 years, the year around A.D. 1100a maybe the key period of climate transition. (3) On the interannual timescale (less than 20years), the years of occurrences of climatic extreme anomalies reflected in Beijing Shihua cave stalagmite proxy records has good correspondence with that of the E1 Ni?o or La Ni?a events (in this paper, only the period of 1960-1980a considered). (4) high-order moment method has a good prospect in detecting the climatic extreme events.As abrupt climate changed and extreme events are often linked together. The second parts of this paper is that: based on physical backgrounds, the four time series of the Gulia (Qinghai-Xizang plateau) ice core (GIC)δ18O, and natural factors, i.e. the rotation rate of earth, sunspots, and ENSO signals are decomposed into two hierarchies of more and less than10-year, and then the running t test is used to reanalyze the data before and after filtering on purpose to investigate the contribution of natural factors to the abrupt climate change in the last one hundred years. The detection and analysis results show that the GICδ18O possesses a quasi-period of 7-9 years, and the abrupt climate changes in the early 1960s and from the end of the 1970s to the beginning of the 1980s arise from the joint effect of the two hierarchies, in other words, the two interdecadal abrupt changes of climate in the last one hundred years are global. The interannual variations of ENSO and sunspots are the important triggering signals for the abrupt climate changes in the last one hundred years. At last, the method of information entropy is employed to estimate the contributions of ENSO signals and sunspots activities to the abrupt climate changes, and it is found that the contribution of the interannual variation of ENSO signals is larger.Based on the above work, the third parts of this paper is that: First, we use the traditional detected abrupt events methods to analysis the series of the Guliya ice core (glacial accumulation) and get the relation and the difference between the detected methods. Second, do research of the relation and the difference between the years of the extreme events and the abrupt years. The results show that (1) as to the abrupt detected, the abrupt years detected will drift with the difference length of the sequence. The length of the sequence is longer and the numbers of the abrupt years will become less, other will become more. But in both cases, the obviously of the abrupt years all been reflected. (2) The abrupt years detected by the running t-test and the Yamamoto are the same. This possibly because although the two methods of the criteria are different, the inspection of the points are the same, i.e. they all differentiate the abrupt by reviewing whether the two series average means are notable. The abrupt years detect by the Crammer's method is the only parts of by the Yamamoto method, and the Mann-Kendall method cans only detect the beginning of the abrupt years. (3) Used the same detected abrupt method to analyze the original series of the Guliya ice core and its irregular mean, the result been got are nearly the same. The possible reason is that the trend can be ignored by used the abrupt method. (4)The extreme events possibly happened between the two abrupt events.