Geological Records of Volcanic Explosions during the Last 12000 Years and the Volcanic Impacts on Climate Changes

Abstract

全新世气候变化的动力成因至今未有定论.大量地质证据揭示了全新世气候多次降温并反映出与火山爆发有时间对应关系.现代气候观测证明了火山灰进入平流层滞留后随环流扩散成为太阳辐射的屏障层从而导致地表降温.停留在地质火山爆发和全新世气候在逐个点遥相关研究上难以从宏观机制上加以认识.本文试图对地质火山影响古气候变化的定性推论与现代火山气候效应这两个环节给予动力机制上的联系和分析.通过火山地质记录的现代气候效应类比对地质火山数据进行集成所反映的五次全新世强火山爆发集中期与地质记录的寒冷期/降温期/新冰期能够对应.对火山爆发集中期和平静期两种气候状况通过三维大气环流模式进行气候数值模拟评估火山灰产生的不同区域的降温效应.模拟结果表明火山灰阳伞效应造成北半球年平均温度普遍降低且具有明显的区域差异.高纬度降温幅度大于低纬度夏季降温幅度大于冬季.全新世火山影响气候时空记录和火山灰敏感性气候试验为进一步探讨全新世气候变化成因提供重要的科学依据也为最终认识现代气候系统变化以及对未来十年-百年尺度的气候预测提供重要的参照系.;It is difficult to fully recognize what the mechanisms are behind Holocene climate changes so far. Numerous geological evidences have suggested that several phases of temperature lowering occurred during the Holocene and the cold phases are correlated with events of volcano explosions. Modern observations in climatology have revealed that volcanic dust plays a role on the radiation blocking and leads to temperature lowering on the earth surface when the volcanic dust enter the stratospheric level. This paper is attempted to focus on both volcanic-climatology and volcanic-geology to understand volcano effects on climate changes, by an integration of geological volcano data and simulation of climate model. The compiling volcanic data show that there were five phases of strong volcanic explosions during 12000-1000 a BP. The volcano-tested climate simulations show that the annual mean temperature is generally decreased during the phase of the strong volcano explosions. Compared to phases of the weak- volcano explosion, the decrease in temperature varied from regions and from seasons. The amplitude of temperature lowering is bigger in high latitude than that in low latitude, and higher in winter than in summer. The results in volcano data set and climate simulations provided the data basis to further study the mechanisms of Holocene climate changes and the today-past analogues to finally predict changes in the future climate in the decade-century scales.