超级火山喷发及其环境效应

Super-eruptions and their environmental impacts

超级火山喷发可以在极短时间内剧烈改变区域地形地貌,引起全球性气候巨变,是人类赖以生存的地球宜居环境的严重威胁。因此,剖析地质历史上的超级火山喷发事件及其环境效应,将有助于我们预测和应对未来可能的超级火山喷发及其造成的自然灾难。本文从超级火山和超级喷发的定义入手,重点介绍超级火山喷发的固相和气相产物、如何鉴别地质历史上的超级火山喷发、以及超级火山喷发可能带来的环境和社会影响。由于最近一次超级火山喷发发生在2.6万年前的新西兰,人类文明并没有经历过超级火山喷发,科学家们主要通过二十世纪以来有记录的小型火山喷发、冰芯和年轮记录、火山-环境-气候模型等来推测、反演和模拟超级火山喷发对气候和环境的影响。已有的研究表明,超级火山喷发产生的碎屑熔岩流和岩浆房塌陷产生的破火山口给周边地区环境造成直接的摧毁;进入平流层的火山气体经过物理化学变化形成气溶胶,有效的反射和吸收太阳辐射,从而导致长达数年的区域甚至全球性的剧烈降温和降水减少。尽管科学家们已经做了很多数值模拟和推演,但超级火山喷发的影响仍然是难以估计的。特别是超级火山喷发发生的季节和地点会带来不同的火山-海洋-大气-植被耦合效应,导致不同规模的气候和环境变化,未来应当加强这方面的研究。

Super-eruptions can significantly alter local topography in a short time interval,induce tremendous changes to local or global climate and severely threaten the friendly global environment which our humanity relies upon.Therefore,investigating the historic super-eruption events and their environmental impacts may help us to predict and cope with possible future super-eruptions and the ensuing natural disasters.This paper started from introducing the concept of supervolcanoes and super-eruptions,with emphasis on their solid and gaseous products,indexes to distinguish super-eruptions in geologic history,and the environmental and societal impacts of super-eruptions.Since the last super-eruption occurred 26,000 years ago in New Zealand,our human civilization did not experience super-eruptions.Scientists try to infer and model the climatic and environmental impacts of super-eruptions through the small-scale volcanic eruptions documented since the 20^(th)century,ice core and tree ring records,and volcano-environment-climate models.Previous studies indicate that the collapsed caldera and pyroclastic flow can directly destroy everything in the surrounding.Volcanic gases that entered the stratosphere can change to aerosol,which can effectively reflect and absorb solar radiation,resulting in several years’intense cooling and decrease of precipitation locally or globally.Although scientists have conducted numerous numerical modelings and deductions,the impacts of super-eruptions are still difficult to estimate.In particular,the season and location of the super-eruption will induce different coupling effects of volcano,ocean,atmosphere and vegetation.Future volcano-environment models should strengthen in this respect.