Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks
Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks
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DOI：
10.1029/2011gl050168
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发表时间：
2012-01-31
影响因子：
5.2
通讯作者：
Thordarson, Thorvaldur
中科院分区：
文献类型：
--
作者：
Miller, Gifford H.;Geirsdottir, Aslaug;Thordarson, Thorvaldur
过去8000年来，北半球夏季气温的变化是由于春分进动导致夏季日照的缓慢减少而变化的。然而，叠加的百年规模的夏季寒冷异常（其中小冰河期（LIA）是最极端的）的原因仍然存在争议，主要是因为自然强迫要么很弱，要么在火山活动的情况下持续时间很短。在这里，我们提供了加拿大北极和冰岛冰盖生长的精确日期记录，显示 LIA 夏季寒冷和冰生长在公元 1275 年至 1300 年间突然开始，随后在公元 14301455 年大幅加剧。冰突然生长的时间间隔与过去千年中火山扰动最严重的两个世纪相吻合。瞬态气候模型模拟表明，爆发性火山活动在这些时候会产生突然的夏季降温，并且在火山气溶胶消失很久之后，寒冷的夏季可以通过海冰/海洋反馈来维持。我们的研究结果表明，LIA 的爆发可能与一次长达 50 年的不寻常事件有关，该事件发生了四次大型富硫爆炸性喷发，每次喷发的全球硫酸盐负荷均超过 60 Tg。寒冷夏季的持续存在最好的解释是在半球夏季日照最低期间随之而来的海冰/海洋反馈；不需要太阳辐照度发生大的变化。引用：Miller, G. H. 等人。 (2012)，由火山活动引发并由海冰/海洋反馈维持的小冰河时代突然开始，地球物理学。资源。快报，39，L02708，doi：10.1029/2011GL050168。
Northern Hemisphere summer temperatures over the past 8000 years have been paced by the slow decrease in summer insolation resulting from the precession of the equinoxes. However, the causes of superposed century-scale cold summer anomalies, of which the Little Ice Age (LIA) is the most extreme, remain debated, largely because the natural forcings are either weak or, in the case of volcanism, short lived. Here we present precisely dated records of ice-cap growth from Arctic Canada and Iceland showing that LIA summer cold and ice growth began abruptly between 1275 and 1300 AD, followed by a substantial intensification 14301455 AD. Intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium. A transient climate model simulation shows that explosive volcanism produces abrupt summer cooling at these times, and that cold summers can be maintained by sea-ice/ocean feedbacks long after volcanic aerosols are removed. Our results suggest that the onset of the LIA can be linked to an unusual 50-year-long episode with four large sulfur-rich explosive eruptions, each with global sulfate loading >60 Tg. The persistence of cold summers is best explained by consequent sea-ice/ocean feedbacks during a hemispheric summer insolation minimum; large changes in solar irradiance are not required. Citation: Miller, G. H., et al. (2012), Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks, Geophys. Res. Lett., 39, L02708, doi: 10.1029/2011GL050168.