Dynamic Antarctic ice sheet during the early to mid-Miocene
Dynamic Antarctic ice sheet during the early to mid-Miocene
复制标题
DOI：
10.1073/pnas.1516130113
复制
发表时间：
2016-03-29
影响因子：
11.1
通讯作者：
Levy, Richard H.
中科院分区：
文献类型：
--
作者：
Gasson, Edward;DeConto, Robert M.;Levy, Richard H.
地质数据表明，在中新世早期至中期，南极冰盖的体积和范围发生了重大变化。模拟如此大规模的变化是有问题的，因为有很强的滞后效应，一旦冰盖达到大陆的大小，就会导致稳定。代用记录显示的大气CO2浓度范围相对狭窄，加剧了这一问题。在这里，我们能够模拟大规模的变化，早中新世中期南极冰盖，因为我们的建模方法的三个发展。(i)我们使用的气候冰盖耦合方法，利用高分辨率的大气成分来解释冰盖气候反馈。(ii)冰盖模型包括最近提出的机制退缩到深冰下盆地所造成的冰崖故障和冰架水力压裂。(iii)我们占冰盖的氧同位素组成的变化，通过使用同位素启用气候和冰盖模型。我们比较我们的模拟结果与冰近端记录出现从罗斯海（Andrill-2A），这是在同伴文章中提出的沉积学钻孔岩心。我们模拟的南极冰量的变化相当于0.52- 0.66%的海水氧同位素信号，或30-36米的海平面等效变化，大气CO2的范围在280和500 ppm之间，并不断变化的天文配置。这一结果在解决中新世南极冰盖和海平面变化的长期模式数据冲突方面取得了实质性进展。
Geological data indicate that there were major variations in Antarctic ice sheet volume and extent during the early to mid-Miocene. Simulating such large-scale changes is problematic because of a strong hysteresis effect, which results in stability once the ice sheets have reached continental size. A relatively narrow range of atmospheric CO2 concentrations indicated by proxy records exacerbates this problem. Here, we are able to simulate large-scale variability of the early to mid-Miocene Antarctic ice sheet because of three developments in our modeling approach. (i) We use a climate-ice sheet coupling method utilizing a high-resolution atmospheric component to account for ice sheet-climate feedbacks. (ii) The ice sheet model includes recently proposed mechanisms for retreat into deep subglacial basins caused by ice-cliff failure and ice-shelf hydrofracture. (iii) We account for changes in the oxygen isotopic composition of the ice sheet by using isotope-enabled climate and ice sheet models. We compare our modeling results with ice-proximal records emerging from a sedimentological drill core from the Ross Sea (Andrill-2A) that is presented in a companion article. The variability in Antarctic ice volume that we simulate is equivalent to a seawater oxygen isotope signal of 0.52-0.66%, or a sea level equivalent change of 30-36 m, for a range of atmospheric CO2 between 280 and 500 ppm and a changing astronomical configuration. This result represents a substantial advance in resolving the long-standing model data conflict of Miocene Antarctic ice sheet and sea level variability.