Nelson Institute Center for Climatic Research, University of Wisconsin-Madison, 1225 W. Dayton Street, Madison, WI, 53706, USA.
College of Earth, Ocean and Atmospheric Sciences, Oregon State University, Corvallis, OR, 97331, USA.
Sci Rep. 2018 Jul 5;8(1):10213. doi: 10.1038/s41598-018-28419-5.
The Marine Isotope Stage 19c (MIS19c) interglaciation is regarded as the best orbital analog to the Holocene. The close of MIS19c (~777,000 years ago) thus serves as a proxy for a contemporary climate system unaffected by humans. Our global climate model simulation driven by orbital parameters and observed greenhouse gas concentrations at the end of MIS19c is 1.3 K colder than the reference pre-industrial climate of the late Holocene (year 1850). Much stronger cooling occurs in the Arctic, where sea ice and year-round snow cover expand considerably. Inferred regions of glaciation develop across northeastern Siberia, northwestern North America, and the Canadian Archipelago. These locations are consistent with evidence from past glacial inceptions and are favored by atmospheric circulation changes that reduce ablation of snow cover and increase accumulation of snowfall. Particularly large buildups of snow depth coincide with presumed glacial nucleation sites, including Baffin Island and the northeast Canadian Archipelago. These findings suggest that present-day climate would be susceptible to glacial inception if greenhouse gas concentrations were as low as they were at the end of MIS 19c.
海洋同位素阶段 19c（MIS19c）间冰期被认为是全新世最好的轨道类似物。因此，MIS19c 的结束（约 777,000 年前）可以作为不受人类影响的当代气候系统的代理。我们的全球气候模型模拟由 MIS19c 末期的轨道参数和观测到的温室气体浓度驱动，比全新世晚期（1850 年）的参考工业化前气候冷 1.3 K。在北极地区，冷却更为强烈，那里的海冰和全年积雪覆盖范围大大扩大。在西伯利亚东北部、北美西北部和加拿大群岛等地区推断出的冰川发育区域。这些地点与过去冰川开始的证据一致，并且受到大气环流变化的青睐，这些变化减少了积雪的消融，增加了降雪的积累。包括巴芬岛和加拿大东北部群岛在内的假定冰川成核地点，与雪深的大幅增加相吻合。这些发现表明，如果温室气体浓度像 MIS19c 末期那样低，那么当今的气候可能容易出现冰川开始。
