Holocene temperature history of northwest Greenland - With new ice cap constraints and chironomid assemblages from Deltaso
Holocene temperature history of northwest Greenland - With new ice cap constraints and chironomid assemblages from Deltaso
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DOI：
10.1016/j.quascirev.2019.05.011
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发表时间：
2019-07-01
影响因子：
4
通讯作者：
Francis, D. R.
中科院分区：
文献类型：
--
作者：
Axford, Y.;Lasher, G. E.;Francis, D. R.
北极温度的变化驱动着碳循环、海冰范围和格陵兰冰盖质量平衡的变化，所有这些都具有全球影响。过去温暖时期的古气候数据为评估这些系统对气候变暖的敏感性提供了独特的手段，但北极许多地区过去温度变化的幅度和时间却知之甚少。在这里，我们评估轨道尺度的全新世温度变化在格陵兰岛西北部附近的边缘的冰盖使用亚化石昆虫组合从湖Deltaso。根据沉积历史，在这个目前的冰前湖，我们也将限制全新世范围相邻的北冰帽，一个大的独立冰帽。重建的夏季温度比目前的湖泊沉积的发病后，区域冰川消退的格陵兰冰盖，有时之间的10.8和10.1万年BP。Deltaso经历了全新世最温暖的夏季温度，大约在10到6.2 ka BP之间，随后随着夏季日照的下降，逐渐冷却，持续到全新世晚期，最终在工业化前的最后一个千年达到最低温度。Deltaso摇蚊表明全新世早期夏季的峰值温度比现代至少高2.5-3摄氏度，比上个千年工业化前至少高3.5-4摄氏度。我们推断湖泊沉积物的有机和生物含量的基础上，在温度下降的反应，北冰帽达到了今天的大小类似于公元1850年，已小于目前通过大部分的前全新世。我们从西北格陵兰岛，埃尔斯米尔岛和北方巴芬湾的古气候证据的合成支持在三角洲推断的温度趋势的时间，并建议定量温度重建三角洲（？）可能代表了区域全新世早期变暖的最小界限。总的来说，该地区的记录表明全新世夏季降温>4摄氏度。强烈的全新世早期温暖的西北格陵兰岛反对延迟发病的温暖比现在的条件，由于附近的劳伦泰德冰盖的影响，并为理解格陵兰冰盖的气候变化的敏感性的影响。(C)2019爱思唯尔有限公司版权所有。
Arctic temperature shifts drive changes in carbon cycling, sea ice extent and Greenland Ice Sheet mass balance, all of which have global ramifications. Paleoclimate data from past warm periods provide a unique means for assessing the sensitivity of these systems to warming climate, but the magnitude and timing of past temperature changes in many parts of the Arctic are poorly known. Here we assess orbital scale Holocene temperature change in northwest Greenland near the margin of the ice sheet using subfossil insect assemblages from lake Deltaso. Based upon sedimentation history in this currently proglacial lake, we also place constraints on Holocene extents of the adjacent North Ice Cap, a large independent ice cap. Reconstructed summer temperatures were warmer than present at the onset of lacustrine sedimentation following regional deglaciation by the Greenland Ice Sheet, sometime between 10.8 and 10.1 ka BP. Deltaso experienced the warmest summer temperatures of the Holocene between similar to 10 and 6.2 ka BP, followed by progressive cooling that continued through the late Holocene as summer insolation declined, culminating in the lowest temperatures during the pre-industrial last millennium. Deltaso chironomids indicate peak early Holocene summer temperatures at least 2.5-3 degrees C warmer than modern and at least 3.5-4 degrees C warmer than the pre-industrial last millennium. We infer based upon lake sediment organic and biogenic content that in response to declining temperatures, North Ice Cap reached its present-day size similar to 1850 AD, having been smaller than present through most of the preceding Holocene. Our synthesis of paleoclimate evidence from northwest Greenland, Ellesmere Island and northern Baffin Bay supports the timing of temperature trends inferred at Deltaso, and suggests that quantitative temperature reconstructions from Deltas(?) may represent a minimum bound on regional early Holocene warming. Collectively, records from the region indicate >4 degrees C summer cooling through the Holocene. Intense early Holocene warmth around northwest Greenland argues against delayed onset of warmer than -present conditions due to the influence of the nearby waning Laurentide Ice Sheet, and has implications for understanding the Greenland Ice Sheet's sensitivity to climate change. (C) 2019 Elsevier Ltd. All rights reserved.