Porter Trevor J, Schoenemann Spruce W, Davies Lauren J, Steig Eric J, Bandara Sasiri, Froese Duane G
Department of Geography, University of Toronto, Erindale Campus, Mississauga, ON, Canada.
Environmental Sciences Department, University of Montana Western, Dillon, MT, USA.
Nat Commun. 2019 Apr 9;10(1):1631. doi: 10.1038/s41467-019-09622-y.
Eastern Beringia is one of the few Western Arctic regions where full Holocene climate reconstructions are possible. However, most full Holocene reconstructions in Eastern Beringia are based either on pollen or midges, which show conflicting early Holocene summer temperature histories. This discrepancy precludes understanding the factors that drove past (and potentially future) climate change and calls for independent proxies to advance the debate. We present a ~13.6 ka summer temperature reconstruction in central Yukon, part of Eastern Beringia, using precipitation isotopes in syngenetic permafrost. The reconstruction shows that early Holocene summers were consistently warmer than the Holocene mean, as supported by midges, and a thermal maximum at ~7.6-6.6 ka BP. This maximum was followed by a ~6 ka cooling, and later abruptly reversed by industrial-era warming leading to a modern climate that is unprecedented in the Holocene context and exceeds the Holocene thermal maximum by +1.7 ± 0.7 °C.
东白令陆桥是少数几个能够进行全新世完整气候重建的北极西部地区之一。然而，东白令陆桥的大多数全新世完整重建要么基于花粉，要么基于蠓虫，而这两者显示出全新世早期夏季温度历史相互矛盾。这种差异妨碍了对驱动过去（以及潜在的未来）气候变化的因素的理解，并需要独立的代理指标来推进相关辩论。我们利用共生永久冻土中的降水同位素，给出了东白令陆桥一部分——育空中部地区约13.6千年前的夏季温度重建结果。该重建结果表明，全新世早期夏季一直比全新世平均温度更温暖，这得到了蠓虫的支持，并且在约7.6 - 6.6千年前出现了一个温度峰值。这个峰值之后是约6千年的降温，后来在工业时代变暖的影响下突然逆转，导致了一种全新世背景下前所未有的现代气候，且比全新世温度峰值高出1.7±0.7°C。
