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Climate of the Past An interactive open-access journal of the European Geosciences Union
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Volume 13, issue 11
Clim. Past, 13, 1527-1537, 2017
https://doi.org/10.5194/cp-13-1527-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: Climate of the past 2000 years: regional and trans-regional...

Clim. Past, 13, 1527-1537, 2017
https://doi.org/10.5194/cp-13-1527-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 16 Nov 2017

Research article | 16 Nov 2017

Episodic Neoglacial expansion and rapid 20th century retreat of a small ice cap on Baffin Island, Arctic Canada, and modeled temperature change

Simon L. Pendleton1, Gifford H. Miller1, Robert A. Anderson1, Sarah E. Crump1, Yafang Zhong2, Alexandra Jahn3, and Áslaug Geirsdottir4 Simon L. Pendleton et al.
  • 1INSTAAR and Department of Geological Sciences, University of Colorado, Boulder, CO 80309-0450, USA
  • 2Space Science and Engineering Center, University of Wisconsin-Madison, Madison, WI 53706, USA
  • 3INSTAAR and Department of Atmospheric and Oceanic Sciences University of Colorado, Boulder, CO 80309-0450, USA
  • 4Department of Earth Sciences, University of Iceland, Askja, Sturlugata 7, 101 Reykjavik, Iceland

Abstract. Records of Neoglacial glacier activity in the Arctic constructed from moraines are often incomplete due to a preservation bias toward the most extensive advance, often the Little Ice Age. Recent warming in the Arctic has caused extensive retreat of glaciers over the past several decades, exposing preserved landscapes complete with in situ tundra plants previously entombed by ice. The radiocarbon ages of these plants define the timing of snowline depression and glacier advance across the site, in response to local summer cooling. Erosion rapidly removes most dead plants that have been recently exposed by ice retreat, but where erosive processes are unusually weak, dead plants may remain preserved on the landscape for decades. In such settings, a transect of plant radiocarbon ages can be used to construct a near-continuous chronology of past ice margin advance. Here we present radiocarbon dates from the first such transect on Baffin Island, which directly dates the advance of a small ice cap over the past two millennia. The nature of ice expansion between 20BCE and ∼1000CE is still uncertain, but episodic advances at ∼1000CE, ∼1200, and  ∼1500 led to the maximum Neoglacial dimensions ~1900CE. We employ a two-dimensional numerical glacier model calibrated using the plant radiocarbon ages ice margin chronology to assess the sensitivity of the ice cap to temperature change. Model experiments show that at least ∼0.44°C of cooling over the past 2kyr is required for the ice cap to reach its 1900CE margin, and that the period from ∼1000 to 1900CE must have been at least 0.25°C cooler than the previous millennium, results that agree with regional temperature reconstructions and climate model simulations. However, significant warming since 1900CE is required to explain retreat to its present position, and, at the same rate of warming, the ice cap will disappear before 2100CE.

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Recent warming in the high latitudes has prompted the accelerated retreat of ice caps and glaciers, especially in the Canadian Arctic. Here we use the radiocarbon age of preserved plants being exposed by shrinking ice caps that once entombed them. These ages help us to constrain the timing and magnitude of climate change on southern Baffin Island over the past ~ 2000 years. Our results show episodic cooling up until ~ 1900 CE, followed by accelerated warming through present.
Recent warming in the high latitudes has prompted the accelerated retreat of ice caps and...
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