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Climate of the Past An interactive open-access journal of the European Geosciences Union
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Volume 14, issue 6 | Copyright
Clim. Past, 14, 887-900, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 22 Jun 2018

Research article | 22 Jun 2018

Arctic warming induced by the Laurentide Ice Sheet topography

Johan Liakka1 and Marcus Lofverstrom2 Johan Liakka and Marcus Lofverstrom
  • 1Nansen Environmental and Remote Sensing Center, Bjerknes Centre for Climate Research, Thormøhlensgate 47, Bergen 5006, Norway
  • 2National Center for Atmospheric Research, 3090 Center Green Dr., 80301, Boulder, Colorado, USA

Abstract. It is well known that ice sheet–climate feedbacks are essential for realistically simulating the spatiotemporal evolution of continental ice sheets over glacial–interglacial cycles. However, many of these feedbacks are dependent on the ice sheet thickness, which is poorly constrained by proxy data records. For example, height estimates of the Laurentide Ice Sheet (LIS) topography at the Last Glacial Maximum (LGM;  ∼ 21000 years ago) vary by more than 1km among different ice sheet reconstructions. In order to better constrain the LIS elevation it is therefore important to understand how the mean climate is influenced by elevation discrepancies of this magnitude. Here we use an atmospheric circulation model coupled to a slab-ocean model to analyze the LGM surface temperature response to a broad range of LIS elevations (from 0 to over 4km). We find that raising the LIS topography induces a widespread surface warming in the Arctic region, amounting to approximately 1.5°C perkm of elevation increase, or about 6.5°C for the highest LIS. The warming is attributed to an increased poleward energy flux by atmospheric stationary waves, amplified by surface albedo and water vapor feedbacks, which account for about two-thirds of the total temperature response. These results suggest a strong feedback between continental-scale ice sheets and the Arctic temperatures that may help constrain LIS elevation estimates for the LGM and explain differences in ice distribution between the LGM and earlier glacial periods.

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Short summary
This study highlights the counterintuitive result that continental ice sheets can also induce a warming, in particular in the Arctic region. The warming is explained by an increased northward heat transport, resulting from interactions between the atmospheric circulation and ice sheet topography. There is thus an important feedback between ice sheets and temperature, which can help to explain the differences in ice distribution between the Last Glacial Maximum and earlier glacial periods.
This study highlights the counterintuitive result that continental ice sheets can also induce a...