Chemistry (all); Biochemistry, Genetics and Molecular Biology (all); Physics and Astronomy (all); General Physics and Astronomy; General Biochemistry, Genetics and Molecular Biology; General Chemistry; Multidisciplinary
Abstract :
[en] The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative to clear skies, using a unique combination of active satellite observations, climate model data and snow model simulations. This impact results from a cloud radiative effect of 29.5 (±5.2) W m(-2). Contrary to conventional wisdom, however, the Greenland ice sheet responds to this energy through a new pathway by which clouds reduce meltwater refreezing as opposed to increasing surface melt directly, thereby accelerating bare-ice exposure and enhancing meltwater runoff. The high sensitivity of the Greenland ice sheet to both ice-only and liquid-bearing clouds highlights the need for accurate cloud representations in climate models, to better predict future contributions of the Greenland ice sheet to global sea level rise.
Disciplines :
Earth sciences & physical geography
Author, co-author :
Van Tricht, K ; KU Leuven, Department of Earth and Environmental Sciences, Celestijnenlaan 200E, Leuven 3001, Belgium
Lhermitte, S ; KU Leuven, Department of Earth and Environmental Sciences, Celestijnenlaan 200E, Leuven 3001, Belgium
Lenaerts, J T M; Institute for Marine and Atmospheric research Utrecht-Utrecht University, Utrecht 3584CC, The Netherlands
Gorodetskaya, I V; KU Leuven, Department of Earth and Environmental Sciences, Celestijnenlaan 200E, Leuven 3001, Belgium
L'Ecuyer, T S; Atmospheric and Oceanic Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
Noël, Brice ; Université de Liège - ULiège > Département de géographie > Climatologie et Topoclimatologie ; Institute for Marine and Atmospheric research Utrecht-Utrecht University, Utrecht 3584CC, The Netherlands
van den Broeke, M R; Institute for Marine and Atmospheric research Utrecht-Utrecht University, Utrecht 3584CC, The Netherlands
Turner, D D; National Severe Storms Laboratory, NOAA, Norman, Oklahoma 73072, USA
van Lipzig, N P M; KU Leuven, Department of Earth and Environmental Sciences, Celestijnenlaan 200E, Leuven 3001, Belgium
K.V.T. and S.L. are funded by the Research Foundation Flanders (FWO). I.V.G. was supported via the project HYDRANT funded by the Belgian Science Policy Office under grant number EN/01/4B. The contributions of T.S.L. to this project were supported by CloudSat/CALIPSO science team grant NNX14AB35G. This study is partly funded by Utrecht University through its strategic theme Sustainability, sub-theme Water, Climate and Ecosystems, and the Netherlands Polar Programme of NWO. Part of this work was carried out under the programme of the Netherlands Earth System Science Centre (NESSC), financially supported by the Ministry of Education, Culture and Science (OCW). This work is further supported by the Belgian Federal Science Policy Office project AEROCLOUD (BR/143/A2). The Summit data were recorded in the frame of the ICECAPS project, which is supported by the US National Science Foundation under Grants ARC-0856773, 0904152 and 0856559 as part of the Arctic Observing Network (AON) programme, with additional instrumentation provided by the NOAA Earth System Research Laboratory, US Department of Energy ARM Program and Environment Canada. We thank the CloudSat Data Processing Center, in particular Phil Partain, for their help with the 2B-FLXHR-LIDAR algorithm runs.
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