Estimating the Greenland ice sheet surface mass balance contribution to future sea level rise using the regional atmospheric climate model MAR
Estimating the Greenland ice sheet surface mass balance contribution to future sea level rise using the regional atmospheric climate model MAR
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DOI：
10.5194/tc-7-469-2013
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发表时间：
2013-01-01
期刊：
影响因子：
5.2
通讯作者：
Gallee, H.
中科院分区：
文献类型：
--
作者：
Fettweis, X.;Franco, B.;Gallee, H.
为了估计格陵兰冰盖（GrIS）表面物质平衡（SMB）变化引起的海平面上升（SLR），我们利用区域气候模式MAR （Modele Atmospherique regional）得到的21世纪气候预估，这些预估是由三个CMIP5（耦合模式比较项目第5阶段）环流模式（GCMs）的输出强制进行的。我们的研究结果表明，在气候变暖的情况下，GrIS冬季降雪增加所带来的质量增加并不能补偿夏季融水径流增加所带来的质量损失。尽管预估的近地表变暖幅度很大，但所有MAR预估都显示出类似的GrIS表面融化体积的非线性增加，因为格陵兰上空的大气环流未发生变化。通过粗略估计GCM输出的GrIS SMB变化，我们发现基于GCM强迫的不确定性约占预估SMB变化的一半。在2100年，CMIP5综合平均预估GrIS SMB减少相当于RCP（代表性浓度路径）4.5和RCP 8.5情景的平均SLR分别为+4 +/- 2 cm和+9 +/- 4 cm。这些估计没有考虑融化高度的正反馈，尽管使用与预估SMB变化一致的受扰动冰盖地形的敏感性实验表明这是一个重要的反馈，并强调了将区域气候模式与冰盖模式耦合的重要性。这种耦合将允许评估未来地表过程和冰动力变化对温度上升的响应，以及它们的相互反馈。
To estimate the sea level rise (SLR) originating from changes in surface mass balance (SMB) of the Greenland ice sheet (GrIS), we present 21st century climate projections obtained with the regional climate model MAR (Modele Atmospherique Regional), forced by output of three CMIP5 (Coupled Model Intercomparison Project Phase 5) general circulation models (GCMs). Our results indicate that in a warmer climate, mass gain from increased winter snowfall over the GrIS does not compensate mass loss through increased meltwater run-off in summer. Despite the large spread in the projected near-surface warming, all the MAR projections show similar non-linear increase of GrIS surface melt volume because no change is projected in the general atmospheric circulation over Greenland. By coarsely estimating the GrIS SMB changes from GCM output, we show that the uncertainty from the GCM-based forcing represents about half of the projected SMB changes. In 2100, the CMIP5 ensemble mean projects a GrIS SMB decrease equivalent to a mean SLR of +4 +/- 2 cm and +9 +/- 4 cm for the RCP (Representative Concentration Pathways) 4.5 and RCP 8.5 scenarios respectively. These estimates do not consider the positive melt-elevation feedback, although sensitivity experiments using perturbed ice sheet topographies consistent with the projected SMB changes demonstrate that this is a significant feedback, and highlight the importance of coupling regional climate models to an ice sheet model. Such a coupling will allow the assessment of future response of both surface processes and ice-dynamic changes to rising temperatures, as well as their mutual feedbacks.