Department of Geosciences, University of Oslo, Oslo, Norway.
SPHERES Research Units, Geography Department, University of Liège, Liège, Belgium.
Nat Commun. 2020 Dec 15;11(1):6289. doi: 10.1038/s41467-020-20011-8.
Future climate projections show a marked increase in Greenland Ice Sheet (GrIS) runoff during the 21 century, a direct consequence of the Polar Amplification signal. Regional climate models (RCMs) are a widely used tool to downscale ensembles of projections from global climate models (GCMs) to assess the impact of global warming on GrIS melt and sea level rise contribution. Initial results of the CMIP6 GCM model intercomparison project have revealed a greater 21 century temperature rise than in CMIP5 models. However, so far very little is known about the subsequent impacts on the future GrIS surface melt and therefore sea level rise contribution. Here, we show that the total GrIS sea level rise contribution from surface mass loss in our high-resolution (15 km) regional climate projections is 17.8 ± 7.8 cm in SSP585, 7.9 cm more than in our RCP8.5 simulations using CMIP5 input. We identify a +1.3 °C greater Arctic Amplification and associated cloud and sea ice feedbacks in the CMIP6 SSP585 scenario as the main drivers. Additionally, an assessment of the GrIS sea level contribution across all emission scenarios highlights, that the GrIS mass loss in CMIP6 is equivalent to a CMIP5 scenario with twice the global radiative forcing.
未来气候预测显示，在 21 世纪，格陵兰冰原（GrIS）径流量将显著增加，这是极地放大信号的直接结果。区域气候模型（RCM）是一种广泛使用的工具，可将来自全球气候模型（GCM）的预测集合缩小规模，以评估全球变暖对 GrIS 融化和海平面上升贡献的影响。CMIP6 GCM 模型比较计划的初步结果显示，21 世纪的升温幅度大于 CMIP5 模型。然而，到目前为止，人们对未来 GrIS 表面融化的后续影响知之甚少，因此对海平面上升的贡献也知之甚少。在这里，我们表明，在我们高分辨率（15 公里）的区域气候预测中，由于表面质量损失，GrIS 海平面上升的总贡献在 SSP585 中为 17.8 ± 7.8cm，比我们使用 CMIP5 输入的 RCP8.5 模拟多 7.9cm。我们确定，CMIP6 SSP585 情景中的北极放大以及相关的云和海冰反馈增加了+1.3°C，是主要驱动因素。此外，对所有排放情景下的 GrIS 海平面贡献的评估表明，CMIP6 中的 GrIS 质量损失相当于 CMIP5 情景下全球辐射强迫增加一倍。
