Decelerated Greenland Ice Sheet Melt Driven by Positive Summer North Atlantic Oscillation

Ruan, Ruomei; Chen, Xianyao; Zhao, Jinping; Perrie, Will; Mottram, Ruth; Zhang, Minghong; Diao, Yiwei; Du, Ling; Wu, Lixin

doi:10.1029/2019jd030689

Cited by 16 publications

(9 citation statements)

References 47 publications

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“…With the improved understanding of the underlying processes, we can bring multiple studies together and diminish the conflicting views that previously existed. In agreement with Wang et al (2018); Ruan et al (2019); Hofer et al (2017), we show that clouds limit the albedo‐melt feedback and decelerate surface melt. We add that this is only the case for the summer ablation area or dark albedo areas; not for other seasons, the accumulation area or high albedo areas.…”

Section: Discussionsupporting

confidence: 93%

“…Furthermore, Wang et al (2018) argue that clouds limit the albedo feedback and decelerate surface melt, referring to a net cooling CRE observed by automatic weather stations. Recently, the deceleration of accelerated GrIS melting since 2013 is linked by Ruan et al (2019) to the reduction in SW radiation in the presence of increasing total cloud cover.…”

Section: Introductionmentioning

confidence: 99%

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The Spatiotemporal Variability of Cloud Radiative Effects on the Greenland Ice Sheet Surface Mass Balance

Izeboud

Lhermitte

Tricht

et al. 2020

Geophysical Research Letters

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To better understand and quantify the impact of clouds on the Greenland Ice Sheet surface mass balance (SMB), we study the spatiotemporal variability of the cloud radiative effect (CRE). The total CRE is separated in short-term and long-term impacts by performing multiple simulations with the SNOWPACK model for 2001-+2010. The annual total CRE is 16.8 ± 4.5 W m −2 , reducing the SMB with −157 ± 3.8 Gt yr −1. Summer cloud radiative cooling is −6.4 ± 5.7 W m −2 in the ablation area, increasing the SMB with 121 ± 2.2 Gt yr −1. The annual integrated impact is cloud-reduced SMB of −36 Gt yr −1. The short-term effect dominates the opposing long-term effects through the albedo-melt feedback. A long-term warming effect decreases the albedo and so preconditions the surface for enhanced (summer) melt. The impact of the CRE, determined by spatial, temporal and initial conditions, explains existing conflicted views on the role of cloud radiation and emphasizes the need for accurate cloud and albedo representations in future studies.

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Section: Discussionsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

The Spatiotemporal Variability of Cloud Radiative Effects on the Greenland Ice Sheet Surface Mass Balance

Izeboud

Lhermitte

Tricht

et al. 2020

Geophysical Research Letters

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“…In the polar regions, and averaged over the year, the longwave warming effect of clouds clearly dominates the shortwave cooling effect because of the high surface albedos and long winter season. However, the cloud radiational effect varies substantially spatially and across seasons; for example, the cloud shortwave cooling effect dominates during the melt season, acting to reduce surface melting overall (Hofer et al, ; Niwano et al, ; Ruan et al, ; Wang et al, , ). Cloud cover frequency, structure, and phase all are important for determining the extent of cloud warming (Shupe et al, ); while, in general, cold and high clouds preferentially dim shortwave radiation, low‐level and liquid‐containing also tend to absorb longwave radiation.…”

Section: Introductionmentioning

confidence: 99%

Impact of Cloud Physics on the Greenland Ice Sheet Near‐Surface Climate: A Study With the Community Atmosphere Model

et al. 2020

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The Greenland Ice Sheet (GrIS) is losing mass in an accelerated fashion, which is for˜60% dominated by an increase in surface melting. Clouds exhibit an important control on the GrIS surface energy balance and surface melt. Therefore, to better simulate present and future GrIS climate, it is essential to represent clouds correctly in climate models. Here we use ground (at Summit Station) and satellite remote sensing (from CloudSat-CALIPSO) observations to evaluate GrIS cloud characteristics in several versions of the Community Atmosphere Model (CAM) over the period 2007-2012. Cloud cover, phase, water path, and radiative effects over the GrIS vary widely across the atmosphere models. Thanks to the inclusion of new cloud physical parameterizations, that is, ice nucleation and prognostic precipitation, in the most recent CAM version (CAM6), this model, amongst the various CAM versions, is best able to represent GrIS clouds, summer temperatures, and surface melting. However, CAM6 shows excessive rainfall over the ice sheet, which is an important outstanding model bias. Our study demonstrates the importance of simulating realistic cloud properties to improve climate model simulations of GrIS climate and climate change.

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“…Regional climate projections of the GrIS melt and near-surface climate unanimously show greater ablation rates with rising Arctic temperature levels 2 . However, the absolute magnitude is still subject to uncertainties, mainly due to imperfect cloud microphysics and missing recent Greenland circulation anomalies 2,8,9,20,28,29 .…”

mentioning

confidence: 99%

Greater Greenland Ice Sheet contribution to global sea level rise in CMIP6

et al. 2020

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Future climate projections show a marked increase in Greenland Ice Sheet (GrIS) runoff during the 21st 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 21st 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.

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Decelerated Greenland Ice Sheet Melt Driven by Positive Summer North Atlantic Oscillation

Cited by 16 publications

References 47 publications

The Spatiotemporal Variability of Cloud Radiative Effects on the Greenland Ice Sheet Surface Mass Balance

The Spatiotemporal Variability of Cloud Radiative Effects on the Greenland Ice Sheet Surface Mass Balance

Impact of Cloud Physics on the Greenland Ice Sheet Near‐Surface Climate: A Study With the Community Atmosphere Model

Greater Greenland Ice Sheet contribution to global sea level rise in CMIP6

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