气候变化领域集成服务门户(CCPortal): Modeling the response of Greenland outlet glaciers to global warming using a coupled flow line-plume model

CCPortal

DOI	10.5194/tc-13-2281-2019
	Modeling the response of Greenland outlet glaciers to global warming using a coupled flow line-plume model
	Beckmann J.; Perrette M.; Beyer S.; Calov R.; Willeit M.; Ganopolski A.
发表日期	2019
ISSN	19940416
EISSN	13
起始页码	2281
结束页码	2301
卷号	13 期号:9 页码:2281-2301
英文摘要	In recent decades, the Greenland Ice Sheet has experienced an accelerated mass loss, contributing to approximately 25% of contemporary sea level rise (SLR). This mass loss is caused by increased surface melt over a large area of the ice sheet and by the thinning, retreat and acceleration of numerous Greenland outlet glaciers. The latter is likely connected to enhanced submarine melting that, in turn, can be explained by ocean warming and enhanced subglacial discharge. The mechanisms involved in submarine melting are not yet fully understood and are only simplistically incorporated in some models of the Greenland Ice Sheet. Here, we investigate the response of 12 representative Greenland outlet glaciers to atmospheric and oceanic warming using a coupled line-plume glacier-flow line model resolving one horizontal dimension. The model parameters have been tuned for individual outlet glaciers using present-day observational constraints. We then run the model from present to the year 2100, forcing the model with changes in surface mass balance and surface runoff from simulations with a regional climate model for the RCP8.5 scenario, and applying a linear ocean temperature warming with different rates of changes representing uncertainties in the CMIP5 model experiments for the same climate change scenario. We also use different initial temperature-salinity profiles obtained from direct measurements and from ocean reanalysis data. Using different combinations of submarine melting and calving parameters that reproduce the present-day state of the glaciers, we estimate uncertainties in the contribution to global SLR for individual glaciers. We also perform a sensitivity analysis of the three forcing factors (changes in surface mass balance, ocean temperature and subglacial discharge), which shows that the roles of the different forcing factors are diverse for individual glaciers. We find that changes in ocean temperature and subglacial discharge are of comparable importance for the cumulative contribution of all 12 glaciers to global SLR in the 21st century. The median range of the cumulative contribution to the global SLR for all 12 glaciers is about 18mm (the glaciers' dynamic response to changes of all three forcing factors). Neglecting changes in ocean temperature and subglacial discharge (which control submarine melt) and investigating the response to changes in surface mass balance only leads to a cumulative contribution of 5mm SLR. Thus, from the 18mm we associate roughly 70% with the glaciers' dynamic response to increased subglacial discharge and ocean temperature and the remaining 30% (5 mm) to the response to increased surface mass loss. We also find a strong correlation (correlation coefficient 0.74) between present-day grounding line discharge and their future contribution to SLR in 2100. If the contribution of the 12 glaciers is scaled up to the total present-day discharge of Greenland, we estimate the midrange contribution of all Greenland glaciers to 21stcentury SLR to be approximately 50 mm. This number adds to SLR derived from a stand-alone ice sheet model (880 mm) that does not resolve outlet glaciers and thus increases SLR by over 50 %. This result confirms earlier studies showing that the response of the outlet glaciers to global warming has to be taken into account to correctly assess the total contribution of Greenland to sea level change. © Author(s) 2019.
语种	英语
WOS研究方向	Physical Geography ; Geology
来源期刊	The Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/102757
作者单位	Climate Impact Research (PIK), Membe. of Leibniz Association, P.O. Box 60 12 03, Potsdam, 14412, Germany; Alfred Wegener Institute, Bremerhaven, 27570, Germany
推荐引用方式 GB/T 7714	Beckmann J.,Perrette M.,Beyer S.,et al. Modeling the response of Greenland outlet glaciers to global warming using a coupled flow line-plume model[J],2019,13(9):2281-2301.
APA	Beckmann J.,Perrette M.,Beyer S.,Calov R.,Willeit M.,&Ganopolski A..(2019).Modeling the response of Greenland outlet glaciers to global warming using a coupled flow line-plume model.The Cryosphere,13(9),2281-2301.
MLA	Beckmann J.,et al."Modeling the response of Greenland outlet glaciers to global warming using a coupled flow line-plume model".The Cryosphere 13.9(2019):2281-2301.