气候变化领域集成服务门户(CCPortal): A recent tipping point in the Arctic sea-ice cover: Abrupt and persistent increase in the seasonal cycle since 2007

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DOI	10.5194/tc-7-275-2013
	A recent tipping point in the Arctic sea-ice cover: Abrupt and persistent increase in the seasonal cycle since 2007
	Livina V.N.; Lenton T.M.
发表日期	2013
ISSN	19940416
卷号	7 期号:1
英文摘要	There is ongoing debate over whether Arctic sea ice has already passed a "tipping point", or whether it will do so in the future. Several recent studies argue that the loss of summer sea ice does not involve an irreversible bifurcation, because it is highly reversible in models. However, a broader definition of a "tipping point" also includes other abrupt, non-linear changes that are neither bifurcations nor necessarily irreversible. Examination of satellite data for Arctic sea-ice area reveals an abrupt increase in the amplitude of seasonal variability in 2007 that has persisted since then. We identified this abrupt transition using recently developed methods that can detect multi-modality in time-series data and sometimes forewarn of bifurcations. When removing the mean seasonal cycle (up to 2008) from the satellite data, the residual sea-ice fluctuations switch from uni-modal to multi-modal behaviour around 2007. We originally interpreted this as a bifurcation in which a new lower ice cover attractor appears in deseasonalised fluctuations and is sampled in every summer-autumn from 2007 onwards. However, this interpretation is clearly sensitive to how the seasonal cycle is removed from the raw data, and to the presence of continental land masses restricting winter-spring ice fluctuations. Furthermore, there was no robust early warning signal of critical slowing down prior to the hypothesized bifurcation. Early warning indicators do however show destabilization of the summer-autumn sea-ice cover since 2007. Thus, the bifurcation hypothesis lacks consistent support, but there was an abrupt and persistent increase in the amplitude of the seasonal cycle of Arctic sea-ice cover in 2007, which we describe as a (non-bifurcation) "tipping point". Our statistical methods detect this "tipping point" and its time of onset. We discuss potential geophysical mechanisms behind it, which should be the subject of further work with process-based models. © Author(s) 2013.
学科领域	amplitude; data set; ice cover; numerical model; satellite data; sea ice; seasonal variation; Arctic Ocean
语种	英语
scopus关键词	amplitude; data set; ice cover; numerical model; satellite data; sea ice; seasonal variation; Arctic Ocean
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/120309
作者单位	National Physical Laboratory, Teddington, Middlesex TW11 0LW, United Kingdom; School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom; College of Life and Environmental Sciences, University of Exeter, Hatherly Laboratories, Exeter EX4 4PS, United Kingdom
推荐引用方式 GB/T 7714	Livina V.N.,Lenton T.M.. A recent tipping point in the Arctic sea-ice cover: Abrupt and persistent increase in the seasonal cycle since 2007[J],2013,7(1).
APA	Livina V.N.,&Lenton T.M..(2013).A recent tipping point in the Arctic sea-ice cover: Abrupt and persistent increase in the seasonal cycle since 2007.Cryosphere,7(1).
MLA	Livina V.N.,et al."A recent tipping point in the Arctic sea-ice cover: Abrupt and persistent increase in the seasonal cycle since 2007".Cryosphere 7.1(2013).