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TitleHigh Arctic Holocene temperature record from the Agassiz ice cap and Greenland ice sheet evolution
AuthorLecavalier, B S; Fisher, D A; Milne, G A; Vinther, B M; Tarasov, L; Huybrechts, P; Lacelle, D; Main, BORCID logo; Zheng, JORCID logo; Bourgeois, J; Dyke, A S
SourceProceedings of the National Academy of Sciences of the United States of America vol. 114, no. 23, 2017 p. 5952-5957, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20182284
PublisherProceedings of the National Academy of Sciences
Mediapaper; on-line; digital
File formatpdf (Adobe® Reader®); html
ProgramClimate Change Geoscience Risk Analysis
Released2017 05 16
AbstractWe present a revised and extended high Arctic air temperature reconstruction from a single proxy that spans the past ~12,000 y (up to 2009 CE). Our reconstruction from the Agassiz ice cap (Ellesmere Island, Canada) indicates an earlier and warmer Holocene thermal maximum with early Holocene temperatures that are 4-5 ¡C warmer compared with a previous reconstruction, and regularly exceed contemporary values for a period of ~3,000 y. Our results show that air temperatures in this region are now at their warmest in the past 6,800-7,800 y, and that the recent rate of temperature change is unprecedented over the entire Holocene. The warmer early Holocene inferred from the Agassiz ice core leads to an estimated ?1 km of ice thinning in northwest Greenland during the early Holocene using the Camp Century ice core. Ice modeling results show that this large thinning is consistent with our air temperature reconstruction. The modeling results also demonstrate the broader significance of the enhanced warming, with a retreat of the northern ice margin behind its present position in the mid Holocene and a ~25% increase in total Greenland ice sheet mass loss (~1.4 m sea-level equivalent) during the last deglaciation, both of which have implications for interpreting geodetic measurements of land uplift and gravity changes in northern Greenland.
Summary(Plain Language Summary, not published)
Snow deposits with atmospheric information, linking to climate and environmental changes. With modern technologies for detection of low-level contaminants in samples, it is readily possible to detect atmospheric composition changes. Therefore, information of long-term climate and environmental changes can be retrieved from snow/ice in Canadian ice caps. With existing data sets from ice cores and new updates to such data sets with firn cores from Agassiz Ice Cap, a study on polar amplification of climate warming was carried out. Results show, in the past ~12,000 years, polar amplification was stronger (4-5³C warmer). This means high-latitude warming led to a larger response of the Greenland ice sheet, ~1 m equivalent to global mean sea levels since last glacial maximum. Results also show present air temperatures at Agassiz ice cap are at their warmest in the past 6,800-7,800 yrs and century-scale rates of temperature change in this region are at their highest since 11,700 yrs ago.

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