Spatial gradients of temperature, accumulation and δ 18O-ice in Greenland over a series of Dansgaard–Oeschger events

Guillevic, M.; Bazin, L.; Landais, A.; Kindler, P.; Orsi, A.; Masson-Delmotte, V.; Blunier, T.; Buchardt, S. L.; Capron, E.; Leuenberger, M.; Martinerie, P.; Prié, F.; Vinther, B. M.

Air and water stable isotope measurements from four Greenland deep ice cores (GRIP, GISP2, NGRIP and NEEM) are investigated over a series of Dansgaard–Oeschger events (DO 8, 9 and 10), which are representative of glacial millennial scale variability. Combined with firn modeling, air isotope data allow us to quantify abrupt temperature increases for each drill site (1σ = 0.6 °C for NEEM, GRIP and GISP2, 1.5 °C for NGRIP). Our data show that the magnitude of stadial–interstadial temperature increase is up to 2 °C larger in central and North Greenland than in northwest Greenland: i.e., for DO 8, a magnitude of +8.8 °C is inferred, which is significantly smaller than the +11.1 °C inferred at GISP2. The same spatial pattern is seen for accumulation increases. This pattern is coherent with climate simulations in response to reduced sea-ice extent in the Nordic seas. The temporal water isotope (δ 18O)–temperature relationship varies between 0.3 and 0.6 (±0.08) ‰ °C −1 and is systematically larger at NEEM, possibly due to limited changes in precipitation seasonality compared to GISP2, GRIP or NGRIP. The gas age−ice age difference of warming events represented in water and air isotopes can only be modeled when assuming a 26% (NGRIP) to 40% (GRIP) lower accumulation than that derived from a Dansgaard–Johnsen ice flow model.

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Guillevic, M. / Bazin, L. / Landais, A. / et al: Spatial gradients of temperature, accumulation and δ18O-ice in Greenland over a series of Dansgaard–Oeschger events. 2013. Copernicus Publications.

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