Evidence for stratigraphic distortion in the Greenland Ice Core Project (GRIP) ice core during Event 5e1 (120 kyr BP) from gas isotopes

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Landais, Amaelle, Steffensen, Jørgen Peder, Caillon, Nicolas, Jouzel, Jean, Masson-Delmotte, Valérie, Schwander, Jakob
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), University of Copenhagen = Københavns Universitet (UCPH), Climate and Environmental Physics Bern (CEP), Physikalisches Institut Bern, Universität Bern / University of Bern (UNIBE)-Universität Bern / University of Bern (UNIBE)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2004
• Subjects: 1827 Hydrology: Glaciology (1863); 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology; 3349 Meteorology and Atmospheric Dynamics: Polar meteorology; ice core; rapid climatic change; air isotopic composition; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Greenland; Greenland ice core; Greenland Ice core Project; GRIP
• Online Access: https://hal.science/hal-03103789; https://hal.science/hal-03103789/document; https://hal.science/hal-03103789/file/2003JD004193.pdf; https://doi.org/10.1029/2003JD004193

International audience The disturbed stratigraphy of the ice in the lowest 10% of the Greenland GRIP ice core has been previously demonstrated using gas measurements (d 18 O of O 2 and CH 4) on a few meters depth scale. However, rapid ice isotopic variations (on the scale of 20 cm) are experienced in the bottom of the GRIP ice core with complex chemical signatures that make them difficult to reconcile with a disturbed stratigraphy of the ice. This is the case for event 5e1, first described as a dramatic cooling 120 kyr BP. We analyzed at a 5 cm resolution the isotopic composition of the air from 2 m of the GRIP bottom ice core covering event 5e1. The d 15 N measurements, combined with a basic firn modeling, lead to the solid conclusion that the rapid event 5e1 is not a climatic event. Rapid variations of d 18 O of O 2 (d 18 O atm) are in agreement with a disturbed ice stratigraphy. However, the double peak shape of the d 18 O atm , recalling chemical data at the same depth, requires processes of diffusion after the mixing or even postcoring, placing limits to the interpretation of some classical paleoclimatic proxies in small scale mixed ice (<1 m).