Precise interpolar phasing of abrupt climate change during the last ice age

Precise interpolar phasing of abrupt climate change during the last ice age

A new ice core from West Antarctica shows that, during the last ice age, abrupt Northern Hemisphere climate variations were followed two centuries later by a response in Antarctica, suggesting an oceanic propagation of the climate signal to the Southern Hemisphere high latitudes. Climate seesaw swin...

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Published in:Nature (London) Vol. 520; no. 7549; pp. 661 - 665
Main Authors: Buizert, Christo, Adrian, Betty, Ahn, Jinho, Albert, Mary, Alley, Richard B, Baggenstos, Daniel, Bauska, Thomas K, Bay, Ryan C, Bencivengo, Brian B, Bentley, Charles R, Brook, Edward J, Chellman, Nathan J, Clow, Gary D, Cole-Dai, Jihong, Conway, Howard, Cravens, Eric, Cuffey, Kurt M, Dunbar, Nelia W, Edwards, Jon S, Fegyveresi, John M, Ferris, Dave G, Fitzpatrick, Joan J, Fudge, T J, Gibson, Chris J, Gkinis, Vasileios, Goetz, Joshua J, Gregory, Stephanie, Hargreaves, Geoffrey M, Iverson, Nels, Johnson, Jay A, Jones, Tyler R, Kalk, Michael L, Kippenhan, Matthew J, Koffman, Bess G, Kreutz, Karl, Kuhl, Tanner W, Lebar, Donald A, Lee, James E, Marcott, Shaun A, Markle, Bradley R, Maselli, Olivia J, McConnell, Joseph R, McGwire, Kenneth C, Mitchell, Logan E, Mortensen, Nicolai B, Neff, Peter D, Nishiizumi, Kunihiko, Nunn, Richard M, Orsi, Anais J, Pasteris, Daniel R, Pedro, Joel B, Pettit, Erin C, Price, P Buford, Priscu, John C, Rhodes, Rachael H, Rosen, Julia L, Schauer, Andrew J, Schoenemann, Spruce W, Sendelbach, Paul J, Severinghaus, Jeffrey P, Shturmakov, Alexander J, Sigl, Michael, Slawny, Kristina R, Souney, Joseph M, Sowers, Todd A, Spencer, Matthew K, Steig, Eric J, Taylor, Kendrick C, Twickler, Mark S, Vaughn, Bruce H, Voigt, Donald E, Waddington, Edwin D, Welten, Kees C, Wendricks, Anthony W, White, James W C, Winstrup, Mai, Wong, Gifford J, Woodruff, Thomas E
Format: Journal Article
Language:English
Published: London Nature Publishing Group UK 30-04-2015
Nature Publishing Group
Subjects:
704/106/125
704/106/2738
704/106/413
704/106/694
82/80
82/83
Climate change
Continental interfaces, environment
Cooling
Cores
Heat
Humanities and Social Sciences
Ice ages
letter
Methane
multidisciplinary
Ocean circulation
Ocean, Atmosphere
Paleoclimate
Propagation
Science
Sciences of the Universe
Water circulation
Antarctica
Southern Ocean
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Summary:A new ice core from West Antarctica shows that, during the last ice age, abrupt Northern Hemisphere climate variations were followed two centuries later by a response in Antarctica, suggesting an oceanic propagation of the climate signal to the Southern Hemisphere high latitudes. Climate seesaw swings north to south The bipolar seesaw theory explains certain abrupt episodes of climate change as a consequence of an interhemispheric redistribution of heat; when one polar region is warming, the other cools. So far, it has been unclear if the Northern Hemisphere is forcing the Southern Hemisphere or vice versa, and whether the seesaw operates via oceanic or atmospheric mechanisms. This study, synthesizing data from several climate laboratories, uses high-resolution data from the recently drilled WAIS Divide Antarctic ice core, combined with data from Greenland, to show that during much of the past 65,000 years, the north has led the south for both cooling and warming events. Abrupt Northern Hemisphere climate variations were followed two centuries later by a response in Antarctica, suggesting an oceanic propagation of the climate signal to the Southern Hemisphere high latitudes. The last glacial period exhibited abrupt Dansgaard–Oeschger climatic oscillations, evidence of which is preserved in a variety of Northern Hemisphere palaeoclimate archives 1 . Ice cores show that Antarctica cooled during the warm phases of the Greenland Dansgaard–Oeschger cycle and vice versa 2 , 3 , suggesting an interhemispheric redistribution of heat through a mechanism called the bipolar seesaw 4 , 5 , 6 . Variations in the Atlantic meridional overturning circulation (AMOC) strength are thought to have been important, but much uncertainty remains regarding the dynamics and trigger of these abrupt events 7 , 8 , 9 . Key information is contained in the relative phasing of hemispheric climate variations, yet the large, poorly constrained difference between gas age and ice age and the relatively low resolution of methane records from Antarctic ice cores have so far precluded methane-based synchronization at the required sub-centennial precision 2 , 3 , 10 . Here we use a recently drilled high-accumulation Antarctic ice core to show that, on average, abrupt Greenland warming leads the corresponding Antarctic cooling onset by 218 ± 92 years (2 σ ) for Dansgaard–Oeschger events, including the Bølling event; Greenland cooling leads the corresponding onset of Antarctic warming by 208 ± 96 years. Our results demonstrate a north-to-south directionality of the abrupt climatic signal, which is propagated to the Southern Hemisphere high latitudes by oceanic rather than atmospheric processes. The similar interpolar phasing of warming and cooling transitions suggests that the transfer time of the climatic signal is independent of the AMOC background state. Our findings confirm a central role for ocean circulation in the bipolar seesaw and provide clear criteria for assessing hypotheses and model simulations of Dansgaard–Oeschger dynamics.
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ISSN:0028-0836
1476-4687
DOI:10.1038/nature14401