Younger Dryas cooling and the Greenland climate response to CO2

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Liu, Zhengyu, Carlson, Anders E., He, Feng, Brady, Esther C., Otto-Bliesner, Bette L., Briegleb, Bruce P., Wehrenberg, Mark, Clark, Peter U., Wu, Shu, Cheng, Jun, Zhang, Jiaxu, Noone, David, Zhu, Jiang
• Other Authors: Liu, ZY (reprint author), Univ Wisconsin, Ctr Climat Res, Madison, WI 53706 USA., Univ Wisconsin, Ctr Climat Res, Madison, WI 53706 USA., Univ Wisconsin, Dept Atmospher & Ocean Sci, Madison, WI 53706 USA., Peking Univ, Lab Climate Ocean & Atmosphere Studies, Beijing 100871, Peoples R China., Univ Wisconsin, Dept Geosci, Madison, WI 53706 USA., Natl Ctr Atmospher Res, Climate & Global Dynam Div, Boulder, CO 80307 USA., Oregon State Univ, Coll Earth Ocean & Atmospher Sci, Corvallis, OR 97331 USA., Nanjing Univ Informat Sci & Technol, Key Lab Meteorol Disaster, Minist Educ, Nanjing 210044, Jiangsu, Peoples R China., Univ Colorado, Dept Atmospher & Ocean Sci, Boulder, CO 80309 USA., Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80309 USA.
• Format: Journal/Newspaper
• Language: English
• Published: proceedings of the national academy of sciences of the united states of america 2012
• Subjects: oxygen isotope; arctic climate; global warming; LAST GLACIAL MAXIMUM; ICE; DEGLACIATION; TEMPERATURE; VARIABILITY; ATLANTIC; CONSTRAINTS; ISOTOPES; SURFACE; MODEL; Arctic; Greenland; albedo; Global warming; Greenland ice core; ice core; North Atlantic
• Online Access: https://hdl.handle.net/20.500.11897/393098; https://doi.org/10.1073/pnas.1202183109

Greenland ice-core delta O-18-temperature reconstructions suggest a dramatic cooling during the Younger Dryas (YD; 12.9-11.7 ka), with temperatures being as cold as the earlier Oldest Dryas (OD; 18.0-14.6 ka) despite an approximately 50 ppm rise in atmospheric CO2. Such YD cooling implies a muted Greenland climate response to atmospheric CO2, contrary to physical predictions of an enhanced high-latitude response to future increases in CO2. Here we show that North Atlantic sea surface temperature reconstructions as well as transient climate model simulations suggest that the YD over Greenland should be substantially warmer than the OD by approximately 5 degrees C in response to increased atmospheric CO2. Additional experiments with an isotope-enabled model suggest that the apparent YD temperature reconstruction derived from the ice-core delta O-18 record is likely an artifact of an altered temperature-delta O-18 relationship due to changing deglacial atmospheric circulation. Our results thus suggest that Greenland climate was warmer during the YD relative to the OD in response to rising atmospheric CO2, consistent with sea surface temperature reconstructions and physical predictions, and has a sensitivity approximately twice that found in climate models for current climate due to an enhanced albedo feedback during the last deglaciation. Multidisciplinary Sciences SCI(E) 12 ARTICLE 28 11101-11104 109