Younger Dryas Cooling and the Greenland Climate Response to CO2

TitleYounger Dryas Cooling and the Greenland Climate Response to CO2
Publication TypeJournal Article
Year of Publication2012
Authors
JournalProceedings of the National Academy of Sciences of the United States of America
Number28
Pages11101-11104
Date Published07/2012
Abstract / Summary

Greenland ice-core δ18O-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 °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 δ18O record is likely an artifact of an altered temperature-δ18O 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.

URLhttp://www.pnas.org/content/109/28/11101.abstract?sid=c295a683-8feb-498c-957f-feae161b9611
DOI10.1073/pnas.1202183109
Journal: Proceedings of the National Academy of Sciences of the United States of America
Year of Publication: 2012
Number: 28
Pages: 11101-11104
Date Published: 07/2012

Greenland ice-core δ18O-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 °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 δ18O record is likely an artifact of an altered temperature-δ18O 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.

DOI: 10.1073/pnas.1202183109
Citation:
2012.  "Younger Dryas Cooling and the Greenland Climate Response to CO2."  Proceedings of the National Academy of Sciences of the United States of America 11101-11104.  https://doi.org/10.1073/pnas.1202183109.