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GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L04804, doi:10.1029/2007GL032759, 2008

Aerosol radiative forcing and climate sensitivity deduced from the Last Glacial Maximum to Holocene transition

Petr Chylek

Space and Remote Sensing, Los Alamos National Laboratory, Los Alamos, New Mexico, USA


Ulrike Lohmann

Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland


Abstract

We use the temperature, carbon dioxide, methane, and dust concentration record from the Vostok ice core to deduce the aerosol radiative forcing during the Last Glacial Maximum (LGM) to Holocene transition and the climate sensitivity. A novel feature of our analysis is the use of a cooling period between about 42 KYBP (thousand years before present) and LGM to provide a constraint on the aerosol radiative forcing. We find the change in aerosol radiative forcing during the LGM to Holocene transition to be 3.3 ± 0.8 W/m2 and the climate sensitivity between 0.36 and 0.68 K/Wm−2 with a mean value of 0.49 ± 0.07 K/Wm−2. This suggests a 95% likelihood of warming between 1.3 and 2.3 K due to doubling of atmospheric concentration of CO2. The ECHAM5 model simulation suggests that the aerosol optical depth during the LGM may have been almost twice the current value (increase from 0.17 to 0.32).

Received 21 November 2007; accepted 14 January 2008; published 19 February 2008.

Keywords: climate sensitivity; radiative forcing; Last Glacial Maximum.

Index Terms: 1616 Global Change: Climate variability (1635, 3305, 3309, 4215, 4513); 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801, 4906); 0724 Cryosphere: Ice cores (4932); 9310 Geographic Location: Antarctica (4207); 1626 Global Change: Global climate models (3337, 4928).

Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 2028770 bytes)

Citation: Chylek, P., and U. Lohmann (2008), Aerosol radiative forcing and climate sensitivity deduced from the Last Glacial Maximum to Holocene transition, Geophys. Res. Lett., 35, L04804, doi:10.1029/2007GL032759.