HR: 09:00h
AN: A21H-04    [Abstracts]
TI: Aerosol Optical Depth, Climate Sensitivity and Global Warming
AU: * Chylek, P
EM: chylek@lanl.gov
AF: Los Alamos National Laboratory, Space and Remote Sensing, Los Alamos, NM 87545, United States
AU: Lohmann, U
EM: ulrike.lohmann@env.ethz.ch
AF: ETH Zurich, Institute for Atmospheric and Climate Science, Zurich, 8092, Switzerland
AU: Dubey, M
EM: dubey@lanl.gov
AF: Los Alamos National Laboratory, Earth and Environmental Sciences, Los Alamos, NM 87545, United States
AU: Mishchenko, M
EM: mmishchenko@giss.nasa.gov
AF: NASA, Goddard Institute for Space Studies, New York, NY 10025, United States
AU: Kahn, R
EM: Ralph.Kahn@jpl.nasa.gov
AF: California Institute of Technology, Jet Propulsion Laboratory, Pasadena, CA 91109, United States
AB: Recent satellite and ground-based observations suggest that the global average of the tropospheric aerosol optical depth has been decreasing during at least the last decade. Consequently, the observed global warming is the result of an increasing concentration of carbon dioxide and a decreasing concentration of tropospheric aerosols. The climate sensitivity parameter, which relates the top-of-the-atmosphere radiative forcing to the change of the global surface air temperature, is derived from analyses of satellite observations of the aerosol optical depth, changes in the carbon dioxide concentration, and the increase in the global temperature. Considering the last decade, when both the decreasing aerosol optical depth and the increasing carbon dioxide concentration have been causing warming, we deduce the climate sensitivity to be 0.4 (with uncertainty of 0.1)K/Wm-2. This value corresponds to a warming of about 1.6 (with uncertainty of 0.4) deg C due to doubling the amount of carbon dioxide from its pre-industrial level. The deduced value is close to the lower end of the IPCC 4AR assessment of 2 to 4.5 deg C (with 66% probability). It is also in agreement with the recent results (0.44 and 0.41 K/Wm-2) of experiments with cloud resolving models embedded within GCMs.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1626 Global climate models (3337, 4928)
DE: 1640 Remote sensing (1855)
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3360 Remote sensing
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting