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Radiative Forcing and Temperature Response to Changes in Urban Albedos and Associated CO2 OffsetsThe two main forcings that can counteract to some extent the positive forcings from greenhouse gases from pre-industrial times to present-day are the aerosol and related aerosol-cloud forcings, and the radiative response to changes in surface albedo. Here, we quantify the change in radiative forcing and surface temperature that may be obtained by increasing the albedos of roofs and pavements in urban areas in temperate and tropical regions of the globe. Using the catchment land surface model (the land model coupled to the GEOS-5 Atmospheric General Circulation Model), we quantify the response of the total outgoing (outgoing shortwave+longwave) radiation to urban albedo changes. Globally, the total outgoing radiation increased by 0.5 W/square m and temperature decreased by -0.008 K for an average 0.003 increase in albedo. For the U.S. the total outgoing total radiation increased by 2.3 W/square meter, and temperature decreased by approximately 0.03 K for an average 0.01 increase in albedo. These values are for the boreal summer (Tune-July-August). Based on these forcings, the expected emitted CO2 offset for a plausible 0.25 and 0.15 increase in albedos of roofs and pavements, respectively, for all global urban areas, was found to be approximately 57 Gt CO2 . A more meaningful evaluation of the impacts of urban albedo increases on climate and the expected CO2 offsets would require simulations which better characterizes urban surfaces and represents the full annual cycle.
Document ID
20090032051
Document Type
Preprint (Draft being sent to journal)
Authors
Menon, Surabi (California Univ. Berkeley, CA, United States)
Akbari, Hashem (California Univ. Berkeley, CA, United States)
Mahanama, Sarith (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Sednev, Igor (California Univ. Berkeley, CA, United States)
Levinson, Ronnen (California Univ. Berkeley, CA, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2009
Subject Category
Meteorology and Climatology
Funding Number(s)
CONTRACT_GRANT: DE-AC02-05CH11231
Distribution Limits
Public
Copyright
Public Use Permitted.

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