World Library  


Add to Book Shelf
Flag as Inappropriate
Email this Book

Clouds and the Faint Young Sun Paradox : Volume 6, Issue 3 (10/06/2010)

By Goldblatt, C.

Click here to view

Book Id: WPLBN0004007068
Format Type: PDF Article :
File Size: Pages 45
Reproduction Date: 2015

Title: Clouds and the Faint Young Sun Paradox : Volume 6, Issue 3 (10/06/2010)  
Author: Goldblatt, C.
Volume: Vol. 6, Issue 3
Language: English
Subject: Science, Climate, Past
Collections: Periodicals: Journal and Magazine Collection (Contemporary), Copernicus GmbH
Historic
Publication Date:
2010
Publisher: Copernicus Gmbh, Göttingen, Germany
Member Page: Copernicus Publications

Citation

APA MLA Chicago

Goldblatt, C., & Zahnle, K. J. (2010). Clouds and the Faint Young Sun Paradox : Volume 6, Issue 3 (10/06/2010). Retrieved from http://www.ebooklibrary.org/


Description
Description: Space Science and Astrobiology Division, NASA Ames Research Center, MS 245-3, Moffett Field, CA 94035, USA. We investigate the role which clouds could play in resolving the Faint Young Sun Paradox (FYSP). Lower solar luminosity in the past means that less energy was absorbed on Earth (a forcing of -50 W m−2 during the late Archean), but geological evidence points to the Earth being at least as warm as it is today, with only very occasional glaciations. We perform radiative calculations on a single global mean atmospheric column. We select a nominal set of three layered, randomly overlapping clouds, which are both consistent with observed cloud climatologies and reproduce the observed global mean energy budget of Earth. By varying the fraction, thickness, height and particle size of these clouds we conduct a wide exploration of how changed clouds could affect climate, thus constraining how clouds could contribute to resolving the FYSP. Low clouds reflect sunlight but have little greenhouse effect. Removing them entirely gives a forcing of +25 W m−2 whilst more modest reduction in their efficacy gives a forcing of +10 to +15 W m−2. For high clouds, the greenhouse effect dominates. It is possible to generate +50 W m−2 forcing from enhancing these, but this requires making them 3.5 times thicker and 14 K colder than the standard high cloud in our nominal set and expanding their coverage to 100% of the sky. Such changes are not credible. More plausible changes would generate no more that +15 W m−2 forcing. Thus neither fewer low clouds nor more high clouds can provide enough forcing to resolve the FYSP. Decreased surface albedo can contribute no more than +5 W m−2 forcing. Some models which have been applied to the FYSP do not include clouds at all. These overestimate the forcing due to increased CO2 by 20 to 25% when pCO2 is 0.01 to 0.1 bar.

Summary
Clouds and the Faint Young Sun Paradox

Excerpt
Anderson, G. P., Clough, S. A., Kneizys, F. X., Chetwynd, J. H., and Shettle, E. P.: AFGL atmospheric constituent profiles (0–120 km), Environmental Research Papers 954, Air Force Geophysical Laboratory, Hanscom AFB, MA, 1986.; Bendtsen, J. and Bjerrum, J.: Vulnerability of climate on {E}arth to sudden changes in insolation, Geophys. Res. Lett., 29, 1706, doi:10.1029/2002GL014829, 2002.; Bergman, N. M., Lenton, T. M., and Watson, A. J.: COPSE: a new model of biogeochemical cycling over the {P}hanerozoic, Am. J. Sci., 304, 397–437, 2004.; Bréon, F.-M., Tanré, D., and Generoso, S.: Aerosol effect on cloud droplet size monitored from satellite, Science, 295, 834–838, 2002.; Caldeira, K. and Kasting, J. F.: The life span of the biosphere revisited, Nature, 360, 721–723, 1992a.; Caldeira, K. and Kasting, J. F.: Susceptibility of the {E}arly earth to irreversible glaciation caused by carbon-dioxide clouds, Nature, 359, 226–228, 1992b.; Chambers, L., Lin, B., and Young, D.: Examination of new CERES data for evidence of tropical Iris feedback, J. Climate, 15, 3719–3726, 2002.; Charlson, R., Lovelock, J. E., Andreae, M., and Warren, S.: Oceanic phytoplankton, atmospheric sulphur, cloud albedo and climate, Nature, 326, 655–661, doi:10.1038/326655A0, 1987.; Christidis, N., Hurley, M. D., Pinnock, S., Shine, K. P., and Wallington, T. J.: Radiative forcing of climate change by CFC-11 and possible CFC replacements, J. Geophys. Res., 102, 19597–19609, 1997.; Clough, S. A., Shephard, M. W., Mlawer, E. J., Delamere, J. S., Iacono, M. J., Cady-Pereira, K., Boukabara, S., and Brown, P. D.: Atmospheric radiative transfer modeling: a summary of the AER codes, J. Quant. Spectrosc. Ra., 91, 233–244, 2005.; Collins, W. D., Ramaswamy, V., Schwarzkopf, M. D., Sun, Y., Portmann, R. W., Fu, Q., Casanova, S. E. B., Dufresne, J.-L., Fillmore, D. W., Forster, P. M. D., Galin, V. Y., Gohar, L. K., Ingram, W. J., Kratz, D. P., Lefebvre, M.-P., Li, J., Marquet, P., Oinas, V., Tsushima, Y., Uchiyama, T., and Zhong, W. Y.: Radiative forcing by well-mixed greenhouse gases: Estimates from climate models in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4), J. Geophys. Res., 111, D14317, doi:10.1029/2005JD006713, 2006.; Curry, J. A. and Webster, P. J.: Thermodynamics of the Atmospheres and Ocean, Academic Press, London, 471 pp., 1999.; Forster, P., Ramaswamy, V., Artaxo, P., Berntsen, T., Betts, R., Fahey, D., Haywood, J., Lean, J., Lowe, D., Myhre, G., Nganga, J., Prinn, R., Raga, G., Schulz, M., and Van Dorland, R.: Changes in atmospheric constituents and in radiative forcing, in: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K., Tigno

 

Click To View

Additional Books


  • Coupled Climate Model Simulation of Holo... (by )
  • Consistency of the Multi-model Cmip5/Pmi... (by )
  • Variability of Sulfate Signal in Ice-cor... (by )
  • A 70-yr Record of Oxygen-18 Variability ... (by )
  • A Two Thousand Year Annual Record of Sno... (by )
  • On the Origin of Multi-decadal to Centen... (by )
  • Multiproxy Reconstruction for Kuroshio R... (by )
  • Proxy Benchmarks for Intercomparison of ... (by )
  • High Resolution Measurements of Carbon M... (by )
  • Corrigendum to Impact of Co2 and Climate... (by )
  • The Magnesium Isotope Record of Cave Car... (by )
  • The Faint Young Sun Problem Revisited wi... (by )
Scroll Left
Scroll Right

 



Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.