There is another new paper that provides additional confirmation of our conclusions in
Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell, W. Rossow, J. Schaake, J. Smith, S. Sorooshian, and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413. Copyright (2009) American Geophysical Union
where we report that the only scientific hypothesis that cannot be rejected is that
“In addition to greenhouse gas emissions, other first- order human climate forcings are important to understanding the future behavior of Earth’s climate. These forcings are spatially heterogeneous and include the effect of aerosols on clouds and associated precipitation [e.g., Rosenfeld et al., 2008], the influence of aerosol deposition (e.g., black carbon (soot) [Flanner et al. 2007] and reactive nitrogen [Galloway et al., 2004]), and the role of changes in land use/land cover [e.g., Takata et al., 2009]. Among their effects is their role in altering atmospheric and ocean circulation features away from what they would be in the natural climate system [NRC, 2005]. As with CO2, the lengths of time that they affect the climate are estimated to be on multidecadal time scales and longer.”
The new paper is
Li Q and Y. Xue, 2010: Simulated impacts of land cover change on summer climate in Tibetan Plateau. Environ. Res. Lett. 5, 015102. doi: 10.1088/1748-9326/5/1/015102
“The Tibetan Plateau (TP) is a key region of land–atmosphere interactions with severe eco-environment degradation. This study uses an atmospheric general circulation model, NCEP GCM/SSiB, to present the major TP summer climate features for six selected ENSO years and preliminarily assess the possible impact of land cover change on the summer circulation over the TP. Compared to Reanalysis II data, the GCM using satellite derived vegetation properties generally reproduces the main 6-year-mean TP summer circulation features despite some discrepancies in intensity and geographic locations of some climate features. Two existing vegetation maps with very different land cover conditions over the TP, one with bare ground and one with vegetation cover, derived from satellite derived data, are tested and produce clearer climate signals due to land cover change.’
“It shows that land cover change from vegetated land to bare ground decreases the radiation absorbed by the surface and results in weaker surface thermal effects, which lead to lower atmospheric temperature, as well as weaker vertical ascending motion, low-layer cyclonic, upper level anticyclonic, and summer monsoon circulation. These changes in circulation cause a decrease in the precipitation in the southeastern TP.”
The paper further extends what has become increasingly obvious; land use/land cover change has a major effect on regional (and global climate). Li and Xue, for example, write
The impact of land cover change (LCC) on the regional and global climate has been extensively investigated by using
the general circulation model (GCM) and regional climate model (RCM) coupled with land surface parameterization schemes (e.g., Xue and Schukla 1993, Pan et al 1999, Suh and Lee 2004). Land degradation in East Asia has significant impact on the local circulation and monsoon system (Xue 1996, Xue et al 2004, Cui et al 2006). For example, Xue et al (2004) found that land degradation could cause delayed monsoon onset.
In any new assessment of the climate system, as has been repeatedly emphasized on my weblog, land use/land cover needs to be considered with the same attention as has been given to other human climate forcings.