Papers continue to appear which document that the role of humans on the climate system is much more than that from the emissions of CO2. One new paper [h/t Marc Morano] is
Chakrabarty, R. K., M. A. Garro, E. M. Wilcox, and H. Moosmüller (2012), Strong radiative heating due to wintertime black carbon aerosols in the Brahmaputra River Valley, Geophys. Res. Lett., 39, L09804, doi:10.1029/2012GL051148.
The abstract reads [highlight added]
The Brahmaputra River Valley (BRV) of Southeast Asia recently has been experiencing extreme regional climate change. A week-long study using a micro-Aethalometer was conducted during January–February 2011 to measure black carbon (BC) aerosol mass concentrations in Guwahati (India), the largest city in the BRV region. Daily median values of BC mass concentration were 9–41 μgm−3, with maxima over 50 μgm−3 during evenings and early mornings. Median BC concentrations were higher than in mega cities of India and China, and significantly higher than in urban locations of Europe and USA. The corresponding mean cloud-free aerosol radiative forcing is −63.4 Wm−2 at the surface and +11.1 Wm−2 at the top of the atmosphere with the difference giving the net atmospheric BC solar absorption, which translates to a lower atmospheric heating rate of ∼2 K/d. Potential regional climatic impacts associated with large surface cooling and high lower-atmospheric heating are discussed.
In the conclusion the authors also write that
The shortwave atmospheric absorption translates to a clear-sky lower atmospheric heating rate of ~2 K/d. This large surface cooling accompanied with significant atmospheric heating could qualitatively explain the regional climate change in the BRV region. Such a situation could intensify low-level inversion, which slows down convection and in turn inhibits cloud formation. Additionally, indirect effects associated with BC aerosols such as the cloud ‘burn off ’ effect [Ackerman et al. 2000] could affect the normal precipitation pattern over this region.
This study adds to the aerosol and land use effects on climate in India that we have docummented in our papers led by Dev Niyogi of Purdue University:
Roy, S.S., R. Mahmood, D. Niyogi, M. Lei, S.A. Foster, K.G. Hubbard, E. Douglas, and R.A. Pielke Sr., 2007: Impacts of the agricultural Green Revolution – induced land use changes on air temperatures in India. J. Geophys. Res. – Special Issue, 112, D21108, doi:10.1029/2007JD008834.
Pielke Sr., R.A., D. Dutta S. Niyogi, T.N. Chase, and J.L. Eastman, 2003: A new perspective on climate change and variability: A focus on India. Proc. Indian Natn. Sci. Acad., 69, No. 5, 585-602.
Douglas, E.M., D. Niyogi, S. Frolking, J.B. Yeluripati, R. A. Pielke Sr., N. Niyogi, C.J. Vörösmarty, and U.C. Mohanty, 2006: Changes in moisture and energy fluxes due to agricultural land use and irrigation in the Indian Monsoon Belt. Geophys. Res. Letts, 33, doi:10.1029/2006GL026550.
Niyogi, D., H.-I. Chang, F. Chen, L. Gu, A. Kumar, S. Menon, and R.A. Pielke Sr., 2007: Potential impacts of aerosol-land-atmosphere interactions on the Indian monsoonal rainfall characteristics. Natural Hazards, Special Issue on Monsoons, Invited Contribution, DOI 10.1007/s11069-006-9085-y.
Douglas, E., A. Beltrán-Przekurat, D. Niyogi, R.A. Pielke, Sr., and C. J. Vörösmarty, 2009: The impact of agricultural intensification and irrigation on land-atmosphere interactions and Indian monsoon precipitation – A mesoscale modeling perspective. Global Planetary Change, 67, 117–128, doi:10.1016/j.gloplacha.2008.12.007
Lei, M., D. Niyogi, C. Kishtawal, R. Pielke Sr., A. Beltrán-Przekurat, T. Nobis, and S. Vaidya, 2008: Effect of explicit urban land surface representation on the simulation of the 26 July 2005 heavy rain event over Mumbai, India. Atmos. Chem. Phys. Discussions, 8, 8773–8816.
Kishtawal, C.M., D. Niyogi, M. Tewari, R.A. Pielke Sr., and J. Marshall Shepherd, 2009: Urbanization signature in the observed heavy rainfall climatology over India. Int. J. Climatol., 10.1002/joc.2044.
It should be clear to everyone that the human input of CO2 into the atmosphere is only one of climate forcings, and, for at least some regions, is not the dominate one.