From the Roger Pielke Sr. has been saying this for years department comes this paper where Dr. Richard Betts of the UK Met Office is a co-author. h/t/ to Betts Twitter feed today. It is published in Climate Dynamics. Unfortunately, it has a $40 price tag, since it is part of Springer publications, so I can’t offer much more than the abstract. It does look interesting though, even though it is not observationally based, but model based. However, despite that limitation, when the climate modelers start looking at things other than CO2, that can only be a good thing.

Other efforts include this database from the Université de Lausanne that shows just how much has changed over the last nearly three millenniums: (1000BC to 1850 AD)

Clearly, it is a global scale forcing when viewed at this scale.

The money quote from the new paper is this:

Our results suggest that land-use changes over the past century may represent a more important driver of historical climate change then [sic] previously recognised and an underappreciated source of uncertainty in global forcings and temperature trends over the historical period.

Effective radiative forcing from historical land use change

Timothy Andrews, Richard A. Betts, Ben B. B. Booth, Chris D. Jones, Gareth S. Jones

The effective radiative forcing (ERF) from the biogeophysical effects of historical land use change is quantified using the atmospheric component of the Met Office Hadley Centre Earth System model HadGEM2-ES. The global ERF at 2005 relative to 1860 (1700) is −0.4 (−0.5) Wm−2, making it the fourth most important anthropogenic driver of climate change over the historical period (1860–2005) in this model and larger than most other published values. The land use ERF is found to be dominated by increases in the land surface albedo, particularly in North America and Eurasia, and occurs most strongly in the northern hemisphere winter and spring when the effect of unmasking underlying snow, as well as increasing the amount of snow, is at its largest. Increased bare soil fraction enhances the seasonal cycle of atmospheric dust and further enhances the ERF. Clouds are shown to substantially mask the radiative effect of changes in the underlying surface albedo. Coupled atmosphere–ocean simulations forced only with time-varying historical land use change shows substantial global cooling (dT = −0.35 K by 2005) and the climate resistance (ERF/dT = 1.2 Wm−2 K−1) is consistent with the response of the model to increases in CO 2 alone. The regional variation in land surface temperature change, in both fixed-SST and coupled atmosphere–ocean simulations, is found to be well correlated with the spatial pattern of the forced change in surface albedo. The forcing-response concept is found to work well for historical land use forcing—at least in our model and when the forcing is quantified by ERF. Our results suggest that land-use changes over the past century may represent a more important driver of historical climate change then previously recognised and an underappreciated source of uncertainty in global forcings and temperature trends over the historical period.

Andrews, T., Betts, R.A., Booth, B.B.B. et al. Clim Dyn (2016). doi:10.1007/s00382-016-3280-7

Note: At the suggestion of Dr. Roger Pielke Sr. The title was updated to say “the global climate heat budget” instead of just “global warming”.

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