There is an important, well written new paper that documents the role of land-cover on synoptic weather features; in this case cold fronts. The paper is
J. Kala, T. J. Lyons, and U. S. Nair, 2010: Numerical Simulations of the Impacts of Land-Cover Change on Cold Fronts in South-West Western Australia. Boundary-Layer Meteorol DOI 10.1007/s10546-010-9547-3
The abstract reads
“The south-west of Western Australia has experienced significant land-cover change as well as a decline in rainfall. Given that most precipitation in the region results from frontal passages, the impact of land-cover change on the dynamics of cold fronts is explored using the Regional Atmospheric Modeling System version 6.0. Frontal simulations are evaluated against high resolution atmospheric soundings, station observations, and gridded rainfall analyses and shown to reproduce the qualitative features of cold fronts. Land-cover change results in a decrease in total frontal precipitation through a decrease in boundary-layer turbulent kinetic energy and vertically integrated moisture convergence, and an increase in wind speed within the lower boundary layer. Such processes contribute to reduced convective rainfall under current vegetation cover.”
The conclusion has the text at the end
“Sensitivity tests are carried out to investigate effects of historical land-cover change and it is found that land-cover change results in a decrease in precipitation for both fronts, with a higher decrease for the summer front. The decrease in precipitation is attributed to a decrease in TKE [turbulent kinetic energy] and moisture flux convergence as well as an increase in wind speed within the lower boundary layer. The suggested mechanism is that the enhanced vertical mixing under pre- European vegetation cover, with the decrease in wind speeds close to the ground, enhances microphysical processes leading to increased convective precipitation. The higher decrease in precipitation for the summer front is most likely due to enhanced convection during summer.
Whilst this study was limited to two events, it highlights a significant change in microphysical processes caused by land-cover change. Even without large-scale shifts in the climate, local land-use practices affect atmospheric processes and need to be adequately managed under a changing climate.”
This is another research study with recommendations regarding the diversity of human climate forcings beyond CO2 which the next IPCC assessment must include, if it is going to be a credible evaluation of climate science.