I discussed this excellent paper
A. J. Pitman, F. B. Avila, G. Abramowitz, Y. P.Wang, S. J. Phipps and N. de Noblet-Ducoudré, 2011: Importance of background climate in determining impact of land-cover change on regional climate. Nature Climate Change.: 20 November 2011 | DOI: 10.1038/NCLIMATE1294
in my post
Erik has alerted me to a new related paper
Avila, F. B., A. J. Pitman, M. G. Donat, L. V. Alexander, and G. Abramowitz (2012), Climate model simulated changes in temperature extremes due to land cover change, J. Geophys. Res., 117, D04108, doi:10.1029/2011JD016382
with the abstract [highlight added]
A climate model, coupled to a sophisticated land surface scheme, is used to explore the impact of land use induced land cover change (LULCC) on climate extremes indices recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI). The impact from LULCC is contrasted with the impact of doubling atmospheric carbon dioxide (CO2). Many of the extremes indices related to temperature are affected by LULCC and the resulting changes are locally and field significant. Some indices are systematically affected by LULCC in the same direction as increasing CO2 while for others LULCC opposes the impact of increasing CO2. We suggest that assumptions that anthropogenically induced changes in temperature extremes can be approximated just by increasing greenhouse gases are flawed, as LULCC may regionally mask or amplify the impact of increasing CO2 on climate extremes. In some regions, the scale of the LULCC forcing is of a magnitude similar to the impact of CO2 alone. We conclude that our results complicate detection and attribution studies, but also offer a way forward to a clearer and an even more robust attribution of the impact of increasing CO2 at regional scales.
Excerpts from the paper are
“….we have been examining the impact of LULCC on the ETCCDI temperature indices at large spatial scales. LULCC has a strong and statistically significant impact at the climate model grid-scale on many of the ETCCDI temperature indices at these scales. And even where the impact of LULCC seems small compared to increasing CO2, in some regions it adds to the impact of elevated CO2 and in some regions it counters this impact. There are also regions that appear to show quite large impacts due to LULCC despite the perturbation in LULCC being locally small.”
“We also note that we have focused on the impacts of one major type of LULCC and omitted urbanization, irrigation and other types of land use change that could strongly affect regional climate [Pielke et al., 2011].”
“Our results demonstrate that the impact on the ETCCDI indices of doubling CO2 is almost always much more geographically extensive and mostly of a larger magnitude than the impact of LULCC. However, many of the temperature indices show locally strong and statistically significant responses to LULCC, such that commonly 30– 50% of the continental surfaces of the tropics and northern and southern hemispheres are changed by LULCC. The scale of the impact is large enough to be field significant on seasonal timescales.”
The role of land use-land cover change on climate is finally getting the attention it deserves. I look forward to the next research study from this group.