There is a very important new paper that highlights the role of land surface processes, including its human management, as an integral component of climate variability and change. The paper is
McAlpine C. A., J. Syktus, R. C. Deo, P. J. Lawrence, H. A. McGowan, I. G. Watterson, S. R. Phinn (2007), Modeling the impact of historical land cover change on Australia’s regional climate, Geophys. Res. Lett., 34, L22711, doi:10.1029/2007GL031524.
The abstract reads
“The Australian landscape has been transformed extensively since European settlement. However, the potential impact of historical land cover change (LCC) on regional climate has been a secondary consideration in the climate change projections. In this study, we analyzed data from a pair of ensembles (10 members each) for the period 1951–2003 to quantify changes in regional climate by comparing results from pre-European and modern-day land cover characteristics. The results of the sensitivity simulations showed the following: a statistically significant warming of the surface temperature, especially for summer in eastern Australia (0.4–2C) and southwest Western Australia (0.4–0.8C); a statistically significant decrease in summer rainfall in southeast Australia; and increased surface temperature in eastern regions during the 2002/ 2003 El Nino drought event. The simulated magnitude and pattern of change indicates that LCC has potentially been an important contributing factor to the observed changes in regional climate of Australia.”
The conclusions read,
“The findings of our sensitivity experiment indicate that replacing the native woody vegetation with crops and grazing in southwest Western Australia and eastern Australia has resulted in significant changes in regional climate, with a shift to warmer and drier conditions, especially in southeast Australia, the nation’s major agricultural region. The simulated changes in Australia’s regional climate suggest that LCC is likely a contributing factor to the observed trends in surface temperature and rainfall at the regional scale. While formal attribution studies are required, the outcomes raise important questions about the impact of LCC on Australia’s regional climate, and highlight a strong feedback effect between LCC and the severity of recent droughts impacting on Australia’s already stressed natural resources and agriculture.”
This a very important paper, and yet another example of an issue concering climate change that was mostly ignored by the IPCC assessment.