The Impact of Land-use Change on the Global and Regional Climate


Principal Investigator

A. J. Pitman

Physical Geography

Macquarie University



Mei Zhao

Physical Geography

Macquarie University



g96 - VPP and PC

We have been exploring the hypothesis that "Land-
use change has an impact on the global and
regional climate that is at least as large as hypothesized for a doubling of anthropogenic greenhouse gases". This is part of an International Geosphere-Biosphere Project (IGBP) core project. To explore this hypothesis, we have performed four 17 year simulations with the CCM3 coupled to a mixed layer model. We are only part way through the experiments and have only conducted the land use change experiments and hope to do the greenhouse experiments later in 1999.


What are the results to date and the future of this work?

Results to date indicate that the change in land use of the order that has been observed over the last century has had a global impact on the Earth's climate. Elements of the general circulation of the climate have changed, particularly in the mid- to high-latitudes of the northern hemisphere. We think this is related to a snow-albedo feedback but we need to explore this analysis further.

The changes in climate we simulated have been assessed statistically using t-tests and F-tests and, at least regionally, the results are statistically significant at the 90% level. While the overall, global, effects are not that large, regionally they are important. While we have not done the parallel simulations with increasing greenhouse gases yet, we expect that some of the regional land use changes will be of a similar magnitude to changes induced by increasing greenhouse gases.

What computational techniques are used?

We are basically just running the climate model CCM3 which was originally developed at the National Center for Atmopsheric Research in Colorado. We are using this model coupled to a mixed layer model. We would prefer to be using a fully coupled ocean model but this is too expensive computationally.


Pitman, A.J., Zhao, M. and Desborough, C.E., Investigating the sensitivity of a land surface scheme to spatial and temporal leaf area index variability within the Global Soil Wetness Project, J. Meteorological Society of Japan (Special Issue). Accepted.

- Appendix B